maxcncsam

New Product Notice! Course Curriculum: Maximizing CNC Utilization

Dear CNC Instructor,

I constantly hear technical instructors voice their concerns about the number of students coming to their CNC courses. While numbers vary from one area to another and from semester to semester, you too may be concerned with maintaining a student base that justifies your CNC program. Wouldn’t it be nice if you could find a whole new audience? That’s exactly what this ready-made curriculum will do for you!

This curriculum is aimed at experienced CNC people – people who already know CNC basics (they would never come to your basic CNC courses) – but still want to improve their knowledge of CNC. You’ve probably never seen many of them before. Maybe they’re self-taught. Maybe they’ve received their basic CNC training on-the-job. Maybe they’ve been through machine tool builders’ courses. Or, of course, they may have received their basic training from your school. The number of new potential students for this new course is staggeringly more than the students now coming to your basic courses. You’ll have a whole new audience! You may even have to limit attendance for the first few offerings of this course!

Enclosed is a brochure that describes the new curriculum in detail. We’ve also enclosed a single sheet brochure aimed at potential attendees of this course. (This document is actually included with the curriculum and can be used to help you promote the new course.) Here are just a few highlights.

• All instructor materials are FREE with initial order of student manuals – Just have your bookstore place an initial order for twenty student manuals. 625 page student manual is extremely comprehensive, and reinforces your presentations. Our price to your bookstore is $95.00 each. Our suggested list price is $120.00. In essence, the students in your first class will be acquiring the curriculum for you.

• Download FREE samples – From our web site (www.cncci.com), you can download more about how we intend the curriculums to be used, including complete outlines, samples of the slide shows, and a portion of the student manual.

• This curriculum has been developed during the teaching of live courses for over 12 years. The comments printed in the brochure reflect these courses.

Thank you for taking the time to view this information. Admittedly, there’s a lot to see. If you have any questions, be sure to contact me (847-639-8847).

Sincerely,

Mike Lynch President CNC Concepts, Inc. P.S. Check out the Schools Forum on our web site (www.cncci.com). Listings are free and allow you to promote your school’s CNC-related courses.

44 Little Cahill Road Cary, IL 60013 Ph: 847-639-8847 Fax: 849-639-8857 Email: [email protected]

Getting Started Page 1

Getting Started With Maximizing CNC Utilization: The need for higher level CNC training CNC people get their CNC training in one of two ways. First, many machine tool builders, colleges, vocational schools, technical schools, and universities offer courses that teach basic CNC usage. In these courses, students learn how to program, setup, and run CNC machine tools. Since almost all students are at entry level (at least when it comes to CNC), instructors must keep presentations quite elementary. A student may just begin to grasp an important topic when it’s time to move on to the next. The student isn’t ready for discussions that may take what they just learned to the next level. And of course, safety must be the highest priority. But since safety and efficiency almost always conflict, the methods they learn will not be the most efficient. When the student finishes one of these courses, they’re ready to begin working with CNC machine tools. It is unlikely, however, that they have a complete grasp on how to make the best use of the machines they’ll be working with. While a student coming out of a machine tool builder’s or technical school’s CNC courses may not have a complete grasp of every related function, at least they have had some formal training. Many CNC people are self-taught. Maybe they’ve taken over a position from someone that moved on. They may have learned all they know from someone else in the company (likely another self-taught individual). They’ve probably had to struggle through most problems, eventually learning enough to make the machine do what they want it to. But again, it’s unlikely that they’re making the most of the machines they’re working with. While the sheer productivity of CNC machines often masks inappropriate methods, companies are becoming more and more concerned with their CNC machine tools. Changes in manufacturing including lowered lot sizes, shorter lead times, and improved quality requirements (among other things) have most CNC-using companies struggling to maintain profit margins. They need to improve their methods if they are to remain in business. The most basic objective of this course curriculum is to help instructors relate concepts, techniques, and ideas that will help students make they’re CNC machines more productive. Note that it’s aimed at CNC people who already have some CNC experience, meaning you’ll be drawing from an entirely new potential student base.


The modules of Maximizing CNC Utilization We divide the curriculum into eight modules. Each is self-sufficient, meaning you can pick and choose those modules you wish to include in your course/s. While there is a little overlap, especially among modules three, six, and seven, you can, of course, present all modules in one course. We offer some suggestions about presenting this course a little later. Module one: Basic premises (57 slides, about 1-1.5 hour presentation time) This short, but important, module lays the groundwork for what is to come. Included are presentations that acquaint students with important needs of CNC using companies. We discuss application versus utilization and machine utilization versus personnel utilization to help them understand the reasoning behind improving CNC machine utilization. We also introduce the four CNC-using company types and discuss factors making up a company’s corporate identity. Finally, we discuss the importance of value added principles in the CNC environment. Module two: Review of CNC basics (346 slides, about 6-10 hours presentation time, depending upon the current student level) Since you won’t have control of how much previous experience your students have (not all of them will have attended your school’s basic courses), you’ll want to make sure that they have a good grasp of basic CNC principles before digging in to more advanced topics. Again, many students coming to this course will be (for the most part) self-taught. It’s likely that they’ve missed out on some important basic concepts and techniques. In the advance courses I’ve taught myself, I’m always surprised at how often a so-called expert is unfamiliar with a very basic CNC feature or function. This module allows you to review the basics using our proven key concepts approach. There are ten key concepts (see the instructor’s outline). We begin each key concept by introducing the reasoning behind the key concept. Then we address how the key concept applies to machining centers and then to turning centers. Again, this is a review. Students should be quite familiar with the presentation –and if they are – you’ll be able to buzz through quite quickly (possibly under six hours). But, if they’re questioning each step along the way, it should be taken as a signal that more basic training is needed. SPECIAL SAFETY NOTE: Many of the techniques you’ll be showing later in the course require a firm understanding of basic CNC practices. Misapplication could lead to serious consequences including machine crashes and possible injury. You cannot present more complex topics until students understand the basics. Module three: Advanced implications of basic CNC features (911 slides, about 14-18 hours presentation time, depending upon questions, comments, and extra discussions) Many CNC features have multiple uses. But most basic CNC courses introduce only the most important use. Additionally, most basic courses don’t show all implications related to how a


given feature can be best used to meet the company’s applications. If it’s a basic function, and if it’s not commonly addressed in a basic CNC course, it’s included in this module. Included in this lengthy module (the longest of the course) are presentations on parameters, N words, G codes, M codes, and other CNC words. We also discuss advanced applications for tool offsets, fixture offsets, and wear offsets. Again, see the instructor’s outline to see just how comprehensive this module is. Module four: Advanced CNC features, functions, and concepts (432 slides, about 2-8 hours presentation time, depending upon students’ interests) There are many CNC features that are not addressed in basic courses. Admittedly, many of these features will not be of interest to a given CNC user. However, this module gives you the presentation material you need to discuss features like advanced interpolation types (helical, cylindrical, polar coordinate, and nurbs), scaling, mirror image, coordinate rotation, and three dimensional coordinate conversion. We also include presentations on certain machine accessories like bar feeders, index chucks, U axis, and part catchers. Finally, we provide materials for teaching some important CNC concepts like tool life management, qualifying CNC programs, and appropriate documentation. Again, see the instructor’s outline for more on what’s addressed in this module. Since many of the features in this module will not be of interest to every attendee, it’s difficult to predict how long this discussion will be. Module five: Parametric programming (556 slides, about 4-24 hours presentation time, depending upon the level to which you want to go) We’ve often said that parametric programming is CNC’s best kept secret. There are still many in the industry that don’t know what it is, let alone how to take full advantage of it. These materials allow you to dive into parametric programming as deep as you want to go. We stress Fanuc’s version of parametric programming – custom macro B (the most popular version). Note that many control manufacturers claim to be Fanuc-compatible, and use custom macro B as their version of parametric programming. If you just want to present a cursory view of what it is, (I like to include this presentation even in my basic CNC courses) you’ll just be acquainting students with it’s applications and basic features. This can be done quite quickly (under 4 hours). But if you want to present a full course, these materials still allow you to do so. With limited time for practice (a workbook and answer book is included with the instructor materials), this full course can be completed in about 16 hours. If you want to allow time (during class) for students to do the exercises, allow about 24 hours. Module six: Setup time reduction (295 slides, about 7-9 hours presentation time, depending upon students’ questions, comments, and discussions) This is a very hot topic. All CNC using companies are concerned with how long their machines are down between production runs. This module lets you first present the principles of setup time reduction (that can be applied to any form of production equipment). We then offer specific CNC-related techniques to improving setup time in the approximate order setups are


made (tear down, work holding setup, cutting tools, program zero assignment, program loading, program verification, and first workpiece inspection). Module seven: Cycle time reduction (411 slides, about 7-9 hours presentation time, depending upon students’ questions, comments, and discussions) This is also a hot topic. All CNC using companies are concerned with how long it takes to complete their production runs. As with setup time reduction, this module lets you first present the principles of cycle time reduction. We then offer specific techniques to reducing cycle time in four areas, workpiece load/unload, program execution time, tool maintenance, and preventive maintenance. Module eight: Spindle probe programming (519 slides, about 4-16 hours presentation time, depending upon the level you wish to go) Actually, the student manual includes discussions on several types of probes (spindle probes, tool touch-off probes, and tool length measuring probes). However, the slide presentation is limited to spindle probes. Admittedly, most spindle probe uses depend solely on the probing programs supplied by the probe manufacturer. Only a small percentage of probe-using companies develop their own probing programs. For this reason, most students may not be very interested in learning how probes are programmed. You may elect to simply introduce the basics (under 4 hours of presentation time). But if you do need to teach a full course on spindle probe programming, these materials let you do so. Presentations include introduction to probe programming, applications for probing, how the probe works, calibration techniques, and writing spindle probe programs.


Presentation alternatives As you can see, the Maximizing CNC Utilization curriculum is very comprehensive! Including over 3,000 slides and a 625 page student manual, you’ll have plenty to do. Here are a few suggestions for how you can use the curriculum. The whole course As you can see from our approximate presentation times, there is quite a variation based upon student level, question, comments, extra discussions, and even how deeply you wish to dig into the course content for certain topics. When you total the “worst case” presentation times shown earlier, you’re looking at 86.5 hours of presentation time. If you’re teaching in a seminar environment (consecutive full days), it’s over ten days of presentation time. If you’re teaching an evening course two nights a week at three hours per session, it will require about 14 weeks. Either way, this may be an excessive amount of time for you, your school, and your students. The CNC tune-up One of the benefits of this curriculum is that each module will stand on it’s own. You can easily pick and choose those modules that are appropriate for your needs. Here is one popular way that will allow you to relate a great deal of information, yet minimizes the time required: Module one: Basic premises (1.5 hours) Module two: Review of basics (4 hours) Module three: Advanced implications of basic features (10 hours) Module four: Advanced CNC features, functions, and concepts (4 hours, just touching on items of interest to everyone) Module five: Parametric programming (12 hours, limiting time for practice in class) Module six: Setup time reduction (7 hours) Module seven: Cycle time reduction (7 hours) Module eight: Probe programming (Skip) With this popular course, there is 45.5 hours of presentation time. If teaching in a seminar environment, it’s under six consecutive days. If teaching a night class two evenings a week for three hours per session, it’s about an 8-week class. We’re simply trying to give you some idea of what each module takes to present. The times given are based upon my own experience in presenting the material. Of course, teaching times will vary dramatically from one instructor to another. Also, these times allow no time for reviewing material. Until you get some experience under your belt, you may want to allow even more time for presentation.


A two-day setup & cycle time reduction course If teaching in a seminar environment, you can easily complete modules one, six, and seven in two days. This should make an attractive course to companies in your area. A two-day or three-day parametric programming course Depending upon how much practice you want your students to do in class (remember – we offer a workbook/answer book at an additional charge), you can easily complete the parametric programming module in two days. A two-day or three-day spindle probe programming course In similar fashion, this curriculum includes everything you need to teach a probe programming course. Note that spindle probes are programmed with parametric programming techniques. You may want to make the parametric programming course a pre-requisite for this course. Or be sure to allow time to explain the parametric programming features required for programming spindle probes. A one-day advanced techniques course Though you may be a little pressed for time, you can include modules one and two for a very intensive session! A one-day setup time reduction course You can easily complete module six in one day. A one-day setup time reduction course You can easily complete module seven in one day. About the student manual Again, the student manual includes all eight modules. For the most part, we recommend that students purchase the entire manual, even if you’re not presenting the entire course. This makes it easy for them to attend several sessions without having to purchase more materials. We do, however, sell three manuals individually: Parametric programming Setup and Cycle time reduction Probe programming Take it on the road! Any of these courses can be taught on an in-plant basis. There are many portable projection systems available. See the various methods to display the slide shows later in this document. The least expensive way (if you don’t have a portable projector) is a laptop computer with TV-out and a television.


Instructor materials This curriculum truly minimizes the preparation you must do to get ready to teach! Here’s what you get. Microsoft PowerPoint slide presentations PowerPoint is becoming the presentation software of choice by most presenters. These presentations total over 3,000 slides to provide your visuals for the entire course. Note that they’re developed in PowerPoint 97 (which is part of Microsoft Office 2000). These presentations are included on a cd and most include audio narrations (you’ll need a multimedia computer having a cd-rom drive to display and hear the presentations). There are nine slide presentations included on the cd-rom. Each is locally named from INTRODUCTION.PPT through MODULE 8_SPINDLE PROBES.PPT. These slide presentations can be accessed right from the cd-rom or if your hard drive has room, you can copy them to your computer’s hard drive (there’s over 300 megs of data). Each slide includes a visual (in the form of a book) that lets students know the page number in the student manual that is currently being discussed. Guidance during slide shows Each slide show includes audio narrations (we call guidance) to help you understand how to make your presentations. Note that these narrations are not intended for your students. Each is directed at the instructor getting ready to teach the course. A special icon on selected slides can be activated to play the related narration. Microsoft PowerPoint Viewer Though we highly recommend that you have the actual PowerPoint software, we do include the PowerPoint Viewer. It does allow you to display the slide shows, but you’ll have no way to modify them. Additionally, the slide shows are quite long (most over 300 slides). PowerPoint Viewer does not allow you to move around in the slide show nearly as easily as the actual PowerPoint software. Instructor’s outline This outline serves two purposes. First, it lets you know exactly what is presented in each slide module. You’ll be able to quickly see what’s included. Second, it shows the slide number for each topic, making it easy to find slides as you move around in each slide show. For most topics, it also includes student manual page numbers. Workbook and answer book for Parametric Programming module Since this portion of the course requires practice to master, we provide you with a way of printing exercises and programming activities for students to do during this module. It can be used as homework or done during class. We also provide you with the ability to print the answer book.


Ability to print slide show hard copy PowerPoint allows you to print a hard copy of each slide show (Microsoft calls this printing handouts). This may help you prepare if you don’t have the computer available. You can include 4, 6, or 8 slides per page. Even so, there are over 3,000 slides. Be ready for a lot of printing! Promotional materials We’ve even included a brochure that you can use to help you promote this course. It’s in the “promotions” folder of the cd rom. It’s in PowerPoint format, so you can easily modify anything you want! Note that there is space to include your school’s registration information (logo, phone number, fax number, etc.). Free phone assistance Again, there’s a lot of information in this curriculum. If you have questions about any topic, we welcome your phone calls (847-639-8847). Or email us at [email protected]. Student materials While your presentation is an extremely important part of the learning environment, your students must have reference material. 625 page student manual This extremely comprehensive manual follows along with your presentation step-by-step and again, the slide presentations reference page numbers throughout the course. Though we don’t recommend actually reading from it, the slide presentations will be specifying the page number in this manual that current information is being discussed so students can easily follow along in the book. It will make for excellent homework reading assignments. And, it’s an excellent way for students to review material once the course is finished. Because there is so much information in the book, we recommend that students have some way to remember key pages (a highlighter pen or post-it notes to act as tabs in the book work nicely). Note that the manual includes all eight modules. What you still need In order to show the PowerPoint slide presentations to a group of people, you need the following items. A computer with Windows 98 (or higher) - Just about any current model computer will work. For best results, Pentium class is recommended (minimum 64 megs internal). If using a desktop computer, you can easily watch the monitor of the computer (facing your audience) to see the slide show as slides are displayed behind you by the projection system. Since the left mouse button advances the slides, you even have a remote slide advance button (as is commonly used with a 35 mm slide projector). If portability is an issue, keep in mind that many of the notebooks and sub-notebooks have ample power to run the presentation software. However, be careful in your selection. Many notebooks do not allow you to send data out through the


VGA port and see the slide show on the LCD screen of the notebook at the same time. Without this ability, you may have to turn around to see your slides, which can be distracting to your audience. Also, for maximum flexibility, look for a laptop that has the TV-OUT feature. This lets you send composite video to any television that has a TV-IN port with a simple RCA cable. Microsoft PowerPoint Software (PowerPoint 97 version was used to create the slide show) - Though you can display all presentations with PowerPoint Viewer (included with this curriculum), you will need Microsoft PowerPoint if you intend to modify the slide shows given in this curriculum (and to easily get around and start the slide show from any slide). We highly recommend that you have this ability. This software can be found in any computer store for a price of about $250.00 (it also comes with most editions of Microsoft Office). You will find this to be a very powerful presentation-generating program; one you can use to develop your own slide shows for other courses (or of course, modify those in this course curriculum). A way of displaying the screen show - You have several alternatives in this regard. Most involve using a device that takes data from the VGA port of your personal computer. First, many schools already have a projection system that can display information from a personal computer. Basically, anything that can be shown on the computer screen can be displayed through the projection system. Second, you can use a device that sits on top of an overhead projector to display your screen shows. In essence, this device makes a transparency of what ever is on the display screen of the computer (I don’t like this kind because the light from the overhead is very bright and hurts my eyes). Third, and especially if price is a concern, you can use a simple scan converter (about $200.00 - $300.00) and display your screen show on any television that has a video in connector (as most do). Note that many laptops are now coming with a TV-OUT port, having this scan converter built in to the computer. If you must use the RF connector of the television (where an antenna plugs in), an RF converter must be purchased. Since there are so many alternatives for displaying your slide shows, we welcome phone calls (847) 639-8847 if you have questions about your alternatives. A note about the students you’ll attract In my experience, experienced CNC people have a rather narrow focus. They know a lot about the things they must do every day, but little or nothing about other important CNC-related topics. I’m always amazed by how surprised experienced CNC people are about many relatively basic features they just haven’t been exposed to. For example, a person that does general purpose CNC machining will know little about five axis machining – and vise versa. Be sure to take advantage of your students’ strong points. As you present the course, be sure to solicit questions and comments each step along the way. We encourage student participation quite often during the slide presentations. The more you can get people to contribute during the class, the better the class will be. And you may be able to collect ideas for future classes! Remember that your students for this course will have (possibly extensive) CNC experience. I’ve found that most catch right on to the presentations being made, even for those topics that


they’ve never been exposed to. With the exception of the parametric programming module, you can minimize the tutorial method you’re probably using to teach your basic CNC courses. While reviews are still helpful, they can be minimized. Instead of lengthy reviews at the beginning of each session, I simply poll the class for questions. When students have questions, I’ll dig back in as deep as necessary to make sure they understand. And I will, of course, bring everyone up to speed on where we left off in the last session, but I do minimize review time.


Putting It All Together Getting Ready To Teach As stated earlier, though these course curriculums dramatically reduce the amount of preparation you must do, they do not eliminate it completely. And as any experienced instructor will agree, the key to successful presentations is in becoming comfortable with the material you present. And the only way to get comfortable is through adequate preparation. Before your first course: Skim the entire curriculum (at least those modules included in your current course) - Though you do not have to be perfectly comfortable with every detail of the curriculum to begin teaching, you will at least need to understand where the course is going. You can use the course outline, guidance in the slide shows, and student manual to gain an appreciation for the material being presented. Before beginning each module: Get comfortable will all discussions in the module - While some modules are relatively short, most are lengthy. Be sure you feel comfortable with all points you need to make before you begin teaching. Again, use the course outline and student manual to increase your comfort level with the entire module. Before you deliver a session: Get ready to teach! - Study the lesson plan, guidance, and slide presentation in order to gain an understanding of key points that must be delivered during your presentation. Because modules vary in length, be prepared to review material covered in previous sessions if appropriate. During your presentation of each session: Tell them what you’re going to tell them - The lesson plan (key points in the slide show at the beginning of each module) will help you prepare your students for what they will be learning. While you don’t have to dwell on this slide too long, it will help them know what is coming up. Tell them - Go though the session, using your slide show as a guide. Be sure to point out the page numbers and sections in the student manual where the information is also included for their own independent study. Be sure everyone is catching on. Encourage participation, questions, and comments. In fact, some of the best suggestions for future additions to your class will come from students. You’ll be getting some pretty high level attendees, so take advantage of this opportunity. Have a blackboard or overhead available for making special points. Tell them what you told them - The lesson summary (included in the slide show for each module) will let you summarize the key points of each lesson.


As you get deeper into the course: Review often - No student will retain every word of every presentation you make during a course as lengthy as these. On average, you should spend about 10% to 20% of your session time in review, depending upon how well your students are doing. The more problems they are having, the more time you should spend on review. Let students know where they stand - Be sure everyone knows how they are doing as they progress through the course.

IN STRUC TOR TIME OUT LINE FOR MAX I MIZING CNC UTILIZATION

Mod ule one: Ba sic Prem ises 1-1Time for pre sent ing mod ule one: 1-1.5 hoursSlide: De scrip tion:2 Les son plan3 De cep tive ness of ma chine pro duc tiv ity8 Uti li za tion ver sus ap pli ca tion11 Ma chine uti li za tion vs personell utilization19 Com pany di ver sity22 Com pany types23 Fac tors con trib ut ing to com pany pro file37 Con flict in volv ing cor po rate iden tity 43 Def i ni tion of CNC en vi ron ment46 Value added prin ci ples in man u fac tur ing53 Com pla cency in the CNC en vi ron ment46 Re view of ba sic themes

Mod ule two: Re view of CNC Ba sics 2-1Slide: De scrip tion:2 How did you get your train ing?6 The key con cepts ap proach 2-19 Key con cept num ber one - Know your ma -

chine from a pro gram mer’s view point 2-210 The im por tance of ba sic ma chin ing prac tice

2-211 Ma chining cen ter con fig u ra tions 2-339 Ma chining cen ter pro gram ma ble func tions

2-440 Turn ing cen ter con fig u ra tions 2-549 Turn ing cen ter pro gram ma ble func tions 2-750 More on spin dle speed and feedrate con trol

2-952 Un der stand ing pro gram zero 2-10164 Ab so lute ver sus in cre men tal mo tions 2-10165 De ter mining pro gram zero as sign ment val -

ues 2-11181 The two ways to as sign pro gram zero 2-11184 Key con cept num ber two - You must pre -

pare to write pro grams 2-13193 Pre pare the ma chin ing pro cess 2-15198 Doing the math 2-17202 Check the re quired tool ing 2-17205 Plan the work hold ing set-up 2-18208 Key con cept num ber three - You must un -

der stand the three most ba sic mo tion types2-20

209 -Mo tion com mon al i ties 2-20210 G00 Rapid mo tion (also called po si tion ing)

2-20211 G01 lin ear in ter po la tion (straight line mo tion)

2-21

212 G02 and G03 cir cu lar mo tion com mands2-22

213 Ma chining cen ter ex am ple284 Turn ing cen ter ex am ple301 Key con cept num ber four - You must un der -

stand the com pen sa tion types 2-25305 Tool length com pen sa tion 2-26308 Cut ter ra dius com pen sa tion 2-28309 Fix ture off sets 2-31310 Wear off sets 2-35311 Tool nose ra dius com pen sa tion 2-40312 Ge om e try off sets 2-44313 Key con cept num ber five - Pro grams must

be struc tured with a strict for mat 2-47314 Rea sons for pro gram for mat ting 2-47315 How to use the for mats 2-48316 Pro gram Start-Up For mat: 2-49317 Tool End ing For mat: 2-49318 Tool Start-Up For mat: 2-49319 Pro gram End ing For mat: 2-49320 Turning cen ter us ing ge om e try off sets to as -

sign pro gram zero 2-50321 Tool end ing for mat 2-50322 Tool start-up for mat 2-50323 Pro gram end ing for mat 2-50324 Key con cept num ber six - Spe cial pro gram -

ming fea tures 2-50326 Les son three - Re view of setup & op er a tion

ba sics 2-62328 Key con cept num ber seven - Know your ma -

chine from an op er a tor’s view point 2-62329 Setup tasks ver sus pro duc tion main tain ing

tasks 2-62330 Tasks re lated to set ting up 2-62331 Tasks re lated to main tain ing pro duc tion 2-66332 The two op er a tion pan els 2-68333 The con trol panel 2-68335 The ma chine panel 2-70336 Key con cept num ber eight - The three

modes of op er a tion 2-72338 The man ual mode 2-72339 The man ual data in put mode 2-72340 The man ual data in put po si tion of the mode

switch 2-73341 Key con cept num ber nine - Know the most

im por tant op er a tion pro ce dures 2-74342 The most im por tant pro ce dures 2-75343 Key con cept num ber ten - Safely ver i fy ing

pro grams 2-75

CNC Concepts, Inc. Machining Center Programming and Operation Page 1

Mod ule three: Ad vanced im pli ca tions of ba sic fea turesSlide: De scrip tion:2 Pre sen ta tion plan4 Un der stand ing pa ram e ters 3-17 Di ver sity of pa ram e ters11 Eight bit bi nary type 3-219 Whole num ber type 3-222 Im por tance of back ing up pa ram e ters 3-225 Doc u menting in the pro gram 3-328 Pro gram head ers 3-332 Tool in for ma tion 3-436 At ev ery pro gram stop 3-637 Sim ple setup in struc tions 3-638 De scribing changes made af ter a dis pute

3-739 Doc u menting some thing out of the or di nary

3-740 Getting mes sages into pro grams for con trols

that do not dis play mes sages 3-843 Block de lete tech niques (also called op tional

block skip) 3-947 Using block de lete mid-command 3-951 Con flicting words in a com mand 3-1056 Trial ma chin ing 3-1158 Trial bor ing on a ma chin ing cen ter 3-1182 Trial turn ing on a turn ing cen ter 3-1396 Elim i nating tool pres sure when fin ish ing on

turn ing cen ters 3-1498 Con clu sion to trial ma chin ing with block de -

lete 3-17100 Using block de lete with un ex pected rough

stock 3-17103 An other op tional stop 3-19106 Spe cial note about mul ti ple ap pli ca tions

3-20109 Se quence num ber tech niques 3-20112 Elim i nating with lim ited mem ory ca pac ity

3-20115 Using for re start blocks 3-20119 Se quence num bers as state ment la bels

3-22124 Looping with block de lete 3-22125 Changing ma chin ing or der 3-23131 G code com mon al i ties 3-26134 Max i mum num ber of G codes per com mand

3-26137 How to monitor 3-27140 Un der stand ing G code groups 3-27143 Ini tial ized G codes146 Safety blocks151 G00 & G01 rapid and straight line mo tion for

po si tion ing (not cut ting) 3-28151 What is your max i mum feedrate? 3-28

160 Which is faster, G00 or G01? 3-28171 Using G01 for fast feed ap proach 3-31177 G01 - Straight line cut ting mo tion (also

called lin ear in ter po la tion) 3-32180 Ef fi ciency of ba sic mo tion types 3-32183 Min i mizing cor ner round ing 3-33191 G03 & G03 - cir cu lar mo tion com mands

3-33194 Which way is clock wise? 3-33200 Lim i ta tion of the R word 3-34206 Di rec tional vec tors 3-34209 Arc lim i ta tions 3-34213 Full cir cle in one com mand 3-35216 Arc in and out tech niques 3-35231 G04 - Dwell tech niques 3-36234 Can you spec ify the dwell pe riod in num ber

of spin dle rev o lu tions? 3-36237 Re lieving tool pres sure 3-36246 Are you dwell ing to over come ma chine prob -

lems? 3-37249 Poorly in ter faced M codes 3-37259 G09 - one-shot ex act stop check com mand

3-38265 G10 - data set ting by pro grammed com -

mand 3-38268 How G10 works 3-39286 En tering tool length and cut ter ra dius com -

pen sa tion val ues for ma chin ing cen ters 3-39321 Can you read off set val ues?324 Set ting pa ram e ters from within the pro gram332 G17, G18, & G19 - plane se lec tion com -

mands 3-44335 Plane se lec tion with right an gle heads 3-45341 Cir cu lar com mands 3-46344 Plane se lec tion on turn ing cen ters 3-50348 G20 & G21 - Inch and met ric se lec tion 3-50351 How to se lect the inch or met ric mode 3-51354 How to tell which mode you’re in367 Ad van tages of the met ric mode377 G32 - thread cut ting com mand 3-57380 Com par i son to G01383 Using G32 for tap ping 3-58386 G40, G41, & G42 - cut ter ra dius com pen sa -

tion for ma chin ing cen ters and tool nose ra -dius com pen sa tion for turn ing cen ters 3-58

389 The two ways to use off sets 3-59436 How cut ter ra dius com pen sa tion works 3-59441 Alarms and pos si ble causes 3-61481 Other lim i ta tions of cut ter ra dius com pen sa -

tion 3-65511 Do you re ally need con trol based tool nose

ra dius com pen sa tion? 3-69516 Ma chining on both sides of but ton tool 3-69

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Page 2 Machining Center Programming and Operation CNC Concepts, Inc.

