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Using technology-based manufacturing.

When the Plumley family took an assessment of their OEM automotive rubber parts sales about 10 years ago, they perceived two trends on the horizon. During the subsequent years, both trends have become realities in their market and, because of the actions the company undertook and continues to the present, Plumley Companies of Paris, TN achieved and remains in a leadership position as a primary vendor to Detroit.

The two trends they saw were a growing customer demand for the zero defect goal in piece part production, coupled with a fundamental change in the manufacturability of rubber parts which resulted directly from improvements in molding machine technology, vice president of sales and marketing Larry Callon said.

In the late 1970s and early 1980s, as injection molding became the predominant means of producing high quality rubber parts, Plumley moved its marketing focus in the direction of this change. Compression and transfer molding, while they continue to be viable methods, do not produce the quality parts achievable on injection presses. Or, if they do, the documentation of that quality is largely unavailable, owing to the lack of sophisticated monitoring, control and data analysis equipment attending the presses.

Rubber parts, unlike electronic components or other hardware built for automotive OEM, were never before viewed as zero defect goal potentials by either the customers or parts producers. This fact was assumed to be true, because of the dynamic and fluid chemical reactive process involved in producing the seals, gaskets, hoses and ducts which went into cars, trucks and buses.

However as injection molding evolved. so did the demands of the customer, according to Callon.

"Where once a reject or return rate was simply a given, the SPC and SQC standards changed all that, even for rubber and thermoplastic parts vendors to Detroit. We were fortunate to have the right contacts and to have kept our ears open, as the customers changed in this fundamental way. Being close to zero defects simply wasn't going to keep us or any supplier in the hunt," Callon continued.

Thus, in the late 70s, a fundamental change also occurred at Plumley. They formed a partnership with a major injection press supplier, REP Corp., of Bartlett, IL to develop a software system which had several goals. First, the system would be able to monitor all the press parameters of speed, injection shot volume, pressure, temperature and more, thus assuming a statistical base for comparison to set values and set points of operation. Next, the system would be able to log all these data on a PC-based terminal for immediate call up and adjustment. In concert with this goal, the press would need to be user friendly as the phrase went in the 70s, so operators would not become intimidated by the sophistication of electronic control.

Finally the most ambitious goal of this co-engineered software system was the ultimate achievement of a data highway. All the presses at Plumley's multiple plants would be linked, each feeding the production data of every cycle downline to a host computer, where every parameter of every part produced by the company would be recorded, stored and available for full statistical analysis by Plumley's personnel.

"We wanted to be able to demonstrate our part production monitoring, our quality and our consistent attention to controlling the output of our plants to our customers," observed Rusty Moore, VP of molded operations at Plumley. He also cited the ancillary internal benefits of achieving this last goal.

"Plumley prides itself on a 10-point management plan, which includes SPC training for all of our employees, so they can each participate in the implementation and improvement of our company's quality plan.

"What this production management system provides us, then, is not only superior part quality and proof of it, but also a means for assessing and evaluating our own performance on the floors at our factories." Moore alluded to the often competitive spirit which develops between the company's main molding operations in Paris and nearby McKenzie, TN.

As an example, when multiple presses are producing the same part, or when multiple operators are running the same machine, the system monitors the cycles run on each machine or each shift. Thus, in addition to online alarm capability, which will shut down any machine which runs out of tolerance, precluding unacceptable parts production, the system also acts as a true production management aid.

With all these goals in mind, Plumley and REP embarked on the development of a networking software system.

During the next few years, as REP presses began to carry more on board controls and closed-looped microprocessor monitoring hardware, the sought after system became more feasible.

As with any custom developed system, the application specific hierarchy of electronic data must be addressed. The system under consideration had the obvious ability to monitor and log far more data than the customer or even the Plumley personnel would ever need to know. This fact became a critical issue when the first version of the new REP-NET software system was brought to Plumley by REP engineering in 1985.

"At no point," said Moore, "was the company going to lose sight of why we sought the system in the beginning. Just having data wasn't enough. It needed to be managed and that meant vigorous statistical analysis procedures needed to be an integral part of our overall system implementation. These were and are very competitive market conditions and we wanted to be sure the best data were being analyzed, so we wouldn't waste time, effort and money."

