The Use of Scanners in Computer-Based Materials Handling Systems

8/12/2019 The Use of Scanners in Computer-Based Materials Handling Systems

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M aterial andlingC lassicsP a p e r s i n t h e c l a s s i c s s e r i e s h a v e a p p e a r e d i n p r e v i o u s p u b l i c a t i o n s o f t h e

M a t e r i a l H a n d l i n g I n s t i t u t e a n d a r e a t l e a s t t e n y e a r s o l d . N o n e t h e l e s s t h e i r v a l u e

i n c o n t r i b u t i n g t o t h e e v o l u t i o n o f t h e i n d u s t r y a n d t o c u r r e n t p r a c t i c e i s v i e w e dt o b e t i m e l e s s e v e n t h o u g h i n m a n y c a s e s t h e a u t h o r s a n d c o m p a n i e s c r e d i t e d a r e

n o l o n g e r i n t h e i n d u s t r y .

THE USE OF SCANNERS IN COMPUTER-BASED

MATERIALS HANDLING SYSTEMS1979 AUTOMATED MATERIAL HANDLING & STORAGE SYSTEMS CONFERENCE

EDMUND P. ANDERSONCOMPUTER IDENTICS CORPORATION

MARCH 14, 1979

INTRODUCTION

Several years ago, a classmate of mine visited our booth at the National Materials HandlingShow. We hadnt seen each other for many years. After exchanging pleasantries, my friendasked what our company did and what were our products. Pleased with his interest, I gave him atour of the booth and proudly demonstrated each product. As I talked, he kept nodding, which Iinterpreted as his appreciation of the work we were doing. Several minutes later, whileexplaining a hand-held scanning device, my friend interrupted me. Ed, he said, I dont meanto sound rude or stupid, but, SO WHAT? Youve got something that reads that silly lookingcode and sends numbers into a computer. Whats so good about that?, he demanded to know.

His question momentarily startled me. Was scanning so remote and our explanation so poor thata mature and intelligent businessman couldnt relate its value in a real life application? Iseriously wondered if we were communicating with people, or confusing them. Having beeninvolved in this field for nearly ten years, I often wonder how many people have tried to explainscanning to their bossor the boss bossand what were the results.

My presentation today is made within this framework. I want to communicate with you so youwill have a clear understanding of how and why scanners fit into the scheme of materialshandling systems. The approach I will take will be to describe four systems that are popular andrepresentative of the use of scanners in computer-based systems. These systems are used for:


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1) Production Sortation

2) Production Monitoring

3) Order Verification

4) Component Assembly

Before we begin, youll need some indoctrination for the terms I will use and some backgroundto give you a perspective of where scanner-based computer systems have come from.

Lets look at some terms and what they mean.

SCANNER.is merely a data collection device.

MOVING BEAM SCANNER.a scanner that automatically collects information fromcodes on passing products.

HAND-HELD SCANNER.a scanner that automatically reads codes but must bemanually stroked over the code.

BAR CODES.affixed to products to tell the scanner, I am _____ or Send me to ______, or both.

Lets now look at the development of scanning systems from the early 70s to now. The use of scanners as systems tools got off the ground in early 1971 when the first Laser scanner wasintroduced. The significance of the Laser scanner was that this ingenious light source made it

possible to identify products and goods with a very cheap label. This type of scanner could

accurately and reliably read, several times per second, simple black marks composed in the formof binary codes. Earlier scanners worked on the principle of retro-reflectivity and requiredrelatively expensive labels costing several pennies each. By reducing the label cost to fractionsof a penny, or, producing free labels, the use of scanners became very attractive because it wascost-effective to invest in labeling. (Note: Free labels are those to which a bar code can beadded at no additional cost or produced via a computer-driven line printer.)

The earliest use of scanners was as a replacement for people involved in boring and tedious jobsof counting, identifying, and recording information from products passing by some control point.

Not only were these people poorly utilized, but, even the most conscientious and alert were prone to error. Their mistakes were often manifested in unreliable data base information,

misroutings, erroneous shipments, and delays. Scanners, as many applications proved, could dothe job better, faster, cheaper, and with outstanding accuracy and reliability. People could now

be allocated to more important tasks.