Mod ule three con tin ued: Sec ond file (labled B)Slide: Description1 Tool length compensation4 Using sec ond ary off sets with tool length

com pen sa tion 3-7110 G50 - Spin dle lim iter for turn ing cen ters 3-7213 Chuck changes 3-7218 Out-of-round workpieces 3-7328 Bar feed ers that can not keep up with the

main spin dle 3-7347 G52 - tem po rary shift of pro gram zero on

ma chin ing cen ters 3-7564 G53 - rapid move ment rel a tive to the ma -

chine’s zero re turn po si tion 3-7767 An other way to send the ma chine to the

zero re turn po si tion 3-7770 Use with man ual pal let chang ers 3-7875 Com mon tur ret in dex po si tion on turn ing

cen ters 3-7879 G54-G59 - fix ture off sets 3-7882 The two ways to use fix ture off sets 3-7892 Shifting the point of ref er ence for pro gram

zero as sign ment value en tries 3-7895 Subplates104 Hor i zon tal ma chin ing cen ters111 Deal ing with align ment prob lems af ter a

crash 3-82115 48 fix ture off set op tion 3-83118 What can a spin dle probe do for you? 3-83121 Run ning out of fix ture off sets? 3-83125 G60 - sin gle di rec tion po si tion ing 3-84131 G61 - ex act stop check mode 3-86132 G64 - nor mal cut ting mode 3-86133 G70 - Turn ing cen ter fin ish ing cy cle 3-86137 Using G70 to re peat com mands 3-86144 G71 & G72 - rough turn ing and fac ing 3-87147 Using G71 or G72 to semi-finish 3-87155 Spin dle range chang ing within G71 3-88162 Re tract amount with G71 and G72 3-89167 G76 - thread ing cy cle 3-89171 Max i mum feedrate when thread ing 3-89174 What is thread chamfering? 3-89186 Threading pa ram e ters189 Taper thread ing182 Mul ti ple start threads 3-91198 Using the E word when thread ing 3-93201 G73-G89 - hole ma chin ing canned cy cles on

ma chin ing cen ters 3-93204 Pa ram e ters re lated to hole ma chin ing

canned cy cles 3-94213 L0 with canned cy cles 3-94216 Canned cy cles in the in cre men tal mode 3-96

219 G90 & G91 - ab so lute and in cre men talmode 3-97

222 Using both in one com mand 3-97226 Other ap pli ca tions for the in cre men tal mode

3-97231 G96 - con stant sur face speed mode for turn -

ing cen ters 3-98236 Elim i nating spin dle dead time when us ing

con stant sur face speed 3-98285 X, Y, Z, A, B, C - axis des ig na tion words

3-101288 Which value do you pro gram?296 Re ducing rapid ap proach dis tance 3-101324 F word tech niques 3-103325 S word tech niques 3-103328 Range se lec tion on ma chin ing cen ters334 T word tech niques for turn ing cen ters 3-104337 Right or left hand tools? 3-104340 Can celing wear off sets with T0 3-105343 Ap pli ca tions for sec ond ary wear off sets

3-106350 T word tech niques for ma chin ing cen ters

3-115353 Must you load tools se quen tially? 3-115354 Ori ent the spin dle on the move ment to the

tool change po si tion 3-115355 M code tech niques 3-115358 Scour your ma chine tool builder’s pro gram -

ming man ual to learn more about the avail -able M codes 3-115

361 Inconsistencies365 M codes you may not agree with368 Do you have some M codes that are not fully

in ter faced? 3-117375 M41 & M42 - spin dle range chang ing on

turn ing cen ters 3-118378 Cor rect way to de ter mine spin dle range384 M98 & M99 - subprogramming com mands

3-119387 Ap pli ca tions for subprogramming 3-119

Mod ule four: Ad vanced CNC fea tures, func tions, andconcepts

Slide Description:2 Mod ule four les son plan7 Spe cial in ter po la tion types 4-19 He li cal in ter po la tion 4-111 Ba sic ter mi nol ogy 4-244 Thread mill ing cut ters 4-349 Your ap proach to thread mill ing 4-452 Pro gramming con sid er ations 4-558 Ex am ple thread mill ing pro gram

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78 Spi ral in ter po la tion for taper thread mill ing4-7

84 Cy lin dri cal in ter po la tion 4-886 Why cy lin dri cal in ter po la tion is requierd87 Pro gramming consideratins113 Nurbs in ter po la tion 4-11115 Po lar co or di nate in ter po la tion 4-11117 Ad di tional fea tures of turn ing cen ters with

live tool ing 4-12121 Pro gramming a ro tary axis 4-14126 Co or di nate sys tem149 Poly gon turn ing 4-20151 Ex tended G codes 4-21153 G15 & G16 - po lar co or di nates for ma chin -

ing cen ters 4-21155 Ba sic use166 How G52 helps169 G50 & G51 - Scaling 4-21171 Words involved174 G50.1 & G51.1 - Mir ror im age com mands

4-22176 Application193 Words involved197 On a turn ing cen ter?202 G68 & G69 - co or di nate ro ta tion for ma chin -

ing cen ters 4-24204 Words involved208 G68 & G69 - Three di men sional co or di nate

con ver sion 4-25213 3d Ma chining 4-25333 Bar feed ers for turn ing cen ters 4-28335 When to bar feed336 A subprogram for barfeeding346 A cus tom macro for bar feed ing350 Im proving the ef fi ciency of bar feed ers on

turn ing cen ters 4-35369 Part catch ers 4-37371 Pro gramming for the U axis on ma chin ing

cen ters 4-37373 De scrip tion and ap pli ca tion377 Con stant sur face speed380 Ex am ple program381 Tool life man age ment sys tems 4-44383 Gen eral de scrip tion and ap pli ca tion392 Qual ifying CNC pro grams 4-47397 Pro gram prep a ra tion and stor age de vice is -

sues 4-55420 Is sues re lated to pro gram stor age 4-60425 Pro gram trans fer de vice is sues 4-60430 Pro gram ver i fi ca tion de vice is sues 4-62

Mod ule five: Para met ric Pro grammingSlide: De scrip tion2 Les son plan for mod ule five3 In tro duc tion to para met ric pro gram ming 5-14 What is para met ric pro gram ming? 5-15 Com par i son to subprogramming 5-110 Com par i son to com puter pro gram ming 5-312 Com par i son to canned cy cles 5-214 Ap pli ca tion cat e go ries 5-315 Fam ilies-of-parts 5-318 User cre ated canned cy cles 5-638 Util ities 5-744 Geo met ric shapes 5-950 Driving ac ces sory de vices 5-1153 Lim i ta tions 5-1154 In tro duc tion to fea ture types 5-1357 In tro duc tion to vari ables 5-1558 What are vari ables? 5-1565 Ar gu ments 5-1666 Ar gu ments with user cre ated canned cy cle

ap pli ca tions 5-1672 Lo cal vari ables with ar gu ment as sign ment

num ber one 5-2188 Ar gu ment as sign ment examples118 Com mon vari ables 5-23120 Cal cu lating val ues up front122 As ar gu ments in part fam i lies125 Re taining val ues from pro gram ot pro gram130 Part fam ily ex am ple153 Per ma nent com mon vari ables 5-24155 Setting your own sys tem con stants 5-25165 Sys tem vari ables 5-26167 Arith me tic ca pa bil i ties 5-28170 Ba sic func tions 5-28171 Com bining op er a tions to form an ex pres sion

5-28173 Trig o nom e try func tions 5-30183 Square root185 Ab so lute value187 Rounding func tions 5-31188 Ap pli ca tions for round ing 5-31199 Ex am ple show ing arithmentic204 Logic and pro gram flow con trol 5-43231 State ment la bels 5-43234 Un con di tional branch ing 5-43235 Ap pli ca tions for un con di tional branch ing

5-44238 Con di tional branch ing 5-47240 The con di tional ex pres sion 5-47246 Ap pli ca tions for con di tional branch ing 5-49250 Ar gu ment flags 5-49251 To set defaluts

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256 Ar gu ment er ror trap ping260 Testing for other er rors265 Loops 5-55266 A loop de fined267 Com par i son to subprogramming297 A loop that counts to ten 5-55312 Steps to gen er at ing loops 5-58316 When is a loop re quired? 5-59317 How many times must the loop be ex e -

cuted? 5-60325 What changes each time through the loop?350 Any other in i tial ized val ues?352 Do you need a prior move ment?535 What must hap pen each time?354 Peck drill ing example386 Sys tem vari ables 5-72387 Alarm gen er a tion389 Part coun ter ex am ple390 Stop with mes sage392 Timers394 Sin gle block sup pres sion395 Feed hold sup pres sion396 Feedrate over ride sup pres sion397 Tapping ex am ple398 Ac cess to ma chin ing cen ter offsets407 Fix ture off sets 5-74411 Sim u lating cut ter comp415 Sim u lating wear off sets428 Check ing off sets for cor rect ness441 Turn ing cen ter wear off sets 5-74446 Turn ing cen ter ge om e try off sets 5-75448 Im proving G50 com mands449 Ac cess to cur rent po si tion 5-81452 Man ual prob ing ex am ple474 Tool length mea sur ing ex am ple489 Testing ma chine po si tion492 Ac cessing turn ing cen ter po si tion497 Modal G codes500 Other CNC Fea tures 5-97501 Modal call ing com mands507 Ar gu ment as sign ment num ber two511 User de fined G codes518 User de fined M codes523 Pro tec tion for im por tant pro grams 5-97524 Out putting data527 Ap proaching and ver i fy ing para met ric pro -

grams 5-101528 Ap proaching fam ily-of-parts ap pli ca tions

5-101534 Ap proaching user-created canned cy cle ap -

pli ca tions 5-116540 Ap proaching util ity ap pli ca tions

541 Ap proaching com plex geo met ric shape ap -pli ca tions 5-121

547 Mis takes be gin ners are prone to mak ing5-127

Mod ule six: Setup time re duc tionSlide: Description2 Setup time re duc tion prin ci ples 6-12 Introduction25 Setup time de fined 6-333 Eval u ate cur rent meth ods37 Two setup task types48 The three ways to re duce setup time 6-572 Four steps to setup re duc tion77 Avail able re sources85 Setup time re duc tion tech niques 6-1094 Prep a ra tion and or ga ni za tion for setup 6-10100 Tool cart102 Priortize set ups103 Non pro duc tion time104 Job or der planning108 Workholding setup110 Re lated tasks111 Elim i nating workholding setup114 Moving workholding setup off line119 Fa cil i tating workholding set ups124 Cut ting tool is sues 6-17125 Re lated tasks126 Elim i nating cut ting tool tasks130 Moving cut ting tool tasks off line133 Tool length com pen sa tion off set

measurment145 Fa cil i tating cut ting tool tasks152 Pro gram zero as sign ment 6-29153 Re lated tasks154 De scrip tion of pro gram zero156 Eliinating pro gram zero as sign ment tasks161 De ter mining pro gram zero as sign ment val -

ues up front173 Shifting point of ref er ence for pro gram zero

as sign ment207 Pro gramming pro gram zero as sign ment val -

ues209 Turn ing cen ter pro gram zero as sign ment212 Fa cil i tating pro gram zero as sign ment tasks215 Pro gram de vel op ment 6-43219 Moving off line220 Facilitating226 Pro gram trans fer227 Re lated tasks228 Elim i nating231 Moving off line

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233 Fa cil i tating pro gram transfers240 CNC Pro gram ver i fi ca tion 6-45241 Re lated tasks243 Def i ni tion of pro gram ver i fi ca tion263 Trial ma chin ing270 Using block de lete to fa cil i tate trial ma chin -

ing278 Changing ma chin ing or der285 Pro gram op ti miz ing294 Pro gramming cut ting con di tions with

variables

Mod ule seven: Cy cle time re duc tionSlide: De scrip tion:2 Pre sen ta tion plan3 Cy cle time re duc tion prin ci ples 7-16 Cy cle time de fined 7-125 Eval u ate your cur rent meth ods31 Watch for pro cess im prove ments39 Task types for cy cle time re duc tion 7-265 The three ways to re duce cy cle time 7-266 One sec ond rule71 How fast can your ma chines rapid? 7-481 Re ducing workpiece load ing and un load ing

time 7-596 Re ducing CNC pro gram ex e cu tion time 7-999 Things we think of as be yond our control104 Ef fi cient pro gram for mat ting 7-9105 The ef fects of spe cial pro gram ming fea tures

7-9127 How M codes re late to pro gram ex e cu tion

time 7-12134 Re ducing rapid ap proach dis tance 7-14162 Pro gramming ef fi cient mo tions 7-16178 Ap proach and re tract in all axes 7-17187 Which is faster G00 or G01?194 Turn ing cen ter sug ges tions 7-18195 Moving warm-up time off-line 7-18200 Pro gramming spin dle range changes ef fi -

ciently 7-19218 The ef fects of con stant sur face speed on cy -

cle time 7-20271 How tool ing style can af fect pro gram ex e cu -

tion time 7-24287 Im proving the ef fi ciency of bar feed ers on

turn ing cen ters 7-24307 Ma chining cen ter sug ges tions 7-26308 Mul ti ple iden ti cal workpieces 7-26310 Ef fi cient au to matic tool changer pro gram -

ming 7-27311 Range chang ing320 Re ducing tool main te nance time 7-32320 Sug ges tions for mov ing off line

373 Helping op er a tors make off set ad just ments404 How pre ven tive main te nance helps

Mod ule eight: Spin dle probe programmignSlide: Description3 The con cept of prob ing 8-122 Ap pli ca tions for prob ing 8-723 Setup help 8-871 In-process gaug ing 8-17104 Util ities 8-21108 How Touch Probes Work 8-22115 Sig nal trans mis sion types119 Bat tery con sid er ations124 Un der stand ing over shoot and droop 8-26174 Cal i bra tion to com pen sate for over shoot and

droop 8-29210 Probing cy cles 8-44228 CNC Com mands Used With Probing 8-45232 G31 - skip cut ting com mand 8-45257 G00 and G01 - rapid and straight line mo tion

com mands 8-47265 G10 - off set set ting by pro grammed com -

mand 8-47282 G20 and G21 - inch and met ric modes 8-48294 Tool length com pen sa tion can cel - G49 8-50298 Co or di nate ma nip u la tion com mands 8-50301 M codes needed for prob ing313 Cus tom macro B sys tem vari ables of im por -

tance when prob ing 8-53319 #2000 se ries - ac cess to tool off sets 8-53338 #3000 se ries - mis cel la neous con trols of ma -

chine func tions 8-54361 #5000 se ries - ac cess to the ma chine’s cur -

rent po si tion 8-56382 Lo cating a probed surface414 Pro gramming for setup help ap pli ca tions

8-64453 Pro gramming in-process gaug ing ap pli ca -

tions 8-85516 Pro gramming util ity ap pli ca tions 8-97

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Be yond the ba sics

Maximizing CNC Uti li za tionGetting the most from your

CNC ma chin ing cen ters and turn ing cen ters

© Copy right 2000, CNC Con cepts, Inc.

Pub lished By:

NO TICE!!

This man ual is pro tected by copy right laws of the United States Gov ern -ment. No part of this man ual may be re pro duced with out the writ ten con -sent of CNC Con cepts, Inc. Ad di tional cop ies of this doc u ment must bepur chased di rectly from CNC Con cepts, Inc. (847) 639-8847Written by Mike Lynch

Doc u ment num ber: S000061

Eight Mod ules!

• 1: Ba sic pre mises• 2: Re view of ba sic CNC us age• 3: Ad vanced im pli ca tions of ba sic fea tures• 4: Ad vanced CNC fea tures, func tions, and con cepts• 5: Para met ric pro gram ming• 6: Setup time re duc tion• 7: Cy cle time re duc tion• 8: Pro gramming spinlde probes

Mod ule one

1.1. Ba sic Prem isesWe will be gin by pre sent ing the most im por tant themes that are stressed through out the course. Whileyou may not agree with ev ery de tail of what is said in this dis cus sion since your spe cific ex pe ri ences maydif fer from the gen er al iza tions we pres ent, these im por tant prin ci ples do ap ply nicely to the vast ma jor ity of CNC-using com pa nies. Un der stand ing and ac cept ing these prin ci ples will help you get the most fromthis course.

1.1.1. The im por tance of im prov ing CNC ma chine uti li za tion

All CNC-using com pa nies want to get the most from their CNC ma chine tools. And of course, each ma -chine’s max i mum out put po ten tial is di rectly tied to how well it is be ing uti lized. How ever, there is muchcon tro versy and con fu sion re lated to just how a com pany should best uti lize their CNC ma chine tools.Given the di ver sity of CNC ma chine ap pli ca tions, what is right for one com pany will be in ap pro pri ate foran other. In this course, not only will we ex pose many ways to im prove CNC uti li za tion, we will also clar -ify which meth ods are most ap pro pri ate based upon a com pany’s spe cific needs.

1.1.1.1. CNC ma chine uti li za tion ver sus ap pli ca tion

Do not con fuse uti li za tion with ap pli ca tion. Uti li za tion is the ef fec tive ness level of the CNC ma chine tool.The pro duc tiv ity of the CNC ma chine is, of course, dic tated by how well it is be ing uti lized. The ap pli ca -tion for the CNC ma chine is sim ply the kind of work it is per form ing.

Con sider for ex am ple, two com pa nies that own iden ti cal CNC ver ti cal ma chin ing cen ters. One com panymakes molds and uses their CNC ma chin ing cen ter for ma chin ing com plex mold cav i ties. The other com -pany makes man i folds and uses their CNC ma chin ing cen ter to drill (many) holes in man i fold plates.They may have a lim ited num ber of dif fer ent man i folds and run them over and over again. The mold ap -pli ca tion is, of course, much more so phis ti cated than the man i fold ap pli ca tion. But it would be in cor rectto say that one com pany is underutilizing their ma chin ing cen ter based solely upon its ap pli c a tion. Thecom pany that uses the CNC ma chin ing cen ter as lit tle more than a glo ri fied drill press de pends upontheir ma chine ev ery bit as much as the com pany that makes com plex molds.

Actually, ei ther com pany could be underutilizing their ma chine. If a CNC ma chine is not out put ting atits max i mum po ten tial, it is be ing underutilized. The com pany that makes molds, for ex am ple, may notknow about a help ful pro gram ver i fi ca tion sim u la tor that would al low them to ver ify their pro gram’s toolpath on a per sonal com puter be fore it is sent out to the CNC ma chine. They may be ex pe ri enc ing waste ful down time while mis takes are found and cor rected at the ma chine dur ing setup. On the other hand, thecom pany mak ing man i folds may not be aware of how an au to matic dis trib u tive nu mer i cal con trol (DNC)sys tem can re duce pro gram trans fer time to un der thirty sec onds. They may be wast ing time as the setup per son walks be tween the CNC ma chine and the serv ing com puter to com mand pro gram trans fers.

1.1.1.2. Ma chine uti li za tion ver sus per son nel uti li za tion

Through out this course we place the high est em pha sis on max i miz ing CNC ma chine tool uti li za tion. And this should be of ex treme im por tance to any CNC-using com pany. How ever, to many com pa nies i t is alsoof great im por tance to get the most out of the peo ple that pro gram, setup, and op er ate their CNC ma -chines. You must un der stand that when you strive to max i mize per son nel uti li za tion, ma chine uti li za -tion usu ally suf fers.

Think about a con tract shop that em ploys one per son to take care of each CNC ma chine the com panyowns. In this kind of com pany, each in di vid ual must com pletely pro gram, setup, and run pro d uc tion forev ery job that co mes to their ma chine. It is quite likely that the CNC ma chine will sit idle for long pe ri odswhile this per son is pro gram ming and set ting up the ma chine. While the com pany is get ting the mostfrom its CNC peo ple, it is not com ing close to achiev ing max i mum po ten tial in ma chine uti li za tion.

Even many prod uct-producing com pa nies com monly at tempt to max i mize per son nel uti li za tion. And un -for tu nately, they may not be con sid er ing the im pact this has on CNC ma chine uti li za tion. Since manyman age ment peo ple can not stand to see any one sit ting idle (even while the CNC ma chines they are run -ning are pro duc ing), they as sign their op er a tors other du ties to per form dur ing each pro d uc tion run.

Ba sic Premises

CNC Concepts, Inc. Maximizing CNC Utilization Page 1-1

When it co mes to ma chine uti li za tion, this may be just fine as long as CNC ma chines don’t sit idle whileop er a tors per form their other du ties. But in re al ity, this is dif fi cult to achieve. It is not un com mon thatCNC ma chines do of ten sit idle wait ing for the op er a tor to fin ish some sec ond ary task.

Some com pa nies even have their CNC op er a tors run ning two or more CNC ma chines. Again, they’re re -ally get ting the most out of their CNC op er a tors. How ever, one ma chine may be con stantly sit ting idlewhile the op er a tor fin ishes up with tasks on the other ma chine/s (load ing workpieces, chang ing in serts,in spec tions, etc.).

In all ex am ples to this point, con sider the high price com pa nies are pay ing to max i mize per son nel uti li za -tion. The shop rate (the amount the com pany charges per hour for the CNC ma chine’s use) for a typ i calCNC ma chine is usu ally at least four to ten times the wage of a CNC op er a tor, based upon the c om plex ityof the ap pli ca tion and ma chine size. From a bot tom-line stand point and given the choice, you should bemore will ing to have a CNC op er a tor sit ting idle wait ing on a CNC ma chine than a CNC ma chine sit tingidle wait ing for a CNC op er a tor.

Some com pa nies fully ac cept the im pact that max i miz ing per son nel uti li za tion has on CNC ma chine uti -li za tion. In fact, it may be part of the com pany’s gen eral phi los o phy. For in stance, many com pa nies in -cor po rate man u fac tur ing cells. A cell may have sev eral CNC ma chine tools (pos si bly along with othercon ven tional equip ment) and may be at tended by just one per son. The pri mary goal in most man u fac tur -ing cells is to com plete a workpiece (or pos si bly even a com plete as sem bly of sev eral workpieces) right inthe cell. This can dra mat i cally im prove the through-put of prod ucts flow ing through the com pany. How -ever, it is not un com mon for one or more ma chines in the cell to be idle while other op er a tions are be ingper formed, mean ing ma chine uti li za tion may be rather low. Since the pri or ity is im proved though-put,the com pany will ing pays the price in lower ma chine uti li za tion.

As stated, this course will em pha size im prov ing CNC ma chine uti li za tion. Since your CNC ma chines’max i mum out put is di rectly tied to how many peo ple are avail able in your CNC en vi ron ment, we will of -ten as sume you have an ad e quate sup port staff - or at least that you are will ing to con sider changes in theway you cur rently uti lize your per son nel.

We want to make one last point about im prov ing CNC ma chine tool uti li za tion. There are com p a nies that have very pre dict able pro duc tion sched ules. Many au to mo tive com pa nies, for ex am ple, know with greatpre ci sion just how many workpieces will be re quired dur ing a day, week, month, and/or year. This kind of com pany will pur chase an ad e quate num ber of ma chines to en sure that their pro duc tion sched ule is met.Once started, as long as there are no changes in re quired pro duc tion vol umes, there will be no need toever im prove ma chine uti li za tion. The vast ma jor ity of com pa nies, how ever, do not share this lux ury,and will greatly ben e fit from im prove ments in ma chine uti li za tion. We’re as sum ing you work for one ofthem.

1.1.2. Cri te ria for wise de ci sions

De ci sions that af fect your CNC uti li za tion must of course be based upon your own com pany’s best in ter -ests. As stated, there are many ex pert sales peo ple in this field who can make the fea tures of theirCNC-related prod ucts sound right for just about ev ery one. Poor de ci sions lead to mis ap pli c a tion. Mis ap -pli ca tion leads to underutilization. Here we in tend to ex pose in or der of im por tance those fac tors thatcon trib ute to mak ing wise de ci sions.

Ad mit tedly, ev ery rule has an ex cep tion. Ex cep tions fuel the fires of con tro versy and con fu sion re gard ing your best choices. In this early pre sen ta tion, we speak in very gen eral terms. As you view this dis cus sion, you may quickly spot some ex cep tions to what is be ing pre sented. Rest as sured that we will fur ther clar -ify a com pany’s spe cific needs as well as how they are best ad dressed as we look at some spe cific ex am ples.

1.1.2.1. Com pany type

There are but four types of com pa nies us ing CNC ma chine tools. Though there are some over laps, allCNC us ers can be placed in one of these four ba sic cat e go ries.

Prod uct-producing com pa nies get their rev e nue from the sale of a prod uct. In a sense, profit is onestep re moved from man u fac tur ing since a prod uct will not even come to mar ket if the com pany can notmake a profit. Prod uct-producing com pa nies tend to have elab o rate en gi neer ing de part ments (de sign en -

Mod ule Num ber One

Page 1-2 Maximizing CNC Utilization CNC Concepts, Inc.

gi neer ing, in dus trial en gi neer ing, man u fac tur ing en gi neer ing, pro cess en gi neer ing, tool en gi neer ing,qual ity con trol, etc.). All fac ets of man u fac tur ing tend to be well thought-out - and good rea sons can begiven for just about ev ery thing that is done in the CNC en vi ron ment. These com pa nies also t end to breakup the tasks re lated to CNC ma chine us age. One per son de vel ops the ma chin ing pro cess. An other per son de signs/or ders the re lated tool ing. An other de vel ops the pro gram. An other gath ers, as sem bles, and ifnec es sary, mea sures the tool ing. An other makes the ma chine setup and runs the first workpiece. An -other in spects the workpiece/s. An other com pletes the pro duc tion run. De pending upon the prod uct be -ing man u fac tured, prod uct-producing com pa nies can have rather com pli cated CNC en vi ron men ts. If the com po nent workpieces to be ma chined are quite di verse, it is likely that a wide va ri ety of dif fer ent CNCma chine types (along with con ven tional and spe cial ma chines) will be re quired to pro duce them.

Workpiece-producing com pa nies (also called con tract or job shops) get their rev e nue from the sale ofcom po nent workpieces to prod uct pro duc ing com pa nies. Profit is di rectly tied to man u fac tur ing sincework is quoted based upon an hourly rate for ma chine us age. While there are ex cep tions, mostworkpiece-producing com pa nies can not af ford to en gi neer their jobs as elab o rately as prod uct-producingcom pa nies. In fact, they must com monly make com po nent workpieces with out the ben e fit of the prod -uct-producing com pany’s help, and for less money than the prod uct-producing com pany can. This meansCNC peo ple work ing for workpiece pro duc ing com pa nies must be ex tremely re source ful and in no va tive.Most tend to spe cial ize in but a few ma chin ing op er a tions, mean ing most will have fewer ma chine typesthan prod uct-producing com pa nies. This tends to sim plify their CNC en vi ron ments. CNC peo p le work -ing for workpiece-producing com pa nies must nor mally per form more than one func tion. It is not un com -mon, for in stance, that one per son will com pletely pro gram, setup, and op er ate their CNC ma c hine/s forthe jobs they run.

Tooling-producing com pa nies get their rev e nue from the sale of tool ing (jigs, fix tures, dies, molds,gauges, etc.) to prod uct-producing and workpiece-producing com pa nies. They share many at trib utes ofboth prod uct-producing and workpiece-producing com pa nies. Since they ac tu ally make a prod uct (thejig, fix ture, die, etc.) profit is com monly one step re moved from man u fac tur ing, mak ing them sim i lar toprod uct pro duc ing com pa nies. How ever, the quan tity of tools (their prod uct) be ing pur chased is usu allyvery small. And most have lim ited re sources, mak ing them sim i lar to workpiece pro duc ing com pa nies.Most tool ing pro duc ing com pa nies do tend to spe cial ize in a tool ing type (jigs, fix tures, gauges, molds,etc.), mean ing they will typ i cally have fewer ma chine types than prod uct-producing com pa nies. As withworkpiece-producing com pa nies, CNC peo ple work ing for tool ing-producing com pa nies tend to per formsev eral tasks.

With some tool ing-producing com pa nies, the prod uct is per ish able (wears out and must be re placed on areg u lar ba sis). Tooling-producing com pa nies that man u fac ture cut ting tools, like car bide in serts and tool hold ers re ally don’t fit the mold of the kind of tool ing-producing com pany as we have de fined it. Truly,this kind of com pany is more a prod uct-producing com pany than a tool ing-producing com pany.

