CIM comes to thermoforming.

CIM Comes to Thermoforming

Two pioneering processors tackled computer integration on their own without benefit of off-the-shelf CIM packages for thermoforming that are beginning to hit the market.

Most major processors of thermoformed appliance, automotive, and packaging products have sophisticated process controls, at least on machines built within the past two or three years. Most also have computerized their back-office jobs like data entry for inventories, job schedules, material ordering and billing. Yet only some half-dozen to a dozen thermoforming processors have created computer-integrated manufacturing (CIM) environments with real-time monitoring of process and production data at a remote terminal. So says Steven Thomas, based on his own research as marketing v.p. of PlantStar Div. of Syscon International Inc., South Bend, Ind., a firm that specializes in CIM packages for plastics. Oddly, not one of those few thermoforming CIM pioneers apparently uses commercial, off-the-shelf software or hardware for CIM. Each developed its own. Some weren't aware of commercially available packages. But most feared generic systems would swamp them with too much data, would not be easy for machine operators to use, and most important, wouldn't accurately measure production of good vs. bad (scrap) parts.

In this article, two of those thermoforming pioneers tell how they built their own CIM systems to serve different markets with different goals, but with very similar results. At GE Appliances in Decatur, Ala., the captive-forming operation exists within a highly automated refrigerator manufacturing plant. About two years ago, GE turned to CIM in order to drive down the cost of a new high-volume refrigerator model with tight control of the process and materials usage. GE's CIM system, just coming to full fruition now, ties in several giant state-of-the-art, in-line formers that were brought in from Japan for the new refrigerator project. (It does not involve older rotary machines at the plant.)

Also within the past two years, Inline Plastics Corp. of Milford, Conn., implemented a home-grown CIM system to cut scrap and downtime on machines that may change jobs two to three times a week. Inline is a thermoformer of custom medical products and proprietary food-service trays, with two plants and 45 small roll-fed formers.

Both firms say CIM immediately improved scrap, downtime and setup efficiency at least 50% and is steadily improving efficiency in other areas like hourly labor, management, JIT capability, inventory, maintenance scheduling and quality. In short, the payback was better and faster than they anticipated.

Commercial CIM providers aren't quite sure why companies like GE and Inline developed their own software and hardware. The immediate answer is probably that they have someone inhouse who can do it. But PlantStar's Thomas notes an inherent risk in building a one-of-a-kind system: "If the inventor leaves the company, typically the ability to repair or enhance the CIM system leaves with him."

Nevertheless, thermoforming processors seem to be "unaccountably averse to a systems-wide approach to CIM, although it's feasible and relatively easy," says Frank Dyke, manager of plastics automation at Allen-Bradley Co., Highland Heights, Ohio. Whatever the reason, major CIM providers like Allen-Bradley, PlantStar, and Mattec Corp. in Loveland, Ohio, say they have no thermoforming customers, despite dozens of successful CIM installations for other plastics processes, notably injection molding. That could change, though, as an appliance thermoformer later this year expects to be the first thermoformer with PlantStar's Focus 100 system.

In the near future, however, thermoforming machinery suppliers may hold the key to bringing commercial CIM to thermoforming. So far, their efforts addres real-time monitoring of process variables like heat, pressure, vacuum, and indexing, but have not attempted one of processors' greatest concerns--real-time counting of bad parts. Thermoforming Technologies Inc. (formerly AAA Plastics Equipment Inc.) in Seabrook, N.H., may have been first with unusual new control and monitoring software and hardware. Another multi-machine CIM software program is available from Lyle Industries Inc. in Beaverton, Mich.; and still another is in the works at Sencorp Systems Inc. in Hyannis, Mass.

Somewhere in the southwest corner of GE Appliances' new multi-million-dollar Decatur plant, ABS sheet is extruded and giant vacuum formers make doors and liners for a new refrigerator model. The entire plant, of which thermoforming is just a part (it also includes injection molding), has approximately 1500 employees in a maze of conveyors, automated testing equipment, manual data-entry terminals, robots, welding and foaming stations--all coordinated by a plantwide computer network that GE calls "Smart."

Smart is a central factory monitoring system, which GE devised to schedule production. Smart runs on Digital Equipment Corp.'s Microvax central processing units (CPUs). A dozen of them gather plant data, three to four process information, and two do nothing but handle traffic of users logging on and off the system. The CPUs connect to DEC PDP 1183 "front-end" computers, which in turn communicate with over 200 GE Fanuc programmable logic controllers (PLCs), which control machine processes throughout the plant.

