Shore scales are used to measure hardness: Shore A, B, C, D, 0 y 00. The Shore A scale is the most suitable for measuring elastomers, although the Shore D scale can also be used for the measurement of hardness of harder gums. Approximately 40 Shore D correspond to 90 Shore A.
To determine the hardness of the rubber or elastomer, the most common and most frequent test is performed by measuring the strength of the rubber material at the penetration of a ball or a tipThere is no relationship between hardness and other mechanical properties as normally happens with steels. Harder does not mean, for example, greater tensile strength. Materials with the same hardness can be completely different.
- Shore A / D
The measurement is performed with an instrument called a durometer, based on the penetration of a frusta conical tip against the reaction of a calibrated metal spring. When readings above 90 ° are obtained with the Shore A durometer, it is recommended to use the Shore D durometer, which has a conical tip and a stiffer spring. Both methods are described in the Spanish standard UNE 53130, the American ASTM D2240 and the German DIN 53505.
There are several specific scales for measuring the hardness of very soft rubbers, cellular or spongy materials as well as a wide variety of different materials. The Shore 0 and shore 00 scales meet the specifications of ASTM D2240.
- IRHD (International graduation of rubber hardness)
It is a method for characterizing an elastomer by its resistance to the penetration of a known geometric inventor by a known force. The readings are similar, but not identical, to the Shore (TM, Wilson – Shore Instruments) model.
ASTM D 1415
ASTM D 2240
|shore a||irhd||shore d||shore 0||shore 00|
|DIN 53505||ASTM D 1415||DIN 53505||ASTM D 2240||ASTM D 2240|
|Compact Elastomers||Polyurethanes, rigid PTFE ,
Thermoplastics and hard
|Compact and celullars
wit half density
|Half and low density