Pro to type-producing com pa nies get their rev e nue from the sale of trial workpieces to prod -uct-producing com pa nies. The method of pro duc ing pro to types may be quite con ven tional, in volv ingCNC equip ment to make the pro to type workpiece/s. It may also in volve pro duc ing a die or mold that inturn makes the pro to type workpiece/s. On the other hand, the method may in volve newer pro cesses (likeste reo li thog ra phy) to pro duce the pro to types. While this di ver sity makes it is dif fi cult to make too manygen er al iza tions, pro to type-producing com pa nies tend to share much in com mon with tool ing pro duc ingcom pa nies when it co mes to com plex ity of work, per son nel uti li za tion, pro gram ming meth ods, etc.

Over laps in com pany types are com mon. A prod uct pro duc ing com pany may, for ex am ple, have a toolroom (in clud ing CNC ma chines) to make their pro duc tion tool ing. And/or they may have a re search andde vel op ment de part ment to pro duce their pro to types. On the other hand, a con tract shop that gets thebulk of its rev e nue from the sale of com po nent workpieces may also have a prod uct of its own. Com panieswith over laps must ap ply CNC ma chines in com pletely dif fer ent ways and tend to have the most com pli -cated CNC en vi ron ments.

1.1.2.2. Other fac tors con trib ut ing to a com pany’s iden tity

While we have ex posed some im por tant gen er al iza tions about how a com pany op er ates based u pon com -pany type alone, sev eral other fac tors fur ther clar ify a com pany’s true iden tity. These fac tors can have a

Ba sic Premises


pro found ef fect on the com pany, and in some cases, will con flict with the gen er al iza tions given for com -pany type. For in stance, a con tract shop that has over 90% re peat busi ness and can pre dict when jobs will be re peated (many au to mo tive con tract shops have this lux ury) will share more in com mon with a prod -uct pro duc ing com pany than with a workpiece pro duc ing com pany. On the other hand, a prod uct pro duc -ing com pany that sees lit tle re peat busi ness will closely re sem ble a workpiece pro duc ing com pany.

Un for tu nately, it may be dif fi cult to gauge the pre cise im pact of one or more of these fac tors on your owncom pany’s true na ture. Worse, they may have a dif fer ent im pact on your com pany’s per for mance fromone de part ment of your com pany to an other. The more di verse your CNC en vi ron ment, the more likelythis pos si bil ity. In this pre sen ta tion, we’ll show the most im por tant fac tors in or der o f im por tance and of -fer pre sen ta tions re lated to how they af fect a com pany’s iden tity. We will con tinue to gen er al ize.

Lot sizes - Al most all de ci sions made in the man u fac tur ing en vi ron ment be gin with the ques tion “Howmany parts are we mak ing?”. This makes lot sizes among the most im por tant fac tors con trib ut ing to acom pany’s iden tity. It can be very dif fi cult to ap pro pri ately gauge just what should be done to at tain agood bal ance among workpiece qual ity, min i mized pro duc tion ex penses, and ef fi ciency. But the re latedde ci sions are al most al ways based pri mar ily upon how many workpieces are be ing pro duced. The moreworkpieces be ing made, for ex am ple, the eas ier it is to jus tify what ever it takes to pro duce the workpiecesas ef fi ciently as pos si ble. On the other hand, the fewer the num ber of workpieces be ing ma c hined, theless a com pany will be will ing to do to en hance ef fi ciency. These de ci sions can mean the dif fer ence be -tween profit and loss for a given job or prod uct.

Un for tu nately, many com pa nies must deal with a wide range of lot sizes. Lot sizes may range, for ex am -ple, from un der ten workpieces to well over one thou sand workpieces. To make mat ters worse, the sameCNC ma chines used to pro duce the small est lots are com monly used to pro duce the larg est lots.

Re peat busi ness - This is the amount of jobs that must be run on a CNC ma chine more than once. It iscom monly mea sured in per cent age. In a com pany that has 50% re peat busi ness, half the jobs that cometo a CNC ma chine have been run on that ma chine at least once be fore (the other half are new jobs, hav ingnever been run be fore).

An im por tant theme in this course is re lated to re peated tasks. The more you re peat a task, the eas ier itwill be to jus tify im prov ing it. With re peat busi ness, the task is the en tire job. Since many de ci sions thataf fect the elab o rate ness of the pro cess (ma chin ing pro cess, cut ting tools used, workholding setup, ef fi -ciency of the pro gram, etc.) will be based upon how of ten the job must be run, re peat busi ness is an ex -tremely im por tant fac tor con trib ut ing to a com pany’s pro file.

Many prod uct pro duc ing com pa nies have very pre dict able pro duc tion vol umes. It is not un com mon for aprod uct pro duc ing com pany to be able to pre dict a tar get num ber of units that will be sold dur ing a year.In deed, some work from a back log of out stand ing or ders. In this case, ev ery one in the com p any will knowpre cisely how many units of the com pany’s prod uct will be re quired dur ing the back log pe riod. Based onhav ing known an nual quan ti ties, and in or der to avoid hav ing to in ven tory large num bers of com po nentworkpieces, many com pa nies have in cor po rated just-in-time prin ci ples. Most com pa nies will break uptheir an nual quan ti ties into smaller lots and run them sev eral times through out the year. As stated, themore a task is re peated, the eas ier it will be to jus tify im prov ing it. If a com pany has pre dict able re peatbusi ness, it is rel a tively easy to jus tify the costs re lated min i miz ing the amount of time it takes to com -plete the job (mostly hav ing to do with re duc ing setup time). Knowing how many workpieces are neededand how of ten jobs will be run also makes it easy to en gi neer and op ti mize all re lated pro cesses (ma chin -ing pro cess, fix tures, cut ting tools, pro gram, etc.).

Note that some com pa nies have quite a bit of re peat busi ness, but it is not pre dict able. Con sider theworkpiece-producing com pany that gets a job for the first time. While this job may be re peated in the fu -ture, most con tract shops will not know it at the time of the first or der. Other than sim ply be ing fa mil iarwith re peated jobs, this sce nario pro vides lit tle ad van tage for fu ture times when the job must be run.Since so many jobs will never be re peated, most con tract shops han dle ev ery new job as if they will neversee it again.

Per cent age of new busi ness - This is sim ply the op po site of re peat busi ness. Again, for a com pany hav -ing about 50% new busi ness, about half the jobs have never been run be fore. And ap prox i mately twicethe time and ef fort is re quired to run a new job as com pared to a re peated job (one prop erly planned and

Mod ule Num ber One


doc u mented). Ad di tional tasks for new jobs in clude setup de sign (work hold ing and cut ting tools), pro -gram ming, doc u men ta tion prep a ra tion, pro gram ver i fi ca tion, and op ti miz ing. A high per cent age of newjobs com bined with small lot sizes, short lead times, and short cy cle times (a com mon sce nario for aworkpiece pro duc ing com pany) can make for a very chal leng ing CNC en vi ron ment.

Lead time - By our CNC-related def i ni tion, lead time is the amount of time from when a com pany’s CNCpeo ple know that a job must be run on a given CNC ma chine to the time when it is ac tu ally run. Thegreater the amount of lead time, the eas ier it is to ad e quately pre pare to run jobs. Com panies that havepre dict able an nual pro duc tion vol umes and break them up into a se ries of lots that are run at sched uledtimes through out the year tend to have the lon gest lead times (nor mally prod uct-producing com p a nies).On the other hand, it is not un com mon in a workpiece pro duc ing com pany to have an or der come in themorn ing that must be shipped that same day.

Hav ing lon ger lead times also al lows the peo ple sched ul ing jobs for a given CNC ma chine to plan the or -der of jobs in a way that min i mizes time and ef fort for the setup per son. If, for ex am ple, all jobs re quir ingthe eight inch ta ble vise can be run se quen tially, the setup per son can keep the workholding setup fromjob to job, min i miz ing setup time.

Note that some com pa nies de sign their en tire CNC en vi ron ment for fast turn-around. Con sider, for ex -am ple, a tool ing-producing com pany that makes spe cial tool ing. If their cus tom ers can’t get a given toolquickly enough, they’ll go else where. While this may be an ex treme con di tion, all com pa nies are con -cerned with pro vid ing their prod ucts as quickly as pos si ble - mak ing short ened lead time an im por tantfac tor in ev ery CNC en vi ron ment.

Typical setup time - By our def i ni tion, setup time is the amount of time it takes to go from mak ing thelast workpiece in the pre vi ous pro duc tion run to mak ing the first good workpiece (ef fi ciently) in the nextpro duc tion run. Truly, the en tire length of time the ma chine is down be tween pro duc tion runs is setuptime.

Setup time will, of course, af fect the through-put time for a job to flow through the CNC en vi ron ment, and for this rea son, all com pa nies are highly con cerned with min i miz ing setup time. For com pa nies that have pre dict able an nual pro duc tion vol umes and break them into smaller lots that are run sev eral times ayear, set ups are re peated on a reg u lar ba sis. This makes it rel a tively easy to jus tify do ing what ever ittakes to min i mize setup time. On the other hand, com pa nies that have a high per cent age of new jobs willal ways be mak ing new set ups - set ups that will not be re peated. This makes it very dif fi cult to jus tify do -ing things that will min i mize setup time for a given job. In stead, this kind of com pany will be look ing forways to stream line re peated tasks in volved with set ups (tool as sem bly, tool mea sure ment, off set en try,pro gram zero as sign ment, etc.).

Note that since re duc ing setup time is so very im por tant to al most all CNC-using com pa nies, we de votean en tire mod ule of this course to setup time re duc tion.

Typ i cal cy cle time - There are two im por tant def i ni tions for cy cle time. One pop u lar def i ni tion goes like this: “Cy cle time is the in ter val that passes from a given event in one cy cle to the same event in the next cy -cle.” Most peo ple use the press ing of the cy cle start but ton as the event. A per son mea sur ing cy cle time in this man ner will start a stop watch at the in stant the op er a tor presses the cy cle start but ton. The CNC cy -cle will run. At its com ple tion, the op er a tor will re move the workpiece just ma chined and load the nextone. As they press the cy cle start but ton again, the timer would stop the stop watch.

While this is an im por tant cy cle time def i ni tion, it is rather sim plis tic. It does not take into con sid er ationthings that don’t hap pen dur ing ev ery cy cle (tool main te nance, sam pling in spec tions, per sonal time, etc.)that add to the length of time it takes to com plete the pro duc tion run. If, for ex am ple, you have a 1,000workpiece pro duc tion run and a cy cle-start-to-cycle-start time of 1 min ute, you won’t com plete the pro -duc tion run in 1,000 min utes do to these ad di tional tasks. A more re al is tic def i ni tion of cy cle time is: “Cy -cle time is the to tal length of time it takes to com plete the pro duc tion run di vided by the num ber ofworkpieces pro duced.”

This fac tor tends to vary widely even within a given com pany for a spe cific CNC ma chine tool. Thoughthis is the case, it is some times pos si ble to de ter mine an av er age time. In many com pa nies, for in stance,the typ i cal cy cle time for two axis turn ing cen ters is in the neigh bor hood of 4-5 min utes. The lon ger thecy cle time, of course, the more likely it is that the CNC op er a tor can be do ing other things (run ning mul ti -

Ba sic Premises


Mod ule two

2.1. Re view of CNC Ba sicsThis mod ule is made up of two discussions. In this discussion, we’ll re view pro gram ming-related con -cepts. Then we’ll re view setup- and op er a tion-related con cepts. We urge you to view this mod ule even ifyou have ex ten sive CNC ex pe ri ence for three rea sons. First, you may have learned most of what youknow by at tend ing ba sic courses con ducted by ma chine tool build ers or tech ni cal schools. In thesecourses, in struc tors com monly show but one way that can be used to han dle a CNC func tion. In ad di tion,you won’t have any idea of which func tions and fea tures of CNC even have al ter na tive us age tech niques.Here we will place the great est em pha sis on those CNC fea tures that can be ap plied in mul ti p le ways,even in their ba sic forms.

Sec ond, you may be (for the most part) self-taught. If so, you’ve prob a bly had to come up with ways tohan dle CNC prob lems com pletely on your own. While you may be quite proud of the meth ods you’ve de -vel oped, you should at least agree that you may have missed some thing quite im por tant when it c o mes tothe ba sics. This quick re view may fill in some blanks.

And third, this mod ule will lay the ground work for the next mod ule (ad vanced im pli ca tions of ba sic fea -tures). You may be sur prised at how many seem ingly ba sic fea tures can be ap plied in ad vanced ways.

And fi nally, you may have ex ten sive com puter aided man u fac tur ing (CAM) sys tem ex pe ri ence, but lim -ited man ual pro gram ming ex pe ri ence. Some of the best ways to im prove CNC uti li za tion re quire a goodcom mand of man ual pro gram ming. Here, we’ll be re view ing G code level man ual pro gram ming.

Note that this mod ule is in tended to be only a re view. If you have CNC ex pe ri ence, you should find thema te rial quite fa mil iar and easy to un der stand. If you find that much of this in for ma tion is new to you, itshould be taken as a sig nal that you need to go back and learn more about the ba sics of CNC (note that weof fer self study man u als to help you learn both ma chin ing cen ter and turn ing cen ter pro gram ming, setup, and op er a tion).

2.1.1. The key con cepts ap proach

With our teach ing meth ods, there are ten key con cepts re lated to CNC ma chine us age. And the same tenkey con cepts can be ap plied to any kind of CNC ma chine tool, in clud ing ma chin ing cen ters and turn ingcen ters. Six of the key con cepts are re lated to pro gram ming, and we’ll re view them first. Four of the keycon cepts are re lated to setup and op er a tion.

For each key con cept, we’ll first pres ent gen er al iza tions that ap ply to all kinds of CNC ma chine tools.Then we’ll show how the key con cept ap plies spe cif i cally to ma chin ing cen ters. Finally, we’ll show how itap plies to turn ing cen ters. Here is a list of the ten key con cepts.

Pro gramming-related:1) Know your ma chine from a pro gram mer’s view point2) Pre pare to write pro grams3) You must un der stand the three most ba sic mo tion types4) You must un der stand the com pen sa tion types5) Pro grams must be struc tured with a strict for mat6) Spe cial pro gram ming fea tures

Setup- and op er a tion-related:7) Know your ma chine from an op er a tor’s view point8) Un der stand the three modes of op er a tion9) Know the most im por tant op er a tion pro ce dures10) Ver ifying pro grams safely

Ad mit tedly, de ter min ing the dif fer ence be tween ba sic tech niques and more ad vanced tech niques israther sub jec tive. We’ll only be in clud ing top ics in this re view that are com monly ad dressed in typ i cal ba -sic CNC courses.

Re view of Basics


Re view of pro gram ming ba sics

The kind of pro gram ming we’re re view ing is man ual pro gram ming (also called G code level pro gram -ming). While com puter aided man u fac tur ing (CAM) sys tems au to mate much of the pro gram ming pro -cess, many of the ad vanced tech niques we show later can not be im ple mented (at least not eas ily) withCAM sys tems and must be han dled at G code level. This means you must un der stand man ual pro gram -ming if you are to get the most out of this course.

2.1.2. Key con cept num ber one - Know your ma chine from a pro gram mer’s view point

It is from two dis tinctly dif fer ent view points that you must un der stand a CNC ma chine if you are to com -pletely mas ter its us age. Here in key con cept num ber one, we dis cuss the ma chine from a pro gram mer’sper spec tive. Later, in key con cept num ber seven, we’ll dis cuss the ma chine from an op er a tor’s per spec -tive.

This key con cept ac tu ally in cludes seven top ics:1) The im por tance of ba sic ma chin ing prac tice2) Ma chine con fig u ra tions3) Gen eral flow of the pro gram ming pro cess4) Vi su al izing the ex e cu tion of a CNC pro gram5) Un der stand ing pro gram zero6) De ter mining the pro gram zero as sign ment val ues7) The two ways to as sign pro gram zero

Some of these top ics are quite sim ple, and we’ll barely men tion them. Oth ers have more dra matic im pli -ca tions, es pe cially for ef fi cient ma chine us age - and we’ll elab o rate.

2.1.2.1. The im por tance of ba sic ma chin ing prac tice

This point can not be over stressed: The more you know about ba sic ma chin ing prac tice as it re lates to thekind of ma chine you’re work ing with, the better use of the ma chine you can make. This is why ma chin istsmake the best pro gram mers. A good ma chin ist knows what they want the ma chine to do. It will be a sim -ple mat ter of trans lat ing this into a lan guage the CNC ma chine can un der stand.

We also can not over stress the dra matic im pact your ma chin ing prac tices will have on qual ity, ef fi ciency,safety, and just about ev ery other is sue re lated to the man u fac tur ing en vi ron ment. While ba sic ma chin -ing prac tice is be yond the scope of this course, al most all com pa nies can ben e fit from im prove ments intheir un der stand ing of ma chin ing meth ods. It should go with out say ing that your CNC peo ple shouldkeep abreast of cur rent trends in cut ting tools, machinability is sues, workholding de vices, and ap pro pri -ate pro cess ing.

One sim ple ex am ple that stresses how CNC peo ple can ben e fit from a better un der stand ing of ba sic ma -chin ing prac tices has to do with mill ing tech niques. Con sider a ma chin ist who has only run knee-stylemill ing ma chines. As you know, a knee-style mill ing ma chine does not have nearly the ri gid ity that a bedstyle mill ing ma chine has. This ma chin ist would (cor rectly) say that you must be very care ful to en surethat all mill ing be done in a con ven tional mill ing man ner. They would say that it would be a nasty mis -take to climb mill. (With most knee style mill ing ma chines, in clud ing knee-style CNC mill ing ma chines,the mill ing cut ter will pull it self along the cut since the ma chine’s way sys tem usu ally has some back -lash.)

If this ma chin ist’s ex pe ri ence is lim ited to knee style mill ing ma chines, they may in cor r ectly ap ply thisthink ing to all forms of mill ing ma chines, in clud ing bed style ma chines. When the ma chine h as ad e quateri gid ity and sup port to al low climb mill ing, most ex pe ri enced ma chin ists would agree that it is wiser toclimb mill, es pe cially for fin ish ing op er a tions (though many CNC peo ple climb mill for rough ing op er a -tions as well). Gen erally speak ing, climb mill ing pro vides a better fin ish with less tool wear than con ven -tional mill ing.

Our main point is that many ma chin ists tend to get a lit tle com pla cent when it co mes to ba sic ma chin ingprac tice. They tend to stick with ways to ma chine workpieces that they know will work. While this maysound good, con sider the ma chin ist from the knee style mill ing ma chine ex am ple. When this per sonchanges to a bed style ma chine, it’s likely that they will con tinue to un wit tingly con ven tional mill, be ing

Mod ule Num ber Two


un aware of the ben e fits that climb mill ing can pro vide. They will be more than a lit tle sur prised whenthey learn that, not only will climb mill ing work, that it will be the pre ferred mill ing method.

Note that through out this course we as sume your ma chin ing pro cesses are ap pro pri ate to your needs.We will be of fer ing sug ges tions for im prove ments based upon your cur rent meth ods.

When it co mes to ma chin ing cen ter us age, com mon ma chin ing op er a tions in clude hole ma chin ing op er a -tions like cen ter drill ing, spot drill ing, drill ing, tap ping, ream ing, and bor ing - as well as mill ing op er a -tions like face mill ing and con tour mill ing. When it co mes to turn ing cen ters, com mon ma chin ingop er a tions in clude rough turn ing, rough bor ing, rough fac ing, fin ish turn ing, fin ish bor ing, fin ish fac ing,thread ing, neck ing, and knurl ing. And since al most all cur rent model ma chin ing cen ters and turn ingcen ters can hold mul ti ple tools that can be au to mat i cally se lected from within the pro gram, the ma chin -ing or der (pro cess) is of par a mount im por tance to the suc cess of the CNC pro gram. Gen erally speak ing,even a poorly de vel oped CNC pro gram can be even tu ally made to work if the pro cess is good. But even aper fectly writ ten CNC pro gram (one that does ex actly what the pro gram mer in tends) will fail if the pro -cess is bad.

2.1.2.2. Ma chining cen ter con fig u ra tions

While a CNC user does not have to be a ma chine de signer, it is help ful if pro gram mers, setup peo ple, andop er a tors know the ba sic com po nents mak ing up the CNC ma chine tools they’ll be work ing with. For thepur pose of our dis cus sions, the de vice that sep a rates CNC ma chin ing cen ters from CNC mill ing ma -chines is the au to matic tool changer. This de vice al lows the ma chine to store sev eral tools within the ma -chine’s tool mag a zine and au to mat i cally change tools dur ing the pro gram’s ex e cu tion. This meansma chin ing cen ters are multi-tool ma chines and can per form a mul ti tude of ma chin ing op er a tions on theworkpiece dur ing the CNC cy cle.

Ma chining cen ters are avail able in a va ri ety of styles, but are most ba si cally clas si fied based upon the ori -en ta tion of the spin dle. If the spin dle is in a ver ti cal at ti tude it is re ferred to as a ver ti cal ma chin ing cen -ter. If it is in a hor i zon tal at ti tude, it is called a hor i zon tal ma chin ing cen ter.

Ma chine tool build ers vary dra mat i cally when it co mes to ma chine de sign. Within the ver ti cal ma chin ing cen ter clas si fi ca tion, for ex am ple, there are three ba sic styles - knee style, C-frame style (also called bedstyle), and gan try style (also called bridge style). Ma jor com po nents mak ing up a spe cific C NC ma chin ing cen ter in clude base (or bed), col umn, spin dle, ways, au to matic tool changer sys tem, and the CNC con trol.Ma jor spec i fi ca tions that CNC us ers tend to be most in ter ested in in clude axis trav els, m ax i mum spin dlespeed, rapid rate, max i mum feedrate, max i mum weight of workholding setup, tool change time, max i -mum tool weight, and con trol style.

Based upon these vari a tions (and oth ers), de cid ing which CNC ma chin ing cen ter will be best suited to agiven ap pli ca tion is no easy task. We’re as sum ing through out this course that you have ap pro pri ate ma -chines for your ap pli ca tions. Mis takes in this re gard will, of course, lead to se vere underutilization. Com -mon mis takes in clude: 1) Pur chasing a ver ti cal ma chin ing cen ter when a hor i zon tal is better suited forthe ap pli ca tion. 2) Pur chasing ma chines with ul tra-high spin dle speeds (over 10,000 rpm) when the ma -chine will be used pri mar ily to ma chine harder ma te ri als like steel (most of these ma chines will have nopower at low spin dle speeds). 3) Pur chasing ma chines with lower spin dle speeds when only light duty ma -chin ing is re quired. 4) Mis takes in way con struc tion se lec tion. Again, mis ap pli ca tion leads tounderutilization.

1. Ma chining cen ter di rec tions of mo tionAll ma chin ing cen ters have at least three lin ear axes named X, Y, and Z. With ver ti cal ma chin ing cen tersand as view from the front of the ma chine, the left/right di rec tion of mo tion is the X axis. The fore/aft di -rec tion of mo tion is the Y axis. Up/down is the Z axis. The mov ing com po nent of the axis var ies with ma -chine de sign. With knee style ma chines, the mov ing com po nent for the X and Y axes is the ta b le. Themov ing com po nent for the Z axis is com monly the quill (though it could be the knee). With C-frame stylever ti cal ma chin ing cen ters, the mov ing com po nent for the X and Y axes is still the ta ble. The mov ing com -po nent for the Z axis is the headstock. With gan try style ver ti cal ma chin ing cen ters, the h eadstock is themov ing com po nent for the X and Y axes (tool moves along with the axes). The quill is the mov ing com po -nent for the Z axis.

Re view of Basics


With hor i zon tal ma chin ing cen ters, and as viewed from the front of the ma chine, the left/right mo tion di -rec tion (most com monly ta ble mo tion) is the X axis. The up/down mo tion of the headstock is the Y axis.The fore/aft mo tion di rec tion (com monly ta ble mo tion) is the Z axis.

Many ma chin ing cen ters have ad di tional (ro tary) axes. If placed upon the ta ble of a ver ti cal ma chin ingcen ter, an ad di tional ro tary axes could be named A, B, or C, de pend ing upon its ori en ta tion with the ma -chine. If placed in the ta ble mech a nism of a hor i zon tal ma chin ing cen ter (ta ble ro tates), it is called the Baxis.

Ev ery axis has a po lar ity (plus ver sus mi nus di rec tion) With the ver ti cal ma chin ing cen ter de picted, the

ta ble moves to form the X and Y axis and the headstock moves to form the Z axis. Note that the headstockin cludes the spin dle that ac tu ally holds the cut ting tool. For this kind of ma chine, the po lar ity (plus ver -sus mi nus) of the Z axis is very easy to un der stand. As the tool (headstock) moves closer to the ta ble top(down), the Z axis is mov ing in the mi nus di rec tion. As it moves away from the ta ble top (up), it is mov ingin the plus di rec tion.

How ever, with the X and Y axes (for this style of ma chine), the cut ting tool does not ac tu ally move withthe axis. In stead, the ta ble moves. This makes un der stand ing the axis po lar ity a lit tle more dif fi cult.When con sid er ing axis po lar ity from the pro gram mer’s view point, it is al ways best to think of axis po lar -ity as if the tool is mov ing. In or der for the tool to move in the plus di rec tion (to the right), the ta ble mustmove to the left.

Note that gan try ver ti cal ma chin ing cen ters in cor po rate trav el ing col umns to form the mo tion of the Xand Y axes. For these ma chines, un der stand ing axis po lar ity is eas ier since the tool is ac tu ally mov ingwith the axis. When ever the tool is sta tion ary dur ing an axis move ment, the axis po lar ity will be a lit tlecon fus ing. This is true of any kind of CNC ma chine tool, in clud ing ver ti cal as well as hor i zon tal ma chin -ing cen ters.

2. Ma chining cen ter pro gram ma ble func tionsTo day’s full blown ma chin ing cen ters al low the pro gram mer to con trol just about any func tion re quiredthrough pro grammed com mands. Here we list the things that the pro gram mer can usu ally con trolwithin the pro gram and give a cur sory view of how each func tion is pro grammed.

Spin dle speed - A pro gram mer can con trol pre cisely how fast the spin dle ro tates in one RPM i n cre ments.An S word is used for this pur pose. If the pro gram mer wishes 350 RPM, the word S350 is com manded.

Mod ule Num ber Two


Spin dle di rec tion - A pro gram mer can con trol which di rec tion the spin dle ro tates, for ward or re verse.The for ward di rec tion is com monly used for right hand tool ing and the re verse di rec tion is used for lefthand tool ing. Two M codes con trol this func tion. An M03 turns the spin dle on in the for ward di rec tion.M04 turns the spin dle on in a re verse di rec tion.

Spin dle range - Most larger ma chin ing cen ters have more than one spin dle range. Like the gear shift le -ver in an au to mo bile, the low spin dle range will be used for slow speed and pow er ful ma chin ing. The highspin dle range will be used for faster speed with less power avail able.

The se lec tion of the spin dle range can be some what trans par ent to the pro gram mer. With most ma -chines, the spin dle speed word (S) helps the con trol to se lect the re quired spin dle range. If the spin dlespeed is in the low range, the con trol will au to mat i cally se lect the low range prior to turn ing the spin dleon. If the speed is in the high range, the con trol will au to mat i cally se lect the high range prior to the spin -dle start.

Say, for ex am ple, your ma chin ing cen ter’s low range runs from 20 to 1500 RPM. The ma chine’s highrange runs from 1501 to 3500 RPM. If you com mand a speed of S500, the con trol will au to mat i c ally se lectthe low range. If you com mand a speed of S2000, the con trol will au to mat i cally se lect the high range.

Feedrate - A pro gram mer can con trol the mo tion rate for any ma chin ing op er a tion. This is done with an F word. The F word spec i fies feedrate in per min ute mode. If you wish to work in the inch sys tem, thisfeedrate will be in inches per min ute. If you work in the met ric, the feedrate will be in mil li me ters permin ute. A feedrate of 3.5 IPM would be pro grammed as F3.5 in the inch mode.

Cool ant - A pro gram mer can turn cool ant on and off at any time from within a pro 0000gram. An M08com mand turns (flood) cool ant on and an M09 turns the cool ant off.

Tool changes - All ma chin ing cen ters have au to matic tool chang ers that al low tools to be loaded into thespin dle au to mat i cally dur ing the pro gram’s cy cle. This, of course, al lows a mul ti tude o f ma chin ing op er a -tions to be per formed within one pro gram cy cle.

Though this func tion will change slightly from one ma chin ing cen ter to an other, many ma chin ing cen ters use a T word to ro tate the ma chine’s tool mag a zine to the de sired po si tion. For ex am ple, a T05 ro tates themag a zine to sta tion num ber five (sta tion five is in the ready po si tion). An M06 com mand is used to ac tu -ally make the tool change and ex changes the tool in the ready po si tion with the tool in the spin dle. As -suming the ma chine is at its tool change po si tion, the com mand T05 M06 will place tool num ber five in the spin dle.