Four to five years ago, GE considered buying a ready-packaged thermoforming CIM system, but opted to develop its own Alphix controls instead, which are still in use. When the Decatur plant was laid out, engineers decided to order the thermoformers, built by Asano Laboratories in Japan, with machine controls but without elaborate supervisory controls, and to hook them instead into the "Smart" system simply because it was already there.

The handful of 80-ft-long Asano thermoformers were the last part of the new plant to arrive a year ago. They were a formidable startup, with 516 separately controlled strip-metal heating elements and multifunction trim-and-punch dies, equipped to change tooling automatically in as little as 75 sec for trim-and-pierce tooling and 4-5 min for the forming mold.

Each Asano came with three PLCs controlling preheat, final heat (allowing GE to use patterns in both), index speed and closing velocity of the 75-ton forming press and 150-ton pierce-and-trim press. A fourth GE Fanuc Series 6 PLC oversees the three other PLCs and connects each thermoformer to the central Smart system.

For the first nine months after the thermoformers were delivered, technicians just struggled to get the complex machines up and running. Then in late January, GE began exercising the first CIM control by adding Smart monitoring hardware to each thermoformer. GE installed small IBM-compatible DEC 3865 SX computers on each former as gateways to the Smart Ethernet local-area network.

As original equipment, each thermoformer also had an IBM 7532 industrial version of a personal computer. To save space, GE made one video terminal, keyboard and small printer do for both the DEC/Smart gateway computer and the IBM on the machine. A switch toggles the display from one to the other. The IBM computer records and graphs data on heater-element performance and temperature readings from the infrared pyrometers in preheat and forming stations. The IBM also records setup data and moves it as needed from machine to machine.

The DEC/Smart computer takes time-and-position data from the thermoformer's GE Fanuc PLC and stores and displays, for example, the last 100 heat cycles, showing the time for sheet to reach a given temperature. DEC/Smart also gives operators about 40 X-Bar & R charts of process variables (of which three or four are commonly used, the others are for diagnostics). And DEC/Smart gathers real-time data from all the thermoformers onto a summary screen, accessible from any PC in the plant.

Using Smart to monitor thermoforming processes also allows GE engineers at Louisville, Ky., GE Appliances headquarters, to watch the same diagnostic screens and real-time summaries as the Decatur production people. This aids troubleshooting. It's also a big plus for R&D, now that GE is at the point of running frequent new material tests and trying out ways to shorten cycles or reduce sheet thickness.

Smart, however, is a short-term storage system. It only holds data for 80 hr. So information that is wanted longer is stored in mainframe management programs in Louisville. Maintenance data, like thermoforming trim-die history, for instance, is stored so that after 60,000 trimming "hits," dies go to the shop. The thermoformer's PLCs do a 50-millisec program scan, while the DEC/Smart data management program takes 20 sec to scan, but that's fast enough to record every thermoforming cycle.

RUNNING ON AUTOMATIC, ALMOST

The initial monitoring program written for the DEC/Smart computers on the Asano machines tracked only process time and machine position, though it did so with millisecond precision. Time was a convenient place to begin monitoring because it relates to a lot of other machine variables. "Transfer-forward time, for instance, is a health-and-well-being check on a lot of the machine's functions--the motor that runs the transfer, the gear box, the bearing it rides on, and all the switches," says GE senior controls engineer Jesse "Mike" Felker. The danger in gathering machine data, he says, is to gather too much and create "an avalanche of false alarms that just aggravates people."

Felker wants eventually to monitor temperature as well. But for the moment, no diagnostic flags tell an operator if sheet hasn't reached a given temperature because the program doesn't yet control temperature. Instead, it watches the time it takes to reach a temperature and sends an electronic warning if the time is off. Interpreting time-based data isn't always easy. For instance, when a graph of time to reach forming temperature suddenly stops--leaving a gap that literally means it took zero seconds for sheet to reach forming temperature--it means no sheet fed through the machine and the pyrometer is looking straight at the bottom heater.

The program also can't be trusted to count good and bad parts yet. The machine can blow a hole in a part and not raise a blip on a screen because the program isn't monitoring pressure. So parts are manually counted before a tool change, a process known as "walking the line," when a production scheduling person physically threads the maze of overhead catwalks, counting as many as 3000-4000 parts in an hour before ordering a mold change.

