Page 35 - MetalForming September 2010

products on our turret presses, we also form, emboss and punch louvers.”
Long, describing how important fitup and punched features are in these components, adds: “These punched parts are highly visible in the finished product, so punched features must show well. And, the components are assem- bled and welded together, so sheared and punched parts must be flat and precise. We can’t tolerate uneven, rough edges or burrs. The punch-press tooling we’ve been using (fully guided Marathon tools from Mate Precision Tooling) not only provides the necessary quality, but also delivers outstanding tool life. We’re still using the shearing tools that we bought 7 yr. ago for our daily punching operations. They’ve never cracked or chipped, and rarely need sharpening.”
Moving Metal by the Ton
Owens Products punches 9000 lb. of sheetmetal every week, averaging 550 steel parts and 100 aluminum parts per 8-hr. work day. “That’s a lot of parts
when you consider lot sizes are small,” adds Long, “often from just one or two parts per order to as many as a dozen. That’s a lot of tool changes.”
The firm operates a Murata Wiede- mann Motorum 2044EZ press at a 100- percent feed rate for shearing opera- tions, equal to 220 hit/min; nibbling operations run at 600 hits/min. “That’s very near top speed for the press,” says Long, “putting a heavy burden on the tooling and the machine.”
The press runs a servo-driven ram, making high-speed and low-noise punching possible by controlling accel- eration and deceleration of the ram drive and by controlling ram power, all during the punch stroke. This servo hydraulic design, when outfitted with the Mate Marathon tooling, makes for high precision processing with accura- cy to ±0.1 mm.
Designed specifically for Murata presses, the Mate tool system features punches fully guided by a metal stripper contained within punch holders. The
combination of the punch and guided stripper optimizes punch-point stabil- ity, eliminating part damaging saw- toothing, which adds stress and wear to the tool components. The result is pre- cise, smooth tool-to-workpiece contact that ensures sheet flatness, “very impor- tant to the quality of our products,” adds Long, “even when producing close- ly located holes.”
The punches are produced from spe- cially formulated and controlled M-2 high-speed steel to offer good wear resistance while maintaining accuracy in shearing parts and punching accurate holes at high press speeds. Their near polished punch flanks and minute back taper reduce friction of the tool com- ponents, eliminating punch build-up (galling) and improving stripping, while extending tool life.
The tooling also has a unique twist- and-click stripper mechanism that allows rapid tool changes without using tools. “Our press operators can set the optimum tool length by hand without
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