What else might be pro gram ma ble? - While have ac quainted you with the most com mon pro gram ma blefunc tions of ma chin ing cen ters, you must be pre pared for oth ers. Other fea tures that may be equipped onyour own ma chines in clude pal let chang ers, pro gram ma ble chip con vey ers, spin dle probes, tool lengthmea sur ing probes, and a va ri ety of other ap pli ca tion based fea tures.

2.1.2.3. Turn ing cen ter con fig u ra tions

All CNC turn ing cen ters have at least two (lin ear) axes. And for the most pop u lar style of CNC turn ingcen ter, the tool (held in a tur ret) moves along with each axes. The X axis is the di am e ter-controlling axis.It is the di rec tion of mo tion per pen dic u lar to the spin dle cen ter line. For al most all cur rent model turn ingcen ters, X is spec i fied in di am e ter. If turn ing a 2.5 in di am e ter, for ex am ple, this X axis po si tion is spec i -fied as X2.5. The Z axis is the length-controlling axis. It is the di rec tion of mo tion par al lel to the spin dlecen ter line.

Each axis has a po lar ity (plus ver sus mi nus di rec tion). For al most all ma chines, the X mi nus di rec tion ismo tion to ward the spin dle cen ter, get ting smaller in di am e ter. X plus is the mo tion away from the spin -dle cen ter, get ting big ger in di am e ter. (We do know of two turn ing cen ter man u fac tures that re verse thepo lar ity for the X axis.) Z mi nus is mo tion to ward the work hold ing de vice (chuck). Z plus is the di rec tionof mo tion away from the work hold ing de vice. The draw ing shows these two axes as well as po lar ity forthe most pop u lar form of turn ing cen ter.

Note that al most all cur rent model turn ing cen ters ad here to these stan dards for the X and Z axis. Thismakes pro gram ming for dif fer ent types of tun ing cen ters quite sim i lar. Though the con fig u ra tions mayap pear rad i cally dif fer ent from one an other, the same two-axis pro gram could be loaded and cor rectly run

Re view of Basics


in any of the ma chines. (X is al ways the di am e ter-controlling axis and Z is al ways the length con trol lingaxis.)

De pending on their ap pli ca tion, some turn ing cen ters are equipped with a third (ro tary) axis mountedwithin the headstock. This axis is named the C axis. When a turn ing cen ter has a C axis, it will al ways beequipped with live tool ing as well. This means the turn ing cen ter can ac tu ally ro tate cut ting tools (likedrills, taps, ream ers, and end-mills) that are held in the tur ret.

C axis and live tool ing al low the CNC user to per form op er a tions not com monly as so ci ated with turn ingcen ters. With these fea tures, sec ond ary op er a tions that would nor mally have to be done af ter the turn ing cen ter op er a tion can be done right in the turn ing cen ter. This min i mizes the num ber of op er a tions it willtake to com pletely ma chine a workpiece.

The C axis can be used to ro tate the workpiece to a pre cise an gu lar po si tion. The live tool (drill, reamer,tap, etc.) can then be used to ma chine cross holes (par al lel to the X axis) or through holes (par al lel to the Zaxis). The C axis can even ro tate dur ing ma chin ing, and when equipped with a spe cial mo tion type calledpo lar co or di nate in ter po la tion, the CNC user can even use a mill ing cut ter to ma chine elab o rate con toursin the out side di am e ter of the workpiece (com bin ing X and C axis mo tions). When a turn ing cen ter has aC axis with live tool ing, it’s al most like hav ing a ma chin ing cen ter (or mill ing ma chine) b uilt right into the turn ing cen ter.

One se vere lim i ta tion of the three axis turn ing cen ter (X, Y, and C) is that the cut ting tool can only movein one plane (the X-Z plane). This lim its what can be done with mill ing cut ters. For this rea son, someturn ing cen ter man u fac tur ers equip their live tool ing turn ing cen ters with an axis that al lows the tur retto move per pen dic u lar to the X-Z plane. This axis is called the Y axis. When equipped with a Y axis, theturn ing cen ter truly is very much like a mill ing ma chine or ma chin ing cen ter.

The uni ver sal slant bed turn ing cen ter

This is the most com mon form of CNC turn ing cen ter. By far, this con fig u ra tion out-numbers any of theother forms. This form of turn ing cen ter is so pop u lar be cause all ma jor ap pli ca tions for turn ing can beac com plished, in clud ing shaft work (by us ing the tailstock), chuck ing work, and bar work (if a bar feederis used).

Uni ver sal style slant bed turn ing cen ter (axis po lar ity re flects tur ret mo tion)

Note that most other turn ing cen ter con fig u ra tions are sim ply off-shoots of the uni ver sal style slant bedturn ing cen ter. A chuck ing style turn ing cen ter, for ex am ple, is iden ti cal, ex cept it does not have atailstock (shaft work can not be per formed). A ver ti cal style turn ing cen ter has the spin dle ori ented in aver ti cal at ti tude (X is still the di am e ter-controlling axis and Z is still the length-controlling axis). Twinspin dle turn ing cen ters (both slant bed and ver ti cal) have the abil ity to run two pro grams at once and can

Mod ule Num ber Two


Mod ule three

3.1. Ba sic CNC fea tures with ad vanced im pli ca tionsThere are count less ways to han dle even the most ba sic of CNC fea tures. But it’s likely that i n most ba sicCNC courses you’ve at tended, you’ve been ex posed to but the most ru di men tary ways to han dle CNCfunc tions. Again, the pri mary (and some times the only) ob jec tive of most ba sic CNC courses it to get stu -dents to the point that they can be gin work ing with their CNC ma chines. Given the amount of new in for -ma tion pre sented in ba sic CNC courses, en try level stu dents may not be ready for much more at this early stage of their de vel op ment.

Once a stu dent gains ex pe ri ence with the CNC ma chine/s, they will be come fa mil iar and con f i dent withthe meth ods they reg u larly use. In quis i tive nov ices will soon be gin to won der about other tech niques(those not taught in ba sic courses) that will en hance their gen eral un der stand ing of CNC.

In this mod ule, we’ll ex pose you to many tech niques that are not com monly taught in ba sic CNC courses.How ever, we will limit our pre sen ta tion in this mod ule to in clude only rel a tively ba sic CNC fea tures thatare in tro duced in ba sic CNC courses. You may be sur prised at how many ba sic fea tures do have mul ti pleuses. We’re call ing any sec ond ary use that is not pre sented in a typ i cal ba sic course an ad vanced im pli ca -tion.

Ad mit tedly, many of the func tions we show are still pretty ba sic. The more time you’ve spent aroundCNC ma chines, the more likely it is that you’ve come across some of the tech niques we show. This mod ule will be of most ben e fit to stu dents that have been ex posed to the ba sics, but have but a lim ited amount ofac tual CNC ex pe ri ence (three months to one year). Though this is the case, even highly ex pe r i enced CNCpeo ple will likely find many of the tech niques we show in this mod ule to be new and unique.

The or ga ni za tion of this mod ule (and most to come) is ref er ence in na ture. When it co mes to CNC pro -gram ming words, for ex am ple, we’ll be pre sent ing this ma te rial by word or der in CNC com mands as fol -lows.

Mes sage (pa ren the ses) tech niquesSlash code (/) tech niquesN word tech niquesG word tech niques (ad dress ing G codes in nu mer i cal or der)Axis spec i fi ca tion tech niquesSpin dle speed tech niquesFeedrate tech niquesT word tech niquesM word tech niques (ad dress ing M codes in nu mer i cal or der)

Com pare this ref er ence method to the highly tu to rial method by which mod ule two (re view of ba sics) ispre sented. While the pre sen ta tion for each in di vid ual tech nique will be as tu to rial as w e can make it, thegen eral or der of pre sen ta tion will have no log i cal or tu to rial flow.

3.1.1. Un der stand ing pa ram e ters

All CNC us ers will even tu ally have to be come fa mil iar with pa ram e ters. Though they are not even men -tioned in most ba sic CNC courses, and though most CNC peo ple would agree that the con trol of pa ram e -ters is more the re spon si bil ity of a ser vice or main te nance per son than a CNC pro gram mer, setup per son,or op er a tor, there are many pa ram e ters that af fect the way CNC pro grams are ex e cuted. Ev ery CNC per -son should, at the very least, be aware of their ex is tence. Better yet, they should be on the con stant look -out for ma chine be hav ior that is af fected by pa ram e ter set tings.

Again, pa ram e ters af fect the way the CNC ma chine be haves. And through out this mod ule, in deedthrough out the rest of this course, we will men tion many ma chine and con trol func tions that are af fectedby them. There are two ba sic types of pa ram e ters.

Like tool off sets, all pa ram e ters are num bered and pa ram e ters are al ways re ferred to by their num bers.With most con trols, there are well over one thou sand pa ram e ter func tions.

Ba sic Fea tures That Have Ad vanced Implications


3.1.1.1. Eight bit bi nary type

Each eight bit pa ram e ter con trols up to eight in di vid ual func tions. Each digit of the pa r am e ter is called abit. The bit num ber ing is a lit tle un usual, and fol lows bi nary struc ture. The right most bit is bit num berzero and num bers as cend from right to left. The left most bit is bit num ber seven. (Note that bit num berfive is the sixth bit from the right.) The draw ing shows an ex am ple.

Draw ing of eight bit bi nary pa ram e ter

Each bit of this pa ram e ter type will con trol an in di vid ual func tion, and con tains a zero or a one. Zero isused to rep re sent off, no, or some neg a tive con di tion. One is used to rep re sent on, yes, or some pos i tivecon di tion. The pa ram e ter doc u men ta tion will com monly use three char ac ter ab bre vi a tions for each bitname and spec ify ex actly what will hap pen if the bit is set to a one or a zero.

3.1.1.2. Whole num ber type

Many pa ram e ters need to spec ify more than but one of two pos si bil i ties (0 or 1). They will con tain ac tualval ues. One turn ing cen ter pa ram e ter, for ex am ple, spec i fies the min i mum depth of cut for the G76thread ing cy cle.

Note that most do not al low dec i mal points to be in cluded in the pa ram e ter’s value, so a fixed for mat mustbe used for dec i mal en tries. If work ing with a four place dec i mal for mat, for ex am ple, the value 0050 willbe 0.005 inch.

3.1.1.3. Im por tance of back ing up pa ram e ters

Pa ram e ters are vol a tile. Like CNC pro grams and tool off sets, they are backed up by a bat tery when thepower is turned off. But the day will even tu ally come when the bat tery will go dead. Most con trols willsound an alarm as the bat tery starts to de te ri o rate, but you must be pre pared for the worst. If the ma -chine is off for a long pe riod of time with a fail ing bat tery, it is pos si ble that you will not get any warn ingprior to the bat tery fail ing. Any data re tained by the bat tery (in clud ing pa ram e ters) will be lost!

All cur rent model con trols al low you to back up your pa ram e ters us ing stan dard dis trib u tive nu mer i calcon trol (DNC) de vices, us ing the same tech niques you do for trans fer ring CNC pro grams. Con sult yourcon trol man u fac turer’s op er a tion man ual to find the pro ce dure to back up pa ram e ters.

We can not over stress the im por tance of main tain ing a backup copy of pa ram e ters. Ac cord ing to FanucUSA, the larg est sin gle source of ma chine down time is when a ma chine fail ure oc curs that causes pa ram -e ters to be lost, yet the CNC user has not main tained a backup copy of pa ram e ters. Much time is wastedwhile trial-and-error tech niques are used to man u ally en ter pa ram e ter data. BE SURE TO BACK UPYOUR PA RAM E TERS! Also re mem ber to up date your backup copy when you make pa ram e ter changes.

Mod ule num ber three


01234567

201: Transfer conditionNCR ASC SB2

0 0 0 0 0 0 1 1NCR 0: The EOB code used in output is LF, CR, CR

1: LF onlyASC 0: The code used for data output is ISO

1: ASCIISB2 0: The number of stop bits is one

1: two

01234567





1: two





1: two

As the CNC user, you - and you alone - are re spon si ble for main tain ing the backup copy of your pa ram e -ters.

3.1.2. Doc u menting in the pro gram

You prob a bly know that al most all cur rent model CNC con trols al low you to in clude mes sages withinyour CNC pro grams for doc u men ta tion pur poses (though many ba sic CNC course don’t even men tionthem). Even if this fea ture is in tro duced in the ba sic CNC course, most in struc tors will not de scribe thevar i ous times when doc u ment ing mes sages should be used.

Fanuc and Fanuc-compatible con trols use pa ren the ses [()], which are also called con trol in and out, forthe pur pose of in clud ing mes sages in the pro gram. When the con trol reads a left pa ren the sis, it ig noresany text it sees un til it co mes to a right pa ren the sis. At this point it con tin ues ac tu ally ex e cut ing thewords and com mands it sees in the pro gram. While some con trols al low both up per and lower case char -ac ters, most Fanuc and most Fanuc-compatible con trols re quire that the mes sage in cluded within the pa -ren the ses be in up per case (all cap i tal let ters).

Some con trols use dif fer ent char ac ters to des ig nate that mes sages are be ing given (some use a dol larsign, for ex am ple). Re gard less of how mes sages are la beled, al most all cur rent model CNC con trols al lowsome way for the pro gram mer to in clude doc u ment ing mes sages right in the CNC pro gram that will ap -pear on the dis play screen when the setup per son or op er a tor views the pro gram.

Older con trols may not have the abil ity to ac tu ally dis play mes sages on the dis play screen, but at leastthey can be in cluded on the pro gram’s print out (hard copy). Also note that some con trols do have the abil -ity to dis play mes sages on the dis play screen but do not have the pa ren the ses char ac ters (or all let ters ofthe al pha bet) on the con trol panel key board. For this kind of con trol, mes sages can not be en tered or mod -i fied at the ma chine.

You will no tice that just about ev ery com mand of ev ery ex am ple pro gram given in this text will have ames sage within pa ren the ses to help you un der stand what is go ing on within the com mand. Ad mit tedly,our us age of mes sages is ex treme (doc u ment ing ev ery com mand) and we do not rec om mend that you doso. While this fea ture is not at all ad vanced, many pro gram mers do not use this fea ture to doc u mentnearly as ex ten sively as they should. In this dis cus sion, we in tend to ex poses the most im p or tant ap pli ca -tions for in clud ing mes sages in CNC pro grams.

3.1.2.1. Pro gram head ers

A well doc u mented CNC pro gram be gins with a se ries of mes sages that re move any doubt about the pro -gram’s use. Here is a sam ple pro gram be gin ning that in cludes suf fi cient doc u men ta tion for this pur pose.

O0001(*** PRO GRAM QUAL IFIED 2/12/99 ***)( MA CHINE: MORI SEIKE SL4)( PART NUMBER: A-2355-2C)( PART NAME: BEARING FLANGE)( RE VI SION: F)( CUS TOMER: ABC COM PANY)( OP ER A TION: 20, MA CHINE BORED END OF PART)( PRO GRAMMER: MLL)(DATE FIRST RUN: 4/11/98)(PRO GRAM RE VI SION: C)( LAST PRO GRAM RE VI SION: 1/30/98 BY CRD)( RUN TIME: 00:05:25)N005 T0101 M41N010 G96 S400 M03



N015 G00 X3. Z.1 M08...

No tice that any one view ing this header in for ma tion can eas ily tell which CNC ma chine the pro gram isfor, the workpiece and op er a tion the pro gram is ma chin ing, who wrote the pro gram, who last changed it,and three im por tant dates. Though this kind of in for ma tion may seem quite ba sic, re mem ber that manycom pa nies even tu ally ac cu mu late thou sands of CNC pro grams. With out this ba sic doc u men ta tion ineach pro gram, it can be next to im pos si ble to keep track of which pro grams are used for a given job.

No tice that the first doc u ment ing line deals with whether the pro gram is qual i fied, or proven. When theyhave many re peated jobs, most com pa nies strive to min i mize the num ber of changes re quired af ter thejob is first run. In deed, many com pa nies do not al low their setup peo ple and op er a tors to mod ify whatthey con sider to be qual i fied or proven pro grams with out get ting the ap proval of the CNC pro gram mer.This mes sage spec i fies to the op er a tor that the pro gram is qual i fied, and should run with out the need formod i fi ca tion.

Also of im por tance in our ex am ple header are the cur rent re vi sions for workpiece and pro gra m. Re mem -ber that the de signs for pro duc tion workpieces are com monly changed, mean ing changes in CNC pro -grams. These changes can wreak havoc with the or ga ni za tion and main te nance of CNC pro grams. In the event that a re vi sion may not be per ma nent (the de sign en gi neer may de lete the re vi sion), many com pa -nies main tain a mas ter copy of each CNC pro gram for ev ery re vi sion, mean ing a given op er a tion for oneworkpiece may even tu ally have sev eral CNC pro grams. The setup per son and/or CNC op er a tor must bevery cau tious to con firm that the CNC pro gram they are about to run will ma chine the workpiece to itsmost re cent re vi sion. Doc u menting and main tain ing the re vi sion in for ma tion at the be gin ning of ev eryCNC pro gram makes this check ing easy.

Pro cess changes may also oc cur. Even if the workpiece re vi sion stays the same, the pro gram mer mayelect to in cor po rate new tool ing, workholding de vices, or ma chin ing or der to im prove qual ity or cy cletime. The pro gram re vi sion should be doc u mented on the setup sheet and in the CNC pro gram so thesetup per son can con firm they are run ning the most re cent ver sion of the pro gram.

Also no tice the spec i fi ca tion of run time. Once the pro gram has run, it can be help ful to doc u ment its runtime right in the CNC pro gram (es pe cially for a re peat ing job). Any one look ing at the pro gram in the fu -ture, while the pro gram is not cur rently run ning, can eas ily de ter mine how long the pro gram takes torun. Ad di tionally, there are things that oc cur in setup that may af fect the run time. If for ex am ple, toolsare loaded in a ma chin ing cen ter’s tool mag a zine in se quen tial or der, tool chang ing time will be min i -mized (even with ran dom ac cess tool chang ers if ma chin ing time is very short for a given tool). When thejob does run again, the setup per son can con firm that it is run ning as ef fi ciently as it has i n the past if therun time is in cluded in the pro gram header.

3.1.2.2. Tool in for ma tion

A CNC pro gram, es pe cially a long one, can be quite dif fi cult to read, even for ex pe ri enced CNC setup peo -ple and op er a tors. Since the CNC op er a tor will be hav ing to re run tools of ten, the CNC pro gram mer canmake it much eas ier to find crit i cal re start po si tions in the pro gram by doc u ment ing the be gin ning of ev -ery tool. By hav ing this doc u men ta tion avail able in the pro gram, the CNC op er a tor can eas ily con firmthat they have found the cor rect po si tion within the CNC pro gram from which to start a given tool. Hereis an ex am ple turn ing cen ter pro gram which il lus trates this tech nique.

O0001(*** PRO GRAM QUAL IFIED 2/12/99 ***)( MA CHINE: MORI SEIKE SL4)( PART NUMBER: A-2355-2C)( PART NAME: BEARING FLANGE)( RE VI SION: F)( CUS TOMER: ABC COM PANY)



( OP ER A TION: 20, MA CHINE BORED END OF PART)( PRO GRAMMER: MLL)(DATE FIRST RUN: 4/11/98)(PRO GRAM RE VI SION: C)( LAST PRO GRAM RE VI SION: 1/30/98 BY CRD)( RUN TIME: 00:05:25)

N005 T0101 M41 (ROUGH TURNING TOOL)N010 G96 S400 M03 N015 G00 X3.040 Z0.1N020 G01 Z-1.995 F0.017N025 X3.25N030 G00 X6.0 Z5.0N035 M01N040 T0303 M41 (2" DRILL)N045 G97 S300 M03N050 G00 X0 Z0.1N055 G01 Z-2.6 F.009N060 G00 Z0.1 N065 G00 X6.0 Z5.0N070 M01

N075 T0404 M41 (1.5" ROUGH BORING BAR)N080 G96 S400 M03 N085 G00 X2.085 Z0.1N090 G01 Z-1.995 F0.010 N095 X2.0 N100 G00 Z0.1 N105 X6.0 Z5.0N110 M01

N115 T0505 M42 (1.5" FIN ISH BORING BAR)N120 G96 S600 M03N125 G00 X1.125 Z0.1 N130 G01 Z-2.0 F0.006N135 X2.0 N140 G00 Z0.1 N145 G00 X6.0 Z5.0

N150 T0202 M42 (FIN ISH TURNING TOOL)N155 G96 S600 M03N160 G00 X3. Z0.1N165 G01 Z-2.0 F0.006



N170 X3.25N175 G00 X6.0 Z5.0N180 M01N185 M30

No tice how in lines N005, N040, N075, N115, and N150, the mes sage makes it clear as to which tool is be -ing used. An op er a tor wish ing to re run the fin ish bor ing bar, for ex am ple, could eas ily con firm that lineN115 is the cor rect block from which to start. Also note that the spaces in this pro gram fur ther sep a ratetools. These spaces can be inluded by en ter ing an ex tra end-of-block character.

3.1.2.3. At ev ery pro gram stop

De pending upon the ma chin ing op er a tions be ing per formed, there may be times when the CNC op er a tormust per form a spe cial (man ual) task dur ing the CNC pro gram’s ex e cu tion at a pro gram stop, com monlycom manded by an M00. For ex am ple, a ver ti cal ma chin ing cen ter pro gram may be per form ing sev eraltap ping op er a tions. Due to chips build ing up in side the holes, the CNC pro gram mer may in c lude a pro -gram stop just be fore the tap ping op er a tions. Dur ing this pro gram stop, the op er a tor is ex pected to brushaway the chips and add tap ping com pound to the holes. In or der to con firm that the CNC op er a tor knowswhat it is they are sup posed to do, the CNC pro gram mer should place a mes sage in the pro gram close tothe pro gram stop com mand.

.

.N095 M00 (CLEAR CHIPS AND ADD TAPPING COM POUND)..

Other in stances of when the CNC op er a tor may be ex pected to per form man ual op er a tions in this fash ionthat should be well doc u mented in clude break ing cer tain clamps loose on ma chin ing cen ters for fin ish ingop er a tions, re duc ing chuck pres sure on turn ing cen ters for fin ish ing op er a tions, and turn ing a workpiece around in the chuck of a turn ing cen ter to ma chine the op po site end of the workpiece. Truly, any time apro gram mer in cludes a pro gram stop in the pro gram, a mes sage should be in cluded close-by to tell the op -er a tor what it is they are sup posed to do.

Mes sages used for this pur pose as sume the op er a tor is mon i tor ing the pro gram page of the con trol’s dis -play screen. In this case, when the ma chine stops due to the M00, the mes sage will be vis i ble. How ever, ifthe op er a tor is mon i tor ing an other page of the dis play screen, say the po si tion page, the mes sage will notbe vis i ble. The op er a tor can, of course, sim ply ac ti vate the pro gram page to see the mes sage. How ever,this as sumes the op er a tor knows that the ma chine stopped due to an M00 (the ma chine is n’t hung up foran un ex plained rea son).

Some con trols al low a more fail-safe method of dis play ing mes sages dur ing a pro gram stop. At the pro -gram stop, the dis play screen of the con trol will au to mat i cally switch to a spe cial mes sage page and dis -play the mes sage, re gard less of what dis play screen page the op er a tor hap pens to be mon i tor ing. Theex am ple com mand we show is given in the for mat used with the most pop u lar ver sion of para met ric pro -gram ming, cus tom macro B.

#3006 = 101 (TURN PART AROUND)In cus tom macro B lan guage, #3006 is a stop-with-message sys tem vari able. When this com mand is ex e -cuted, the dis play screen of the con trol will au to mat i cally switch to the mes sage page. Mes sage num berMC101 that states “TURN PART AROUND” will be shown. Af ter the part is turned around in the chuckand the op er a tor re ac ti vates the cy cle, the mes sage will dis ap pear (though the dis play will still be show -ing the mes sage page).

3.1.2.4. Sim ple setup in struc tions

With sim ple set ups, some pro gram mers like to in clude mes sages at the very be gin ning of the pro gram totell the op er a tor how to setup the job. The pro gram mer can be as ver bally spe cific as nec e s sary, let tingthe op er a tor know ex actly what is ex pected in the setup. Note that most CNC con trols limit the num berof char ac ters that can be in cluded per mes sage to about 80 char ac ters. Also, to keep a mes sage from



Mod ule four

4.1. Ad vanced CNC fea tures, func tions, and con cepts In mod ule three, we dis cussed nu mer ous ad vanced ap pli ca tions for rel a tively ba sic fea tures - fea turesthat would nor mally be in tro duced in a ba sic CNC course. It’s likely that you have had at least some ex pe -ri ence with many of the fea tures in tro duced in mod ule three.

Here we’re go ing to dis cuss many im por tant CNC fea tures that are sel dom, if ever, even men tioned inmost ba sic CNC courses. We must point out, how ever, that many of these fea tures have a nar row fo cus intheir ap pli ca tion. For any given CNC fea ture dis cussed in this mod ule, the com pa nies that need it willprob a bly use it on a reg u lar ba sis. But the ma jor ity of com pa nies may never need the fea ture.

For this rea son, many of the fea tures dis cussed in this mod ule will not be of im me di ate need. You must, of course, know that a fea ture is avail able (and how it’s used) be fore you can be gin to ap ply it. Think of thismod ule as ex pos ing you to what is avail able. For some dis cus sions, we may sim ply ac quaint you with thefea ture and tell you why it’s avail able. Some day, you may have use for it. And this text should make agreat way to re view the fea ture at the time when it is im por tant to you.

4.1.1. Spe cial in ter po la tion types

The vast ma jor ity of CNC pro grams re quire but three mo tion types: rapid, straight line, and cir cu lar in -ter po la tion. And these mo tion types are well dis cussed in ba sic courses. We add to their ap pli ca tions inmod ule three. Here in mod ule four, we pres ent the more ob scure in ter po la tion types. In ev ery case, thein ter po la tion type will have a very spe cific ap pli ca tion. If you don’t have the ap pli ca tion, you’ll neverneed the re lated in ter po la tion type. In ad di tion, most con trol man u fac tur ers will not pro vide these in ter -po la tion types as a stan dard fea tures. Un less the ma chine tool builder de ter mines that they are an in te -gral part of their ma chine and makes them stan dard, you’ll have to pay ex tra to get them. In thisdis cus sion, our main ob jec tive is to let you know what each ex tended in ter po la tion type is and when youwill need it. For the more pop u lar ones, we’ll also give ex tended pre sen ta tions about how they’re used.

4.1.1.1. He li cal in ter po la tion

He li cal in ter po la tion causes three axes to move to gether. Two of the axes (usu ally X and Y) move in a cir -cu lar fash ion, while the third axis (usu ally Z) moves in a lin ear fash ion. The re sult ing mo tion re sem bles a cork screw, but the ra dius of the cork screw re mains con stant.

Note that, like cir cu lar mo tion, he li cal mo tion re quires a plane se lec tion (G17, G18, or G19). In al most allap pli ca tions, you’ll be mill ing in the XY plane, so G17 must be in ef fect. Note that if you use a right an glehead and mill threads in the XZ or YZ plane, you must in voke the re lated plane se lec tion com mand (G18for XZ or G19 for YZ).

For most con trols, he li cal in ter po la tion is com manded by G02 and G03 (the same G codes used for cir cu lar mo tion. The X and Y co or di nates, as well as the arc cen ter spec i fi ca tion (with R or I, J, & K), are spec i fiedin ex actly the same man ner in a he li cal mo tion com mand as they are in a cir cu lar mo tion com mand. How -ever, he li cal mo tion ad di tion ally re quires a Z spec i fi ca tion.

By far, the most pop u lar ap pli ca tion for he li cal in ter po la tion is thread mill ing on a ma chin ing cen ter andthe bulk of this pre sen ta tion ad dresses how you use he li cal in ter po la tion for thread mill ing. How ever,there are CNC ma chin ing cen ter us ers that use he li cal mo tion when mill ing pock ets. They’ll use it toramp in to the pocket, min i miz ing stress on the mill ing cut ter (the mill ing cut ter must, of course, be of acen ter-cutting type).

If you don’t per form thread mill ing op er a tions, and if you don’t feel you need to ramp into pock ets, youdon’t need he li cal in ter po la tion. For this rea son, many ma chine tool build ers do not pro vide he li cal in ter -po la tion as a stan dard fea ture. You may have to pay ex tra to get it (al most all ma chine tool build ers make it a field-installable fea ture, mean ing you can add it at any time).

He li cal in ter po la tion for thread mill ing

Thread mill ing is be com ing quite com mon-place in com pa nies us ing CNC ma chin ing cen ters. Any holethat is too large to tap or re quires a better fit than can be achieved by tap ping can be thread milled. And

Ad vanced CNC Fea tures, Func tions, and Concepts


out side di am e ters that re quire threads that would nor mally re quire some kind of thread die can be eas ilymilled. An other ad van tage of thread mill ing (over tap ping) is that the di am e ter of the thread mill ing op -er a tion is ad just able with cut ter ra dius com pen sa tion. When you tap, you have no con trol of the fi nal hole size.

