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CMM success: focus on teamwork.

Project 1356 at Borg-Warner Automotive Transmission Systems plant, Muncie, IN, represents several firsts. It's a focused factory-a plant area dedicated to completely machining a major product component, in this case, medium-duty transfer cases. The area's 21 Heller BEA2 machining centers are tended by designated "owner-operators" given broad responsibility for every facet of machine operation and part quality.

Launched late in 86, the project was their first use of the focused factory and owner-operator concepts. It was also their first use of magnesium for case covers, extensions, and bearing caps, and their first use of a single coordinate measuring machine to replace a multitude of traditional hard gages.

The verdict is in

Today, the verdict is in on BorgWarner's 1356 experiment:

1. The firm gained significant time, cost, and floor-space savings in both material handling and in-processed inventory.

2. The owner-operator concept tapped new levels of employee expertise and involvement.

3. The use of magnesium dramatically reduced part weight with no loss in part strength or function.

4. The CMM-A Bravo 2104/1 single-arm machine from DEA, Livonia, MI-logged 98.9-percent uptime over a three-year period, running three shifts/day.

"The project was a resounding success for us," says John P Corrunker, Jr, director of quality, Borg-Warner Automotive, "but it's taken teamwork-between labor and management, and between BorgWarner and its suppliers-to bring it off.

CMM under pressure

The CMM is a good example. They chose the DEA CMM for its accuracy and speed, and their previous experience with a DEA bridge-type machine operating in their transmission line for over a decade. However, with the project launch date drawing near, some serious problems had become apparent.

"We were depending on that CMM," says Dan Church, BorgWarner systems engineer. "It was the only gage out there to measure true position and flatness, so it had to do the job, or production would come to a halt! "

Together with Gary Cross, the Bravo's designated owner-operator, Church began to troubleshoot the machine and the process. After some preliminary checking, they suspected that the wide variation in measurements was resulting not from machine malfuntion, but from expansion and contraction of the parts.

"Magnesium has a high coefficient of expansion and there were wide temperature swings in the shop," explains Cross. Together with a co-worker, Jeff Sorrell, Cross set up an experiment to get some baseline data on these parts.

Party time?

"I clocked out, got in the car, and drove to the local party store," says Cross. To get a six-pack? "No, I bought two bags of ice, and we used that to bring down the temperature of a part, and then recorded its measurements at that temperature. As the part gradually warmed up, we recorded its dimensions at various temperatures. We had expected some variation, but we were very surprised at the extent of those variations."

The results of this and subsequent tests convinced them that inspection of the transfer-case components should be performed in a temperature-controrred environment. "Cross and I developed a proposal for a temperature-controlled room and took it to management," recalls Church. "The basic project concept was to bring quality gaging to the manufacturing process. Management had decided not to build islands of quality gaging, so we needed conclusive data to sell the idea of a room around the CMM."

After reviewing this data, management agreed that the DEA Bravo had to be placed in a controlled environment. "They gave full support to the recommendation from our owner-operator team," reports Church, "and by September, we had the room built. This type of management support helped solidify and give validity to the engineer/owner operator team."

Probing for vibration

But they weren't out of the woods yet, as Church explains. "We were pushing that CMM to the max-in some cases taking 100 inspection points in six minutes. At higher speeds, it would shut down, and nobody had a clue why that was happening. At that point, we passed the ball back to DEA."

Explains Larry Clarke, DEA project administrator, "We took their data and checked every possible thing we could think of and came up negative. " DEA then put a loaner machine in the Borg-Warner plant and flew in two of their top CMM experts from Italy to check out the Bravo 2104/1 from the ground up. After a thorough examination, they came up with what they though might be the problem-the extension length of the probe.

"DEA had built a special fixture for this application," says Clarke, and because of the design of this fixture, a long probe extension had to be used to measure some part surfaces. We had unwittingly exceeded the Bravo's specified probe length. At higher speeds, the fully extended probe would vibrate, and the machine would respond by automatically shutting down. It was a fail-safe response to prevent inaccurate measurement. "

Once the problem had been identified, the CMM builder corrected it at its own expense. DEA designed and built a new fixture that allowed the part to be measured with shorter probe extensions, and the mysterious shutdowns ceased.

Predicting future problems

Today the CMM not only performs a quality audit on machined parts as originally specified, it also spot checks raw castings and performs periodic in-process control checks. Because it provides real numbers rather than the simple go/ no-go information of hard gages, it has enabled Borg-Warner to detect machine and tooling problems before out-of-spec parts go to assembly.

"Companies usually don't like to talk about problems," admits John Corrunker, "even though everybody has them at one time or another. We feel that our cooperative, results-oriented approach to the challenges of manufacturing is one of our strengths. We look for that same sort of approach in our suppliers, and we found it in DEA."
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Copyright 1990 Gale, Cengage Learning. All rights reserved.

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Title Annotation:coordinate measuring machine; includes product information
Publication:Tooling & Production
Article Type:product announcement
Date:Jul 1, 1990
Words:957
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