Page 28 - MetalForming March 2011

decreases throughput time and per- manently reduces operating costs.
“A further highlight is the Technol- ogy Master function, which automati- cally 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 hard- ness by electrolysis or electrochemical corrosion, respectively, to a minimum. Your advantages of this patented system: No pitting even for long processing dura- tion. The new generator significantly reduces problems caused by poor wash- outs of removed materials, such as bind-
ing agents of sintered materials and thermally induced micro cracks. High quality surface fin- ishes mean reworks are reduced to a minimum.”
To Principal Mfg., this translates into faster pro- duction, 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 incre- mental 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 bush- ings and anchor them, and assemble everything, rather than having to spend a lot of time grinding blocks and such.”
The firm builds standard fineblank- ing 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 perfect- ly 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.” MF
Toolroom Technology
The assembly room at Principal Mfg. dedicated to build- ing the substructure for the Camaro convertible top includes dozens of new assembly fixtures and jigs, like the one shown here.
Toolroom Takes a Front Seat for Investment at Mitchell Metal Products
Atrio of new projects completed since 2008 have allowed Mitchell Metal Products, a Merrill, WI, metal stamper and fabricator, to maintain machining as an inhouse core compe- tency. The impetus came a few years ago when new company management recognized the need to increase stamp- ing-press capacity, to improve its abil- ity to compete on larger stampings and tooling. Its realization came as it sought to increase activity on its newest mechanical press—a 400-ton model from Blow Press, acquired in 2004, with a 48- by 96-in. bed and 32-in. windows. Before that acquisition, press capacity
topped out at 150 tons.
“That Blow press is at capacity now,
and we’re in the market for a new com- plementary press to further increase our capacity,” says company president Tim Zimmerman, who along with two others acquired Mitchell Metal Prod- ucts in 2008. “Immediately after we took over the company we focused on beefing up our tooling department,” he adds, going on to describe three major projects that fit that charge.
Software Upgrade Becomes Job One
“First, we married our SolidWorks
CAD programming to 3D QuickPress three-dimensional tool-design soft- ware. 3DQuickPress is a SolidWorks add-on for progressive-die design that allows our designers to more efficient- ly develop strips and then detail the dies,” says Zimmerman. The software includes feature-recognition technol- ogy and provides a knowledge base for springback and bend allowance.
“The project reduced our timeline from die design to build by 30 per- cent,” Zimmerman estimates. “We’re saving anywhere from a few hours on a simple blanking die to several days when developing complex dies.”
MetalForming/March 2011
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