Shore A Hardness Testing on Cable Materials

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. 

Shore Hardness Scale Comparison Table

A B C D 0 00
100 85 77 58    
95 81 70 46    
90 76 59 39    
85 71 52 33    
80 66 47 29 84 98
75 62 42 25 79 97
70 56 37 22 75 95
65 51 32 19 72 94
60 47 28 16 69 93
55 42 24 14 65 91
50 37 20 12 61 90
45 32 17 10 57 88
40 27 14 8 53 86
35 22 12 7 48 83
30 17 9 6 42 80
25 12     35 76
20 6     28 70
15       21 62
10       14 55
5       8 45

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.

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