While thread mill ing is be com ing quite pop u lar, there are still some con fu sion re gard ing how it’s done.Here we in tend to ex plain thread mill ing in de tail. This should help any one who has never had to per form a thread mill ing op er a tion un der stand what is in volved with thread mill ing (it may also clar ify a fewthings for peo ple that have per formed thread mill ing op er a tions). We’ll dis cuss some ba sic ter mi nol ogy,show the re lated tool ing, ex plain the meth ods, and pres ent the pro gram ming tech niques used for threadmill ing.

1. Ba sic ter mi nol ogyThread des ig na tion - As you know, all threads have two ma jor des ig na tions. First is the thread’s di am e -ter. This des ig na tion is the thread’s ma jor di am e ter. The sec ond has to do with the thread’s pitch(crest-to-crest dis tance). If the thread is spec i fied in inch fash ion, this des ig na tion will be inthreads-per-inch. The pitch will be equal to one di vided by the num ber of threads per inch. If ma chin ingan in ter nal 2"-8 thread, the ma jor di am e ter is two inches and the pitch is 1/8 (0.125) inch.

If work ing with a met ric thread, the pitch will be spec i fied as part of the thread des ig na tion (an ex ter nal50-1.5 met ric thread has a fifty mil li me ter ma jor di am e ter and a 1.5 mil li me ter pitch). While there areother im por tant des ig na tions re lated to thread ing (pitch di am e ter, thread depth, in cluded an gle, etc.),gen er ally speak ing, these are the two most im por tant des ig na tions for pro gram ming a thread mill ing op -er a tion.

Blind ver sus through holes - When ma chin ing threads in holes, if the hole does not pro trude all the waythrough the workpieces, it is called a blind hole. If it does, it is called a through hole. The type of hole(blind or through) will have im pli ca tions re lated to the thread mill ing di rec tion.

Climb ver sus con ven tional mill - Just like any other mill ing op er a tion, you’ll be able to choose which styleof mill ing you’d like. If your ma chine al lows it (has am ple ri gid ity), we rec om mend climb mill ing when -ever pos si ble since it pro duces the better fin ish. Note that you can per form your de sired method of mill -ing (climb or con ven tional) and still ma chine the ap pro pri ate hand of thread (right or left hand). Ifma chin ing with a right hand cut ter (spin dle run ning in the for ward M03 di rec tion), ma chin ing an in ter -nal thread in a con ven tional mill ing man ner re quires a down ward, clock wise mo tion. This will ren der aright hand thread. If you wish to mill in a climb mill ing fash ion, you must thread in an up ward, coun ter -clock wise man ner. This will still ren der a right hand thread.

To ma chine a left hand thread, you will need a left hand thread mill ing cut ter (spin dle will be run ningcoun ter clock wise). Con ven tional mill ing will re quire a down ward, coun ter clock wise mo tion. Climb mill -ing will re quire an up ward clock wise mo tion.

Cut ter ra dius com pen sa tion - For con tour mill ing op er a tions, this fea ture al lows you to pro gram the work sur face (not the cut ter’s cen ter line path). The setup per son will spec ify the cut ter ra dius (or di am e ter) inthe tool’s cut ter ra dius com pen sa tion off set. Dur ing ma chin ing, the CNC con trol will keep the cut ter theap pro pri ate dis tance (the cut ter’s ra dius) away from the pro grammed sur faces. As with any other mill -ing op er a tion us ing cut ter ra dius com pen sa tion, you’ll be al lowed to size the sur faces be ing milled (thethread) by ad just ing the cut ter ra dius com pen sa tion off set.

He li cal in ter po la tion - This mo tion type is re quired for thread mill ing. It will cause the cut ter to movealong a cir cu lar path in two axes while mov ing in a straight path along the third axis. If ma c hin ing in theXY plane (G17) as you al most al ways will, X and Y will be gen er at ing the cir cu lar mo tion path while Zforms the straight path mo tion. He li cal in ter po la tion is con sid ered by Fanuc to be an op tion. While many ma chin ing cen ter man u fac tur ers in clude in their stan dard pack age of Fanuc op tions, you must con firmyour ma chines have he li cal in ter po la tion be fore you can thread mill.

Here’s a quick test you can per form to see if your ma chin ing cen ter has he li cal in ter po la tion: Manuallymove the axes to the mid dle of their trav els (at least 3-4 inches from the zero re turn po si tion in each axis)and give this com mand in man ual data in put (MDI) mode:

G17 G91 G02 I-1.0 Z-1.0 F30.0

Mod ule Num ber Four


This he li cal mo tion com mand tells the con trol to make a two-inch-diameter full cir cle clock w ise mo tion inXY while mov ing down one inch in Z at thirty inches per min ute. If the ma chine ex e cutes this com mand,it has he li cal in ter po la tion. But if it gen er ates an alarm (prob a bly hav ing to do with im proper plane se lec -tion) it does not have he li cal in ter po la tion.

Fanuc and Fanuc-compatible con trols use G02 and G03 for thread mill ing. As with cir cu lar mo tion, G02is clock wise mo tion and G03 is coun ter clock wise mo tion (in XY). The arc size can be spec i f ied with R or I& J and all rules re lated to mak ing cir cu lar mo tions still ap ply. A Z de par ture is also spec i fied along withthe feedrate.

Arc-in ap proach and es cape - As when mill ing coun ter-bored holes (just XY cir cu lar move ment), it is im -por tant to arc-in and arc-out to and from the thread be ing ma chined. If you don’t, a nasty wit ness markwill be left at the end point of the ap proach or the be gin ning point of the es cape. While a small wit nessmark may some times be ac cept able when mill ing a coun ter-bore, the wit ness mark left dur ing threadmill ing (with out an arc-in ap proach) will be much worse - so much worse that the thread will prob a bly beun ac cept able. As with the ma chin ing of the thread it self, the arc-in and arc-out ap proach m ust be in theform of a he li cal mo tion.

2. Thread mill ing cut tersWhile there will al ways be po ten tial in ter fer ence to deal with when ma chin ing in ter nal threads, anystyle of thread mill ing cut ter can ma chine both in ter nal and ex ter nal (fe male and male) threads. Thenext draw ing shows the three most com mon forms of thread mill ing cut ters. Each has its pros and consre lated to ef fi ciency and flex i bil ity.

Three styles of thread mill ing cut ters.

One (the one on the left) re sem bles a slot ting cut ter hav ing the thread form (60 de gree an gle) ma chinedinto its out side di am e ter. A vari a tion of this style of cut ter is a bor ing bar fly-cutter with the thread formma chined into the tool’s in sert. This is the least ex pen sive style of thread mill ing cut ter, since it can bemade right in the com pany from ex ist ing tool ing by the peo ple who need it. The ma jor ad van tage of thisstyle of cut ter is that it can ma chine threads with any pitch. The ma jor dis ad van tage is that it will re -quire sev eral cir cu lar passes to ma chine the thread to its spec i fied depth. For ex am ple, at least eightpasses will be re quired for a 2"-8 thread (hav ing a 0.125 pitch) ma chined through a one inch thickworkpiece (one inch thick di vided by 0.125 pitch). This does not in clude the arc-in and out ap p roach andes cape move ments.

The other two styles of thread mill ing cut ters are spe cif i cally made for thread mill ing. One (the one in themid dle) re sem bles a cross be tween a hog mill ing cut ter and a tap. Com monly made of high speed steel orco balt (they are also avail able in car bide), this type of cut ter is more ex pen sive, but it can ma chine to adepth of sev eral pitches in one pass around the thread. In many cases, the en tire thread can be ma chinedin one pass around (not in clud ing the ap proach and es cape). This, of course, dra mat i cally min i mizes cy -cle time as com pared to the pre vi ous style of thread mill ing cut ter (though no thread mill ing op er a tioncan beat the ef fi ciency of tap ping). One dis ad van tage (other than its higher price) is that this style ofthread mill ing cut ter can only ma chine one spe cific pitch. If made for a 0.125 inch pitch (eight threads per inch), for ex am ple, the thread mill ing cut ter can not ma chine a 0.0625 pitch (six teen threads per inch).One other lim i ta tion of this style of thread mill ing cut ter is that it is quite dif fi cult to sharpen. Many com -pa nies sim ply re place them when they’re dull.



The third style of thread mill ing cut ter (the one on the right) is be com ing the most pop u lar style since itover comes most of the lim i ta tions of the two pre vi ous styles. Its cut ting edge is pro vided by a car bide (orcoated car bide) in sert. The de sired pitch is ma chined into the in sert it self. If you need to ma chine athread with a dif fer ent pitch, you sim ply use a dif fer ent in sert. Since each in sert has the form of sev eralpitches, you can ma chine sev eral pitches in one pass around the thread. Again, you can usu ally ma chinethe en tire thread with one pass around (not in clud ing ap proach and es cape). This thread mill ing cut ter is also rel a tively eco nom i cal, since only the in sert is re placed when it gets dull. Tool main te nance (in sert re -place ment) is also faster for the same rea son. Since the in sert is made of car bide (not hss), it’s also quiteef fi cient, al low ing rather fast cut ting speeds.

Mul ti ple depths - If ei ther of the last two styles of thread mill ing cut ters can not ma chine a thread to its to -tal depth in one pass, re mem ber that mul ti ple passes can be eas ily made. The trick to do ing so is sim ply to make the sec ond (and suc ces sive) Z pass in even in cre ments of the thread’s pitch.

Right hand ver sus left hand threads - Only the first cut ting tool (the slot-milling cut ter style on the left)can ma chine both left and right hand threads. The other two styles must be spe cially made in right- orleft-hand ver sions. A right hand cut ter ma chines only right hand threads. This cut ter will be ro tat ing inthe for ward di rec tion (M03) as threads are ma chined. A left hand cut ter (ro tat ing in the re verse di rec -tion) will ma chine left hand threads.

A mis con cep tion about feeds and speeds - When it co mes to cut ting con di tions, some peo ple con fusethread mill ing with tap ping. As you know, tap ping re quires per fect syn chro ni za tion be tween feed andspeed (feedrate must be set to rpm times thread pitch). If feed and speed are not syn chro nized, the tapwill break. This kind of syn chro ni za tion is not re quired for thread mill ing. While you must ma chine withap pro pri ate cut ting con di tions, the feedrate will have noth ing to do with the thread’s pitch. Sim ply cal cu -late speed and feed as you would for any mill ing cut ter (use the rec om men da tions sup plied by the threadmill ing cut ter’s man u fac turer).

3. Your ap proach to thread mill ingThe ba sic ma chin ing prac tice of thread mill ing is based upon sev eral fac tors. Here we of fer a few sug ges -tions.

Climb or con ven tional mill ing? - This is prob a bly the most im por tant ques tion re lated to how you millthreads. While some light duty ma chines are in ca pa ble of climb mill ing (their way sys tems can not sup -port it with out vi bra tion), most ma chin ing cen ter have am ple ri gid ity to al low climb mill ing. Since climbmill ing pro vides better sur face fin ish, most pro gram mers use climb mill ing tech nique when e ver pos si ble. For right hand in ter nal threads (spin dle run ning for ward - M03), this means ma chin ing the thread in acoun ter clock wise (G03) di rec tion while com ing out of the hole (bot tom to top). For right hand ex ter nalthreads, this means ma chin ing the thread in a clock wise di rec tion (G02) while mov ing neg a tive in Z (topto bot tom). Re verse the cir cu lar mo tion for left hand threads (con ven tional mill ing re quires a down wardcoun ter clock wise di rec tion with the spin dle run ning in re verse M04).

Am ple cool ant (or air blow) to re move chips - Chips ma chined at the be gin ning of the thread ing op er a tioncan not be al lowed to in ter fere with ma chin ing at the end of the thread. If chips are al lowed to ac cu mu -late, it’s pos si ble that they will be re-machined sev eral times as the thread is ma chined. This can re sult in poor sur face fin ish, or worse, vari a tions in thread size. This prob lem can be most trou ble some on hor i zon -tal ma chin ing cen ters, since chips do not freely fall from the ma chin ing op er a tion. This is an other rea sonto climb mill in holes, es pe cially on ver ti cal ma chin ing cen ters. The up ward mo tion of the thread mill ingcut ter in Z will tend to make the cut ter avoid re-machining chips.

Blind or through hole? - This also has to do with chip re moval. Again, you must en sure that chips arewashed from the hole. This is eas i est to do with through holes, and es pe cially on ver ti cal ma chin ing cen -ters (chips will sim ply fall through the hole). How ever, if ma chin ing blind holes, it can be very dif fi cult towash chips out of the hole, es pe cially on ver ti cal ma chin ing cen ters. This is an other rea son to use climbmill ing (bot tom to top) tech nique. As the thread is ma chined, the thread mill ing cut ter will be com ing outof the hole. At the end of the thread mill ing op er a tion it will be one pitch higher than it was at the start.This pro vides ad di tional clear ance for chips. As long as your ma chine has the ri gid ity to climb mill, use abot tom to top mo tion (coun ter clock wise mo tion - G03) when thread mill ing blind holes on ver ti cal ma -chin ing cen ters.



Ap proach/es cape po si tion - This sug ges tion has to do with the po ten tial for chip in ter fer ence on hor i zon -tal ma chin ing cen ters (it is not a fac tor on ver ti cal ma chin ing cen ters). Since chip re m oval can be a prob -lem, we rec om mend start ing the thread mill ing op er a tion at the X mi nus side of the hole (the nine o’clockpo si tion as viewed from the spin dle nose) if mill ing from the hole bot tom to its top. With this method, youcan min i mize the amount of chips that will be at the Y mi nus side of the hole (six o’clock po si tion) whenthe thread mill ing cut ter passes by this po si tion. This can be es pe cially im por tant with blind holes whenchip re moval is most dif fi cult. A good cool ant sys tem, of course, will over come any prob lems re lated tochip re moval.

4. Pro gramming con sid er ationsSome (but not many) con trols have a spe cial canned cy cle for thread mill ing. Ad di tionally, i f your con trolhas para met ric pro gram ming, you can de velop your own spe cial thread mill ing cy cle (we’ll pro vide anthread mill ing ex am ple para met ric pro gram in a fu ture mod ule). If your con trol has para m et ric pro -gram ming, or if it has a spe cial cy cle for thread mill ing, by all means, study its use. These fea tures willdra mat i cally sim plify the com mands re lated to thread mill ing. This pre sen ta tion will as sume you do nothave ei ther fea ture.

As stated, Fanuc (and most con trol man u fac tur ers) use G02 and G03 for clock wise and coun ter clock wisehe li cal mo tion. And ev ery thing you know about pro gram ming cir cu lar mo tions still ap plies (end point isspec i fied in X and Y, R can be used to spec ify ra dius for mo tions up to 180 de grees, I & J can be used tospec ify full cir cle mo tion, etc.). But as we’ve also men tioned, a he li cal mo tion com mand ad di tion ally re -quires the spec i fi ca tion of a Z axis de par ture. This will cause the cut ter to move in a cir cu lar path in XYand a lin ear path in Z. The re sult re sem bles a cork screw mo tion. But the ra dius of the cork screw will re -main con stant (the ra dius changes in a true cork screw mo tion).

The trick to cor rectly pro gram ming thread mill ing op er a tions is match ing the Z axis de par ture dis tancein each he li cal mo tion com mand to the thread pitch. How much the thread mill ing cut ter must de part inZ is re lated to the per cent age of a full cir cle that is be ing com manded in XY. If mak ing a full cir cle move -ment in XY, for ex am ple, the thread mill ing cut ter must de part by the pitch of the thread in Z . If mak ing a half cir cle (180 de gree) move ment in XY, the thread mill ing cut ter must de part by one-half the pitch in Z.If mak ing a one-quarter cir cle (as is com monly the case when mak ing arc-in and arc-out mo tions) move -ment in XY, the thread mill ing cut ter must de part by one-quarter of the pitch in Z.

Re mem ber that arc in and arc out ap proach and es cape move ments must also be pro grammed with a he li -cal mo tion. If you al ways make arc in and arc out ap proach and es cape mo tions with one-quarter cir cle(90 de gree) mo tions, the Z axis de par tures dur ing ap proach and es cape mo tions will al ways beone-quarter of the pitch. But if you are try ing to min i mize cy cle time by keep ing the ap proach and es capepo si tions closer to the sur face be ing thread milled, you must de ter mine the per cent age of a full cir cle be -ing made dur ing the ap proach and es cape mo tions (in XY) in or der to cal cu late the ap pro pri ate Z de par -ture. The next draw ing stresses the point.

Arc-in mo tions. You must de ter mine the per cent age of a full cir cle in or der to de ter mine how much to make theZ axis move dur ing the he li cal mo tion.



The pre vi ous il lus tra tion, the left draw ing shows the thread mill ing cut ter mak ing a one-quarter (90 de -gree) arc in ap proach. If this thread has twelve threads per inch, the pitch is 0.0833 inch. Dur ing this ap -proach, since the mill ing cut ter is de part ing one-quarter of a full cir cle in XY, it must de p art one-quarterof the pitch (0.0208 inch) in Z. But no tice that the mill ing cut ter will be “cut ting air” dur ing much of thisap proach mo tion. The draw ing on the right shows how to min i mize this air cut ting time, but re quiresthat you know the per cent age of a full cir cle be ing com manded in XY. Since we’re de part ing one-eighth ofa full cir cle (45 de grees), this ap proach would re quire a de par ture in Z of one-eighth the pitch (1/8 of0.0833 is 0.0104 inch).

An ex am ple

The next il lus tra tion shows the draw ing to be used for the ex am ple pro gram.

Draw ing for thread mill ing ex am ple

We’ll be us ing a one inch di am e ter, right-hand thread mill ing cut ter that can ma chine the en tire threadin one cir cu lar pass (not in clud ing ap proach and es cape). To get the best fin ish, we’ll use climb mill ingtech niques (bot tom to top with coun ter clock wise - G03 - mo tion)

The thread mill ing cut ter will first be sent to the cen ter of the 0.75 inch ap proach ra dius (point 1) in X andY (X1.5, Y1.75) to be gin. Tool length com pen sa tion will then be in stated dur ing the cut ter’s Z axis ap -proach to a po si tion just above the work sur face in Z (Z0.1). Prior to be gin ning the se ries of he li cal mo -tions to ma chine the thread, we’ll po si tion the cut ter be low the bot tom of the workpiece in Z with enoughroom to make a full cir cle com ing up (Z-0.7). Cut ter ra dius com pen sa tion will be in stated on the move -ment from point one to two.

It can be a lit tle cum ber some to spec ify Z axis de par tures in the ab so lute mode, but that’s what our ex am -ple will. If you feel more com fort able do ing so, re mem ber that you can po si tion the XY mo tions in ab so lute mode while de part ing in Z in the in cre men tal mode. Con sider the fol low ing com mand.

N185 G90 G03 X1.5 Y2.5 R0.75 G91 Z-0.0312No tice how it causes the ma chine to move in the ab so lute mode (G90) for the XY de par ture, but in in cre -men tal for the Z de par ture. While not all con trols al low this tech nique, it can sim plify your thread mill -ing com mands if your con trol/s al low it.

For the move ment from point two to point three (1/4 cir cle), the cut ter must de part in Z by one-quarter ofthe pitch (0.0312 for this thread). Since the Z start ing po si tion for this mo tion is Z-0.7, the cor rect endpoint in Z for this ap proach mo tion will be Z-0.6688. On the move ment from point three to point four (1/2cir cle), it must de part one-half the pitch (0.0625 inch). The cor rect end point for point three will beZ-0.6063. For the move ment from point four to point five (1/2 cir cle again), the tool must de part an otherone-half the pitch (end point: Z-0.5438). And fi nally, as the tool arcs off the thread to point s ix (1/4 cir cle),



Mod ule five

5.1. In tro duc tion to para met ric pro gram mingPara met ric pro gram ming is the best kept se cret of CNC! There are few in this in dus try that even knowwhat para met ric pro gram ming is, and fewer still who know how to ap ply it. Though this is the case, al -most all CNC us ers have ex cel lent ap pli ca tions for para met ric pro gram ming, and as a con se quence, un -der-utilize their CNC equip ment. It is likely that your own CNC ma chine tool uti li za tion can bedra mat i cally im proved by in cor po rat ing para met ric pro gram ming tech niques in your CNC e n vi ron ment.

5.1.1. What is para met ric pro gram ming?

Para met ric pro gram ming goes by many names. Fanuc (or any con trol man u fac turer that claims to be100% Fanuc-compatible) calls it cus tom macro. Fadal calls it macro. Okuma calls it user task. Sodickcalls it Q rou tine. Kear ney & Trecker calls it ad vanced pro gram ming lan guage (APL) for their Gem inicon trols. Sharnoa calls it arithmetics. Some con trol man u fac tur ers have para met ric pro gram ming ca pa -bil i ties but have not named it with any spe cial name. Bridgeports Boss Se ries con trols, for ex am ple, haveex cel lent para met ric pro gram ming func tions yet these fea tures are sim ply in cluded with other G codelevel pro gram ming func tions.

Even within a given con trol man u fac tur ers prod uct line there may be vari a tions in para met ric pro gram -ming func tions. Fanuc, for ex am ple, has cus tom macro ver sion A and ver sion B, with ver sion B be ingmore pow er ful and eas ier to use. Which ver sion of cus tom macro you have is based on which con trolmodel you pur chase within Fanucs prod uct line. In sim i lar fash ion, Okuma of fers user task 1 and usertask 2, with user task 2 be ing more pow er ful and eas ier to use.

While the vari a tions from one ver sion of para met ric pro gram ming to an other lead to dif fer ences in spe -cific us age tech niques, the broader ap pli ca tions and us age for para met ric pro gram ming re main re mark -ably sim i lar. This is ev i denced by the fact that the ma jor ity of spe cific ap pli ca tions de scribed in this textcan be adapted to al most ev ery ver sion of para met ric pro gram ming just men tioned. Just as a given soft -ware ap pli ca tion can be han dled by a va ri ety of com puter pro gram ming lan guages (BA SIC, C Lan guage,PASCAL, etc.), so can a given CNC ap pli ca tion be han dled with a va ri ety of para met ric pro gram ming ver -sions.

5.1.1.1. Com par i son to subprogramming

The best way to get com fort able with any com plex sub ject mat ter is to com pare it to sim pler top ics withwhich you may al ready be fa mil iar. Para met ric pro gram ming is no ex cep tion. If, for ex am ple, you haveworked with the subprogramming func tions of your con trol, you have scratched the sur face of what canbe done with para met ric pro gram ming.

All CNC con trols have subprogramming func tions to al low com mands within the CNC pro gram to be re -peated. This min i mizes the num ber of com mands that must be given in the CNC pro gram. If, for in -stance, five iden ti cal pock ets must be milled in five workpieces on a ma chin ing cen ter dur ing the samecut ting cy cle, it would be cum ber some to pro gram each pocket in de pend ently. In stead, the pro gram mingcom mands nec es sary to ma chine but one of the pock ets can be pro grammed. These re dun dant com mands can be ex e cuted five times to ma chine the five pock ets, elim i nat ing many cum ber some, lengthy, and er ror prone com mands.

While the spe cific com mands re lated to subprogramming vary from one con trol man u fac turer to an other, one pop u lar con trol man u fac turer (Fanuc) uses an M98 to call a subprogram. A P word within the M98spec i fies the subprogram num ber. An L word spec i fies the num ber of ex e cu tions of the subprogram.With this con trol, the com mand

N050 M98 P1000 L5tells this con trol to ex e cute subprogram O1000 five times. As long as pro gram O1000 con tains the com -mands needed to cor rectly ma chine one of the pock ets, the pro grams length can be short ened and the po -ten tial for mis takes is re duced.

Subprogramming tech niques are ob vi ously very help ful. How ever, if any thing changes from one pocketto the next (width, height, depth, etc.), sim ple subprogramming tech niques can not be used. With outpara met ric pro gram ming, each pocket must be pro grammed in de pend ently. In ad di tion to giv ing the

Para met ric Programming


pro gram mer the abil ity to re peat re dun dant com mands, para met ric pro gram ming al lows any thing tochange from one ex e cu tion of the para met ric pro gram to the next. In the pocket ex am ple, if any pocket at -trib ute changes from one pocket to the next (width, height, depth, etc.) these vari a tions can be eas ily han -dled within the para met ric pro gram.

In this sense, para met ric pro gram ming gives the pro gram mer the abil ity to write a gen eral pur posesubprogram. If you have ever found your self wish ing you had the abil ity to write gen eral pur posesubprograms, you have an ap pli ca tion for para met ric pro gram ming.

As you will see in the next chap ter, the things that change from one pocket to the next are called ar gu -ments. Some ver sions of para met ric pro gram ming let you name the ar gu ments be ing passed to the para -met ric pro gram in a very log i cal man ner. Fanucs cus tom macro B, for ex am ple, uses a G65 com mand tocall the para met ric pro gram. Let ters of the al pha bet can be in cluded in this com mand to spec ify ar gu -ment val ues. In the com mand

N050 G65 P1000 X2.0 Y1.5 W4.0 H2.0 D.25G65 tells the con trol this is a cus tom macro call state ment. The P word still spec i fies the p ro gram num ber of the para met ric pro gram that does the pocket mill ing. X and Y are be ing used to spec ify the lower lefthand cor ner po si tion of this pocket along the X any Y axis. W is be ing used to spec ify the pocket width, His spec i fy ing the height of the pocket, and D is spec i fy ing the pocket depth.

No tice how log i cal this ver sion of para met ric pro gram ming makes the en try of val ues that change fromone pocket to an other. Any one can eas ily rec og nize the mean ings of X, Y, W, H, and D. If an other pocketof a dif fer ent size must be ma chined, an other G65 com mand can be eas ily spec i fied that con tains dif fer -ent ar gu ment val ues.

5.1.1.2. Com par i son to canned cy cles

All CNC con trol man u fac tur ers do their best to cre ate a se ries of spe cial pro gram ming fea tures to min i -mize the work a pro gram mer must do. Al most all CNC ma chin ing cen ter con trols, for in stance, comewith a stan dard set of hole ma chin ing canned cy cles (typ i cally spec i fied by G81-G89). Some ma chin ingcen ter con trols also have cer tain mill ing func tions like cir cle pocket mill ing, slot mill ing, thread mill ing,and face mill ing. Turn ing cen ters com monly come with a set of canned cy cles for rough & fin ish turn ingand bor ing, groov ing, hole ma chin ing, and thread ing.

Here are the com mands to drill a se ries of holes on one pop u lar ma chin ing cen ter con trol....N065 G54 G90 S400 M03 (Se lect co or di nate sys tem, ab so lute mode, and start spin dle)N075 G00 X1.0 Y2.0 (Rapid to first hole lo ca tion)N080 G43 H01 Z0.1 (In state tool length com pen sa tion, move to Z ap proach po si tion)N085 G81 R0.1 Z-0.75 F4.5 (Drill first hole)N090 X3.0 (Drill sec ond hole)N095 X5.0 (Drill third hole)N100 X7.0 (Drill fourth hole)N105 G80 (Can cel cy cle)N110 G91 G28 Z0 M19 (Re turn to Z axis ref er ence po si tion)...

In line N085, the first hole is com pletely ma chined based upon the con trols G81 func tion and the wordsin cluded in the com mand (R, Z, F, etc.). The con trol will per form a se ries of strictly planned mo tionsbased on the canned cy cles de sign. In the case of G81, the con trol will first rapid the tool to the XY po si -tion. Next it will rapid the tool to the R plane, plunge the tool to the hole bot tom, and re tract the tool fromthe hole. With G81, four move ments are gen er ated with one com mand. With other canned cy cles (likepeck drill ing) many move ments can be caused by one com mand.

Mod ule Five


No tice how sim i lar the G81 com mand for mat is to that of the pocket mill ing ex am ple call ing com mandshown ear lier (for ver sion B cus tom macro). The R, Z, and F words in the G81 (or any canned cy cle) arelike the ar gu ments be ing passed to the para met ric pro gram. You can think of all canned cy cles as be inglike para met ric pro grams writ ten and main tained by the CNC con trol man u fac turer.

If your con trol does not have a needed canned cy cle, or if you do not agree with how a given canned cy clefunc tions, you can de velop a para met ric pro gram to han dle the ap pli ca tion. In es sence, you can cre ateyour own canned cy cles! If you have ever wanted the abil ity to cre ate your own canned cy cles, you have an ap pli ca tion for para met ric pro gram ming.

5.1.1.3. Com par i son to com puter pro gram ming

If you have had ex pe ri ence with any com puter pro gram ming lan guage, you al ready know much of what isavail able with para met ric pro gram ming. There are many com puter-related fea tures of para met ric pro -gram ming that closely re sem ble the com puter pro gram ming lan guage BA SIC (or just about any othercom puter pro gram ming lan guage). These fea tures in clude vari ables, arith me tic, logic, and loop ing andare ex plained in de tail dur ing fu ture chap ters of part one. For now, suf fice it to say that most of what canbe done in BA SIC pro grams can be done within para met ric pro grams. By the way, if you have had no pre -vi ous ex pe ri ence pro gram ming in BA SIC, we again rec om mend that you pick up a be gin ners book on BA -SIC. It will re in force the pre sen ta tions we make for com puter-related fea tures of para met ricpro gram ming. If you have ever found your self wish ing you could in clude com puter-programming-likecom mands in your CNC pro gram, you have an ap pli ca tion for para met ric pro gram ming.