Each Asano has a dedicated "controlman" tending the machine and an operator checking and removing parts. For now, GE has no plan to reduce that level of supervision. But controlmen are able to use their time more productively since January. For instance, all can leave at once for an hour or more to attend a class in machine controls elsewhere in the plant. The machines have alarms that signal out-of-parameter time conditions. Controlmen also check summary screens from PCs anywhere in the plant.

A START ON PRODUCTION MONITORING

Changes happen almost daily now to the CIM program, at both ends of the thermoforming line, Felker says. In sheet extrusion, technicians have installed and debugged the first production monitoring of the ABS sheet that feeds thermoforming. Sheet pallets are now bar-coded before delivery.

At the other end of the forming lines, where refrigerator liners are taken off by quality-trained operators (and either conveyed for grinding or hung on racks for storage), new Burr-Brown Corp. data-entry terminals (DETs) have been installed. Operators are being trained to point with a pen-like "wand" to a list of possible causes of part failure to record them for later analysis. Bad parts can then be compared with processing data at the time they were made. If the thermoforming machine goes down, the data-entry terminal will prompt operators to enter one of 10 explanations--five operational (like "mold change," "maintenance," or "idle") and five machine-related, identifying the area of mechanical failure.

REVOLUTION IN SCHEDULING

Most of the Decatur plant works two shifts, thermoforming still works three, but not all the third shift is used for thermoforming anymore. Plant systems people say "Vac Forming's" improved efficiency may eventually allow it to work the same schedule as everybody else. Since January, productivity has improved so that forming can now switch production two or three times a week among four models (14- and 16-ft refrigerators with two door styles). "We can have runs as small as 200-300 refrigerators," an operator says. This flexibility has caused much faster product turnaround. Production is no longer based on sales estimates and inventory but responds to orders only a few weeks before.

CIM controls on the thermoformers will also require fewer support people for thermoforming production scheduling. Once operators are entering reject codes with the wands, a production scheduling person, previously dedicated to hand-gathering the same bad-parts data, will be reassigned.

Inline has a history of homegrown innovation. Eight years ago, it pioneered a modification of machine controls (using Xanadu universal time-based programmable controllers) that led to 50%/yr sales growth for the past five years. Manufacturing v.p. Frank Schepp then suggested a system to monitor production, encouraged by president and owner Rudolph Orkisz. Schepp didn't like existing commercial data-acquisition computer (DAC) systems, because they required operators to enter data on the number of reject parts at the end of the day, "so you didn't have real data integrity nor real-time rates of scrap and production."

Unlike GE's "intelligent" system that watches the process, Schepp wanted a "dumb box" to answer simple questions like "Is the machine cycling, and how fast?" He worked a year and a half with a programmer friend and an electrical engineer to design and build custom hardware and software, costing some $25,000, not counting Schepp's time. The result was a box on each thermoformer with a simple array of buttons, lights and buzzers that allows limited communication between operators and a central PC-based DAC.

Schepp made sure his "dumb box" could monitor virtually any make or model of thermoformer. "It doesn't care what you have for a machine," he says. "It makes no sense to integrate two machines and have 10 others operating willy-nilly."

Schepp's box pulls data from only one signal connection on the thermoformer to verify that a part was made. "We sense the forming pressure being turned on, because in a dry cycle that doesn't happen," Schepp says. "All the rest of the data we calculate are based on that."

Data are also exchanged between operators and the DAC. The box lights up and buzzes for operator response at two events: "Unit-of-Measure Complete" and "Machine Down." When the machine has cycled a preset number of times, say 2000, it buzzes for the operator to confirm that he made 2000 good parts. The operator (who meanwhile has been packing stacked parts) pushes a green "Yes" button or a red "No" if rejects have left the job order incomplete.

Similarly, if the machine stops, the DAC wants to know why and signals the operator. The operator can choose from five programmable explanatory buttons (e.g., "Jammed," "Out of Material," "Operator Away," "Machine Repair," or "Tool Repair"). If no response is displayed on the monitor, the foreman knows to check immediately.

The DAC tabulates real-time production data on all jobs running and displays it on a large color monitor on the shop wall within view of operators. The multicolored display shows a machine's data in red if a machine runs slow or is down, green if it runs right. Schepp's program uses cycles to count parts, cumulative uptime from the start of a shift, parts to run, job end, and percent bad parts. The display also identifies the operator, machine type, cavities, job number, standard cycle time for that job, and shift average cycle time. Only someone with password authority can raise or lower job standards. "We run 24 hr/day, and it's like having your best foreman on all three shifts, because you're running against standards established under optimum conditions," Schepp says.

