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Bar codes in manufacturing - part 2, uses on the shop floor.

It's the new language of industry. Instead of letters and numerals that people can read, though, it consists of cryptic symbols made up of uniform bars and spaces--some thick, some thin, all straight and parallel and lined up top and bottom--that only machines can read. And it's being adopted in just about every kind of metal-products manufacturing and assembly plant.

Bar coding began to appear on the shop floor some 18 years ago. In 1967, for example, General Motors installed a bar code system for tracking of work-in-process (WIP) at the Oldsmobile plant in Flint, MI. The system cost $25,000 installed, but replaced a manual WIP-tracking system that cost $75,000 a year in salaries alone.

Since then, the use of bar codes has been spreading quietly but rapidly. The automotive vehicle assembly and components manufacturing industries, along with electronic equipment and components manufacturing, were the first to become major users. In recent years, other industries--including major appliances, ordnance, aerospace, and ship-building--have been putting bar codes to work.

By the end of this year, the total US market for bar code systems, equipment, materials, and services is expected to reach about $500 million, according to a spokeperson for the Automatic Identification Manufacturers (AIM), a trade association based in Pittsburgh, PA. AIM's research indicates that the market will climb to about $1.2 billion annually by 1990. Of that total, over 50 percent will be for systems going into manufacturers' shops, factories, and warehouses.

Why this high rate of growth? Ultimately, users expect to achieve gains in quality control, efficiency, data management, and cost-effectiveness. To reach these goals, they are applying bar code systems for the performance of many discrete functions (see box). Following are a few brief descriptions of how companies in various metal-products industries are using bar code technology.

Tracking WIP in a machine shop

The function for bar coding listed first in the box--tracking of work-in-process (WIP)--is one that could be implemented by almost every manufacturer. In this application, typically the workers scan bar code symbols on their ID badges and on the work orders and travelers or move-tickets (Figure 2).

In some cases, workers may also scan symbols on menus that list specific processing operations: for example, drill, deburr, assemble cap to body. Testers and inspectors may scan from menus bearing symbols for specific types of defects.

One example may be found at Goodyear Aerospace Corp, Akron, OH. The company is a diversified aerospace and defense contractor.

After determining the routing for a batch of parts through the machine shop, the foreman decides which operations need to be tracked. Then, using a microcomputer and Printronix dot-matrix printer, an operator produces a batch traveler that bears not only alphanumerics but also the appropriate bar code symblos for the selected sequence of operations.

"Employing bar codes this way gives us an instant, real-time picture of the production status of each order and each batch," says Terry Dunaway, foreman of material operations. "At any given moment, we can tell which parts are at which stations, and what's waiting in queue.

"We also employ the system to monitor the usage of individual machines," he adds. "This helps us to schedule maintenance, and gives us a handle on the capital productivity of the machines."

There are now seven wand-type scanners (Figure 3) with fixed data-collection terminals in the Goodyear machine shop, assembly shop, and inspection stations. The plant also employs several portable wand-type units in the parts warehouse. All the scanners and data-collection terminals in use at this facility were built by Intermec Corp.

Tracking tools and managing inventories

Another bar code function that can be applied in manufacturing is that of tool tracking and toolroom inventory management. Our example comes from ship-building, but the same equipment and techniques can be used in any hardgoods industry.

Two years ago, the Seattle Div of Todd Pacific Shipyards had a manual filing and retrieval system for tool checkout and inventory maintenance. The facility employs about 3000 craftsmen on three shifts. These workers draw from a tool inventory totaling over 3 million items in 15,000 categories. Items range from six-ton chain falls, through equipment for welding, drilling, riveting, and deburring, to items as small as ear plugs.

With a tool inventory this large, Todd was experiencing sizable problems in tool checkout and return, record keeping, inventory management, and purchasing costs. Reporting of lost, wornout, and broken tools was a slow, tedious procedure, so it was difficualt to maintain supplies that were adequate yet not excessive.

Moreover, tool checkout and return were slow, causing long lines and lost production. Workers hoarded tools that were in good condition, adding to inventory costs. And employee morale was suffering.

In an attempt to ease these problems, Todd added satellite toolrooms, but still didn't have a central control for fast, easy tool tracking and accountability. Unable to forecast tool usage accurately, the company's tool-purchasing agents could not take advantage of volume discounts. Often the agents would have to dash to local retailers just to get needed tools on time. Of course they paid a premium for tools bought in small lots.

Finally, about a year ago, Todd discovered bar coding, and consulted with Data Enterprises of the Northwest (DEN), a Seattle distributor of Intermec equipment. DEN specialists provided a complete system that not only aids in tool management at each of the shipyard's 13 toolrooms, but also prints bar code labels and links the toolroom terminals with a central computer.

