Page 21 - MetalForming May 2011

stamping stainless steel, which we’d never done here before, we felt we could justify the investment needed to bring the work into our facility.”
That Pesky Protective Film
Stamping the stainless-steel range doors and drawers is a simple process of blank and form. However, the pro- tective film covering each blank creates some challenges.
“When you shear that film down, getting the parts in and out of the die and keeping the die clean can be a challenge,” says Michael Sprouse, process owner in the plant’s new stain- less-steel stamping area. “Also, sec- ondary deburring operations required on the parts create opportunities to mar the surface finish of the parts. We had to elevate both processes—die cleaning and deburring—compared to what our supplier had been doing, in order to sufficiently improve quality and reject rate, and reduce deburring costs. That’s how we ultimately were able to justify adding press capacity to handle the job.”
The job: Inherit 23 transfer dies from its supplier to manufacture 30 stamped parts, of 22-gauge Type 201 and 430 stainless. Blank size: 30 by 20 in. Each part requires hits in three or four dies. The plant’s supplier only had presses sized to hold two dies at once, so each part required setup and processing in
Inspectors take a close look at every stainless-steel part exiting the plant’s two new stamping presses, on the lookout for burrs, blemishes and scratches. Left: A Type 201 stainless-steel door panel; below: a Type 5430 drawer panel. Since bringing the work inhouse, scrap costs have been cut in half, to a mere 3 cents/unit manufactured.
A Closer Look at Press Technology
Electrolux’s two new Stamtec presses feature fabricated box-frame construction and four full-length steel tie rods prestressed to 150 percent of press capacity. Eight full- length 90-deg. gibs, with nickel-bronze wear plates, guide the slide. Each press also boasts a high-torque low-inertia clutch and separately mounted air-released spring- actuated brake, automatically synchronized. Dual-valve automatic hydraulic-overload protection systems protect each side of each press individually from overloads. Also, each press includes a set of four die safety blocks interlocked to the press controls to prevent inadvertent operation while the safety blocks are in use.
Press specifications: 14-in. stroke; 20- to 40-strokes/min.; 144- by 60-in. bolster and slide area; parallelism (slide to bolster) of 0.001 in./ft. or less; deflection of 0.0015 in./ft. or less right to left and front to back, with two-thirds of the bed area symmetrically loaded.
Omnilink 5000 press and automation controls on the presses, from Link Systems, provide the plant the opportunity to eventually evolve from manually fed operations to automatically fed. The units offer clutch-brake control, auxiliary-systems control, die protection and process monitoring, signature and tonnage monitoring (which Electrolux hopes to eventually use to gauge burr height and trigger die maintenance), and auto- mated setup of counterbalance, die cushions and shut height.
two presses. This
caused a substantial
amount of in-
process inventory,
and added material handling—opportu-
nities to mar the sur-
face finish. Sprouse
and the rest of his
production team,
including fabrication manager Frank Byrne and senior maintenance engi- neer Mark Frauendienst, specified new presses for their plant that could accommodate as many as four dies, to stamp completed parts in one cycle.
“Bed size was more important than tonnage when we went shopping for presses,” says Byrne. “And although
volumes allowed us to initially perform the work with manual transfer of blanks, we wanted the ability to set up the new presses with feed lines down the road, should volumes grow to a certain point. We also sought flexibili- ty to allow us to run other coil-fed work on the presses.”
5S, OEE Help Clear Floor Space
An 80-by-40-ft. area once used to house inventory now is the home of the firm’s new two-press stainless-steel press shop. Byrne credits the plant’s effective application of the Electrolux Manufacturing System (EMS) with its ability to slash the amount of invento- ry it keeps on hand, thanks to dramat- ic improvement in overall equipment effectiveness (OEE).
“We run a very tight ship here,” he says, noting how hard-pressed the facil- ity is for space. “If you’re looking for evi- dence that paying attention to OEE, 5S and minimizing inventory pays off, this is it. We gained the floorspace we needed to bring in two new presses,
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