As evidence the system worked from the outset, Moore pointed out Plumley's introduction of SPC procedures and accompanying quality control schemes at all their factories were rewarded by the successive achievement of Ford Q1, Chrysler QE and GM SPEAR 1 awards, all within 24 months. Today, the REP-NET system links dozens of rubber injection molding presses at each of Plumley's plants on a central data highway, which feeds a mainframe at the corporate headquarters in Paris.

At each plant, however, quality auditors perform vigorous checks on the parts being produced, accessing all the necessary information through control room terminals which monitor every cycle run on every press on the shop floor.

The advantages this system provides include:

* Traceability of all parts to the exact machine, time of day and operator responsible for their production.

* Instantaneous and periodic statistical quality checks against predetermined variables, through X-bar, Gauss curve and standard deviation graphs.

* Available data for examination as part of an internal audit procedure or SPC documentation request.

* The only means of producing dynamic rubber parts with provable accuracy.

Plumley is a leading supplier of silicone engine sealing gaskets and these special parts required all the accurate and vigorous production control the company could summon. Plumley president Bob Drake recaps the development and how the REP-NET system played a role.

"In the design stage, we worked with our customer on the tooling and already we could see the advantages of having the system available to our engineering staff. In prototyping such an intricate part, the interaction of all the production data would simply overwhelm a manual or less sophisticated electronic control. The old trial and error procedure would be needed and, frankly, won't work in this instance. Too many variables interact when you're molding silicone and especially in thin land areas and contours such as we encounter with this particular component." While up to 80% of the parameters in prototyping translate to the production cycle, states Drake, the balance do not. Thus, numerous problems can arise and acceptable parts are not produced initially. "This condition violates our seventh commandment, which demands the first parts made be good ones." (see 'The Plumley ten point management plan")

REP-NET further enhances trouble shooting the process because it can isolate the very first parameter which falls out of tolerance. An analogy to an industrial process annunciator system is valid. Knowing which particular parameter of the press's operating cycle is abnormal or tending to be out of step can enable faster diagnosis and adjustment of the machine. REP-NET can recall numerous prior cycle conditions to spot a problem area and correct it.

A subsequent development to the system was recently introduced by REP to Plumley which attains an even higher goal than the two companies envisioned originally. Curetrac software can now take out most of the process variables automatically, according to Moore who cited an old rubber industry maxim from the past. "Every cycle can vary, depending on five factors: The press, the mold, the material, the operator and the environment. Curetrac compensates for the majority of these factors by actually self adjusting pressure times to compensate for say, a longer mold-open time, more or less viscosity in the injected material, even the humidity level in the factor, which we've known for years had an effect on the parts we ran."

When a job is first put into production, setup time is radically reduced by REP-NET, according to Moore, because the preset values are downloaded as a program into the press. Plumley has also realized a dramatic improvement in the raw material consistency from their suppliers, who quickly observed their press was now able to closely monitor every foot of every batch of product being processed. With the ability to store up to 10,000 molds in memory, Plumley has significantly shortened job startup, another factor which Moore cites as evidence of Plumley's competitive edge.

Finally, maintenance schedules on every press can be better organized and administered by factory management personnel because of the system, states Moore.

The Plumley ten point management plan

1. Our highest priority must be to be the best, in the whole world, at what we do. This requires team effort where each member of the team is totally committed to quality performance and excellence.

2. We must recognize our achievement of improving quality in the past as only the beginning. Acquiring an awareness of potential improvement in quality for the future is the duty of us all.

3. Through manufacturing engineering, we must identify every element of our process and understand how to control all the elements.

4. Through design engineering we must develop the ability to build in the highest quality at the lowest possible cost.

5. We must recognize the need for change in our own lives and improve our education. The level of performance of every employee must be upgraded just to preserve opportunities to serve our customers.

6. We must improve long-range planning for technology development through our own initiatives to satisfy our customer's future needs. Using automation technology is the only way to become competitive worldwide.

7. We must improve employee participation, process capability and material reliabilities so that the first parts made are all good parts.

8. We must believe that any part can be made better and the possibility of perfection exists.

9. Quality means total conformance; anything less is not quality. Every new process, every new product and every new program or system must be tested before it can be used. This applies to human actions as well as all material things.

10. The price of quality is the cost of doing things wrong. It is always less expensive to do the job right the first time. When we eliminate returns and allowances and waste, quality will be free.

Gilbert Greco is vice president of sales for REP, Inc. He was instrumental in the development of the REP-NET system.
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Title Annotation:Plumley Cos.
Author:Greco, Gilbert
Publication:Rubber World
Date:Jul 1, 1992
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