The monitor displays data from up to 17 machines simultaneously on one screen, then changes to display the next group (the interval between screen changes is programmable). Inline has over 20 machines per plant, so "If we're running more than 17, we can also display only those that are out of parameter," Schepp says. He and the foreman can call up data simultaneously on separate terminals. But Inline's two plants, 12 miles apart, aren't connected by modem--Schepp is concerned about possible unauthorized access by a smart "hacker" at a competitor.

Data are stored in a nonvolatile "bubble" memory--more expensive than a hard or floppy disk, but reportedly more secure in case of power failure because it doesn't require power to store data. Data from every eight thermoforming machines are concentrated into one cable in a multiplexing interface module that sends data to the DAC. The acquired data are backed up to the bubble memory every five minutes, so if power goes out, only the last five minutes of data are lost.

The DAC itself, thanks to multiplexing, can be located up to 1000 ft from the machines it monitors, whereas the RS232 technology, usually used to transmit CIM data, limits transmission distance to 200 ft. The DAC, which occupies an inconspicuous 3 x 3 ft utility cabinet on the shop wall, was built with stock circuit boards, except for a specially designed video-driver for the multicolor monitor.

When the "dumb boxes" were installed in late 1989, productivity rose 20% and the reject rate dropped at least half, Schepp says. "Cut your scrap rate in half and you save real money." Accurate real-time scrap rates also let technicians prioritize repairs; for instance, choosing between 10% rejects on a job with an hour to run and 5% scrap on a job with 40 hr to run.

The DAC is linked to an IBM-compatible PC that stores job histories and parameters and generates reports. "We wanted to make it easy for operators to use and also configure the logic so other uses could be made of it, like accurate scrap estimates on job quotes," Schepp says. At the same time that the "box" was developed, Inline was outgrowing its original materials-resource planning (MRP) software and bought a new inventory system from Data Technical Research, Jacksonville, Fla. In "a year or two," Schepp says he will plug production data from the "boxes" directly into the MRP system. In the meantime, Schepp, who owns rights to his software, is looking for machinery companies to market or license it from him.

Processors Check Out CIM from Machine Builders

Do-it-yourself CIM for thermoforming won't be necessary if machinery suppliers have their way. Several suppliers, including Thermoforming Technologies Inc. (formerly AAA Plastics Equipment Inc.), Seabrook, N.H.; Lyle Industries Inc., Beaverton, Mich.; and Sencorp Systems Inc., Hyannis, Mass., will now be offering commercial CIM systems that address a range of process variables like heat, pressure, vacuum, and indexing. Still, processors say these offerings currently are limited in that they do not monitor the all-important parameter of real-time scrap or rejects production.

THERMOFORMING TECHNOLOGIES

Thermoforming Technologies is one of the first machinery suppliers to have come up with software and hardware (copyright and patents pending) for remote control and monitoring of up to 12 key thermoforming parameters--including sheet and tool temperatures, vacuum, pressure, and cycle time (see PT, Dec. '90, pp. 50-51). According to the company, high/low limits can be set, so part quality is logged, while alarms signal one or more out-of-parameter conditions. The program scans the thermoforming process three times/sec, only recording deviations. Forming data can even be ink-jet printed on parts.

The proprietary software is said to control a multi-machine environment and to use a novel electronic on/off power-phasing system to control highly responsive quartz heaters more smoothly and with more efficient energy use than PLC-based controls. It does not, however, include operator input for a total scrap calculation. It also views only one machine at a time, rather than offering a summary screen. The company will install its CIM system either on its own equipment or retrofits.

LYLE INDUSTRIES

Milprint Inc. in Fremont, Ohio, a former of thin-gauge food trays for cold cuts and dairy products, will be the first to use Lyle Industries' new remote-monitoring controls (see PT, Dec. '90, p. 48). Milprint wants documented quality in a radically downgauged packaging product. Milprint took delivery in March of the first computer-integrated Lyle thermoformers. The new software on Milprint's Lyle 140FH former provides automatic quality records on each job and "relates nicely to our extrusion process, where we already have continuous information," says Milprint plant manager William Hoffert.

Hoffert wants two things from the new controls: "Quicker setups and ability to formulate and store job recipes and historical tracking data for in-place SPC," which Milprint now tracks manually. Documenting quality is an increasing concern, Hoffert says: "We've had to downgauge every package we make--running thinner, but doing the same job. You get to the point where if you're not controlling your process, you're making defective parts."

