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Re: tonneage requirements to punch UHMW.


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Posted By<" ">Randy Kimball on August 31, 2002 at 12:43:33:

In Reply to: tonneage requirements to punch UHMW. posted byDennis Wagner on August 28, 2002 at 17:23:24:

Dennis,
Different plastic sheets have different shear strengths.
Contact your vendor and request the data sheets form
the manufactur.

You are not talking about much tonage, here. (very little) If you
shape your die punch right you could do it by hand, even.
In other words, don't design the punch to hit flat but to
hit first at 0 and 180 degrees and slice around the circle.

Also, you need to know the die clearances between the
die and the punch. With .009 thick plastic you need to
be tight or you will tear the stock. I would GUESS .003
dia. difference between the die button and the punch.

You may want to punch the .328 hole first then progress
the material to the .984 punch. This way the slug from the
hole will be removed and then the slug from the .984
punch becomes your product.

Also, when punching plastics you may get a different size
from the punches than you think. Plastic is bad about
stretching and shrinking during machine process.

Also, a different way with material this thin. You may want
to use a clicker die. This would resemble a thin round blade
looking like a tube with a smaller one inside it. This die
is pressed down on the plastic sheet with a thick piest of
about 90 duro polyurethane under it. Thus the thin plastic is
'cookie' punched in one simple process. This is how most gaskets are made.
The dies are much cheaper and so is the machinery.
The quantity of 'washers' you need to punch will decide this. For
less than few thousand I would purchase a self clearing clicker die.
If you need thousands a months, go with a progressive punch die.

good luck


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