Die Maintenance Handbook Chapter 16

8/16/2019 Die Maintenance Handbook Chapter 16

1/15

Die Maintenance Documentation and Tracking

167

16

Die Maintenance

Documentation and Tracking

Responsible automobile owners realize that periodic mainte-nance and good record keeping is essential to assure dependabletransportation. Like a car, a stamping die also needs these thingsif it is expected to produce good parts without abnormal delays.

A die, like an automobile, must be designed correctly. Both diesand cars are assembled from parts that must work together. De-pendable, safe performance begins with good design. Careless op-eration and poor maintenance will cause great difficulty in spiteof the designer’s best efforts.

New dies may have design problems that must be corrected toassure smooth operation. Dies that do not function correctly areunacceptable.

DIE MAINTENANCE TEAM

The metal-stamping industry has undergone profound changes.Today, pressroom employees and management must work togetheras a team and be actively involved in solving problems. The great-est asset that an employee can bring to the workplace is his or her

knowledge and willingness to contribute to progress.Figure 16-1 is a cartoon of a foolish pressroom reaction to a dieproblem. Like a car that frequently breaks down, requiring repairor replacement, dies that fail in service require solutions. Well-


2/15

Die Maintenance Handbook

168

managed shops expect employees to accurately communicate whenthere are tooling problems.

A SYSTEMATIC DIE MAINTENANCE SYSTEM

Simply stated, shops that do not maximize human resourcesprobably will not survive in a free-market economy. The competi-tion in the industry for high quality, dependable delivery, and costreduction does not permit the luxury of poor communication andinefficient shop organization. Clear, concise communication is anessential factor in efficient die maintenance documentation andtracking. A simple systematic approach to problem identificationand communication is required.

Figure 16-2 shows a typical die room response when a die with-out a work order is dropped off. A work-order system should bepart of a closed-repeating cycle to correct problems. This includeseliminating their root causes.

Figure 16-1. A non-team-oriented pressroom reaction to a broken die

problem. The cartoon indicates a lack of communication between the pressroom and die repair facility.


3/15


169

Using a Die Repair Work Cycle

Figure 16-3 shows a six-step die maintenance work cycle. Main-taining any machine tends to be a repetitive activity. Dies can de-velop problems that require keen troubleshooting skills. Everyoneassociated with the process should understand the basic theory of the stamping processes. The operator should understand the ba-sic functioning of the die, press, and auxiliary equipment.

Training is essential at all skill levels. Ongoing training for ev-eryone from the operator to the tooling engineer and even topmanufacturing management will increase their skills. Everyoneshould be able, willing, and encouraged to provide input into solv-ing tooling process problems.

Training operators in basic press and die operation can bring

about a prompt resolution of problems. Progressive-die stamping variations are often due to pitch changes that are difficult to pre-dict exactly in the design stage. Moving and redoweling die sta-tions in the die room can correct pitch errors. Left uncorrected,

Figure 16-2. Dies sent to the die room without details of the problem to becorrected usually do not get attention.


4/15


170

the die will always have part-uniformity problems and may notfeed smoothly.

Step 1—Identify the Problem

The first step is to identify the problem and originate a work

order for the needed correction (see Figure 16-3).Observing the operation and checking the parts produced is

the most common method of finding problems. The operator is in

Figure 16-3. Six essential steps in a die-repair work cycle.


5/15


171

the best position to make long-term observations. An operator’sopinions are invaluable to the die setters, tool and die technicians,

engineers, and management. Ongoing operator training in thestamping process is essential to insure skillful operation and ob-servation of equipment.

Like maintaining a motor vehicle, dies require periodic shop main-tenance based on the number of hits made. The frequency of mainte-nance, dependant upon on the number of parts produced, requiresfine-tuning based on experience with the die or with similar dies.If the die is subjected to misfeeds or multiple hits, it should be

checked at once for damage by a tool-and-die technician.Statistical Process Control (SPC) data can guide the observa-

tion process. If the process-control charts indicate that controlpoints are drifting, this means that something has gone wrong with the process. It may be the press, the material, or the die.

Finally, customer quality or functionality issues require imme-diate attention. Fast, clear communication is the key to determin-

ing what has changed and what is needed to correct it. A customerrequest may involve an engineering change to the part. This usu-ally requires die modification. All die work requires planning andthe origination of a formal work order.