Lyle's microprocessor records all changes of machine settings and downtime with date and time. Graphics also include machine diagnostics to locate mechanical problems. It also can make many small machine adjustments from a keyboard while the machine is running. The adjustments are controlled by a proprietary position encoder, not a limit switch. The encoder is a shaft connected to the platen, which puts out impulses as it converts platen position into increments of hundredths of an inch, says Lyle's microprocessor specialist William Beltz. Oven temperatures are measured from thermocouples on heating elements (quartz, Calrod, or ceramic) and can be adjusted from a keyboard while the machine is running. For now, the controls don't read sheet temperature or record scrap rates.

Beltz wrote the software himself, rather than adapting a commercial package, "to minimize data going up and down the channels, so thermoforming machines aren't bothered by a lot of data they don't need." For now, the network can oversee 15 machines, but more could be added. Data are gathered by a memory-resident, multitasking program from 96 inputs/outputs on the thermoforming line every 3 sec. Thermoforming is evolving rapidly, Beltz notes, and microprocessor controls are "a good safeguard against machine obsolescence because they can be changed and upgraded so easily."

SENCORP SYSTEMS

Vac-U-Pack Inc., Riverdale, N.J., is interested in testing Sencorp's CIM system when it becomes available in a few months, based on savings it achieved so far from remote monitoring of just one machine. Vac-U-Pack has a Sencorp Model 2500 thermoformer, which can be remotely monitored by modern from any of two PCs at the plant or one at the plant manager's home. One PC can watch one thermoformer, though a second PC can "call" the first PC and both can watch the same screen. But for practical purposes, if Vac-U-Pack president Joseph DeFelice leaves the program on his screen, no one else can use it.

Vac-U-Pack says quality is 75% better, downtime and scrap parts 50% lower on the new remote-monitored machine than on its older Sencorp 2200 with a previous generation of controls (and without servodrive indexing). Setup time is also nearly twice as fast (4 hr now vs. 6-7 hr before) on the new machine, which stores a minimum of 50 setups on a hard disk. Some of the setup is done in seconds, but sheet widths have to be adjusted manually.

Sencorp's remote-monitoring Sentroller II controllers have been available on thermoformers for three years, but Sencorp software engineer Steven Ellstrom is working on the next step--CIM networking to monitor a multimachine environment, which should be ready for testing in a few months. Ellstrom says it's an RS485 multidrop network with a serial transmission protocol, connecting one machine to the next and then the next like beads, rather than connecting to a multiplexer or a central PC. The new program will expand data-acquisition capabilities and allow faster tool sharing between machines, says Sencorp marketing manager Neal Crampton. It will also calculate real-time scrap for the first time, says Ellstrom. Total parts will be counted from the trim cycle by a material sensor; then the operator will answer a prompt from the network as to whether he made a certain number of parts.

Vac-U-Pack's plant manager says it takes a good mechanic six weeks to get used to the remote capabilities and digitized data. (Sencorp's Crampton says it should take just six days to learn.) Machine maintenance begins by searching screen diagrams of the thermoformer, which blink to show problems like open doors or valves.

Remote monitoring can also link a thermoformer to Sencorp's service department. "It might take an hour or two on the modem, but that's a lot cheaper for the processor than having his machine down for a couple of days while technicians fly out to fix something," says Crampton. Service technicians in Hyannis have used the modem to correct control software on machines as far away as Mexico and England.

PHOTO : The view down two giant (80-ft) state-of-the-art Asano thermoformers at GE Appliances (each with seven computers). CIM tracks time and machine position in milliseconds and sends operators an electronic warning if process time is off.

PHOTO : GE senior controls engineer Mike Felker is rewriting and debugging the thermoforming CIM system. Next, Felker wants to implement automatic good/bad parts counting and put barcodes on refrigerator parts so resin and forming data are traceable.

PHOTO : CIM controls on the GE formers allow great product versatility and quick mold changes. Here operators watch as the former ejects trim-and-pierce tooling in 1 min. 15 sec. An entire mold change takes 5 min.

PHOTO : Inline Plastics `dumb box' (right) doesn't look like much, but it saves hundreds of thousands of dollars in scrap. The box counts parts off a single data point in forming, gets operator confirmation, and turns it all into real-time production monitoring. Commercial CIM packages, like PlantStar's Focus 100 (below), are starting to be installed in thermoforming.