Punching Die Problem

I've got this punching die that is giving me trouble. It punches four
holes and cuts a blank to length from an aluminum strip. The blank is
about 5 inches wide by 7 inches long. At the same time four holes are
punched at one end of the blank past the half way mark.
The aluminum is .180 thick 6061. The four holes are .339 on the punches
with .012 clearance on the bottom die. The holes are spaced in a 1.5
inch equal bolt pattern.
The problem is that the punches are seizing on the blank after punching
the holes and pulling the upper die set out of the punch press when the
blank hits the stripper plate. You get about six parts and then the
punches seize even with lubricant. I had a friend of mine look at the
problem and he thought I needed more clearance on the punches. I'm
happy to try this but I'd like to get some other opinions. Any ideas?
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Sounds as if you have too little clearance between punch and die - or the punch/die needs sharpening. Sometimes grinding the punches with a slight angle at the end will improve things.
You could also look into coating the punch & dies:
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J. Nielsen

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