Degrees (4)

Degrees
by Barry 19 years ago

Re: Degrees
by Dave 19 years ago

Re: Degrees
by cole 19 years ago

Re: Degrees
by bes 19 years ago

The following message (subject: Re: Degrees) was posted by bes, on 4/19/2005 9:54:36 AM:

You asked for it - they are referring to IRHD hardness, which is a method for measuring soft rubber.

Below is a detailed explanation that is of little use to anyone not actually doing hardness measurements.

###############################

The International Rubber Hardness Degrees (IRHD) test was developed in Europe several years ago as an alternate to the Shore test. It is intended to provide an indication of the elastic modulus of the material being tested. Using a scale of 0 to 100, a 0 reading represents a material with zero elastic modulus and a 100 reading represents a material with infinite elastic modulus. A curve is provided in the ASTM standard to define the intermediate values. One IRHD point is equal to 0.04mm penetration.

The Shore IRHD test is a little like a Rockwell test in that two test forces are used to measure the depth of penetration and there are two force ranges. The indenters are all steel balls. IRHD units are not portable and can only be used in a stand designed for the test.
Standards

The following test methods cover IRHD testing:

* ASTM D1415
* ISO S 48

Shore IRHD Test Method

* The unit is lowered to the sample until the presser foot is in full contact.
* A low minor force is applied to the indenter for 5 seconds causing it to penetrate the surface slightly.
* The depth indicator is set to zero.
* A higher major force is added to the minor force.
* After a 30 second delay the hardness value is read off of the depth indicator.

Applications

Unlike the Shore test, the IRHD test is limited to testing rubber samples. There are two ranges, standard and micro. The standard range has two sets of minor, major and ball diameters while the Micro has only one. The standard ranges are intended for all normal size materials and the micro range is intended to use when testing small parts like O rings.

Report Abuse