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Die rubber/urethane

I'm in the process of making a bunch of dies for a new product line and there are some drawing dies involved, all the others are fairly simple and similar to many I have made over the years. Drawing dies are black magic, I've only made a couple and the new ones will be more complex. One big issue is the pressure plate that has to hold the blank flat while it's being drawn. Too much pressure and the blank tears, too little and the blank wrinkles. The last drawing die I did used a 6" x 6" cylinder of black urethane. The company I bought it from is gone and my current supplier hasn't a clue what the material is or it's durometer. Is there a way to test it? Any idea what it could be? It compresses a bit more than 2" but it's gentle...for lack of a better term. It's kind of soft like rubber but I know it's urethane. All my other urethane is Red, Green or Orange. But different companies use different colors to designate durometer and each has a different compression ratio.

Reply to
Buerste
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Shore hardness.

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There is a relative comparison of various hardness at the bottom of the page.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

Reply to
Wes

If I remember correctly, urethane does not compress (change volume), so perhaps the proper term is "distort". I can't think of why, but this property is apparently desirable in die making...

Reply to
Mark F

Also look at McMaster Carr part 8450K3, a test pack covering shore OO 30 up to shore D 70, for $21. Dig your fingernail into the rubber and watch how deep and how long to recover, then compare to the test pieces. There are lots of companies that sell polyurethane resin you can cast yourself (I like

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others have posted their favorites here many times) if you just need a simple cylinder so the mold is trivial. Or there are companies that do custom casting. We use
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because they offer semicustom washer shapes at a good price. Specify the length, ID, and OD, and how many, and you get them in a couple of weeks - no muss, no fuss. Looks like they only go up to 2.5" OD, though, but call them for a quote. I'm sure they have a real hardness tester, too, if you could send a sample. Anyway, YMMV, just a satisfied customer, yadda, yadda :-).

----- Regards, Carl Ijames

Reply to
Carl Ijames

Your current supplier doesn't have, or have access to, a durometer tester???

Or is it that you don't have any samples available for testing? If you have sample material for testing and you're near any sort of university, I'll bet you could find someone that has access to one.

Might even be able to read up on testing procedures and cobble up a test yourself to at least get into the ballpark.

Jon

Reply to
Jon Anderson

Do you have a sample to test? If so, you need a durometer of the proper range.

Try this e-bay search for a bunch of them at various ranges and prices:

durometer -golf -club -zodiac -baracuda -oring* -"o ring*"

(lots of negatives in there to trim out the things using durometer as part of the description of the product instead of the actual meter.

Check out the description here:

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to have guess as to what scale you need. At a guess, it looks as though it will be either a 'A' scale, or a "00" scale

Get a durometer of the right scale and measure it. It sounds like the "Sorbothane" in the table of "Durometers of various common materials" in the Wikipedia page.

In the eBay listings I find #120616397528 (A scale) for $20.00 at present. And quite a few others in the first few pages, including some which will do the '0' scale, but not the '00' scale, so you may have to find a new vendor (who would be faster anyway compared to eBay.)

Good Luck, DoN.

Reply to
DoN. Nichols

"DoN. Nichols" wrote in news: snipped-for-privacy@Katana.d-and-d.com:

Most of the cheap digital ones are Chinese (surprise!). Anyone have any experience with them? There seem to be two styles: roundish ones for ~ $50, and taller, more rectangular ones for ~ $170 & up.

If you want to good feel for what kinds of materials Shore A, D, and 00 cover, McMaster Carr has a nice chart:

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(scroll down about half way)

Shore A will cover anything from below rubber bands to ~ shopping cart wheels. It sounds like the rubber the OP is dealing with may be squishy enough to need the OO scale, but A would probably do it.

Doug White

Reply to
Doug White

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