Machining Moves Made to Quicken Speed to Market
By Brad Kuvin - MetalForming Magazine, March 2011
This isn't a car magazine, so I don't get to test-drive the flashy new models that lit up the stage at the Detroit auto show-models like the recently introduced Camaro convertible. So rather than being part of the media frenzy surrounding that particular car, and typing up flashy prose describing its teeth-rattling performance and wind-in-your-hair exuberance, I decided to trace some of the behind-the-scenes manufacturing excellence that has made this dream car a reality.
My Camaro-manufacturing journey took me to a metal stamper known primarily for providing fineblanked throttle plates, lock hardware and similar parts which, virtually overnight, morphed into becoming the sole manufacturer of completely assembled hardware systems for the convertible top on the new Camaro.
"As the Tier Two supplier to Magna for the convertible-top's steel substructure, we're busy running 28 new dies and assembling 41 parts in all, including bushing insertion, riveting, welding and tapping," says Principal Manufacturing toolroom manager John Brazzale. I managed to hit the plant's production floor (in Broadview, IL) during launch week for the Camaro convertible project, so it's newly outfitted assembly room, where all of the stampings, fasteners et al come together, was teeming with activity. What I missed, of course, was the flurry of toolroom activity over the last several months that brought the company to this point.
Toolroom Runs Flat Out to Make Fixtures, Gauges
"Our toolroom designed and built all of the assembly fixturing for riveting and welding," says Brazzale, "a huge project that included gauging and restraining fixtures for our coordinate-measuring machines. Also on the books for this project were design and build of four new fineblanking dies (the rest of the stamped parts are made on conventional progressive tooling that Principal outsourced to other die shops). Our toolroom load more than doubled."
Long before the Camaro convertible hit the streets in February 2011, it created quite a stir on the auto-show circuit. Among its numerous selling points: refinement of the car's top, which had designers seeking a solution to the ever-present rib lines that have plagued every convertible-top designer for decades…until now. Thanks in part to the work of Principal Mfg., the top, wrote one car reviewer, has a "smooth, taut appearance that retains the vehicle's sleek roofline."
The Camaro project now has the pressroom and assembly room at Principal Mfg. turning out 1100 complete units/week-by anyone's calculations, that's a lot of stampings and assembly time. Success on a project of this scope only came thanks to the company's continuous improvements made in its toolroom over recent years-to its die-build procedures, as well as the addition of new CNC wire-EDM machines.
"We invested in new wire-EDM technology (a pair of Mitsubishi FA-20S machines) to increase capacity," shares Brazzale. Comparing the new technology to old, he says that "we achieve the same surface finish on our die blocks and other machined components, but we get there 15 percent faster than we used to. For example, cutting a die block that once required five passes now takes only three. Our throughput has increased greatly, and hence so has our speed to market with new projects."
State-of-the-Art EDM Pays Off
The Mitsubishi FA-20S offers x-y-z axis travel of 19.7 by 13.8 by 11.8 in., and maximum size of 41.3 by 31.5 by 11.6 in. Features include 16-step programmable flushing control, 3D graphical programming, a digital 500-W AC servo-drive system and the ability to make large tapers-45 deg. per side when using special guides, flush cups and Mitsubishi's Angle Master option.
More from Mitsubishi promotional material:
"Generator power and flushing pressure are automatically adapted for the processing conditions, optimizing the cutting speed and minimizing the risk of wire break at the same time. This decreases throughput time and permanently reduces operating costs.
"A further highlight is the Technology Master function, which automatically ensures that the processing of complex workpieces, with differing thickness or with longer distances to the lower flushing nozzle, is performed with ultimate precision.
"The standard HSS-AE (high speed surface anti electrolysis) generator reduces the impairment of surface hardness by electrolysis or electrochemical corrosion, respectively, to a minimum. Your advantages of this patented system: No pitting even for long processing duration. The new generator significantly reduces problems caused by poor wash-outs of removed materials, such as binding agents of sintered materials and thermally induced micro cracks. High quality surface finishes mean reworks are reduced to a minimum."
To Principal Mfg., this translates into faster production, speed to market, expanded capacity and the ability to meet the requirements of game-changing contracts like the Camaro job entrusted to it by Magna.
Hard Milling on Fineblanking Dies
Another move made in the toolroom to quicken speed to market was moving some work away from sinker EDM and to CNC hard milling with carbide cutters. Specifically, the toolroom now hard mills most of its stinger rings-impingement rings found on most fineblanking tools to control material flow during forming. Machining the rings cuts processing time in half, and in the pressroom the tools last 30 percent longer between maintenance cycles.
"Our lead time for new dies-from design through build-has shrunk from 11 to 12 weeks down to an average of 8 weeks," Brazzale says, "due to incremental improvements such as the move to hard milling and to our new wire-EDM equipment. We're doing as much work on the tools as we can before the toolmaker ever receives the die. Typically all he has to do, then, is slide in the pins and bushings and anchor them, and assemble everything, rather than having to spend a lot of time grinding blocks and such."
The firm builds standard fineblanking die sets to 26 in. square, 3.5 in. thick top and bottom. Of its 300 employees, 24 toil in the toolroom.
"Eight years ago we were building dies the 'old-fashioned way,'" Brazzale continues. "We'd transfer holes from die blocks to the die set, manually line it all up and rely on drill presses. Now we put the die set and heattreated blocks in the machining center and locate off of the leader-pin holes and machine all of the holes for the complete tool, so that everything is mounted off of the machining center and aligned perfectly top and bottom. And rather than press pins into the die set we press bushings so that as they wear we can easily replace them. As a result we're holding tighter tolerances on our dies, and they run better in production."