The typical scanning system had other advantages. Since the scanner could identify discrete products and events and transmit this information to a computer in real-time, the entire functionof intermediate data handling became unnecessary. Gone were two major sources of error and


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delay: (1) original data collection and (2) data rehandling. Whats more, we got a bonus. Asopposed to a person pressing buttons, who sees a number and then forgets it, the scanner hasaccess to computer memory under software control. This meant that the scanner-acquired datahad utility beyond the immediate task of, say, activating a diverter in a product sortation system.the data could be used for preparing operations reports and various business documents, such asa Bill-of-Lading.

From 1971 to 1975, much to the credit of the industry, the most popular use of scanning devicesin systems applications was in the materials handling field. Scanners were installed indistribution centers to automate product sortation. Automotive assembly- and componentmanufacturing plants used scanners to monitor and report on the production of transmissions,rear axles, and engines. The U. S. Postal Service, through the Corps of Engineers, equipped the

bulk mail centers with scanners to control the movement of containers within those hugefacilities.

User confidence in scanners grew tremendously during this period. Investments in scanner- based systems were beginning to be justified on improvements other than the pure elimination of people. Improved data base accuracy and receipt of data on a more timely basis became

prominent factors in justifying a new system. In two instances I know of, the benefits made possible through installation of scanner-based systems had an incredible influence on facilitiesdecisions of prominent companies. Sherwin-Williams was able to implement a unique

production line in a new facility in Kentucky in which no workers were required between the beginning and end of the line. Belknap Hardware, also in Kentucky, decided against a newfacility, which would have cost $millions and displaced its work force, in favor of upgrading thecapacity of a 100-year old, multi-level warehouse. The productivity gains expected with a newmaterials handling system under scanner control were achieved. Both of these systems werecarried as feature articles in a leading materials handling magazine.

Scanning technology and scanning systems know-how have made spectacular progress since

1971. Scanners have improved, bar codes contain more data and consume less space, and labelscan be produced automatically, both on- and off-line, with a new generation of outstanding

printing devices. Behind the scanners, an arsenal of products has emerged to aid the systemsdesigner and enhance the use and reduce the cost of scanner-based systems. Mini-computers arelosing some ground to micro-based controllers. Multiplexors have been designed to facilitatethe implementation of numerous scanning devices within distributed networks. Line drivers andother communications devices connect distant scanner-locations with host computers tomaximize the benefits of real-time data collection and processing. As we are about to see, it iscommon for data collected by scanners in a materials handling system to be used for many

purposes: Product sortation, verification of shipments, updating inventories, creation of bills-of-Lading, and providing source data for various reports.

Without further delay, and with the benefit of the preceding background, lets look at what nineyears of systems development has produced.


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PRODUCT SORTING SYSTEM

This system (Figure 1) can be used in virtually every distribution center. It is also an idealsystem for companies engaged in the business of supply, such as a wholesale hardwareoperation. In this example, well look at a product sorting system at Belknap Hardware inKentucky.

Belknap maintains an inventory of approximately 65,000 hardware items. Annual sales are inexcess of $100 million and customers number in the thousands. As is the case in mostdistribution operations, the key to success is quick and accurate turnaround. The longer a retailer has to wait for a supplier to deliver an order, the more money he has to tie up in inventory. So,the supplier who has the largest inventory and provides the fastest turnaround time will get alions share of the business. As I said earlier, labels identify a product or destination. They are

produced at a cost, or they are free. In this system, the labels are an essential ingredient to theorder processing and order picking functions. The host computer, an IBM 370, develops a

picking list for each order. The list is output through an IBM 1403 line printer that prints the listin the form of fan-fold picking labels. The labels contain the customers name and address, P.O.number, Belknap order number, sorting destination and package number. The destination code is

presented in a man readable and bar-coded form. The bar codes are created by thin and thick slugs in the printer. When the picker finds an item, the label is affixed to the carton which isthen placed on a belt conveyor (Figure 3).

Decline conveyors are used to transport the products from the inventory level to the first floor where the shipping docks are located. The conveyor line is operating at over 300 feet per minute. The sorting system is geared to handle 4000 cases per hour, diverting to any of 107accumulation chutes. Two induction stations are used to transfer the boxes from the belts to tilttrays. The tilt trays carry the boxes to an accumulation chute where the customers order isconsolidated. Each induction station is manned and equipped with a moving beam Laser scanner. The workers are needed to place the cartons on the tilt tray. (The boxes are literally

dumped on the first floor conveyor belt and are manually placed on tilt-trays with attention givento placing the labels facing the scanners.) The scanners are justified because of the high speed of the handling system, which exceeds a workers ability to accurately key-in numbers.

