Shore Durometer Measurements - Seeking Instrument and Procedure Recommendations

[Bubba]

I have just been notified that one of our engineers is implementing a durometer test on the material for one of our products. We have never tested for hardness before and I am an extreme novice in this area of measurement. Are there any experts on hardness out there? Does anyone have any good resources I could use to get up to speed in this measurement discipline? What can I expect to have to keep on hand to keep durometer measurements accurate and traceable? Any help with this subject will be greatly appreciated.

 

[energy]

Durometer

It's been awhile. I have used two types. The tips are different for different duro readings. A wider tip for lower Duro readings, like rubber/neoprene. Narrow tip for harder materials like teflon/epoxy. Everything you need to know about Shore Durometers is on their Website. I do know that each durometer comes with its own calibration device. It a spring that deflects to a reading. You just make sure that your dial reads within +/- 5 Duro of the device, each time you use it. It's an easy thing to use. If it's an o'ring, you have to be dead on center and the surface below the ring has to be hard and level. We used a surface block. Gaskets and sheets are easier. I'm guessing here, but you order by the durometer range you want. Like a "D" tip. One may go up to 70 Duro and the other goes above 70. I tried .

 

[David Mullins]

from my hazy memory

Testing is described in a few places including ASTM test methods.

You'll need a set of calibration blocks (varying hardness rubber/sponge/plastic). The type of material the engineer is using determines the dype of durometer and therefore the appropriate type of calibration blocks. Cal frequency is dependant upon specified requirement and environment. The reading calibration piece that comes with the durometers isn't worth much other than to tell you if someone really screwed the thing up.

The other advantage of the cal blocks is that it gets you used to depressing and holding the durometer, and getting the right readings. Frequently the hardness figure is quoted as initial and after 10 or 15 seconds, so you need to be proficient.

Test material thickness is also specified in the test methods to ensure you're not pushing the probe in with your finger or the flat surface under your test piece.

As E suggested, check their website.

 

[energy]

Sure, now you show up!

Don't hear from you for ages, but your always there to put the barb up energy's posterior. I do not know of any other way to calibrate the device, do you? Other than that springy thingy mentioned? And, I used to count to five while balancing the tip on the center of the o'ring. But if you were only sorting Buna-N Butyl Duro 55-60 to E-515 Ethylene Propylene Duro 70+, who gave a rat's arse. You are so smart. I'm embarassed to have posted. Only kidding (about you being smart)! Don't wig on me! Nice to hear from you, even if it is just to do swings and roundabouts!

 

[David Mullins]

Now if you want to talk about tensometers, wyzenbeek abrasion resistance, weatherometers, modulus of elasticity, tear resistance, load deflections and other distructive testing ... I'll see if I can remember any of that.

E - I have in my kit-bag of qualifications a certificate in rubber technology from the University of Akron (via correspondence). I think the year was 1985.

 

[Al Dyer]

Bubba,

What material are you testing?

Shore "A"???

Or?????

 

[energy]

EXpert

Originally posted by David Mullins

E - I have in my kit-bag of qualifications a certificate in rubber technology from the University of Akron (via correspondence). I think the year was 1985.

That does it for me! I bet you're a blast at the neighborhood pharmacy!

 

[Ken K]

Bubba, can you give us an idea as to what kind of material your testing? Would make a reply much simpler.

Now if you want to talk about tensometers, wyzenbeek abrasion resistance, weatherometers, modulus of elasticity, tear resistance, load deflections and other distructive testing ... I'll see if I can remember any of that.

I remember it well...do it every day. If you ever have a brain fart and can't remember...give me a call. Fee's are small. :thedeal:

 

[Bubba]

Thanks everyone for your replies thus far.

Al and Ken, the material we will be testing is a silicone rubber that, from what I have been told, will be in the Shore A category.

Energy and David, you mention visiting somebody's website. What website would that be?

 

[energy]

Shore

Just punch Shore Durometer into whatever search engine you use. I went there after posting yesterday and it's all there. Materials, ranges and types of Testors. See all the rubber experts we have here? I use rubber worms!