5.1.2. Ap pli ca tion cat e go ries

As stated in the pref ace, there are count less ap pli ca tions for para met ric pro gram ming, and al most ev eryCNC user has at least some good ap pli ca tions. In this dis cus sion, we or ga nize all ap pli ca tions for para -met ric pro gram ming into five ba sic cat e go ries.

Given the vast po ten tial ben e fits that can be at tained by uti liz ing para met ric pro gram ming, all CNC peo -ple should be able to rec og nize para met ric pro gram ming ap pli ca tions. In re al ity, this is far from true.The vast ma jor ity of CNC peo ple have never even heard of para met ric pro gram ming. Of those t hat have,few can rec og nize good ap pli ca tions (or have mis con cep tions of what re ally can be done). And fewer stillcan ac tu ally de velop a para met ric pro gram once an ap pli ca tion is rec og nized.

The first step to do ing any thing is know ing it is pos si ble. Be fore you can uti lize the au to -matic-frequency-searching-function of your ste reos FM tuner, you must first know it ex ists. In l ike man -ner, be fore you can solve any prob lem with para met ric pro gram ming tech niques, you must first knowwhich prob lems can be solved. In this dis cus sion, you will see many ap pli ca tions that can not be han dledwith nor mal G code level pro gram ming tech niques. In fact, many ap pli ca tions for para met ri c pro gram -ming are so re mark able that you may have trou ble be liev ing some of the claims we make. While we do not ac tu ally show how to han dle these ap pli ca tions in this in tro duc tory dis cus sion, rest as sured each will bewell doc u mented in fu ture chap ters.

5.1.2.1. Fam ilies-of-parts

Many CNC us ers ma chine a se ries of very sim i lar workpieces. Groups of sim i lar workpieces are com -monly called part fam i lies. Gen erally speak ing, all workpieces in a part fam ily closely re sem ble one an -other and re quire sim i lar (if not iden ti cal) ma chin ing op er a tions. In per fect part fam i lies, only the size ofeach workpiece changes.

Bolts, screws, nuts, wash ers, and pins, for ex am ple, are made in a va ri ety of sizes to suit the needs of in -dus try. The hex shaped sock ets a hand tool man u fac turer makes are made in var i ous sizes to ac ceptchang ing bolt and nut sizes. The rings a pis ton ring man u fac turer makes are made in var i ous sizes andused with a va ri ety of pis ton sizes. The list of com mon part fam i lies is vir tu ally un lim ited.

The sim i lar ity among workpieces in a fam ily com monly cor re sponds to the sim i lar ity of the ma chin ingpro cess used to ma chine each workpiece in the fam ily. For per fect part fam i lies, the same ma chin ing pro -cess and tool ing can be used to ma chine all workpieces in the fam ily. With con ven tional CNC pro gram -ming tech niques, this re sults in a large num ber of very sim i lar CNC pro grams. If you find your self



slightly mod i fy ing one CNC pro gram to cre ate an other, you have a fam ily-of-parts ap pli ca tion for para -met ric pro gram ming.

If you do any re peat busi ness, each hard and fixed CNC pro gram must be main tained. The larger thenum ber of workpieces in the fam ily, the more CNC pro grams are in volved. If an en gi neer ing change ismade to a part fam ily con tain ing thirty workpieces, thirty hard-and-fixed CNC pro grams must bechanged. Ad di tionally, the same ver i fi ca tion pro ce dures re quired for new CNC pro grams must be re -peated thirty times as the mod i fied pro grams are run for the first time. Many CNC pro gram mers, setuppeo ple, and op er a tors dread en gi neer ing changes for these rea sons.

In sim i lar fash ion, if you wish to make a CNC pro gram change to im prove qual ity, in crease tool life, re -duce ma chin ing time, or to achieve any im prove ment in the man u fac tur ing pro cess, the pro grams for allworkpieces in the part fam ily must be changed. This dra mat i cally lim its flex i bil ity and your abil ity to trynew things, since even mi nor im prove ments will in volve a great deal of work. All too of ten, pro cess im -prov ing changes are not in cor po rated due to the work in volved with mod i fy ing all of the pro grams in -volved.

With many fam ily-of-parts para met ric pro gram ming ap pli ca tions, only one base pro gram is re quired toma chine all workpieces in the en tire part fam ily. When ma chin ing a spe cific workpiece in the fam ily, ar -gu ments (vari ables) will spec ify the value of each chang ing el e ment within the part fam ily. In es sence,the para met ric pro gram within the CNC con trol is told which workpiece is cur rently be ing ma c hined.

How these chang ing ar gu ments are spec i fied var ies based on ap pli ca tion. In some com pa nies, the CNCop er a tor or setup per son man u ally changes these ar gu ments dur ing setup. With Fadals macro lan guage, it is even pos si ble to prompt for ar gu ments as the pro gram is ex e cuted. This func tion is pro grammedmuch like the IN PUT state ment of BA SIC.

In other com pa nies, a CNC pro gram mer pro grams the changes. For per fect fam ily-of-parts ap p li ca tions,be lieve it or not, a CNC pro gram con tain ing the ar gu ments can even be au to mat i cally cre a ted by the pro -duc tion con trol de part ment as a pro duc tion or der is is sued. More on how ar gu ments can be passed to thepara met ric pro gram in fu ture chap ters.

As you can imag ine, this dra mat i cally sim pli fies the long term pro gram ming of in di vid ual workpieces(once the para met ric pro gram is de vel oped) and al lows for un lim ited mod i fi ca tions to be made right atthe CNC con trol, which dra mat i cally in creases flex i bil ity. In deed, go ing from one size workpiece to an -other is so sim ple that many com pa nies al low their CNC op er a tors to make the needed changes. Ad di -tionally, mod i fi ca tions that af fect the en tire part fam ily (en gi neer ing and op ti miz ing changes) are mucheas ier to make. Only one pro gram need be changed!

1. How are your prints dimensioned?Some com pa nies uti lize vari able dimensioning tech niques for dimensioning a fam ily-of-parts. The de -sign en gi neer will di men sion will di men sion val ues that change with a let ter of the al pha bet. Any per sonview ing the draw ing will de ter mine the value of a given di men sion by ref er enc ing a chart in cluded on thedraw ing. Based upon know ing the workpieces part num ber, any one can find the val ues of each vari abledi men sion. Fig ure 1.1 shows an ex am ple of this kind of fam ily-of-parts dimensioning. If your com panyuses vari able dimensioning tech niques, you have a fam ily-of-parts ap pli ca tion for para met ric pro gram -ming.

Mod ule Five


Fig ure 1.1

No tice in fig ure 1.1 that di men sions are spec i fied with let ters (A, B, C, etc.). Some ver sions of para met ricpro gram ming even al low you to des ig nate the value of each ar gu ment to be passed to the para met ric pro -gram with the same let ters as are used on the print. To spec ify that part num ber SC-0875 in fig ure 1.1 isbe ing made, for ex am ple, here is one way to do so by us ing Fanucs cus tom macro B.

N060 G65 P1000 A1.375 B0.875 C0.437 D0.1875In this ex am ple, no tice how ar gu ments A, B, C, and D di rectly cor re spond to print di men sions (D spec i fies the top hole di am e ter, which in turn, de ter mines how the rest of the hole must be ma chined). Thoughthere may be other chang ing at trib utes to be han dled by the para met ric pro gram mer for this ap pli ca tion(speed & speed vari a tions, tool sta tion num bers, etc.), this ex am ple com mand should nicely stress howeasy it is to spec ify which workpiece is to be ma chined.

The more workpieces in a part fam ily, the eas ier it is to jus tify para met ric pro gram ming tech niques.Keep in mind, how ever, para met ric pro grams do take lon ger to write than con ven tional CNC pro grams.From a strictly pro gram ming-time-based jus ti fi ca tion stand point, it may be hard to jus tify writ ing apara met ric pro gram for part fam i lies hav ing but a few workpieces. Even for sim ple workpieces, it willtake from 3-5 times as long to write the para met ric pro gram as it will to write a hard and fixed CNC pro -gram for one workpiece in the part fam ily.

Fam ily-of-parts pro gram struc ture

Though we may be get ting a lit tle deeper into spe cific is sues than we should dur ing this in tro duc tion ofap pli ca tion cat e go ries, we wish to in tro duce an im por tant point rel a tive to fam ily-of-parts ap pli ca tions.Most fam ily-of-parts ap pli ca tions for para met ric pro gram ming re quire but one pro gram, com monlycalled the main pro gram. While other pro grams could be in volved, the main pro gram is the para met ricpro gram for part fam ily ap pli ca tions. The ar gu ments that spec ify the val ues of each chang ing el e ment ofthe part fam ily are com monly listed at the very be gin ning of this pro gram. These val ues will be ref er -enced later in the pro gram, when ever they are needed. More on the dif fer ent meth ods of ar gu ment as -sign ment in fu ture chap ters.



5.1.2.2. User cre ated canned cy cles

Even if your companys prod ucts con tain no part fam i lies, it is quite likely that you have at least some sim -i lar ma chin ing op er a tions that oc cur on sev eral workpieces. Para met ric pro gram ming can dra mat i callystream line the pro gram ming of re peated ma chin ing op er a tions. Many ma chin ing op er a tions are sim i larin na ture and eas ily han dled with para met ric pro gram ming tech niques. Here are some ex am p les youshould eas ily rec og nize.

Ma chining cen ters:Thread mill ingRound pocket mill ingRect an gu lar pocket mill ingCir cle mill ingFace mill ingKeyway mill ingSlot mill ingHole ma chin ing (drill ing, tap ping, ream ing, bor ing, etc.)Hole pat terns (bolt hole cir cle, grid pat tern, win dow pat tern, etc.)Turn ing cen ters:Groove neck ingTapping (many turn ing cen ters do not have this cy cle)Deep hole peck drill ing (many turn ing cen ters do not have this cy cle)Knurling

These ma chin ing op er a tions are quite com mon and many con trol man u fac tur ers have de vel o ped cannedcy cles to han dle at least some of them. While con trol-manufacturer-created canned cy cles are ex tremelyhelp ful, you know that they are fixed in their func tion. If you do not like the way they work, t here is lit tleyou can do about it. For ex am ple, the ma chin ing cen ter G83 deep hole drill ing cy cle is quite lim ited onmost con trols. Most con trols do not al low you to change the depth of each suc ces sive peck as the hole getsdeeper. Most do not al low you to com bine the chip break ing cy cle (G73 on many con trols) with the deephole drill ing cy cle. And the method by which the num ber of passes and the depth of each pass are cal cu -lated may not be to your lik ing.

If you have ever found your self wish ing that your con trols canned cy cles worked dif fer ently, you have anuser-created canned cy cle ap pli ca tion for para met ric pro gram ming. Be lieve it or not, para met ric pro -gram ming ac tu ally gives you a way to im prove upon the canned cy cles that come with your ma chine tool.

In ad di tion to mod i fy ing the method by which your cur rent canned cy cles work, you have the ad di tionalabil ity to cre ate your own canned cy cles with para met ric pro gram ming. Most ma chin ing cen ter con trols, for ex am ple, do not have a canned cy cle for thread mill ing. If you per form thread mill ing on a reg u lar ba -sis and if your con trol does not have a thread mill ing cy cle, you are likely writ ing many te dious, re dun -dant, and er ror prone com mands. With para met ric pro gram ming, you can cre ate your own threadmill ing canned cy cle!

In sim i lar fash ion, most turn ing cen ter con trols do not in clude an ad e quate canned cy cle to ma chinegrooves. If you must neck grooves in many workpieces and if your con trol does not have a canned cy cle forgroov ing, again, you must write many te dious, re dun dant, and er ror prone com mands. With para met ricpro gram ming, you can cre ate your own groov ing cy cle!

Many com pa nies per form rather un usual op er a tions that are spe cific only to their own prod ucts andman u fac tur ing pro cesses, and no con trol man u fac turer will con sider cre at ing canned cy c les for ma chin -ing op er a tions that are not help ful to the ma jor ity of their us ers. Rel a tively few ma chin ing cen ter us ers,for ex am ple, ma chine dove tails. This ma chin ing op er a tion nor mally re quires a num ber of suc ces sivemill ing passes with a dove tail cut ter. As when chas ing a thread on a turn ing cen ter, the num ber of passes and the depth per pass changes based on dove tail size, cut ter ma te rial and ri gid ity, and workpiece ma te -rial. If you ma chine dove tails, you have likely found there is no stan dard canned cy cle to help with thesete dious and er ror prone com mands. Wouldnt it be nice if you could com mand this op er a tion to be com -pleted with one sim ple com mand? With para met ric pro gram ming, you can cre ate your own dove tail mill -ing canned cy cle!

Mod ule Five


6.1. Setup time re duc tion prin ci plesMaking a setup is a nec es sary sup port task. It does noth ing to add value to your prod uct. While all CNCpeo ple will agree that any thing that can be done to re duce setup time should be done, com pa nies vary dra -mat i cally with re gard to the lengths they will go to re duce setup time. Prod uct pro duc ing man u fac tur ingcom pa nies tend to heavily staff their CNC en vi ron ments. Their goal is to keep the CNC ma chine toolsrun ning for as high a per cent age of time as hu manly pos si ble. Any un nec es sary down time is seen as awaste of time and they tend to do what ever it takes to elim i nate as much down time as pos si ble. On theother hand, con tract shops tend to min i mize the num ber of peo ple in their CNC en vi ron ments. A con tract shop tends to com pro mise wasted ma chine time dur ing setup for the abil ity to han dle all CNC re latedtasks with as few peo ple as pos si ble.

Re gard less of the com pany type, setup time is com monly viewed as lost pro duc tion time, and all com pa -nies should be highly in ter ested in min i miz ing this lost time. In this chap ter, we in tro duce the ba sic prin -ci ples of setup time re duc tion. These prin ci ples can be ap plied to any form of man u fac tur ing equip ment,in clud ing CNC ma chine tools. In the next chap ter, we will of fer many spe cific tech niques that can be ap -plied to re duc ing setup time on your CNC ma chin ing cen ters and turn ing cen ters. Some of these prin ci -ples will even be help ful dur ing our dis cus sion of cy cle time re duc tion in chap ter nine.

6.1.1. The im por tance of re duc ing setup time

The num ber of workpieces you make per pro duc tion run (quan tity) is the pri mary fac tor that dic tates how im por tant it is that you re duce setup time. The higher your pro duc tion quan ti ties, the greater the per -cent age of time that the ma chine will be in pro duc tion and the fewer the num ber of needed set ups. Withvery high pro duc tion quan ti ties, it may be pos si ble that as lit tle as five per cent (or less) of the ma chinesover all pro duc tion will be spent in setup. There are CNC ma chines, in fact, that are ded i cated to run ningonly one workpiece. Once the jobs setup has been made once, the ma chine will never be in setup again.

For com pa nies that spend less than about ten per cent of a given CNC ma chines time in setup, any re duc -tion in setup time will have but a small im pact on the ma chines over all uti li za tion. While setup time re -duc tion may still be con sid ered some what im por tant, we would rec om mend con cen trat ing on re duc ingcy cle time (the sub ject of chap ter nine) as a way of im prov ing the CNC ma chines uti li za tion.

By far, the vast ma jor ity of CNC us ers run rel a tively low pro duc tion quan ti ties rang ing from one to fivehun dred workpieces. In deed, one of the pri mary rea sons for us ing CNC ma chine tools in the first place istheir abil ity to ef fi ciently run small lot sizes. In fact, many com pa nies (es pe cially in toolroom and pro to -type en vi ron ments) run only one workpiece per pro duc tion run. Fig ure 1.1 de picts the two ex tremes re -lated to per cent age of time spent in setup ver sus per cent age of time run ning pro duc tion.

Fig ure 1.1

It is likely that your com pany cur rently spends much more than five per cent of a given ma chines pro duc -tion time in setup. The greater the per cent age of time spent in setup, the more im por tant it will be that


Setup Time Reduction

Production Run95.0%

Time In Setup5.0%

Production Run5.0%

Time In Setup95.0%

LargeQuantities

SmallQuantities

you stream line your companys setup pro ce dures to re duce setup time, and the more your com pany should be will ing to in vest to achieve this goal. Achieving this goal will re sult in in creas ing the ma chines over allper cent age of time spent ma chin ing workpieces, the value added time.

Keep in mind that the ex tremes in workpiece quan ti ties pres ent spe cial prob lems for in cor po rat ing setuptime re duc tion tech niques. For ul tra-high pro duc tion quan ti ties, we al ready men tioned that so lit tle ofthe ma chines pro duc tion time will be in setup that it would be wiser to con cen trate on re duc ing cy cle timeor workpiece load ing time. How ever, very low pro duc tion quan ti ties also pres ent spe cial prob lems forsetup time re duc tion. Many of the setup time re duc tion tech niques we show de pend on hav ing peo pleper form cer tain setup re lated tasks dur ing the pro duc tion run. If run ning only one or two workpieceswith a short cy cle time, it is likely that noth ing can be done dur ing the pro duc tion run to get ready for thenext setup.

Aside from pro duc tion quan ti ties, a sec ond fac tor that con trib utes to just how im por tant it will be to re -duce setup time is the through-put of workpieces in your com pany. If your com pany in cor po rates just intime (JIT) tech niques, it will be very im por tant to en sure that workpieces ar rive at each point along theman u fac tur ing pro cess when planned. Any en hance ments that al low setup time re duc tion will help toen sure the flow of workpieces.

Re gard less of how im por tant it is that you re duce setup time, do ing so can be quite chal leng ing. Given the wide va ri ety of man u fac tur ing meth ods used to day, each com pany will have its own spe cial ob sta cles toover come. Cer tain ma chine tools, for ex am ple, lend them selves to quick set ups better than oth ers. Barfeed turn ing cen ters are gen er ally quicker and eas ier to setup than hor i zon tal ma chin ing cen ters. Di ver -sity of work also pres ents spe cial setup re lated prob lems. Com panies that pro duce fam i lies of parts willgen er ally find it eas ier to min i mize setup time than those who pro duce a wide va ri ety of very dif fer entworkpieces. Avail able per son nel is yet an other vari able in the setup time equa tion. The more peo ple youhave avail able in your CNC en vi ron ment, the eas ier it will be to in cor po rate setup time re duc tion tech -niques. Even some thing as ba sic as the age of your ma chine tools can af fect how dif fi cult it will be to re -duce setup time. The state-of-the-art in CNC tech nol ogy is con stantly chang ing. Newer ma chines havefunc tions de signed to help min i mize setup time.

6.1.2. Jus ti fi ca tion for setup time re duc tion

Any setup time re duc tion pro gram will cost some thing. Even if you or your peo ple are sim ply ap ply ing atech nique that does not re quire a pur chase of some new de vice, the time it takes to in cor po r ate and testthe tech nique must be con sid ered. De pending on how your com pany op er ates, you may have to pro videjus ti fi ca tion for the time, per son nel, and money your com pany must in vest in the setup time re duc tionpro gram. Doing so re quires an un der stand ing of ba sic jus ti fi ca tion prin ci ples.

Given the high cost of CNC ma chine uti li za tion, it should be rel a tively easy to jus tify most setup time re -duc tion tech niques, es pe cially those that re quire an in vest ment in only time and ef fort. Since we aretalk ing about jus ti fy ing setup time re duc tion, your jus ti fi ca tion must be time based, mean ing you mustknow the shop rate of the ma chine tool/s in volved.

When you have a setup time re duc tion tech nique that re quires jus ti fi ca tion, first cal cu late how muchyour setup/s cur rently cost. Based on the ma chines shop rate and know ing how long it takes to make agiven setup, you can eas ily cal cu late this cost. Based on know ing how many times the setup is made perweek, month, year, etc., you can de ter mine how much your com pany spends on a given setup. If the im -prove ment you in tend to make will be ap plied to sev eral set ups, be sure to re peat this pro cess for each.

Sec ond, ap prox i mate the sav ings in time your im prove ment will pro vide per setup. You should be able toeas ily cal cu late an ex pected sav ings based on the time saved, the ma chines shop rate, and the to tal num -ber of set ups in volved. Com pare the po ten tial sav ings to the cost for im ple men ta tion in or der to de ter -mine if your setup time re duc tion tech nique is jus ti fi able.

Re mem ber that a sav ings in setup time pro vides an equiv a lent in crease in pro duc tion time, mean ing re -duc ing setup time pro vides a dou ble ben e fit. Not only are you sav ing ma chine time, you are in creas ingthe ma chines pro duc tive time. Re mem ber to fac tor this added sav ings into your setup time jus ti fi ca tionequa tion.


Mod ule Six

We can not stress enough the im por tance of know ing your cur rent costs re lated to mak ing set ups as yoube gin any setup time re duc tion pro gram. Only by know ing your cur rent costs can you jus tify any in vest -ment in per son nel, time, ef fort, or equip ment needed to re duce it.

6.1.3. The re la tion ship be tween pro duc tion quan ti ties, pro cess, and setup time

As stated, the num ber of workpieces to be pro duced per pro duc tion run has the great est im pact on howim por tant it is that you re duce setup time. In deed, pro duc tion quan ti ties dra mat i cally im pact all im por -tant de ci sions made for ma chin ing of a given workpiece, in clud ing the pro cess by which the workpiece ispro duced.

Pro duc tion quan ti ties, pro cess, and setup de sign are very closely re lated. The num ber of workpieces to be pro duced is the larg est sin gle fac tor that de ter mines how the pro cess should be en gi neered. Gen erallyspeak ing, the more workpieces to be ma chined, the more im por tant it is that workpieces be ma chined ef -fi ciently, re sult ing in a more elab o rate pro cess.

If, for ex am ple, only twenty-five workpieces are to be ma chined, the only real pri or ity may be ma chin ingac cept able workpieces. The pro cess en gi neer will use stan dard cut ting tools, and un less un avoid able,noth ing spe cial will be pur chased for such a low pro duc tion quan tity. On the other hand, if one thou sandworkpieces are to be ma chined in one pro duc tion run, the pro cess en gi neer will likely de sign a com pletelydif fer ent pro cess. In stead of sim ply hav ing to pro duce ac cept able workpieces, ac cept able workpiecesmust be pro duced ef fi ciently. The higher the pro duc tion quan ti ties, the higher the em pha sis on ef fi -ciency. Much more en gi neer ing will go into the pro cess to min i mize ma chin ing time. The pu r chase ofspe cial com po nents re lated to the setup in clud ing spe cial cut ting tools, fix tures, and pos si bly even ma -chin ery can be jus ti fied if pro duc tion quan ti ties are high enough.

Just as pro duc tion quan ti ties de ter mine how elab o rate the pro cess must be, so does the pro cess de ter -mine how elab o rate the setup must be. Be cause quan ti ties are very high for a given job, for ex am ple, thepro cess may call for mul ti ple workpieces to be ma chined in one ma chine cy cle. This, of course, re quiresthe workholding setup to be ca pa ble of hold ing mul ti ple workpieces.

In sim i lar fash ion, just as the qual ity of the pro cess dic tates the re sult ing cy cle time, so is setup time aslave to the pro cess. Gen erally speak ing, the over all qual ity and so phis ti ca tion of the setup will be a sim -ple re flec tion of the pro cess, which is in turn a re sult of the num ber of workpieces to be ma chined.

As a sim ple anal ogy, we com pare the re la tion ship of pro duc tion quan ti ties, pro cess en gi neer ing, andsetup de sign to match ing tires to your au to mo bile. Your tires should be cho sen to match the kind of caryou drive. If you drive a sports car, the qual ity of your tires must re flect the high per for mance ca pa bil i ties of your car. If you buy tires that were de signed for a fam ily car, the tires will be the weak link in yoursports cars per for mance. If, on the other hand, you drive a fam ily car, pur chas ing high per f or mance tireswould be over-kill. The fam ily car now be comes the weak link. Just as tires must be cor rectly matched toan au to mo bile to en sure that there are no weak links in the cars per for mance, so must pro duc tion quan ti -ties, pro cess, and setup be matched to en sure that there are no weak links in the man u fac tur ing pro cess.

The en gi neer ing ef fort that goes into the de sign of the setup plays the big gest role in de ter min ing howquickie the setup can be made. Just as ev ery pro cess could be en gi neered to al low the ab so lute min i mumcy cle time, so can ev ery setup be en gi neered to al low the ab so lute min i mum setup time. How ever, fea si -bil ity, based on pro duc tion quan ti ties, lim its how much en gi neer ing goes into the pro cess. In sim i larfash ion, fea si bil ity, based on the pro cess, lim its the en gi neer ing that goes into the de sign of the setup.

Though the de sign of the setup plays a ma jor role in de ter min ing setup time, cut ting tool and fix ture de -sign is be yond the scope of this text. While we freely ac knowl edge its im por tance in re duc ing setup time,we limit our scope to of fer ing spe cific CNC tech niques to re duce setup time.

6.1.4. Setup time de fined

Our broad def i ni tion of setup time goes like this: Setup time it the time it takes to go from mak ing the lastworkpiece in the pre vi ous setup to ef fi ciently mak ing the first good workpiece in the next setup. Since the ma chine tool is down (not run ning pro duc tion), any thing that hap pens be tween pro duc tion runs must becon sid ered as setup time.



Here are some tasks com monly as so ci ated with set ting up CNC ma chine tools.Tear-down of old setupMaking of workholding setupTool as sem blyTool mea sure ment (if re quired)Tool load ingPro gram zero mea sure mentOff set en try for tool ing in for ma tionOff set en try for pro gram zero in for ma tionPro gram load ingPro gram ver i fi ca tionFirst workpiece in spec tionMod i fi ca tions based on first piece in spec tionOp ti mizing pro gram (for higher pro duc tion quan ti ties)

By our def i ni tion, sev eral tasks af fect setup time that you may not feel are truly part of a CNC ma chinesetup. Pro gram ver i fi ca tion, for ex am ple, though it is not ac tu ally part of the workholding or cut ting toolsetup, keeps pro duc tion from run ning and must be con sid ered as setup time. First workpiece in spec tion,as well as the time it takes to make ad just ments to the CNC pro gram in or der to get a workpiece to passin spec tion, holds up pro duc tion and must be con sid ered as setup time. Pro gram op ti miz ing time, thoughit may dra mat i cally im prove cy cle time, also holds up pro duc tion and must be con sid ered as part of thesetup. Time spent search ing for tools, in serts, gauges, fix tures, and any thing else needed dur ing thesetup, must be con sid ered as setup time. Even lunch, breaks, and all forms of per sonal time, if takenwhile a ma chine is down in setup, must be con sid ered as setup time - and com pa nies pay an ex tra pen altyfor per sonal time taken dur ing the setup of CNC ma chines that can run un at tended, like bar-feedingturn ing cen ters. These ma chines can nor mally be run ning pro duc tion even dur ing breaks, lunch andother per sonal time.

Though some of these func tions have noth ing to do with set ting up a CNC ma chine tool, most are nec es -sary sup port tasks that hold up pro duc tion - and any thing that can be done to min i mize these tasks willef fec tively re duce setup time.

6.1.5. Find ing a place to start

As you con sider setup time re duc tion for any kind of ma chine tool, you should be gin by an a lyz ing yourcur rent setup pro ce dures. This will pro vide a point of ref er ence for any changes you make and, if donecor rectly, it will usu ally help you to set pri or i ties with re gard to what changes will have the big gest im -pact on setup time.

We rec om mend in volv ing ev ery one in volved with de sign ing and mak ing set ups in your anal y sis. Themore ex perts you in volve, the more po ten tial you have for find ing the best, most fea si ble sug ges tions andso lu tions. To pro vide you with some thing to an a lyze, we rec om mend video-taping the cur rent setup/s inques tion. Again, be sure to in vite ev ery one to an a lyze and cri tique the video/s.

You will find that some setup tasks dur ing setup take lon ger to per form than oth ers. The first step will beto iso late each task in the setup pro cess to de ter mine what per cent age of the over all setup each tasktakes. When fin ished, you can eas ily il lus trate the tasks re lated to the setup by mak ing a g raph sim i lar to the one shown in Fig ure 1.2. This makes it very clear to ev ery one in volved in your anal y sis just how much time each task takes and makes an ex cel lent start ing point for your setup time re duc tion ef fort. Thosetasks that take the most time gen er ally of fer the most po ten tial for im prove ment.