Step 2—Set Priorities

After identifying the work required, a work order should be ini-tiated. Some shops use a paperless, computer-entry system for

work orders. A clear work order that defines the scope of work isessential for scheduling work.

Problems that pose a safety risk should be of the highest priority.Loose die parts, broken cam-return springs, and misalignment areall examples of problems that require immediate correction. Die-component interference can send pieces flying at high velocity

throughout the pressroom. Figure 16-4 illustrates this problem.Customer needs are the next priority after safety. This means,

“if we don’t fix it soon, we can’t make parts for our customer.” A die-process failure sets the ultimate priority because it must becorrected or the product cannot be made.


6/15


172

Step 3—Plan Work

Determining required maintenance time is important becausetime is a finite resource, and production parts must be shippedsoon enough to meet customers’ requirements. Therefore, it isessential to make an accurate estimate of the time required.

The ability of those in the die room to accomplish work is es-

sential. The die room schedule may require overtime work if thereis an emergency involving safety or quality production. In somecases, a repair-capacity shortfall may require the help of a con-tract die shop.

There are times when an equipment smash-up or breakdownmake it necessary to immediately work on a die. This should be a rare exception—never typical.

Getting a tool release from the production schedulers is essen-

tial before working on a die. The scheduling department must workwith the production control department to make sure sufficientparts are on hand. Stampings must be available to cover the time

Figure 16-4. Shattered tool steel is a serious safety concern—it can fly athigh velocity causing severe injury.


7/15


173

needed to rework the die. An advance run requires stock, produc-tion time, and storage for the stampings.

Planning the work includes the determination of required dieparts or details. Some parts, such as springs and punches, are stan-dard items available from vendors on short notice. All special partsshould be ordered before starting work. Parts machined by CNCwill require cutter-path data. Usually, tool steel requires heat treat-ing, often followed by finish machining. The production of specialdie details may require from several days to a week or more.

A cooperative team approach to planning is essential. The al-

ternative to planning is confusion, inefficiency, and the failure toachieve a goal of orderly, economical repairs.

Step 4—Perform Work

Step 4 occurs after the halfway point in a work cycle. If the firstthree steps of clearly identifying the problem, properly prioritiz-ing the work, planning the repair and/or making sure a needed

modification are all done properly, the job should go smoothly (seeFigure 16-3).

Sample parts and progression strips must be sent with the die toa die maker. He or she can read the progression strips and estimatethe required correction needed before opening the die in the dieroom. After a plan is agreed on, the die is taken to the die room forthe required work. A typical sequence of work is as follows:

1. Disassemble and inspect die. The die maker carefully opens

and examines the die. The die alignment system, consisting of guide pins and/or heel blocks, is examined for wear. As thedie is taken apart, all evidence of wear and interference isnoted.

2. Inspect and assign work. A written record of findings is madeand the repair plan is finalized. Additional help is assignedas needed, and a plan to defer corrections not made in theallotted time is documented so a follow-up work order can be

originated.3. Sharpen and refurbish as needed. Good die repair skills are

essential to repair and refurbish the die. This may involve


8/15


174

more work than initially anticipated in the planning and work-order generation process.

4. Assemble and try out in press. After parts are reworked andnew details are installed, the die is tried out. This may bedone in a dedicated tryout press in the die room. An alterna-tive is to use the designated primary production press. A record of tryout and actual production results are essentialparts of building a die history. This data is essential to findways to reduce the cost of die maintenance.

Step 5—Document Work

The next step is to document the work done. The following areitems that require documentation for archival as die history.

• The actual cost of the work in terms of time expended andthe cost of parts is listed in detail and as a total-cost figure. A summary of the die tryout results should list the improve-ment or change in the die operation and the part produced.

• Follow-up work is often required. Continuous improvementhas always been a cornerstone of process-based industries. When the die returns to production, items that can be im-proved should be noted.

Step 6—Archive Data

Data can be archived in a number of ways. Historically, file card,file folder, or die notebook systems have been used. Increasingly,computerized databases are used to store die history and performcost analysis. When results of a repair-work cycle are archived,the following steps should be followed.

