Page 33 - MetalForming February 2012

cost of the new tooling?
• How certain can we be about the
performance and quality of the new tooling?
Answers to these questions came quickly as Dedoes ultimately invested in a nine-hole cluster punch from Mate.
“The large quantity of holes needed per sheet, the thickness of the sheet, hole spacing and part runs were the major criteria we had to work with,” says Troxell. “In particular, we had to carefully consider the material being punched. Stainless steel is very abrasive to the punch, creating a high degree of friction and heat in the punch when it penetrates the material. To remain flat, stainless steel has to be punched clean- ly. Because stainless is a very hard material, it dulls ordinary tools very quickly, especially at higher press speeds. Even when slowing the press, the abrasive effect continues, wearing out the tool while distorting the part. You lose productivity two ways—with lower press speed and by having to fre- quently maintain the tooling.”
M2, Heattreated
Tool design started with the tool- ing material itself. Dedoes’ cluster punch is made of M2 tool steel that resists the abrasive effects of the stain- less steel by reducing heat buildup in the punches. To obtain optimal tool performance, Mate heattreats its punches in NC-controlled furnaces. This combination of high-grade tool steel and heattreating results in punch- es with excellent compressive strength and high wear resistance. Further, punch points are machined with a 1⁄4-deg. back taper to reduce friction during the stripping phase of the punching cycle, further extending tool life.
Another concern when punching stainless steel is slug pulling, addressed by the tool’s special hourglass shape that creates a pressure point acting as a one-way door to prevent slugs from pulling back out of the die. Once squeezed through this pressure point, slugs fall free from the tooling. Dedoes finds this important to maintaining uninterrupted top press speed, which
The fully guided design of the tooling system used at Dedoes pays off particularly when punched sheets have more holes than sheetmetal, by preventing the occurrence of side-loading and twisting forces. Shown are Mate sales engineer Gary Troxell (left) and Dedoes machine operator Pat Vaughn.
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MetalForming/February 2012 31
for the Vipros ranges from 270 to 400 hits/min.
Lastly, Vaughn notes that the fully guided design of the tooling system prevents the occurrence of side-loading and twisting forces, avoiding premature tool-edge cracks, dulling and galling. Fully guided tooling provides a tight clearance between punch and strip- per, optimizing rigidity.
“And,” Vaughn says, “the knurled edged on the stripper plate really helps when handling the tool. It doesn’t slip in your hands. These may seem like little things, but by making our processes more efficient with our punch press tooling, we can be more competitive by offering lower prices and higher quality.”
In addition to the slitting tool and cluster punch, Dedoes also uses Mate louver tools for computer cabinets; embossing tools for floor pans; and lance and form tools to enable cabinet assembly.
“All of these special-application tools allow us to reduce the number of fabricating operations without sacri- ficing quality,” says Vaughn. “We spend less time sharpening our tools and have experienced improved nest yields, while reducing our setup time and improving the edge quality of our punched holes.” MF
Article provided by Mate Precision Tooling: 763/421-0230; www.mate.com.
Special-application tooling plays a vital role at Dedoes, such as this nine-hole cluster punch used to punch thousands of 0.1875-in.-dia. holes in 14-gauge Type 304 stainless steel.