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Turning to Deming.

Turning to Deming

Allor Mfg Inc, Novi, MI, produces chain-conveyer material-handling equipment for the automotive, coal-mining, foundry, steel-mill, and sugar-cane industries. The firm works with tough materials, and the metal-removal rates and tolerances are even tougher.

To get a handle on quality-control procedures to meet these production challenges, VP Bernie Wendt learned the principles of statistical process control (SPC) from Dr W Edwards Deming himself, at seminars held at George Washington Univ in the early '80s.

As a result, everyone at Allor is involved with "total quality." The employees are responsible for the company's success. They develop SPC charts, track them, and keep close watch on tolerances and processes. They have authority to change, implement, and shut down a job at any time. In other words, quality control is more than a slogan; it's a way of life.

The SPC department ensures quality by scheduling refresher courses every six months and through random monitoring. Machine tools are serviced by the original equipment manufacturer quarterly, and they receive a fresh paint job every two years.

Prize for smooth turning

The quality way works. Allor became a Bethlehem Steel Standard Vendor, scoring 97.5 out of 100 on the LTV/Bethlehem audit. With quality in mind, then, Allor managers decided to go to a prize-wining vendor for a new turning machine. They chose a Granitan-bed (Studer license) GT62 turning center from Toyoda Machinery USA, whose parent company in Japan was awarded the Deming Prize for quality.

Wendt recalls, "We couldn't believe the utter lack of vibration when we saw a demonstration of the lathe. With our first test bars, we put a glass of water on the headstock to check for vibration. At 3200 rpm, there was barely a ripple, and I suppose that was caused by air currents created from chuck movement."

The stability is attributed to the machine's granite-epoxy bed, which has eight times the dampening factor of cast iron and about 20 times lower heat conductivity. These characteristics result in a stable bed that is virtually insensitive to temperature variations.

"Our GT62 was delivered in April, with production parts run in May," says Wendt. "Even on long runs, we expected repeatability of [plus or minus] 0.0005", but we got even better performance. Repeatability is [plus or minus] 0.0002", and the turning center often eliminates secondary grinding, even reducing the need for centerless grinding in some cases. Tooling costs are down 25 percent, productivity up 35 percent. And, we can turn off the machine during lunch with automatic repositioning upon return."

Case reports

Wendt says, "The standard of quality produced by the Toyoda machine has come to be the standard by which we judge other machines in our shop. For example, one turned part is a 1045 carbon-steel flanged roller with several counterbores for our bearings. With only 3/4" to hang onto, the part requires 4 1/2"-dia holes. We used to have a lot of vibration and blending zones on the turnaround. With the GT machine, however, tooling costs are down, productivity is up, and I defy anyone to spot the turnaround zone--and that's without grinding!"

On another job, the customer provided Allor with SAE 52100 steel hardened to 60 Rc. The workpieces were 6 1/2"-dia finishing rolls with tapered ends ground to 30 microinch finish. "We had to turn 0.015" off the rolls inside the tapers," says Wendt, "and when we completed the job, we couldn't see the transition line to the tapers. The customer didn't believe us. He though we'd remade the part."

Allor makes parts from 1" dia to 14" dia with lot sizes varying from 5 to 5000. Most of the workpieces are hard, ranging from 23 to 32 Rc. Machining runs the gamut from simple pins to multiple-flange rollers. Most of all, Allor does not like to take its time. It prefers to hog into cuts, and keep the machine cutting that way all day long.

To date, the Granitan bed of the Toyoda GT62, coupled with the centerline spindle design, has performed a successful balancing act. Any heat that does cause spindle growth has balanced out that growth on the workpiece centerline. Most important, the lack of heat and vibration worries allows Allor to go "whole hog" while meeting the high Deming standards it sets for itself.

PHOTO : Typical parts produced on Toyoda GT62 turning center.

PHOTO : Bernie Wendt, Allor VP, discusses quality with machine operator.
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Copyright 1990 Gale, Cengage Learning. All rights reserved.

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Title Annotation:statistical process control; Toyoda Machinery USA's Deming Prize-winning lathe
Publication:Tooling & Production
Date:Mar 1, 1990
Previous Article:Gaging internal geometries.
Next Article:Factory of the future uses AS/RS.

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