• Originate a follow-up work order if needed. When a follow-up work order is originated, the cycle is actually restarted tofurther improve the die and process. The die-repair cycle is a

circle, indicating a continuous process. Dies require periodicmaintenance that is mirrored in the work cycle.• The die work history needs to be stored securely. Simple pa-

per-based systems depend on written forms. These systems


9/15


175

are simple to implement and low in cost. Changes in the pa-per forms are easily made. Duplicate copies of records can be

made and stored in a safe location. This insures that dupli-cate information is available in case the file for a die shouldbe misplaced.

If a computerized die-maintenance system is adopted, the pa-per work-order and die-history system can work in parallel with ituntil everyone is comfortable with computerized data storage.Computer records must be backed up and stored off-site. Goodbackup procedures insure against loss of data.

• Perform root-cause analysis. Achieving continuous improve-ment proceeds more rapidly if the available resources are di-rected to solving the most costly problems. First, cause factorsmust be assigned to the types of process failures that occur.Normally, a limited number of problems cause the majorityof difficulties. The causes are placed on Pareto charts. Asprogress is made toward minimizing the problems, what wereminor problems may become the most troublesome. Chart-ing problems helps insure that the available problem-solving resources are directed toward the most costly ones.

• Analyze the cost versus benefit of the work. The cost versusbenefit of the maintenance program should be documented.If confusion prevails in the workplace, it is very difficult toassign real cost figures to the problems that occur every day.The work-order system and the six-step die-repair work cycleare good ways to bring order and increased profitability to

the stamping shop.

THE REQUEST FOR MAINTENANCE FORM

A die-maintenance-request form should reflect the procedurefollowed in the die-repair- and cost-accounting process in sequen-tial order. Today it is practical to use paperless data-entry systems

that tie in with the plant’s mainframe computer. In some cases, a department may have a local area network (LAN) for this func-tion. However, paper forms having two or three carbonless copiesremain popular.


10/15


176

Advantages of Paper Forms

There are advantages to using a multi-copy paper form ratherthan direct computer terminal entry. One advantage of the paperform is that the necessary approvals and signatures can be ob-tained before inputting the maintenance request into the com-puter system. The form minus the part(s) used for entry into themaintenance-management computer system remains with the dieto provide instant information as to the die repair requirementsand status. Familiarity with the paper tracking system is also an

important consideration.

Designing the Paper Form

A good form starts with basic information entered into the up-per left-hand corner and ends with the results of the correction inthe lower right-hand corner. In this way, the form follows the func-tion of the maintenance process. In small shops, reasonably good

documentation can be accomplished with manual record keeping and cost accounting. However, if more than 15–20 maintenancetechnicians are involved, a computerized system is advised to runin parallel with the paperwork-tracking system to assure accuratedie history and cost accounting.

Most forms are made from three or more sheets of non-carbonpaper. This permits tearing out and sending a copy for computerdata entry when the work order is generated. Another copy withthe information about the work performed during the repair pro-cess will be sent for data entry when the work is complete.

CASE STUDY

The Ford/Mazda Auto Alliance Integrated Stamping and As-sembly Plant (Flat Rock, Mich.) depends upon a team approach tosolve die problems relating to quality and productivity. Team in-

teraction is key to the success of the system. The stamping shopstarted with a total of five transfer-press lines, an open-backedinclinable (OBI) press line, and a blanker. Every die was assigneda home line whenever possible.


11/15


177

Auto Alliance solved its throughput-shortfall problem and theneed for spare press capacity with a pressroom expansion. This

helped to avoid shutting the adjacent assembly plant down in caseof an unforeseen press failure. Auto Alliance, like many plants,had problems with press failures due to die-setting errors, as wellas metal fatigue under sustained usage.

When the facility was built in the late 1980s, the pressroomwas divided into several areas limited to 15–20 maintenance tech-nicians each. This was necessary to cope with the limitations of its paperwork-tracking system. The team size of 15–20 mainte-

nance technicians was considered the upper size limit for a manualpaperwork-tracking system to remain workable.

The three-part die-maintenance-request form shown in Figure16-5 was usually initiated by the transfer press or OBI-line pro-duction team leader who sketched a description of the problem inspace one (1) on the form. After signing the form in space two (2),the person then took the form to the tool and die team leader forapproval.