A purpose of the scanners is to identify the destination code on each passing carton. A shift-encoder is used to track to precise movement of the tilt-trays. A photocell is used to initiate thetiming sequence for each carton. A DEC PDP-11 receives data from the scanners, photocells,and shaft encoder. Software allows the computer to calculate the precise moment to activate thetilt-tray in order to send the carton to the proper accumulation chute. In addition to sorting andtracking, the scanners also assist in order verification by counting the number of cartons sent toeach chute. Photocells are located in each chute to report when an overload occurs. In such

cases, the chute is closed-down by the mini-computer and the boxes recirculate past the scanner continuously until the chute opens-up or the automatic system is over-ridden by entering achange of destination instruction to the mini-computer. A manual entry device is located at theinduction points for lane reassignment purposes and, if necessary, backup to the scanners.

The computer used in a system of this kind can either be a mini or micro. If the basic materialshandling system is going to remain essentially the same (i.e., no significant additions, deletions,


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or modifications in the number of sorts or method of conveying), you might want to consider amicro-based processor. It will be cheaper and can be installed in the factory environment, savingthe hassle of air-conditioning and computer bureaucrats. A micro can be changed, if necessary,

by having the supplier install new ROMs containing the software changes. Some users find thisfeature desirable because it prevents the possibility of some well-meaning software expertmessing up a perfectly good system.

The tracking sequence with tilt-trays is relatively simple because there is no slippagethe cartonwill arrive at the chute in a specific period of time. In a belt or roller system, photocells are

positions at each sorting destination to accommodate slippage. As with the tilt-tray system, thefirst photocell initiates the timing sequence with the shaft encoder. The additional photocellsupdate the location of each box being tracked. First the computer estimates how long it will taketo go from the first photocell to the second. When the box actually arrives, the computer recalculates how long it will take to reach the next, etc. the system, therefore, is self-adjusting.

A standard system configuration will normally handle conveyor speeds of up to 400 feet per minute, 127 sorts, and simultaneously track up to 800 items.

At this conference last year, I heard a spokesman for the conveyor manufacturers estimate therewere approximately 10,000 warehouses in the U.S.A. alone that were potential candidates for asystem like this.

The next system is

PRODUCTION MONITORING SYSTEM

If youre involved in production control, you know how important it is to have timely andaccurate information. Its a lifeline of any manufacturing operation. You must know what isgoing on, are you on-schedule, behind, or ahead. With real-time information, you are in a

position to exercise judgement when problems occur. You can do so with a high degree of confidence because you know precisely what the facts are concerning your operation.

Lets use an automotive industry example to illustrate this point. The industry is very dynamicand production schedules are often changed at component manufacturing plants to accommodate

problems at assembly plants. (For example, a rail shipment of rear-axles may have been lost enroute to the assembly plant and a chartered flight may be needed to get substitutes thereovernight.) A production monitoring system will give those who must make the decisions theanswers they needwhen they need them, no tomorrow or next week. Lets see how.

A typical system configuration is quite simple (Figure 4). First, the products we want to monitor

must be labeled. Products are usually labeled anyway, so it becomes a fairly easy matter to add barcodes to the label format.

If there is mechanized product movement, well, of course, use a moving beam Laser scanner. If no product movement, we can use a hand-held scanner. If there is a recirculating materialshandling system, we probably want to add a second scanner to record rejects or captureinformation on products intentionally diverted to another area for, say, inspection, quality control


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tests, etc. Well again use a photocell to let the computer know if an unlabeled product passes.If there is a possibility of product sway, while in front of the scanner, well use two photocells sowe wont record that product more than once. Well need a minicomputer or microprocessor,and an I/O device for communicating with the system. we can also interface the system with ahost system.

Our objective is to accurately collect the identification of each product that passes the scanner.We record all this information in memory. Data is received and processed in real-time. Reportsare issued on a scheduled and demand basis.

What are the scanners used for? They replace people. In the system were about to see, thescanner does the job that previously required two people, one each shift. Also, we want real-time information. So, we want the data to go immediately from the source, the axles, to thecomputer. This system employs an interesting label, its omni-directional (Figure 5). It ismerely placed on the product side facing the scanner. Attitude makes no difference so anyrotation of the wheel section of the axle will not affect the scanning system.

