Future tool: created at the University of Michigan with funding from the National Science Foundation, the Reconfigurable Machine Tool was designed for

"In the 1990s," says Dr. Zbigniew Pasek, operations manager and assistant research scientist at the Engineering Research Center for Reconfigurable Manufacturing Systems, College of Engineering, University of Michigan, "the important issue was making machine tool investments effective in a changing landscape. In short, accommodating fast product changes given a set initial investment in machinery." Pasek and his colleagues recognized that there was a wild divergence between machine tool lifecycles and product lifecycles: the machines are in use much longer than the products they were developed to make are in production. This led to a National Science Foundation (NSF) grant to help fund the establishment of the Engineering Research Center ... and eventually brought about the development of what is called the "Reconfigurable Machine Tool" (RMT).

The RMT would offer functionality that would place it somewhere between general-purpose and dedicated machines. It would have flexibility within applications. "The main premise is that if you can define the part family--generally, an application area that requires a second set of functions--then we offer something that is matched in value to the need," says Pasek.

Cylinder heads, to name one example, may have major differences based on the included valve angle, number of cylinders, etc., while the basic configuration of each is quite similar. Designing an RMT to perform the machining operations on all members of that part family--even those cylinder heads that have yet to be designed--with equal quality requires modifying the structure in such a way that repeatability is not lost. "The idea is to, within a certain work footprint, change the angular values without having to use a different set of machine tools," says Pasek. So U of M's prototype RMT has the spindle on an arcing mount that covers an area from -15[degrees] to +45[degrees], with hard stops every 15[degrees] of travel. "The hard stops assure accuracy," he says, "though we can place the spindle anywhere within that angular range. If you know where you are with the spindle--and that is defined very accurately at the hard stops--this value goes into the control system to provide the quality and repeatability required." (An associated fast calibration project is underway to increase accuracy between the hard stops.)