Team Leader Review

The team leader reviewed the problem with the production teamleader and other persons having knowledge of the problem asneeded. It was the leader’s responsibility to plan the requiredmaintenance. The tool-and-die team leader determined the cause(s)of the problem and identified all dies that required corrective ac-

tion. The amount of time required to make the correction wasalso determined.

Tracking and Prioritizing Requests

Usually, only a two-day supply of any given part was produced

at a time. Production of more than the usual run of parts might

be needed to provide additional release time. The tool-and-die teamleader coordinated the required release with the production-plan-ning department. When the plan was complete, the tool-and-dieteam leader co-signed the form in the blank space (3).


12/15


178

Figure 16-5. A generic version of a die-maintenance-request form is shown.It can serve as a starting point for developing a maintenance-tracking form.(Courtesy Doug Burke)


13/15


179

One of the three copies was posted on a corkboard at the homeline and the other two copies were inserted into a pipe attached to

the die for that purpose. The production team leader shipped therequired number of sample parts needed for evaluation and try-

out to the die room together with the die(s). The parts were iden-tified and stored in a designated area.

At the start and near the end of each shift, both the production-team leader and the tool-and-die team leader met to review prob-lems, including a review of all outstanding maintenance requestsposted on the line’s corkboard. The outstanding requests were

prioritized based upon the extent to which quality and productionwere affected. There were times when the entire correction neededcould not be made due to the size of the job and urgency of otherrequests. In such cases, the plan was reduced to a partial correc-tion, with a complete correction scheduled for a later date.

Follow-up

The diemaker making the repairs recorded the corrective ac-tion on the middle part of the form (4) and filled out the list of inspection items. After the correction was completed, the second

copy of the die-maintenance request was filed in the die roomrecords for that die, and the first copy was placed in the pipe at-tached to the die. When the die was returned to the press line, thefirst copy was placed in a plastic sleeve attached to the corkboard.

The lower space on the form (5) was filled out by the produc-

tion-team leader and line-team leader, after the success of the re-pair was evaluated during a production run. The white copy wasthen retained in the die repair area as a part of the die’s mainte-nance history.

Conclusion

Simple paper forms can be useful to determine the history of problems with individual dies. However, report generation for cost-accounting purposes requires time-consuming and error-pronemanual data tabulation.


14/15


180

Today, most industries rely extensively on computer integrationof the manufacturing process for most aspects of their operations.

These include inventory control, payroll generation, and govern-ment report accountability—just to name several categories of essential data that must be managed and reported in a readilyunderstood form.

The old Ford/Mazda paper-based die-repair tracking system hasbeen abandoned. It has been replaced with a computerized main-tenance-management and tracking system. Simply stated, the fa-cility is too large for the paper-based system to work effectively.

CONTINUOUS IMPROVEMENT

A simple paperwork maintenance-tracking system is a good wayfor a shop relying on verbal orders to improve performance. It canalways run in parallel with a computerized maintenance-manage-ment and tracking system. Many good computerized maintenance-management systems rely on paper forms for initial data entry

and tracking of the repair process.Tooling design improvements and maintenance cost control are

frequently overlooked as areas for continuous improvement.Through effective database development and report generation,opportunities for continuous improvement in die design and main-tenance can be identified and corrected.

Solving part quality problems may require a new process andnew tooling. Here, a team approach should be used for value-engi-

neering analysis. A cross-functional team including persons fromprocess development, tool engineering, production engineering,and the shop floor can develop a better process and even redesignthe part to reduce total cost (Daga and Choubal 2000).

Training is essential at all skill levels. Providing training op-portunities to everyone from the operator to the tooling engineerand even top manufacturing management will lead to improveddie troubleshooting and good die maintenance practice.

This chapter provides an overview of the topic of die mainte-nance documentation and tracking. If more detailed informationis desired, it is suggested that you contact shops scheduling work


15/15


181

with resources similar to your own to obtain advice on mainte-nance-management tracking procedures.

BIBLIOGRAPHY

Daga, H. and Choubal, S. 2000. Industry Leadership ThroughValue Management, 17th Value Engineering Conference. Bombay,India: Indian Value Engineering Society.

Smith, David. 1991. Quick Die Change. Chapter 16—Mainte-

nance Requirements for Quick Die Change Teams. Dearborn,MI: Society of Manufacturing Engineers.

Documents

Die Maintenance Handbook Chapter 16