This plant produces 21 different styles of axles. They are built in random sequence on a single

assembly line. The labels, which are preprinted in batch form, are manually applied during theassembly process. As the axles pass the scanner, the labels are read and the data sent to thecomputer. The computer, in addition to maintaining production information, works inconjunction with a sorting system. the axles move from the assembly area and are transferred toan overhead power and free conveyor that moves them to a marshalling area where they areloaded onto special shipping racks. The main conveyor line terminates in a high-volumerecirculating loop that feeds axles to nine spurs. Axles produced in high volumes are directed tothe three low-volume spurs. The computer decides which go where based on volume dataderived from scanner input.

Although the axles are assembled randomly, they must be sorted into batches of 10 of identical

styles. The computer assigns axles to spurs in groups of ten by controlling spur switches andrecirculating axles until the sets are produced. The axles are batch released from each spur bythe computer and sent to the shipping dock where they are off-loaded onto special racks.

The production people in this operation can alter schedules armed with the factual data necessaryto weigh the consequences. If the Framingham, Massachusetts Assembly Plant needs a getwell shipment of 500 axles of a particular type, the axle plant can instantaneously determinewhat is on hand, what is to be produced, and make necessary production adjustments.Accountants like this type of system because it reconciles raw material input (at one end of the

plant) with finished product output at the shipping dock.

Lets move on to the next system

ORDER VERIFICATION SYSTEM

This system is really a combination of Product Sortation, Production Monitoring, and theaddition of something well call, Receipts Processing. (Figure 6).


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Lets begin with some facts. Im going to use a meat industry application as my example for thissystem. ITT Gwaltney is located in Smithfield, Virginia. They are a medium-sized pork packingand processing facility employing approximately 1300 people with annual sales of over $150million. Raw material (pigs, etc.) arrive in various forms and is processed into approximately450 products, ranging from hot dogs to the famous Smithfield Ham. The company processesabout 3500 orders per week, which are received from nearly 3,000 customers. From a materialhandling point of view, this volume translates into roughly 130,000 boxes handled per week. Tomaintain its share of the market, this company must process orders, from time of order entry totruck loading, within 6 to 8 hours, including the preparation of fully extended invoices.

The critical points of information and control in this system are (1) accurate and timelyinformation on products moving from Production to Finished Goods Inventory, (2) fast andefficient order picking, (3) accurate and timely information on products moving from FinishedGoods Inventory to the Shipping Dock, and (4) adequate data base and data collection for shipping documentation.

Product identification falls into two categories:

1) Products of standard weight (every box weighs the same).

2) Products of non-standard weight (you pay by the pound and weights vary fromone box to the next).

All products have been assigned a 3-digit code. The product code (Figure 7) itself contains 4digits, 3 for the product ID and the fourth serves as a check digit. All products are labeled with

pre-printed labels at the end of the production lines. (Note: There are four lines in this facilityand all operate the same.) At this point, we are ready to begin our Production Accountingsequence.

A scanner/scale station is located downstream from production. Each station has the followingequipment:

1 Laser Scanner 1 Weigh-in-Motion Scale1 Micro-based Controller 1 On-line Bar Code Label Printer

An IBM 370 serves as the host computer for this plant. Each day, the host computer sends atable of product codes to the micro-controller for items to be produced that day. (The controller can handle up to 250 different codes daily.) The host also provides the tare weights, minimum

and maximum package weights, and package data information, which is called the code date.

As the finished product passes, the scanner reads the code and sends the data to the micro-controller. The product is then weighted and that data is send to the micro-controller, whichmerges the information with that supplied by the host computer. If the carton is within tolerance,the micro-controller activates the on-line bar code label printer and provides both the product


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information and format instructions for preparation of a label containing the following (Figure8):

Product ID Code Date Net Weight

XXXX XXX MAR XXX XXXX

What happens if there is a discrepancy? The micro-controller activates a diverter thatimmediately sorts the problem boxes to an inspection area. (Shrinkage could be one of the

problems.) this is a valuable quality control and security feature that identifies problems with products before they reach the finished goods area or the customer.

The Final step here is to apply the label to the carton. This is a manual function (although itcould be automatic). We now have two labels on the cartonwell see why later.

