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76 MMS June 2014 mmsonline.com feature gantry mill is generally operated in the 3 + 2 mode, so choosing the best workplanes is important. Switching over to PowerMill, the company prepares the tool paths for machining blocks of aluminum or Obomodulan (a dense but resilient polyurethane material that is ideal for short-run dies). QFS has adopted the latest programming features of PowerMill, such as its Vortex high- speed roughing technology, to reduce machining time. Finished dies are then transferred to the forming press of the appropriate size and power. From their years of experience, technicians at QFS know how the die and sheet metal are likely to behave during deep drawing, so tears and springback are anticipated and compensated for. Even so, dies are occasionally returned for rework to get the desired results. Otherwise, the formed parts move to the laser cutters for trimming and piercing, if needed. Soon, finished prototypes are on their way to the customer for testing and evaluation. Graham Howells, owner and founder of QFS, says a typi- cal scenario like this will take four weeks or less— depending on how urgently the customer wants the samples. He says the shop has delivered prototypes in a week when all the stops are pulled. ("But this is expensive," he notes.) Of course, the purpose of the prototypes is to help optimize the design and engineering process so that both efficient manufacturing procedures and highly functional end products are the result. This means changes are expected. QFS is well- prepared for this phase of the highly interactive prototyping process. When Speed CountS In the broadest terms, revising a press-formed prototype involves two steps. The first step is comparing the original part geometry with the new to determine where die surfaces must be altered. Material may need to be removed by remachining, built up with welding or epoxy, and then remachined, or a combination of the two processes. The second step is to create the Completed die sets like the one to the right are rushed to the press department, where presses as large as 250-ton capacity produce components for testing and evaluation. 0614_MMS_QFS.indd 76 5/14/2014 9:52:55 AM