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    Default Suggestions for making blanking die and punch for thin copper sheet

    Hi. Over the next three days or so, I have to cut hundreds of rectangles from some thin copper sheet (0.004"). Ideally, the shape is basically rectangular, with a couple little tabs sticking out near the four corners (the sheet will be folder over itself, and the tabs will be folded over to help keep the sandwich together). The approximate dimensions are 50 mm x 40 mm (plus the tabs).

    I have a CNC mill (PCNC1100), and a bunch of 6061-T6 aluminum stock. Can I make a blanking die and punch out of this and get reasonable results? I'm not too worried about the edge quality (so long as I don't cut myself while working with the blanks) or shape accuracy. Any recommendations for how to undersize the punch relative to the die?

    Thanks!

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    Default Re: Suggestions for making blanking die and punch for thin copper sheet

    No, you can't make a die out of aluminum that will punch out hundreds of pieces of copper. You need to use a material for the die that's harder than the material it's supposed to cut. I'd suggest using tool steel, hardening and tempering it after it's cut. Or get Sheltech to make you a pancake die: Sheltech - Custom Dies and Cutting

    [FONT=Verdana]Andrew Werby[/FONT]
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    Quote Originally Posted by awerby View Post
    No, you can't make a die out of aluminum that will punch out hundreds of pieces of copper. You need to use a material for the die that's harder than the material it's supposed to cut. I'd suggest using tool steel, hardening and tempering it after it's cut. Or get Sheltech to make you a pancake die: Sheltech - Custom Dies and Cutting


    +1

    The die needs to be harder than the material being cut, and for production quantities, a medium to high carbon steel is preferable.



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    Default Re: Suggestions for making blanking die and punch for thin copper sheet

    Hate to break it to you but it sounds as though you haven't the material, machinery, nor the expertise to make a die for these parts.

    ... and a quantity of "hundreds" will not make this worth building a die for, unless you mean "hundreds" of thousands.

    Farm this out to someone with a wire-edm until your talking tens of thousands, then get a die made.

    Should you be determined to diy this:

    Your best bet is A2 heat treated and triple drawn to 60 Rc for the punch and die.

    Ideally you need to wire-edm or hard mill them after heat-treat.

    Your punch profile needs to be .00022"/side smaller than the die. (edited this info)

    Your die land should be .125" - .156" and then open up .5° per side.

    These need to be mounted in a die set to maintain your clearance, preferably with a spring stripper though urethane will suffice for short runs.

    Last edited by KilrB; 07-05-2016 at 11:21 AM. Reason: correction


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    Default Re: Suggestions for making blanking die and punch for thin copper sheet

    That .004" copper would be awkward to handle for the EDM operator, but I suppose you could stack a lot of it up and cut the whole stack at once that way. But with a Tormach mill, he should be able to make a die that will do this job. The urethane stripping pad is a good idea, otherwise the copper will tend to stick to the die and get messed up.

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    Default Re: Suggestions for making blanking die and punch for thin copper sheet

    Quote Originally Posted by awerby View Post
    That .004" copper would be awkward to handle for the EDM operator, but I suppose you could stack a lot of it up and cut the whole stack at once that way. But with a Tormach mill, he should be able to make a die that will do this job. The urethane stripping pad is a good idea, otherwise the copper will tend to stick to the die and get messed up.
    Not awkward at all.

    A stack of shim stock, a pair of stiffener plates, and start holes where you need 'em and your in business.

    We do it every day in .001" - .01" material.

    As for making the die in his mill, well ... that's gonna take some doin'.

    It can be done, but the time and expense is going to be prohibitive for "hundreds" of parts.

    Hitting .00022"/side clearance after heat treat, and then positioning all the components dead-nuts in a die set is not going to be easily done.

    He could, of course, opt to not heat-treat it and just sharpen it every time it gets dull ... in which case I recommend he makes two.

    That way he can still be punching parts while he's sharpening the other die.

    That still leaves him needing to get the clearances and locations just right, but if he wants to learn how to build a die this one sounds simple enough.

    He might also look into a steel-rule die.

    For "hundreds" of .004" copper parts that may be the ticket.

    I've never seen them hold up on anything harder than rubber (ie. plastic and metal shim stock) but a lot of people are real big on them.

    Especially the people trying to sell you one.



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    Default Re: Suggestions for making blanking die and punch for thin copper sheet

    Heat treating A2 steel is easy. For the few hundred pieces he has to make in copper, it doesn't even have to be fully or well tempered.
    However, KilrB is right, it's more than just the punch and die. Google die set alignment and you start to see the bigger picture.
    If you want to learn heat treating and die alignment, check out.... www.thatlazymachinist.com
    Answers to most of you questions.

    Last edited by G59; 07-06-2016 at 12:00 AM.


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Suggestions for making blanking die and punch for thin copper sheet

Suggestions for making blanking die and punch for thin copper sheet