The Shore A Hardness Test is conducted according to ASTM D2240, ISO 868 & ISO 7619-1 and specifies a method of determining the indentation hardness for rubber and soft plastics by means of a Durometer using the 'A scale' in the nominal hardness range. This applies particularly to our rubber flexible cable range.
The Shore A Hardness Scale measures the hardness of rubbers ranging from very soft and flexible, through medium and somewhat flexible, to hard with almost no flexibility at all. Semi-rigid plastics can also be measured on the high end of the Shore A Scale.
The surface of the test piece shall be flat and placed over an area with sufficient size to permit the pressure foot of the Durometer to come into contact with the test piece over a radius of at least 6mm from the indenter point. Satisfactory hardness determinations cannot be made on rounded, uneven or rough surfaces using Durometers.
Where practical, test pieces are conditioned immediately before testing for a minimum period of 1 hour. The test piece is placed on a flat, hard, rigid surface (e.g. glass) and then pressure is applied to the test piece as rapidly as possible but without shock, and ensuring that the indenter is normal to the surface.
The reading from the Durometer is recorded at specified times - 3 seconds for vulcanized rubber and 15 seconds for thermoplastic rubber. Five measurements of hardness at different positions on the test piece, at least 6 mm apart for the A type durometer, are recorded and the mean value is calculated.
There are different Shore Hardness scales for measuring the hardness of different materials. These scales were devised to allow a common language for discussing these materials using common points of reference.