Mod ule Six

Fig ure 1.2

Since it takes time to video-tape the setup and or ga nize the re sults, you may be tempted to by p ass thesesteps and pro ceed di rectly to in cor po rat ing the setup time re duc tion tech nique we show in the next chap -ter. Or you may be tempted to by pass these steps be cause you think you know what your setup peo ple arecur rently do ing. We urge you to avoid this temp ta tion for three rea sons. First of all, with no point of ref -er ence, you will have no way of gaug ing the im pact of the setup time re duc tion ef fort. Sec o nd, with outthis anal y sis, it is likely that you will not come up with the best so lu tions to your par tic u lar setup prob -lems. Third, and most im por tantly, an a lyz ing ac tual set ups is the only way of truly see ing ex actly howlong setup re lated tasks truly take. If you have never in cor po rated setup time re duc tion tech niques, youwill prob a bly be very (un pleas antly) sur prised at just how much wasted time there is in your set ups.

6.1.6. The two types of setup tasks

There are only two types of tasks re lated to mak ing set ups - those that are per formed while the ma chineis down be tween pro duc tion runs and those that are per formed up-front, prior to the ma chin ing of the last workpiece in the cur rent pro duc tion run. Tasks that are done while the CNC ma chine is down are calledon-line tasks (also called in ter nal tasks). Tasks that are done in prep a ra tion for the next setup are calledoff-line tasks (also called ex ter nal tasks).

Some tasks that are com monly per formed as on-line tasks in clude tear ing down the old work hold ingsetup, mak ing the new work hold ing setup, load ing cut ting tools, mea sur ing cut ting tool lengths, mea -sur ing pro gram zero, en ter ing off set val ues for cut ting tools and pro gram zero as sign ment, load ing theCNC pro gram, ver i fy ing the CNC pro gram, and in spect ing the first workpiece. Some tasks that are com -monly thought of as off-line tasks in clude pro gram ming, cut ting tool as sem bly, and lo cat ing fix tures,gauges, and other tools needed for the next setup.

Com panies vary dra mat i cally with re gard to which tasks they per form on- or off-line. In deed, the size ofthe com pany, the num ber of peo ple in the CNC en vi ron ment, and the en gi neer ing that goes into the de -sign of the setup are but a few of the fac tors that con trib ute to which tasks should be on-line and whichshould be off-line. Though this is the case, you must un der stand that the ac tual time your CNC equip -ment is down be tween pro duc tion runs (setup time) is the sum-total of the on-line tasks. Your CNC ma -chine must be down (not pro duc tive) dur ing on-line tasks. It can be run ning pro duc tion dur ing off-linetasks.

6.1.7. The three ways to re duce setup time

There are only three gen eral ways to re duce the time it takes to go from one pro duc tion run to the next,mean ing ev ery setup time re duc tion tech nique we show will fit into one of these three cat e go ries:

1) Elim i nate on-line tasks2) Move on-line tasks off-line3) Fa cil i tate on-line tasks



Since setup time is the sum-total of on-line tasks, when ever you elim i nate an on-line task or move itoff-line, you ef fec tively re duce setup time by the length of time it was tak ing to per form the tasks on-line.For this rea son, min i miz ing the num ber of on-line tasks that must be per formed dur ing setup should bethe high est pri or ity of any setup time re duc tion pro gram. By fa cil i tat ing the on-line tasks, we mean thatyou must make it as easy (and ef fi cient) as pos si ble for the setup per son to per form on-line tasks. In thischap ter, re mem ber that we are sim ply in tro duc ing setup time re duc tion e con cepts. In chap ter eight, wewill dis cuss in much greater de tail how they ap ply to CNC equip ment.

6.1.7.1. Elim i nating on-line tasks

By elim i nat ing on-line tasks, we mean find ing ways to make a setup with out need ing to per form cer tainon-line tasks. Though your so lu tion/s that elim i nate on-line tasks can some times in volve spend ingmoney, it usu ally takes lit tle more than in ge nu ity and the de ter mi na tion not to give up un til an an swer isfound.

The evo lu tion of CNC tech nol ogy in re cent years has a lot to do your abil ity to elim i nate tasks that havebeen tra di tion ally done on-line. Newer CNC con trols of fer fea tures that elim i nate the need to per formcer tain tasks. One ex am ple of elim i nat ing an on-line task is re lated to the mea sur ing pro gram zero po si -tions for ma chin ing cen ter pro grams (this is shown in much greater de tail in chap ter eight). Many com -pa nies re quire their setup per son to mea sure the pro gram zero po si tions for each setup they make. Thison-line task in volves tak ing three mea sure ments (one for X, one for Y, and one for Z) for each pro gramzero po si tion used within the pro gram. For hor i zon tal ma chin ing cen ter ap pli ca tions when ma chin ing on sev eral sur faces, this can re quire sev eral mea sure ments - re sult ing in a great deal of wasted setup time.

By in cor po rat ing cur rent fix ture off set tech niques al lowed by todays CNC con trols, it is likely that thesere dun dant mea sure ments taken dur ing setup can be elim i nated. If some crit i cal ma chine mea sure ments are taken once, early on in the ma chines use, the re sults of these mea sure ments can be used for ev erysetup made. For ex am ple, the lo ca tion of the ma chine ta bles keyslots and crit i cal lo ca tion sur faces can bemea sured one time. If your work hold ing tool ing is keyed to the ta ble us ing these keyslots, the pro gram -mer will be able to eas ily cal cu late the lo ca tion of each pro gram zero po si tion, elim i nat ing the on-line task of mea sur ing pro gram zero for ev ery setup made. The pro gram mer can even in clude fix ture off set set tingcom mands in the pro gram, keep ing the setup per son from hav ing to en ter fix ture off set val ues man u ally,elim i nat ing an other on-line task. Pro gramming fix ture off set val ues in this man ner also elim i nates thepos si bil ity for en try er rors of fix ture off set val ues.

In ge nu ity and a thor ough un der stand ing of your CNC ma chines func tions and fea tures are the keys toelim i nat ing on-line tasks. By scour ing your CNC con trols pro gram ming man ual, and with the as sis tance of your ma chine tool build ers ap pli ca tion en gi neers, you may be sur prised at how easy and i n ex pen sive itcan be to elim i nate most on-line tasks - and given un lim ited fi nan cial re sources, any on-line task can beelim i nated.

6.1.7.2. Moving on-line tasks off-line

The sec ond way to re duce setup time is to move the tasks you are cur rently per form ing on-line to off-line.In stead of per form ing setup tasks while the ma chine is down be tween pro duc tion runs, do as much as you can up-front, be fore it co mes time to ac tu ally make the next setup. While the task still has to be per -formed, at least the CNC ma chine tool can still be pro duc ing workpieces. It is not down, wait ing for thetask to be ac com plished.

One ex am ple of mov ing an on-line task off-line (many more will be shown in chap ter eight) is re lated totool length com pen sa tion on a ma chin ing cen ter. If you are cur rently mea sur ing tool length val ueson-line (re gard less of how ef fi cient your tool length mea sur ing tech niques), you can re duce setup time bymov ing the task of tool length mea sure ment off-line. A tool length mea sur ing gauge (a height gauge, forex am ple) can be used to de ter mine the length of each tool. Each tools length can be writ ten down so theop er a tor can eas ily en ter the tool length value (off set) dur ing the setup. Or better yet, the tool lengthmea sur ing gauge can be at tached (via a se rial port) to a per sonal com puter. As soon as a tool length ismea sured, it can be re corded by the com puter and en tered (au to mat i cally) into a pro gram as part of a tooloff set set ting com mand. Using dis trib u tive nu mer i cal con trol (DNC) tech niques, the off set set ting pro -


Mod ule Six

Mod ule seven

7.1. Cy cle time re duc tionDur ing our in tro duc tion to setup time re duc tion tech niques, we dis cussed how workpiece quan ti ties dic -tate the ef fort that goes into the pro cess. As you know, the higher the pro duc tion quan ti ties, the moreelab o rate the pro cess should be. The better the pro cess, the shorter the cy cle time. We can not stress thisenough. The higher the pro duc tion quan ti ties, the greater the em pha sis that must be placed o n min i miz -ing cy cle time. How short a given CNC cy cle can be is based pri mar ily on the qual ity of pro c ess ing thatgoes into the op er a tion. While we freely ad mit that pro cess ing is the most im por tant facet of the CNC op -er a tion, as we said dur ing the in tro duc tion to setup time re duc tion prin ci ples, it is not within the scope ofthis text to ad dress pro cess ing re lated is sues. We limit our dis cus sion of cy cle time re d uc tion tech niquesto those that can be ap plied af ter a good pro cess has been de vel oped.

Video tap ing is a very im por tant tech nique in tro duced dur ing our dis cus sion of setup time re duc tion prin -ci ples that ap plies equally well to cy cle time re duc tion. While most CNC cy cles do not re quire the kind ofman ual in ter ven tion as so ci ated with mak ing set ups, you can learn a great deal about how your op er a torswork and come up with many ideas for im prove ment by study ing your CNC op er a tors cur rent meth ods.To get a true un der stand ing of what hap pens dur ing each cy cle, be sure you video tape sev eral ac ti va tions of the CNC cy cle. You will need to see the op er a tor do more than sim ply load and un load a fewworkpieces. Be sure you video tape enough to see what hap pens dur ing all tool main te nance (tool re -place ment, in sert in dexes, off set set ting, etc.) in or der to find any bot tle-necks in the flow of how pro duc -tion runs.

7.1.1. Cy cle time re duc tion prin ci ples

The prin ci ples of cy cle time re duc tion are quite sim i lar to those for setup time re duc tion. Armed with afirm un der stand ing of setup time re duc tion prin ci ples, these con cepts should be quite easy to un der -stand. You should be able to eas ily fol low along with all pre sen ta tions in this chap ter even if you have notread the setup time re duc tion pre sen ta tions given in the last two chap ters. How ever, we do elim i nate re -dun dant pre sen ta tions on top ics al ready dis cussed dur ing setup time re duc tion.

7.1.1.1. Cy cle time de fined

We of fer two def i ni tions of cy cle time. First, many CNC peo ple con sider cy cle time as the in ter val thatpasses from a given event in one cy cle to the same event of the next cy cle . For man u ally ac ti vated cy cles, theac ti va tion of the CNC pro gram is com monly the event used to mea sure cy cle time. In this case, cy cle timeis con sid ered as the time that passes from one press ing of cy cle start to the next. For com pletely au to -matic cy cles, like those for CNC turn ing cen ters equipped with au to matic workpiece load ing de vices, theevent used to gauge cy cle time might be the clos ing of the chuck jaws to clamp the workpiece.

Mea suring cy cle time based on this el e men tary def i ni tion is very easy. Any one with a stop watch can goout to the ma chine and sim ply time the cy cle.

While this def i ni tion is the one com monly used when dis cuss ing cy cle time, re mem ber that there areother tasks that add to the time it takes to com plete a pro duc tion run that are not in cluded in this sim plis -tic def i ni tion. These are tasks not nec es sar ily per formed dur ing ev ery cy cle. If the quan tity of workpieces is large enough, for ex am ple, tool main te nance must be done dur ing the pro duc tion run. This is com -monly done on-line, while the ma chine sits idle. Other ex am ples of on-line in ter mit tent tasks in clude theload ing of bars into bar feed ing turn ing cen ters and check ing workpieces on an sam pling ba sis.

These are at least rel a tively pro duc tive tasks, done to keep pro duc tion flow ing. How ever, there may beother, far less pro duc tive things go ing on in your CNC en vi ron ment that add to pro duc tion time, yet arenot truly part of your CNC cy cle. If, for ex am ple, a CNC ma chine tool breaks down dur ing a pro duc tionrun and re quires cor rec tive main te nance, the time it takes to com plete the pro duc tion run i n creases. Ifan op er a tor must halt pro duc tion to take a phone call, pro duc tion time in creases. If the ma chine is shutdown dur ing breaks, lunch, or any other per sonal time, pro duc tion time in creases. Truly, any time thema chine is down for any rea son dur ing a pro duc tion run in creases the time it takes to com plete the pro -duc tion run and must be con sid ered in the def i ni tion of cy cle time.

Cy cle Time Reduction


For this rea son, we of fer a much more re al is tic def i ni tion of cy cle time. Cy cle time is the over all length oftime re quired to com plete a pro duc tion run di vided by the num ber of cy cles needed to com plete the pro duc -tion run. Un for tu nately, by this def i ni tion, cy cle time is much more dif fi cult to mea sure. While cer tainin ter mit tent tasks like tool main te nance can be fac tored in to help cal cu late cy cle time, cer tain things,like ma chine fail ures, make it im pos si ble to per fectly pre dict cy cle time from one pro duc tion run to thenext. With this broader def i ni tion, any thing that adds to the time it takes to com plete a pro duc tion run iscon sid ered in the def i ni tion of cy cle time - and is fair game for your cy cle time re duc tion pro gram.

7.1.1.2. Task types for cy cle time re duc tion

As with setup time re duc tion prin ci ples, there are two types of tasks re lated to cy cle time re duc tion.On-line tasks are those tasks ac tu ally per formed on the CNC ma chine dur ing the cy cle. In fact, the sumof on-line tasks is the cy cle time. Off-line tasks are those tasks per formed out side the ma chine tool and in -ter nal to the ma chin ing cy cle. In or der to fur ther de fine cy cle time, we di vide cy cle time tasks into fourcat e go ries.

A CNC ma chine tool is only truly pro duc tive while chips are be ing cut. We call tasks that con trib utes toac tu ally ma chin ing chips pro duc tive on-line tasks. The ac tual ma chin ing op er a tions them selves makeup the bulk of pro duc tive on-line tasks and are com monly fully au to matic tasks, com pletely con trolled bythe CNC pro gram.

The sec ond cat e gory of cy cle time re lated tasks is non-productive on-line tasks. These are tasks that oc cur within the ma chine tool dur ing the cy cle that do not ac tu ally pro duce chips. These can be fully au to matictasks or man ual tasks. Ex am ples of fully au to matic non-productive on-line tasks in clude tool chang ing(by an au to matic tool changer on a ma chin ing cen ter or tur ret in dex on a turn ing cen ter), rapid ap proachand re tract mo tions, and air cut ting mo tions while tools ap proach sur faces to be ma chined. Ex am ples ofman ual non-productive on-line tasks in clude man ual workpiece load ing and un load ing, tool main te -nance, and any man ual in ter ven tion that oc curs dur ing a pro gram stop (blow ing chips from holes be foretap ping, break ing clamps loose for fin ish ing, chang ing chuck ing pres sure on turn ing cen ters be fore fin -ish ing, etc.).

The third cat e gory of tasks re lated to cy cle time is non-productive off-line tasks. These are usu ally man -ual tasks that the CNC op er a tor per forms to main tain the ma chin ing cy cle while the ma chine is run ningworkpieces. Ex am ples of non-productive off-line tasks in clude off set changes to hold size on t urn ing cen -ters for the pur pose of deal ing with tool wear, workpiece in spec tion, and SPC data re cord ing.

The fourth cat e gory of cy cle time re lated tasks is pro duc tive off-line tasks. These are tasks the CNC op er -a tor per forms dur ing the CNC cy cle that ac tu ally fur ther the com ple tion of ma chin ing op er a tions onworkpieces. Sim ple tasks like deburring, clean ing, and pol ish ing as well as more com plex sec ond ary op -er a tions fall into this cat e gory.

Just as with setup time, re mem ber that cy cle time is the sum to tal of on-line tasks. Also as with setuptime re duc tion, the goal in cy cle time re duc tion will be to elim i nate on-line tasks, move on-line tasksoff-line, or fa cil i tate on-line tasks.

7.1.1.3. The four ways to re duce cy cle time

While we of fer many cy cle time re duc ing tech niques in this chap ter, our broader in ten tion is for you to beable to de velop your own cy cle time re duc tion tech niques. Re gard less of how many tech niques we show, it is likely that your companys spe cial needs will re quire that you de velop many more. As long as you un -der stand the four ways we show to re duce cy cle time, you should be able to mod ify our given tech niques,or come up with your own, to tackle the chal lenges that await you in your own CNC en vi ron ment.

1. Im prove the ef fi ciency of pro duc tive on-line tasksThe first gen eral tech nique we of fer is to im prove the ef fi ciency of pro duc tive on-line tasks. Gen erallyspeak ing, this means op ti miz ing the CNC pro grams ex e cu tion. In chap ter eight, we of fered three ba sicsteps to pro gram op ti miz ing. First, elim i nate in ef fi cien cies caused by the pro grams ba sic for mat. Sec -ond, op ti mize the cut ting con di tions. And third, op ti mize the ma chin ing pro cess.

How much op ti miz ing you do dur ing a given pro duc tion run must be based on the pro duc tion quan ti ties.For low pro duc tion quan ti ties, it may be dif fi cult to jus tify any op ti miz ing. For ex am ple, if you are only

Mod ule Seven


run ning a few workpieces with a short cy cle time, it is un likely that any thing can be done to re duce cy cletime that will shorten the over all pro duc tion run. In this case, mak ing good workpieces may be the onlycri te ria for the pro duc tion run. Maybe the best you can hope for is that your peo ple learn en ough dur ingthis pro duc tion run to im prove cut ting con di tions for fu ture times when the same workpiece (or ma te rial)must be ma chined.

On the other hand, as pro duc tion quan ti ties grow, op ti miz ing can have a ma jor im pact on the over all pro -duc tion time needed to com plete the job. Say, for in stance, you must ma chine 10,000 workpieces with atwo min ute cy cle. If you come up with an im prove ment that saves but one sec ond per cy cle, your pro duc -tion run will be short ened by over 2.5 hours (10,000 sec onds di vided by 60 is 166.6 min utes, or 2.7 hours).In this case, over two hours of op ti miz ing time could be jus ti fied be fore pro duc tion is run.

Most CNC pro gram mers would agree that any new CNC pro gram can be im proved upon. How ever, ashu man be ings, we tend to leave well enough alone. If a CNC pro gram is ma chin ing workpieces in an ac -cept able man ner, it can be dif fi cult to change any thing. You know the say ing, if it isnt broke, dont fix it!How ever, given this great po ten tial for sav ings, CNC peo ple must avoid the nat u ral ten dency to leavewell enough alone.

2. Min i mize non-productive on-line tasksOur sec ond gen eral cy cle time re duc tion tech nique is to min i mize non-productive on-line tasks. Re mem -ber that these can be man ual tasks or au to matic tasks. Since any thing that hap pens on-line dur ing thecy cle is fair game, this cat e gory of ten of fers the great est po ten tial for im prov ing cy cle time.

One ex am ple for re duc ing au to matic non-productive time is re lated to tool chang ing on ma chin ing cen -ters. Re gard less of how fast your au to matic tool changer changes tools, tool chang ing is non-productiveon-line time. If mul ti ple workpieces are run dur ing the ma chin ing cy cle, the tool chang ing time can be av -er aged over sev eral workpieces. An other non-productive on-line task that of fers a great po ten tial for sav -ings is workpiece load ing. Any thing that can be done to re duce workpiece load ing time (whether man ualor au to matic) will ef fec tively re duce cy cle time.

3. Move non-productive on-line tasks off-lineThe third gen eral tech nique is to move non-productive on-line tasks off line. While this as sumes the cy cle time is long enough to be per form ing cer tain tasks off-line, any thing that re duces on-line time re ducesover all cy cle time.

Tool main te nance is one prime can di date for this kind of sav ings. If the ma chine is down while a CNC op -er a tor per forms ba sic tool main te nance like in dex ing in serts for car bide in sert tool ing, a great deal of pro -duc tion time can be wasted. While this task does not oc cur in ev ery cy cle, when tool main te nance isper formed, it will add to the length of time re quired to com plete the pro duc tion run and must be con sid -ered as part of cy cle time. As you will see later in this chap ter, there are sev eral things that can be done tohelp an op er a tor per form tool main te nance tasks off-line.

4. Move pro duc tive on-line tasks off-lineAn other gen eral tech nique that can save a great deal of pro duc tion time is to move pro duc tive on-linetasks off-line. This cat e gory is most im por tant with CNC cy cles hav ing ex tremely long cy cle times. Aslong as the CNC op er a tor has suf fi cient time dur ing the CNC ma chin ing cy cle, they can per form ma chin -ing op er a tions in ter nal to the CNC op er a tion. This not only keeps the op er a tor busy, over all cy cle timecan be dra mat i cally re duced.

One com mon way com pa nies keep their CNC op er a tors busy is to have them per form ing sec ond a ry ma -chin ing op er a tions on the workpiece be ing ma chined by the CNC ma chine tool. In many CNC en vi ron -ments, for ex am ple, the ma chin ing cen ter op er a tor per forms tap ping op er a tions off-line. Since tap pingtends to be a trou ble some op er a tion, and since tap ping re quires no great skill or ac cu racy (it can be doneon a sim ple drill press and re quires al most no setup time dur ing change-overs), even an un skilled CNCop er a tor can per form this sec ond ary op er a tion with a min i mum of train ing. When this tech nique is used,the over all cy cle time can be re duced by the time it would take the CNC ma chine to per form the tap pingop er a tions.



While this is an ex cel lent tech nique that can dra mat i cally re duce cy cle time, keep in mind that the pri or -ity must be placed on re duc ing cy cle time, not keep ing the op er a tor busy. The sec ond ary o p er a tions mustbe well planned in or der to en sure that the op er a tor has time to per form sec ond ary op er a tions dur ing theCNC ma chin ing cy cle and avoid con flicts with the op er a tors other CNC re lated tasks.

If the goal is to sim ply keep the op er a tor busy, it may be wiser to seek an al ter na tive method. In stead ofcaus ing the op er a tor to rush through the sec ond ary op er a tions in or der to keep up with the CNC ma chinetool, have them per form sec ond ary op er a tions on less ur gent workpieces. Or have them per form ing tasks that re quire less skill, like clean ing, pol ish ing, and deburring.

7.1.1.4. The one-second rule

To stress the im por tance of re duc ing cy cle time and to of fer a sim ple method of cal cu lat ing the po ten tialsav ings re lated to in cor po rat ing a cy cle time re duc ing tech nique, we of fer this sim ple rule-of-thumb. Wewill be us ing it through out this chap ter to stress how seem ingly mi nor changes can re sult in dra maticpro duc tion time sav ings. For ev ery sec ond you can re move from cy cle time, you save 16.6 min utes perone-thousand cy cles (one-thousand sec onds di vided by sixty). While at first glance this may not soundlike much, you will be sur prised at how fast the sav ings can add up. For ap prox i mat ing pur p oses, you canround the 16.6 min utes down to a quar ter hour (fif teen min utes). By ap ply ing the one-second rule, if youcan save but four sec onds per cy cle, you will save over one hour of pro duc tion time per one thou sand cy -cles.

1. Other time re lated for mu laeWhile we are on the sub ject of time cal cu la tions, there are sev eral other for mu lae that are help ful whencal cu lat ing a ma chin ing op er a tions in flu ence on cy cle time. We will be us ing them through out this chap -ter. While they as sume you are work ing in the inch sys tem, sim i lar for mu lae can be de vel o ped for usewith the met ric sys tem.

Time in min utes = length of mo tion in inches di vided by the inches per min ute mo tion rateOne sec ond = 0.01666 min utesInches per min ute feedrate = inches per rev o lu tion (IPR) feedrate times rev o lu tions per min ute (RPM)RPM = 3.82 times sur face feet per min ute (SFM) di vided by ma chin ing di am e ter

Though it may be some what ob vi ous to you at this point, keep in mind that feedrate is di rectly pro por -tional to spin dle speed (in RPM). If you dou ble spin dle speed (and you main tain inches per rev o lu tionfeedrate), feedrate will dou ble. For ex am ple, if you wish to ma chine at 0.010 IPR, at 1,000 RPM, yourinches per min ute feedrate will be 10 IPM (0.010 times 1,000). If you dou ble the spin dle speed to 2,000RPM and main tain 0.010 IPR, feedrate in inches per min ute will in crease to 20 IPM.

More im por tantly, al ways re mem ber that cy cle time is in versely pro por tional to feedrate. If the feedratefor a given op er a tion is in creased, the cy cle time re quired for the op er a tion will be re d uced in equal pro -por tion.

This knowl edge that feedrate is in versely pro por tional to cy cle time is very help ful when you are ap prox i -mat ing the im pact chang ing cut ting con di tions will have on cy cle time. Con sider a mill ing op er a tion thatre quires a mo tion dis tance of ten inches. At ten inches per min ute, this op er a tion will take pre cisely onemin ute to com plete (ten inch dis tance di vided by ten inches per min ute). If you dou ble the feedrate totwenty inches per min ute, the re quired time will be cut in half to thirty sec onds (ten inches of mo tion di -vided by 20 inches per min ute).

7.1.1.5. How fast can your ma chines rapid?

The rapid rates of todays (es pe cially smaller) CNC ma chines are amaz ingly high. It is not un c om mon, forin stance, for a small ma chin ing cen ter to have a rapid rates of 1,200 inches per min ute or more. Withthese very fast rapid rates, man u fac tur ing peo ple (and es pe cially CNC pro gram mers) tend to ig nore theim pact rapid move ments have on cy cle time. Al ways re mem ber that rapid move ments do not oc c ur in -stan ta neously. And dur ing many rapid move ments, the ma chine will never reach its true rapid rate. AllCNC ma chine tools uti lize and ac cel er a tion and de cel er a tion func tion dur ing rapid to pro tect the ma -chines servo drive sys tems. Though this pro tec tion var ies based upon ma chine size, it is un likely, for ex -am ple, that any CNC ma chine will ever reach its full rapid rate dur ing a small 0.500 in mo tion.

Mod ule Seven


Re gard less of how fast your ma chines can rapid, any mo tions that oc cur add to cy cle time. Since rapidmo tions tend to get over looked when cy cle time re duc tion tech niques are im ple mented, we wish to em -ploy the time cal cu la tion for mu lae to dem on strate the im pact of rapid mo tions on cy cle time.

In or der to help you de ter mine the im pact of rapid move ments on your own CNC ma chines, cal cu late howfar the ma chine needs to rapid be fore one sec ond is added to your cy cle time. This dis tance will dif fer from one ma chine to an other, based on the ma chines rapid rate. Say, for ex am ple, you have a small ma chin ingcen ter with a rapid rate of 1,200 IPM. For this ma chine, one sec ond will be added to cy cle time for ev erytwenty inches of rapid mo tion (20 di vided by 1,200 equals 0.0167 min utes, which is just slightly morethan one sec ond).

It is not un usual for a ten tool ma chin ing cen ter pro gram to re quire as much as 150 inches of rapid mo -tion, even on a rel a tively small ma chine tool. At 1,200 IPM thats about 7.5 sec onds of rapid mo tion per cy -cle (150 di vided by 1,200 is 0.125 min utes or 7.5 sec onds). In a pro duc tion run of 1,000 workpieces, itequates to just over two hours of pro duc tion time (7,500 sec onds), just for rapid move ments! R e mem ber,this cal cu la tion did not even take into ac count the ac cel er a tion and de cel er a tion of the ma chine. In re al -ity, even more time will be re quired. Also, this cal cu la tion is for one of the fast est rapid rates cur rentlyavail able. With older equip ment hav ing slower rapid rates, the im pact of rapid mo tions on cy cle time willbe even greater. The to tal rapid time for a ma chine that can only rapid at 400 IPM in the pre vi ous ex am -ple will be well over six hours!

We urge you to use this tech nique to cal cu late just what im pact your rapid mo tions have on your ownCNC ma chine tools. It should eas ily stress the need to min i mize rapid mo tions when ever pos si ble withinyour CNC pro grams.

7.1.2. Re ducing workpiece load ing and un load ing time

As stated, the time it takes to load and un load workpieces fits into the cat e gory of non-productive on-linecy cle time. With al most all CNC equip ment, re gard less of how workpieces are loaded (man u ally or au to -mat i cally), the ma chine must be sit ting idle dur ing this task. Any tech nique that re duces on-lineworkpiece load ing time will ef fec tively re duce cy cle time. And as with any facet of cy cle time re duc tion,the higher the pro duc tion quan ti ties, the more im por tant it will be to re duce load ing and u n load ing time.

More and more CNC ma chine tools are be ing equipped with au to matic load ing and un load ing de viceswhich elim i nate the CNC op er a tor from the load/un load task. How ever, since these de vices u su ally havefixed load/un load times (not much can be done to im prove their ef fi ciency), and since the bulk of CNC ma -chines still re quire at least some op er a tor in ter ven tion, we limit our dis cus sions to op er a tor as sistedworkpiece load ing and un load ing.

As with our dis cus sion of setup time re duc tion prin ci ples, any thing that can be done to fa cil i tatenon-productive on-line tasks will have an pos i tive im pact on workpiece load ing time. Steps should betaken to make it as easy as pos si ble for the CNC op er a tor to ef fi ciently com plete the workpiece load ingpro cess. Also as with our dis cus sion of setup time re duc tion prin ci ples, one ex cel lent way to brain stormfor workpiece load ing and un load ing ideas is to video tape the workpiece load ing pro cess.

