Advancing powertrain technology

Automotive Design & Production, Dec, 2007 by Gary S. Vasilash

According to Richard E. Collins, director, Powertrain, Advance Manufacturing Engineering, Chrysler LLC, when it comes to powertrain production, machining is in advance of measuring. That is, they can mill a surface--say a valve body--but through the use of conventional metrology devices not have a comprehensive understanding of the overall flatness of the surface. To say nothing of the surface finish. That's because, he explains, most measurement is based on a few points (in the case of flatness) or on a local area (for surface finish). And if one person measures points A, B, and C, and another person X, Y, and Z, it very well may be that the results will be different even though the same surface is being measured. Which is why Collins--and Chrysler--and his peers at General Motors, Ford, and Roush Enterprises--powertrain manufacturers one and all--have come together to form the Powertrain Engineering and Manufacturing Alliance (PEMA), which has received a $4.9-million grant from the U.S. Department of Commerce through the National Institute of Standard and Technology Advanced Technology Program. Through industry-matching money, this is an $11-million, three-year program. The objective is to develop improvements in process capability that will make the vehicle manufacturers more globally competitive. At the core of this undertaking is holographic imaging technology that captures millions of points on a surface, such as the aforementioned valve body.

Holographic imaging was invented at the University of Michigan, which is also part of PEMA. It has been commercialized and is being further developed by Coherix Inc., another member. And Kettering University, which is promulgating innovation in organizations, is also a PEMA member.

According to Dwight Carlson, chairman and CEO of Coherix (and graduate of Kettering), the PEMA undertaking is analogous to the Auto Body Consortium that was established in the mid-90s to create the "2-mm car." Carlson explains that the Big Three were woefully behind their Japanese competitors in body gaps and fits, so there was a group put together--and which received NIST ATP funding--to address it. Carlson is the founder of Perceptron, which makes metrology equipment that is used in body shops worldwide to assure build quality, and which was a key part of the Auto Body Consortium. With PEMA, he's talking about the "2-micron motor" (with the word "motor" being picked specifically because not only is the program focusing on transmissions and combustion engines, but he foresees the work translating into alternative tech for turning the wheels of vehicles). A two-micron motor would mean being able to machine with a one-micron tolerance, with the two representing the variation. What Perceptron is to bodies, Coherix is working to become to machined parts.

"Three years ago we set our BHAG"--as in "Big, Hairy, Audacious Goal" from Built to Last by Jim Collins--"as reduce motor capital cost by one third, engineering and manufacturing cost by one third, and warranty cost by one third," said Carlson. That's in three years. He thinks it can be done.

Butch Dyer, president of the alliance, said that they are working to measure success through increased profits and market share for the U.S. auto companies. The focus will be on: measuring, machine control, machine capability, and product design. "If you can measure it better, you can make it better. If you can make it better, you can design it better. And if you have the best design, you can win in the marketplace."

The approach that they'll be taking is to fund PhD candidates who will work in 12 focus areas related to metrology and machining at member companies' facilities.

The technology that Coherix presently offers is able to obtain as many as 1,580 points/[mm.sup.2] at a rate up to 100,000 points per second. The output is a human-readable image that indicates where there are variations on the surface. It requires about 15 minutes to setup the machine to handle a different part.

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One of the potential scenarios is to have holography equipment embedded in the powertrain component machining line. Parts would be measured on an on-going basis. If there is a problem in a particular area--say this is face milling the valve body and one of the inserts is loose or there is tool wear or there is flexing of the fixture or some other issue--there would be the ability to automatically (or manually) make an adjustment to the machining parameters.

Initially, they're going to be focusing on flat surfaces. Next, Carlson said, it will be cylindrical shapes. Finally, if they will move on to complex shapes, like gears. "It's not just holography," he said. "We have other technology we are working on." Whatever it takes to reduce variation in machining is what they're pursuing through PEMA.--GSV