The next phase is Order Processing. We now know exactly what is in our inventory. The Hostcomputer maintains a customer file with all essential information needed to process a customers

order. The computer also has a comprehensive table for each product code, which includes theactual number of items in inventory and their location. When orders are entered into the hostcomputer, the system responds by creating an order picking list. Five conveyor lines carry the

picked products from the finished goods area to a merge point under operator control. Justdownstream from this point is another scanner/scale system (without the bar code label printer).The second label is about to be used.

The next step is Shipment Verification. The host computer sends a table of the customers order to be verified en route to the shipping dock. The scanner/scale system checks each passing

product against the profile sent by the host. Were checking here for Product ID, quantity of each product, weight, and date code parameters. The system checks to be sure that each item

belongs in that order, checks the date information to determine if its within specification, andrecords the billable weight data. The information is buffered until called for by the hostcomputer.

The next step is to prepare documentation and update records. The host prepares an extendedinvoice automatically. This is a tremendous advantage for those companies seeking to improvecash flow. There is no delay in the billing process.

Besides reducing labor costs, this system accomplishes several other objectives equallyimportant to this company. Scanners made the system possible and the use of dedicated micro-controllers permitted the system to operate without over-burdening the host computer.

The final system is

COMPONENT ASSEMBLY VERIFICATION SYSTEM

The system has one basic objective: Prove that a complex product has been properly assembled.Were talking about the assembly of products comprised of numerous individual components.


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The mismatch of any of these components could seriously effect the performance or safety of thefinal product. Such products might be aircraft engines, the match-up of tires to a vehicle, anengine to a chassis, chemicals to a mixture, etc. Again, well use an automotive example

because its a real application and we can understand the consequences of poorly assembledengines.

An engine block moving along an assembly line begins its journey with a build ticket (Figure9). This tells the people on the line what type of engine to assemble. Distributors, EGR valves,and carburetors all look alike. So, the part number must be carefully checked to be sure itscompatible with the engine being assembled. Each component, therefore, has an identifyinglabel (Figure 10) containing man readable information and bar coded information. (GeneralMotors requires their suppliers to add the label prior to shipment.) The Build Ticket alsocontains man- and scanner-readable information.

At the end of the engine assembly line, an inspection is made of the engine including verificationthat the engine components were properly assembled (Figure 11). A hand-held scanning deviceis used to read the codes on each component and the code on the Build Ticket. A micro-basedcontroller or mini-computer is used as the dedicated processor. The processor contains a table of

engine types and the acceptable components for each. Audible and visual signals verify thateach inspection sequence has been completed. If the system verifies that the inspection enginewas properly assembled, a line printer outputs a self-adhering label documenting the test. Thelabel is placed on the engine block. If the engine fails inspection, the printer issues a labelrejecting the engine and identifies the faulty component(s). Rejected engines are allowed torecirculate through the assembly error where the proper match is made. The engine is inspectedagain.

This may sound pretty simple. It is. But, it works and its very effective. The automaker hastaken firm and positive steps to ensure that engines are assembled according to the standardsapproved by the Environmental Protection Agency (EPA). The EPA may levy fines of up to

$10,000 for every error it detects that goes uncorrected. In a more positive sense, the automaker can significantly narrow the window of product recall by tracing components from the source tothe end product. This feature could one day save $ millions, which would otherwise be passedalong to the consumer.

CONCLUSION

I hope you have found this information useful. I have purposely avoided discussions on codesand other technical details that I believe distract from a meaningful presentation on how scannersare used.

I wish my classmate was here today. I would ask him if he had a better view of how scanners fitinto the materials handling field. I hope he would say, Yes!

Thank you.


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Mr. Andersson is Director, Corporate Relations, Computer Identics Corp. (CI), Westwood,Massachusetts. He joined CI in 1971 and has been primarily involved in corporatecommunications. He served with Avco Corp. for ten years. With Avco/Economic Systems Div.,he was a consultant to a new corporate division managed and operated by minority personnel.With Avco Systems Div., he served as Manager, Technical Communications for Space Systems.He has authored and co-authored numerous articles and papers dealing with the use of opticalscanners in computer-based control systems for applications in materials handling,transportation, and distribution. He is listed in Whos Who in American Railroading and amember of the American Association of Industrial Management. Mr. Andersson attendedBentley College and Northeastern U.

Figure 1 Flow Chart, Product Sortation


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Figure 9 Sample Build Ticket Used in an Engine Component Verification System


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The Use of Scanners in Computer-Based Materials Handling Systems