Cer tain en hance ments to workpiece load ing/un load ing should be easy to spot. For ex am ple, workpiecesrun on CNC ma chine tools can be very heavy. This, com bined with the fact that CNC op er a tors will be -come fa tigued dur ing a days work (and prone to in jury), make it es sen tial that ev ery step be taken to letthe op er a tor move heavy workpieces safely and ef fi ciently. Over head and boom cranes should b e used forheavy workpieces. Even with these de vices to as sist them, workpiece load ing/un load ing can still be dif fi -cult. Is your op er a tor strug gling with the cum ber some straps used with most cranes? Per haps a mag -netic at tach ment will make the task eas ier to com plete. Is the headstock of the ma chine (or any otherma chine com po nent) in ter fer ing with the op er a tors abil ity to use the crane? Per haps the pro gram can bechanged to po si tion the ma chines axes such that in ter fer ence prob lems are elim i nated. Any num ber ofpos si ble im prove ments can be made to fa cil i tate the op er a tors abil ity to per form the load/un load task. Inthis sec tion, we of fer a few sug ges tions.

7.1.2.1. Turn ing cen ter sug ges tions

The dif fi cul ties as so ci ated with turn ing cen ter workpiece load ing vary dra mat i cally based on the ma -chines ap pli ca tion. Gen erally speak ing, due to the na ture of the work hold ing de vice (com monly an au to -



Mod ule eight

8.1. Probing devicesThere are a va ri ety of probes avail able for use with CNC ma chine tools. Most are touch probes, mean ingthey must con tact a sur face be fore they trig ger. Though some sense con duc tiv ity, most touch probesmust ac tu ally de flect a small amount in or der to trig ger. In ad di tion to touch probes, a grow ing num ber of la ser probes are be com ing avail able. The bulk of this pre sen ta tion deals with de flec tion-type touchprobes.

First we’ll in tro duce the ba sic con cepts be hind how prob ing is done. As you will see, the act of prob ing re -mains very much the same re gard less of probe type or ap pli ca tion. For prob ing nov ices, you will see thatprobes are just an other kind of tool used by a CNC ma chine tool, and this dis cus sion should take the mys -tery out of how probes ac com plish their re quired tasks.

We also in tro duce the three most pop u lar touch probe types. All are con tact sen si tive, mean ing they aretrig gered by the de flec tion of the sty lus within the probe. Most cur rent probes are very ac c u rate, re quir -ing but a very tiny amount of de flec tion to trig ger. Though the mech a nisms used to de tect de flec tion varyfrom one probe man u fac turer to an other, sev eral probe man u fac tur ers claim that their probes will trig -ger within twenty mil lionths of an inch of de flec tion (0.00002 in). This chap ter will sim ply in tro duce theprobe types. In chap ter two, we will in tro duce ap pli ca tions for each type.

8.1.1. The con cept of prob ing

We in ten tion ally keep this dis cus sion very ba sic, and speak in gen er al i ties to avoid be c om ing overly tech -ni cal (a probe spe cial ist may find these dis cus sions overly ba sic). Our in ten tion is sim p ly to take the mys -tery out of how prob ing sys tems (of any kind) work. Rest as sured that fu ture pre sen ta tions will ex plainprob ing in func tions much greater de tail.

From your man ual pro gram ming ex pe ri ence, you know you have the abil ity through pro grammed com -mands to make the ma chine per form many func tions. You can start the spin dle at the de sired speed, turn on the cool ant, rapid a tool into po si tion, and be gin ma chin ing at a de sired feedrate. In d eed, true ma chin -ing cen ters and turn ing cen ters al low you con trol of vir tu ally any thing of which you need c on trol throughpro grammed com mands.

For as pow er ful and func tional as your man ual pro gram ming com mands are, you must un der stand thatthey are in suf fi cient for han dling even the most ba sic probe ap pli ca tions. Stated an other way, we needad di tional pro gram ming ca pa bil i ties (more than are al lowed in most man ual CNC pro gram ming lan -guages) in or der to pro gram prob ing sys tems. This is why para met ric pro gram ming is re quired. The spe -cific ver sion of para met ric pro gram ming we use for ex am ples through out this dis cus sion is Fanuc’scus tom macro ver sion B, the most pop u lar ver sion of para met ric pro gram ming used by sev era l CNC con -trol man u fac tur ers. Note that we de vote an en tire mod ule of this course to para met ric pro gram ming. Inthis dis cus sion, we’ll sim ply in tro duce those fea tures of para met ric pro gram ming that are re quired forprob ing.

8.1.1.1. Cus tom macro B func tions needed for prob ing

Here are some of the func tions cus tom macro B al lows that are re quired for prob ing which are not pos si -ble through ba sic man ual pro gram ming.

1. Ac cess to ma chine po si tion af ter prob ingThe most im por tant prob ing re lated func tion cus tom macro B al lows is the abil ity to at tain the ma chine’spo si tion af ter prob ing takes place. In deed, the probe would be worth less with out this abil ity. Thoughhow the ma chine’s po si tion af ter prob ing is used will vary from one ap pli ca tion to an other, this abil ity isat the very core of any prob ing sys tem.

2. Vari ablesMany prob ing ap pli ca tions re quire mul ti ple touches of the probe. Com par i sons or cal cu la tions in volv ingthe var i ous ma chine po si tions af ter prob ing will com monly be re quired, mean ing you must have a place to store ma chine po si tions for fu ture use. Among many other things, vari ables are used for this pur pose.

Probing Devices


3. Arith me tic ca pa bil i tiesAs men tioned, there will com monly be cal cu la tions to make in prob ing pro grams. You will see (in a fu ture mod ule) that just about any thing that can be done on a sci en tific cal cu la tor can be done with a cus tommacro B pro gram.

4. Ac cess to off sets and other ma chine func tionsMany prob ing ap pli ca tions re quire ac cess to tool off sets. A ma chin ing cen ter prob ing sys tem de signed tomea sure tool length com pen sa tion val ues, for ex am ple, must have the abil ity to ac tu ally set a tool off setonce a tool’s length com pen sa tion value is de ter mined. You will see that all tool off sets are ac ces si blethrough cus tom macro B com mands (tool off sets, fix ture off sets, wear off sets, ge om e try off sets, work shift off set, etc.).

Probing sys tems also re quire ac cess to other ma chine func tions. For ex am ple, you will learn that prob ingmust be done at a con sis tent feedrate. If an op er a tor has placed the feedrate over ride switch at some thing other than one hun dred per cent, it could re sult in in ac cu rate prob ing. For this rea son, cus tom macro Bal lows the probe pro gram mer to dis able feedrate over ride (tem po rarily) dur ing the prob ing cy cle. Manyother ma chine func tions are ac ces si ble with cus tom macro B.

5. LogicMany prob ing ap pli ca tions re quire the prob ing pro gram to make de ci sions and be have dif fer ently basedon the re sult of each de ci sion. For ex am ple, a pro gram mer de vel op ing a prob ing pro gram that mea suresthe width of a slot will have to plan on sev eral con tin gen cies. If, for ex am ple, the mea sured slot is too nar -row, it may be the pro gram mer’s de sire to ad just an off set (au to mat i cally) and re-machine with the tool.If the slot is too wide, pos si bly the workpiece is now scrap. In this case, an alarm may be sounded by theprob ing pro gram to stop fur ther ma chin ing. If the slot is within its tol er ance band but not pre cisely at itsmean value, an off set could be ad justed ac cord ingly so the slot in the next workpiece is ma chined per -fectly. The ma chine could then con tinue in the nor mal man ner. This is but one ex am ple of the manytimes when logic com mands must be used in the prob ing pro gram.

8.1.2. The probe it self

Al ways re mem ber that con tact-triggered touch probes are noth ing more than highly ac cu rate con tactswitches. As men tioned ear lier, all probes dis cussed in this text are touch probes, mean ing they re quirebut a tiny amount of de flec tion to trig ger. When they trig ger dur ing a prob ing com mand (com monlywithin twenty mil lionths of an inch de flec tion), a sig nal is sent to the CNC con trol which halts axis mo -tion. This sig nal tells the con trol to at tain the ma chine’s po si tion as close to the in stant in time the probemade con tact as pos si ble. As stated ear lier, this po si tion (in all axes) is ac ces si ble to the prob ing pro gram.

This un der stand ing that probes sim ply tell the CNC con trol to at tain the ma chine’s po si tion, cou pledwith un der stand ing the ad di tional pro gram ming func tions needed for prob ing that are avail able through cus tom macro B should go a long way to ward help ing you un der stand what goes on in any prob ing sys -tem, re gard less of the sys tem’s com plex ity.

8.1.2.1. Probe types

Again, this text will dis cuss the three most pop u lar forms of touch probes used with CNC ma chin ing cen -ters and turn ing cen ters.

1. The five di rec tion touch probeThis kind of probe can be mounted in the spin dle of a ma chin ing cen ter or in the tur ret of a turn ing cen ter.As the name im plies, it al lows de tec tion of de flec tion for five mo tion di rec tions. When mounted in thespin dle of a ma chin ing cen ter, de flec tion can be de tected dur ing X+, X-, Y+, Y-, and Z- mov e ments. Thenext draw ing shows this type of probe.

Mod ule Eight


Di rec tions of prob ing for a five di rec tion touch probe mounted held in the spin dle of a ma chin ing cen ter.

Probes used in this man ner are com monly called spin dle probes. Through out this dis cus sion, we place aheavy em pha sis on the pro gram ming of spin dle probes for three rea sons. First, they com monly re quirethe most in the way of pro gram ming from end us ers. Other probe types typ i cally re quire very lit tle in theway of spe cial pro gram ming. Sec ond, they tend to be the most com pli cated probes with which to work. Ifyou can un der stand the pro gram ming of spin dle probes, you will be able to eas ily adapt what you know tospe cial pro gram ming for other probe types. Third, of the probe types, spin dle probes al low the most di -ver si fied ap pli ca tions. Other probe types com monly have but one spe cific pur pose. Once they are ini -tially pro grammed for their spe cific ap pli ca tion (com monly by the ma chine tool builder or probeman u fac turer), there will be lit tle, if any, need for fur ther pro gram ming.

The five di rec tion touch probe can also be mounted in the tur ret of a turn ing cen ter. How ever, since mostturn ing cen ters only al low the tur ret to move in two di rec tions, two di rec tions of prob ing are usu ally lostwhen the five di rec tion touch probe is mounted in the tur ret of a turn ing cen ter. The ex cep tion to thisstate ment is the turn ing cen ter hav ing a Y axis. Turn ing cen ters that have X, Y, and Z axes al low the fivedi rec tion touch probe to de tect de flec tion dur ing mo tions in all five mo tion di rec tions. The next draw ingshows this kind of probe mounted in a turn ing cen ter’s tur ret.

Probing Devices


Di rec tions of prob ing for a five di rec tion touch probe when mounted in the tur ret of a two axis turn ing cen ter.

Note that the pre vi ous draw ing shows the most com mon type of (straight) sty lus. For a two axis turn ingcen ter, it al lows de tec tion of de flec tion while mov ing in the X+, X-, and Z- di rec tions. De pending upon theap pli ca tion, how ever, it is pos si ble to de sign the sty lus to probe in dif fer ent di rec tions. For ex am ple, if the sty lus for the probe shown in the pre vi ous draw ing is bent ninety de grees, or if the touch probe is mounted in an X axis tool holder, it will al low prob ing in X-, Z+, and Z-.

2. Spin dle probes with only two prob ing di rec tionsWhile it may sound like a bit of a con tra dic tion, it is pos si ble that a probe placed into the spin dle of a ma -chin ing cen ters may re quire only two di rec tions of prob ing. If the ma chin ing cen ter al lows the pre cisespin dle ori en ta tion to (at least four) an gu lar po si tions, the probe sty lus can be ro tated for prob ing in theX+, X-, Y+, and Y- di rec tions. This means only one di rec tion of prob ing is needed to probe in four dif fer entdi rec tions. Keep in mind that we are not talk ing about the sim ple spin dle ori en ta tion com m and (M19)used in con junc tion with the au to matic tool changer. While this com mand is also used in con junc tionwith five di rec tion spin dle probes (more on why later), the M19 spin dle ori ent com mand will r e sult in butone an gu lar po si tion.

Com mon pro gram ming meth ods

Most probe man u fac tur ers will pro vide their cus tom ers with a set of canned prob ing rou tines they per -ceive their cus tom ers to need (much like the canned cy cles used for hole ma chin ing op er a tions). Thesecanned rou tines are usu ally very easy to use, and in some cases, may be suf fi cient to meet the probe user’s needs. How ever, keep in mind that ap pli ca tions for five di rec tion touch probes are very di verse. It islikely that no two CNC us ers will have iden ti cal needs. For this rea son, five di rec tion touch probe us ersshould strive to gain the knowl edge and abil ity to de velop their own cus tom prob ing rou tines. Also forthis rea son, al most all five di rec tion touch probes are driven with (very flex i ble) para met ric pro gram -ming, com monly cus tom macro B.

3. Tool length mea sur ing probesThere are ac tu ally two vari a tions of tool length mea sur ing probes. First, this form of probe is used for ma -chin ing cen ter ap pli ca tions to mea sure tool off set val ues to be used with tool length com p en sa tion. Ifused only to find tool length val ues, only one di rec tion of prob ing is re quired (Z-). The next draw ing shows

this kind of probe. Tool length mea sur ing probe shown mounted to ta ble of a ver ti cal ma chin ing cen ter.

Mod ule Eight


With the probe placed some where in the ma chine’s work en ve lope (pos si bly mounted right to the ma chine ta ble), a tool tip is brought into con tact with the probe sty lus to de ter mine the tool length com pen sa tionoff set value. More on how this kind of probe works as we pres ent the ap pli ca tions for prob ing a lit tle laterin this chap ter.

The sec ond vari a tion of this kind of probe is that it may be ad di tion ally de signed to mea sure cut ter ra diuscom pen sa tion off set val ues. If this is the case, at least one more di rec tion of prob ing is nec es sary (X+, X-,Y+, or Y-). Of course, cut ter ra dius com pen sa tion is only re quired for mill ing cut ters, and only when mill -ing on the pe riph ery of the cut ter (as when con tour mill ing), mean ing this kind of prob ing is only usedwith mill ing cut ters.

In or der to come up with an ac cu rate cut ter ra dius com pen sa tion off set value, most probe m an u fac tur ersrec om mend that the spin dle be started prior to mea sur ing the cut ter’s ra dius. To keep from ac tu ally ma -chin ing the probe sty lus, most rec om mend that the spin dle be started in re verse (M04 for right hand mill -ing cut ters).

Mount ing to the ma chine

The method by which tool length mea sur ing probes are made avail able to the ma chine tool it self var iesamong ma chine tool build ers and probe man u fac tur ers. Older tool length mea sur ing probes must bephys i cally mounted to the ta ble of the ma chine tool (man u ally) ev ery time tool length mea sure ments arere quired, mak ing them some what cum ber some to work with. (This type of probe is shown in the t wo pre -vi ous draw ings.) Any time saved with tool length mea sure ment is lost when you con sider the time ittakes to mount the probe to the ta ble and re move it when fin ished. The ex cep tion to this state ment is aver ti cal ma chin ing cen ter that has am ple room on the ta ble for both the workholding setup and the toollength mea sur ing probe. Since ver ti cal ma chin ing cen ters gen er ally have more ta ble space than hori zon -tals, older tool length mea sur ing probes are ap plied more com monly to ver ti cal ma chin ing cen ters than to hor i zon tal ma chin ing cen ters.

Newer tool length mea sur ing probes swing into po si tion only when needed and swing out of the way when not. Com monly, two M codes con trol the func tion of the swing arm. This more con ve nient form of toollength mea sur ing probe over comes the lim i ta tions of the older style just dis cussed and is be com ing pop u -lar among probe man u fac tur ers and ma chine tool build ers.

Tool break age de tec tion

Though it is not the pri mary pur pose for this kind of probe, a tool length mea sur ing probe can be used asone form of tool break age de tec tion sys tem. This kind of tool break age de tec tion works best for toolswhose lengths change dra mat i cally if bro ken (like drills, taps, ream ers, and end mills). If f or ex am ple, itis sus pected that a tool has bro ken (pos si bly by an out-of-tolerance mea sure ment taken by a spin dle probe per form ing in-process gaug ing), the tool can be brought into con tact with the tool length mea sur ingprobe. Its cur rent length can be com pared to its orig i nal length. If its cur rent length is sub stan tially lessthan its orig i nal length, it can be as sumed that the tool has bro ken.

Com mon pro gram ming meth ods

Be cause they also re quire a fair amount of flex i bil ity, most tool length mea sur ing probes are also pro -grammed ex clu sively with cus tom macro B com mands. Most probe man u fac tur ers will sup ply a set ofcanned rou tines for the pur pose of mea sur ing tool length and cut ter ra dius com pen sa tion val ues. Thesecanned rou tines are usu ally quite easy to use and will usu ally come much closer to com pletely match ingthe probe user’s needs than stan dard pro grams pro vided with five di rec tion touch probes.

How ever, keep in mind that there are two ways of us ing tool length com pen sa tion. With one method, thelength of the tool is stored as the off set value. With the sec ond method, the dis tance from the tool tip down to the Z axis pro gram zero point is stored as the off set value. We pre fer the first method (tool length is off -set value) since, among other things, it al lows tool length com pen sa tion val ues to be mea sured off-line,and may pos si bly elim i nate the need for on-line tool length mea sur ing with the tool length mea sur ingprobe when there is am ple time dur ing the cur rent pro duc tion run to be as sem bling and mea sur ing cut -ting tools needed in the next job.

Probing Devices


CNC INSTRUCTORS!CNC INSTRUCTORS! Another ready-made curriculum to help you teach CNC courses

Maximizing CNC Utilization

You’ve probably taught many basic CNC courses. Since your students are at entry level, you’ve likely been a little frustrated at times. Just about the time your students are beginning to catch on to one topic, it’s time to move on to another. While you’d like to take your presentations to the next level, there just isn’t time – and doing so may confuse students more than help them. When students complete your basic course, they ’re ready to beginworking with CNC machine tools – but it’s unlikely that they have them mastered.

While your past students may not have been experts coming out of your course, at least they did receive formal training. There are many people working with CNC machines that did not. Maybe they ’re self-taught. Maybe they learned what they know from others on the job. Maybe they attended the quickie sessions held by machine tool builders. In any event, they too are not taking full advantage of all their CNC machines can do.

While the sheer productivity of CNC machines often masks inappropriate methods, companies are becoming more and more concerned with their CNC machine tools. Changes in manufacturing including lowered lot sizes, shorter lead times, and improved quality requirements (among other things) have most CNC-using companies struggling to maintain profit margins. They’ll need to improve their methods if they are to remain in business.

The most basic objective of this course curriculum is to help instructors relate concepts, techniques, and ideas that will help students make they ’re CNC machines more productive. Since it’s aimed at CNC people who already have some CNC experience (we recommend at least six months) you’ll be drawing from an entirely new potential student base. And you’ll finally be able to take your presentations to the next level!

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J #1: Basic premises (57 slides)

J #2: Review of CNC basics (346 slides)

J #4: Advanced CNC features, functions, & concepts (432 slides)

J #5: Parametric programming (556)

J #6: Setup time reduction (295 slides)

This short but important module lays the groundwork for what is to come. Included are presentations that acquaint students with important needs of CNC using companies. We discuss application versus utilization and machine utilization versus personnel utilization to help them understand the reasoning behind improving CNC machine utilization. We also introduce the four CNC-using company types and discuss factors making up a company ’s corporate identity. Finally, we discuss the importance of value added principles in the CNC environment.

Since you won’t have control of how much previous experience your students have (aside from setting some pretty broad prerequisites), you’ll want to make sure that they have a good grasp of basic CNC principles before digging in to more advanced topics. Again, many students coming to this course will be (for the most part) self-taught. It’s likely that they’ve missed out on some important basic concepts and techniques. In the advance courses I’ve taught myself, I’m always surprised at how often a so-called expert is unfamiliar with a very basic CNC feature or function. This module allows you to review the basics using our proven key concepts approach. (This is the same approach used in our basic CNC course curriculums.) There are ten key concepts. We begin each key concept by introducing the reasoning behind the key concept. Then we address how the key concept applies to machining centers and then to turning centers.Again, this is a review. Students should be quite familiar with the presentation –and if they are –you’ll be able to buzz through quite quickly. But, if they’re questioning each step along the way, it should be taken as a signal that more basic training is needed.

J #3: Advanced implications of basic features (911 slides)Many CNC features have multiple uses. But most basic CNC courses introduce only the most important use. Additionally, most basic courses don’t show all implications related to how a given feature can be best used to meet the company’s specific applications. If it’s a basic function, and if it’s not commonly addressed in a basic CNC course, it’s fair game in this module.Included in this lengthy module (the longest of the course) are presentations on parameters, N words, G codes, M codes, and other CNC words. We go over each code, one by one, and in numerical order

We also discuss advanced applications for tool offsets, fixture offsets, and wear offsets. Since we show so many alternative methods of handling basic CNC functions, there’s plenty of audio guidance during the slide show to help you prepare to teach this module.

There are many CNC features that are not addressed in basic courses. Admittedly, many of these features will not be of interest to a given CNC user. However, this module gives you the presentation material you need to discuss features like advanced interpolation types (helical, cylindrical, polar coordinate, andnurbs), scaling, mirror image, coordinate rotation, and three dimensional coordinate conversion. We also include presentations on certain machine accessories like bar feeders, index chucks, U axis, and part catchers. Finally, we provide materials for teaching some important CNC concepts like tool life management, qualifying CNC programs, and appropriate documentation.

We’ve often said that parametric programming is CNC’s best kept secret. There are still many in the industry that don’t know what it is, let alone how to take full advantage of it. These materials allow you to dive into parametric programming as deep as you want to go. We stress Fanuc ’s version of parametric programming – custom macro B (the most popular version). If you just want to present a cursory view of what it is, you’ll just be acquainting students with it’s applications and basic features. This can be done quite quickly. But if you want to present a full course, these materials still allow you to do so. With limited time for practice (practice exercises with answers are also provided), this full course can be completed in about 16 hours.

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All CNC using companies are concerned with how long their machines are down between production runs. This module lets you first present the principles of setup time reduction (that can be applied to any form of production equipment). We then offer specific CNC-related techniques to improving setup time in the same order setups are made (tear down, work holding setup, cutting tools, program zero assignment, program loading, program verification, and first workpiece inspection).

J #7: Cycle time reduction (411 slides)All CNC using companies are concerned with how long it takes to complete their production runs. As with setup time reduction, this module lets you first present the principles of cycle time reduction. We then offer specific techniques to reducing cycle time in four areas, workpiece load/unload, program execution time, tool maintenance, and preventive maintenance.

J #8: Spindle probe programming (519 slides)Actually, the student manual includes discussions on several types of probes (spindle probes, tool touch-off probes, and tool length measuring probes). However, the slide presentation is limited to spindle probes. Admittedly, most spindle probe uses depend solely on the probing programs supplied by the probe manufacturer. Only a small percentage of probe-using companies develop their own probing programs. For this reason, most students may not be very interested in learning how probes are programmed. You may elect to simply introduce the basics. But if you do need to teach a full course on spindle probe programming, these materials let you do so. Presentations include introduction to probe programming, applications for probing, how the probe works, calibration techniques, and writing spindle probe programs.

Instructor materials:Microsoft PowerPoint slide presentationsPowerPoint is fast becoming the presentation software of choice by most presenters. These presentations total over 3,000 slides to provide your visuals for the entire course. Note that they’re developed in PowerPoint 97 (which is part of Microsoft Office 2000). These presentations are included on a cd and most include audio narrations. There are ten slide presentations included on the cd-rom. Each is locally named from INTRODUCTION.PPT through MODULE 8_SPINDLE PROBES.PPT. These slide presentations can be accessed right from the cd-rom drive or if your hard drive has the room, you can copy them to your computer’s hard drive (there’s over 300 megs of data).Each slide includes a visual (in the form of a book icon) that lets students know the page number in the student manual that is currently being discussed.

Guidance during slide showsMost slide shows includes audio narrations (we call guidance) to help you understand how to make your presentations. Note that these narrations are not intended for your students. Each is directed at an instructor getting ready to teach the course (they help with preparation). A special icon on selected slides can be activated to play the related narration.

Microsoft PowerPoint ViewerThough we highly recommend that you have the actual PowerPoint software, we do include the PowerPoint Viewer. It does allow you to display the slide shows, but you’ll have no way to modify them. Additionally, the slide shows are quite long (most over 300 slides). PowerPoint Viewer does not allow you to move around in the slide show nearly as easily as the actual PowerPoint software does.

Instructor’s outlineThe outline serves three purposes. First, it lets you know exactly what is presented in each module. You’ll be able to quickly see what’s there. Second, it shows the slide number for each topic, making it easy to find slides as you move around in each slide show. For most topics, it also includes student manual page numbers so you can reference what the student will see as you give your presentation. Note that this will help you read up on topics you are unfamiliar with.

Workbook and answer book for Parametric Programming moduleSince this portion of the course requires practice to master, we provide you with a way of printing exercises and programming activities for students to do during this module. It can be used as homework or done during class. We also provide you with the ability to print the answer book.

Ability to print slide show hard copyPowerPoint allows you to print a hard copy of each slide show (Microsoft calls this printing handouts). This may help you prepare if you don’t always have a computer available. You can include 4, 6, or 8 slides per page. Even so, there are over 3,000 slides. Be ready for a lot of printing!

Promotional materialsWe’ve even included a brochure that you can use to help you promote this course. It’s in the “promotions ” folder of the cd rom. It’s in PowerPoint format, so you can easily modify anything you want! Note that there is space to include your school’s registration information (logo, phone number, fax number, etc.).

Free phone assistanceAgain, there’s a lot of information in this curriculum. If you have questions about any topic while your preparing to teach the course, we welcome your phone calls (847-639-8847). Or email us at [email protected].

644 page student manual

Free with initial textbook order!

This extremely comprehensive manual follows along with your presentation each step of the way, and again, the slide presentations reference page numbers throughout the course. It will make for excellent homework reading assignments and it’s an excellent way for students to go back and review material once the course is finished.

A note about the students you’ll attractRemember that your attendees will have (possibly extensive) CNC experience. I’ve found that most catch right on to the presentations being made, even for those topics that they’ve never been exposed to. Frankly speaking, most aren’t interested in a grade at all - they ’re interested in learning things that can be applied immediately in their shops. When they latch on to an idea that will help them, they’ll stick with it until they figure it out! For this reason, we minimize the amount of practice assigned in this course. With the exception of the parametric programming module, it’s mostly lecture.Be sure to take advantage of your students ’strong points. As you present the course, solicit ideas and comments each step along the way. We encourage student participation quite often during the slide presentations. The more you can get people to contribute during the class, the better the class will be. And you’ll be able to collect ideas for future classes!

Not only will you be teaching with the best state-of-the-art CNC curriculums in the industry, you’ll be doing so free of charge! All we ask is that your school bookstore buys the student manuals from us! With an initial order of just 20 manuals, we’ll ship the instructor’s materials free of charge! All instructor materials (slide shows, PowerPoint Viewer, instructors manual, and Adobe Acrobat Reader to view/print the manual) come on one cd-rom disk.Our net price to your school (or bookstore) for manuals is $95.00 each. Suggested retail price is $120.00 each. Future orders can be in any quantity. This cost will be recovered, of course, as students enroll in your classes and buy the manuals. In essence, your first 20 students will be paying for the curriculum!

What you’ll still needIn order to show the PowerPoint slide presentations to a group of people, you need the following items.A computer with Windows 98 (or higher) Just about any current model computer with a cd-rom drive will work. For best results, Pentium class is recommended (minimum 64 megs internal). If using a desktop computer, you can easily watch the monitor of the computer (facing your audience) to see the slide show as slides are displayed behind you by the projection system. Since the left mouse button advances the slides, you even have a remote slide advance button (as is commonly used with a 35 mm slide projector). If portability is an issue, keep in mind that many of the notebooks and sub-notebooks have ample power to run the presentation software.

However, be careful in your selection. Many notebooks do not allow you to send data out through the VGA port and see the slide show on the LCD screen of the notebook at the same time. Without this ability, you may have to turn around to see your slides, which can be distracting to your audience. Also, for maximum flexibility, look for a laptop that has the TV-OUT feature. This lets you send composite video to any television that has a TV-IN port with a simple RCA cable.Microsoft PowerPoint 97 Software (or above) Though you can display all presentations with PowerPoint Viewer (included with this curriculum), you will need Microsoft PowerPoint if you intend to modify the slide shows. PowerPoint 97 also makes it much easier to get around in the slide shows than the viewer. We highly recommend that you have this ability. A way of displaying the screen show - You have several alternatives in this regard. First, many schools already have a projection system that can display information from a personal computer. Basically, anything that can be shown on the computer screen can be displayed through the projection system. Second, and especially if price is a concern, you can use a simple scan converter (about $200.00 - $300.00) and display your screen show on any television that has a video in connector (as most do). Note that many laptops are now coming with a TV-OUT port, having this scan converter built in to the computer.

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