Hardness

The resistance of an elastic material to the penetration of a body . In Europe, the hardness of an elastomer is measured in Shore A according to DIN 53505 or IRHD (International Rubber Hardness Degrees) according to DIN 53519 Bl. 2.

Hardness is usually measured using a Shore A device, in which a truncated cone needle is pressed into the rubber surface by a spring. The further the needle can penetrate into the rubber - i.e. the softer the rubber - the smaller the needle deflection on the measuring scale, which ranges from 0 Shore A to 100 Shore A.

A Shore A hardness tester can be used effectively in the range of 10-90 Shore A when testing standard bodies or finished parts with corresponding geometries and wall thicknesses. For thin-walled finished parts or products with curved surfaces (e.g. O-rings), the hardness should ideally be determined using an IRHD stand-alone device.

For harder mixtures and hard rubber, however, measurements are taken using a Shore D device. It has a sharper needle and a stronger spring.

Synonyms: Shore A