Now each toolroom has wand-type scanners and fixed data-collection terminals equipped with CRT screens. Each tool bin and drawer bears a bar code label that identifies the category of tools at that location. Every worker wears a bar-coded ID badge.

When a worker needs a tool, he can go to the main toolroom or any of the 12 satellite toolrooms. To check out a tool, he gives his ID badge to the toolkeeper, who scans the symbol. The toolkeeper then goes to the appropriate storage location and scans the bar code label for the requested tool (Figure 4).

Back at the window, the toolkeeper gives the tool to the worker, and scans another bar code symbol on a menu attached to a CRT terminal. The CRT then brings the toolkeeper up to date on the total number of tools, by type, that have been checked out to that individual worker.

If the requested tool is not available at one toolroom, an inquiry to the computer will instantly reveal the location of the nearest toolroom that has the tool in stock.

Since installing the system, Todd Pacific Shipyards reports impressive gains in the speed of tool checkout and return, reduction of inventories, and savings in purchasing costs. The workers say they like the new system, and overall productivity has risen.

Company managers estimate that they will realize complete payback for the system within two years of the startup date.

Controlling test machines

in a transmission plant

Another function that is beginning to gain acceptance is control over machines and processes. An outstanding example is found in the General Motors Hydramatic plant, Warren, MI. A prime source of transmissions for GM autos and trucks, the plant uses an extensive bar code system, provided by Scope Inc, to control program selection in automated test stations.

At the upstream end of the conveyorized assembly line, operators affix a printed bar code lable or laser-etched tag to each transmission. The symbol carries data for the serial number, plant ID, product number, model number, and year of manufacture.

At one point on the line, each palletborne transmission passes under a fixed-mount, moving-beam scanner (Figure 1). This scans the symbol, seeking the model code data.

The scanner's controller sends these data to a DEC PDP 11/34 minicomputer. While the transmission is being positioned in a test-stand simulator, the 11/34 downloads a test-procedure program for that particular transmission model to the simulator.

Once the transmission is in place, the simulator runs the specified tests. The 11/34 analyzes and records data from more than 700 test points. If a transmission does not meet specs, it is diverted to a repair shop. There a printout from the 11/34 aids the technicians in diagnosing the problems.

Since putting the system into operation, GM has been realizing fast, error-free, automatic data entry. Other results include automatic program selection and process control, and generation of detailed test histories.

An unexpected bonus has been a big savings in labor costs. Where a test-stand operator could previously run only one simulator, he can now easily monitor five.

Managing cutting tools

in automated machining

Bar codes are now used for management of cutting tools on NC machining and turning centers. A growing number of machine-tool builders--among them, Burgmaster Houdaille, Giddings & Lewis, and Kearney & Trecker--offer bar coding as an option on their automatic tool storage and changing systems. General Electric Company's Carbology Systems Dept is one of several tool manufacturers that offer the bar code option.

In this type of application (Figure 5), bar coded labels or tags are applied on the toolholders. A fixed-mount, moving-beam scanner is mounted on the machine-tool frame near the tool magazine.

In some cases, a small electric robot is also mounted on the frame. During operation, the robot picks a tool from the magazine, then swings over and holds the tool in front of the scanner so it can read the bar code symbol. The robot then transfers the tool to the ready station.

In other cases, as shown in the photo, the scanner is positioned near the magazine, and reads the codes directly from tools still in the magazine.

The bar code system verifies that the correct tool is being chosen for the programmed part and process. This technique can be used either to check the correctness of NC programming of tool locations, or to replace that type of programming.

"We're seeing much interest in bar coding of tools," says Leo Thomas, marketing manager at Burgmaster. "Lots of workpieces are more expensive than the tooling that machines them. Application of a bar code system helps to prevent having the wrong tool come tearing down into the wrong place on a costly part.

"Then too, the use of bar codes makes it possible to store tools at random in magazne pockets. The scanner doesn't have to rely on a program, but can simply look for the correct tool as the magazine moves."

Many motives, many ways

Space limitations do not permit us to relate additional case histories on bar codes in manufacturing. A few synopses will give you an idea, though, of the great variety of industries, functions, goals, and techniques involved.

* In Ford and General Motors assembly plants, bar coding is used all the way through to final inspection. "Coding permits cost-effective identification to adjust the sequence in the assembly lines," explains Charles Mara, director of market development for Computer Identics Corp. "Cars built to customer specifications are inserted at optimum positions in the main flow of standardized cars, which are built to blends based on forecasts. This enables the automakers to balance the workload and fill custom orders more quickly than they could otherwise."

