ISO 48:1994 pdf free.Rubber, vulcanized or thermoplastic一Determination of hardness (hardness between 10 IRHD and 100 IRHD)
These methods are modifications of methods N, H, L and M for cases where the rubber surface tested is
curved. Two cases exist, depending whether
a) the test piece or article tested is large enough forthe hardness instrument to rest upon it;
b) it is small enough for both the test piece and theinstrument to rest upon a common support.
A variant of b) would be where the test piece restson the specimen table of the instrument.
The procedures described cannot provide for all possible shapes and dimensions of test pieces but cover some of the commonest types such as “O” rings, Determination of the apparent hardness of rubber-covered rollers is dealt with separately in ISO 7267-1:1 986, Rubber-covered rollers — Determi-nation of apparent hardness — Part 1.. IRHD
method, ISO 7267-2:1986, Rubber-covered rollers — Determination of apparent hardness — Part 2:Shore-type durometer method and ISO 7267-3:1988,Rubber-covered rollers — Determination of apparent hardness — Part 3: Pusey and Jones method.
3 Principle
The hardness test consists in measuring the difference between the depths of indentation of a ball into the rubber under a small contact force and a large total force. From this difference, multiplied when using the microtest by the scale factor 6. the hardness in international rubber hardness degrees (IRHD) is obtained by using tables 3 to 5 or on graphs based on these tables or a scale, reading directly in international rubber hardness degrees, calculated from the tables and fitted to the indentation-measuring instrument. These tables and curves are derived from the empirical relationship between indentation depth and hardness given in annex A.
4 Definitions
For the purposes of this International Standard, the following definitions apply.
4.1 international rubber hardness degrees (IRHD): A hardness scale chosen so that “0” represents the hardness of material having a Young’s modulus of zero and “100” represents the hardness of a material of infinite Young’s modulus, with the following conditions being fulfilled over most of the normal range of hardness:
a) one international rubber hardness degree always represents approximately the same proportionate difference in the Young’s modulus;
b) for highly elastic rubbers, the scales of IRHD and the Shore A durometer are comparable.
4.2 standard hardness (denoted by the letter S):
The hardness, reported to the nearest whole number in international rubber hardness degrees, obtained using the procedures described in methods N, H, L and M on test pieces of the standard thickness and not less than the minimum lateral dimensions specified.
4.3 apparent hardness: The hardness, reported to the nearest whole number in internat,onal rubber.ISO 48 pdf download.