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EDM Polishing In Ribs

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Joined: Fri May 03, 2019 7:47 am

EDM Polishing In Ribs

Post by rwingham » Fri May 03, 2019 8:44 am

Roger Wingham Royer Corp

We have a 48 cavity mold with a rib on each part of .090" depth x .050" wide x 2" long. It has (2) 3/64" ejector pins for ejection. We requested 400 paper finish or better before the mold build. Our mold builder is telling us that this EDM finish is around 600 finish, of course, its not. He refuses to polish the mold for us.

Steel is S-7 and ejector pin is a DME EX Style... 40-45 HRC core and Nitrided 60-67 HRC .001-.007 case.

The part has shear gates (delayed sprue) and it springs off the mold in this area and sometimes breaks in the cross rib. See attached picture.

Any suggestions is appreciated.

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