I need to get the durometer tested on a rubber part. This part just came in, the customer doesn't know what the durometer is, and he needs parts friday. I would just order a durometer overnight but the cheapest I can find is $280.00. The whole job isn't worth it. Since it may or may not turn into more work, I'm reluctant to spend the money on it. The customer said I only need to be close, not perfect on the hardness. Is there a way I can approximate it with a weight and a properly shaped probe tip? Thanks, Eric R Snow
Anybody know about Durometers?
Jul 06, 2005
10 Replies
How about $60.00?
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- - Rex Burkheimer
Eric R Snow wrote:
I've got one at work, but it's been years since I've looked at it. You might be able to find the ASTM test standard and get a description from that, or maybe something from the RMA (Rubber Manufacturers Association)
Wish I could have been more help
I don't have a tester, but it looks like you can really easily make an indenter like this (type A) and press it against the material with
1.81 lbs of force and read the indentation in inches as 100 (no penetration) to 0 (100 thou penetration).
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Dimensions of the indenter are given in metric here as:
Hardened steel rod 1,10 mm - 1,14 mm dia, with a truncated 35º cone, 0,79 mm dia.
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Confirmed here in this data sheet for a commercial durometer:
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Best regards, Spehro Pefhany
Perhaps you could use a dial indicator with a spring and either a conical or ball foot.
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Find a material specimen of known durometer that most closely matches the measurement on the part to be matched.
Thanks Spehro, I googled but did not find the above sites. Cheers, Eric
Don, Thanks for the link. If I had a known sample it would be easy. But the only samples I have are the ones I need to measure. Thanks for the link. Eric
o-rings are available in 70 durometer and 90 durometer in Buna - n
in fluorocarbon or viton they are 75 durometer
were I in your shoes I would take the parts down to the local rubber and gasket house they should have a variety of known materials to compare it to and might have a tester
Eric I have in my desk a set of urethane samples (1" Diameter) of different durometers from
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It has the following durometer samples: 40A, 60A, 80A, 90A, 95A, and 75D. I don't know if your rubber is in that range or not. Write to them and ask for one, or if you really want I can mail this one to you. I live just across the sound from you.
Another idea; where ever you got the rubber from that you want to measure should be able to tell you all you want to know about it, shouldn't they?
Lane
Measuring durometer, even with a meter specifically designed to so, is very subjective. Different part shapes and thicknesses can almost make it a guessing game. We use ours only to compare o-rings of the same size and hardness. The same goes for checking sheet stock. Go to
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and search "rubber hardness". You will find a rough comparison chart and also a sample kit for about $10.
Thanks everybody for the responses. After posting I looked at ebay and found two that were reasonable. I ended up getting both. I will order the sample from McMaster Carr. But I will also be ordering the rubber sheet at the same time. Now that I live on an island it is hard to some stuff done fast. Like going to a local rubber supplier and asking them to measure the sample. That trip would end up being at least 4 hours round trip because of ferries and traffic. ERS
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