* The automakers are requiring many suppliers of critical components--e.g., brake parts, seatbelt anchors, pistons--to laser-etch permanent bar code symbols on the products. Etched symbols can withstand the rigors of manufacturing, and also hold up well even after long operation in the field.

One reason for following this practice is the quest for quality. Through their coded symbols, key parts can be traced back not only to suppliers, but also to individual material batches, workstations, and operators.

Reduction of warranty costs is another reason for the practice. If an auto manufacturer discovers that a batch of bad parts--say, in the brake assemblies--has slipped through and is in use by drivers, the company can consult bar code records to pinpoint the individual autos and owners affected. As a result, the company recalls fewer units, fewer owners are inconvenienced, and warranty and recovery costs ae minimized.

* An automated foundry uses bar code symbols in a novel way to control process machinery. In this facility, the hangers on the power-and-free conveyors carry patterns for metal molds. Each hanger bears a customized bar code label containing information on process cycle time, contents and amounts for the sand mix, compaction cycle time, and other critical data pertaining to the pattern being carried.

At one point along the conveyor line, a fixed-mount scanner reads the bar code symbols on the hangers. The scanned data are relayed to the controllers for diverters, pugmills, molding machines, and other automated equipment downstream. The control system then directs each hanger with its pattern to the nearest available casting station, where data acquired from the bar code symbol automatically govern the processes.

Laser-etched for permanence

* Ordnance manufacturers are bar coding ammunition and weapons, usually with laser-etched symbols. As part of a US Dept of Defense feasibility program, suppliers now code over 1000 weapons, including M16A1 and M16A2 rifles, M60 machine guns, and .38-caliber revolvers. The suppliers use the DoD-approved version of Code 39.

* Manufacturers of electronic equipment were pioneers in the use of bar codes, and continue to employ them extensively. For instance, at Apple Computer's paperless plant in Fremont, CA, where they build the Macintosh, bar code labes are used to track all components and computers as they pass through assembly, inspection, and test. Data collected by scanners go to the host computer, which maintains files for production scheduling, inventory update, and manufacturing resource planning (MRP II).

Another example may be found at MiniScribe Corp, a manufacturer of computer disk drives in Longmont, CO. "Miniscribe uses bar coding to maintain quality control, and to cut down on warranty costs," says Charles Mara. "Continuous shop-floor reporting gives valuable data on failure rates of printed circuit boards, components, and finished disk drives. To ensure quality in their system, MiniScribe can monitor elements of production processes, assembly, and test activities, and can monitor the history of individual finished products." The system was supplied by Computer Identics Corp.

* Some suppliers of electronic components are bar coding them, and many equipment assemblers apply coded labels or tags to purchased components. "It is common practice in this industry to code components such as printed circuit boards, hard disk platters, and silicon wafers," says Richard Bravman, vice-president of Symbol Technologies Inc. "The symbols provide timely, accurate data for lot tracing, quality control, and inventory management."

PC boards usually carry coded labels that have been coated for protection during soldering, burn-in, and other harsh processes (Figure 6). Normally the symbols on disk platters and silicon wafers are laser etched.

Becoming universal

What about the future of bar coding in manufacturing? One bit of well-qualified prognostication comes from Terry Glude, president of Productivity Systems Inc, a systems integration company based in Roswell, GA. Glude has been involved in systems work and bar coding for 20 years.

"I'm convinced the bar coding will become virtually universal in US shops and factories," he asserts. "With a personal computer as the base unit, even a small company can afford to get into bar coding. You can buy a complete system for shop WIP-tracking--including the computer, printer, software, a few wand scanners, and some labels or tags--for $20,000 or less."

Glude points out that pressures from the DoD and the automobile manufacturers are forcing many component supplier companies into applying bar code symbols not only on shipping labels and containers, but also directly on the products themselves. As a supplier gets deeper into bar coding, he becomes familiar and comfortable with the technology. Eventually he looks for ways to apply it in his own processes.

"We saw this progression in the food products and supermarket industries a few years ago," Glude continues. "It took them a while to get comfortable with bar coding and integrate it into their computer systems.

"Now, though, the use of bar coding in food production and distribution is so common that we take it for granted. The same thing will happen in manufacturing."
COPYRIGHT 1985 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1985 Gale, Cengage Learning. All rights reserved.

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Author:Quinlan, Joseph C.
Publication:Tooling & Production
Date:Sep 1, 1985
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Next Article:Three new packages announced for robot off-line programming.

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