The Accuracy of Shore Hardness Scale Based on the Conversion from Vickers Hardness

Shore hardness testers are calibrated against five standard blocks of different hardness, the value of which is determined by converting their Vickers hardness into Shore hardness in accordance with a prescribed formula. The accuracy of the Shore hardness scale thus determined is investigated in two ways. Firstly, the consistency of the relation between Vickers and Shore hardness in commercial standard hardness blocks is investigated by making a factorial experiment and is found to be within ±0.6∼1.0 Hs, including the error of Vickers hardness tests. Secondly, the discrepancy of the scales of different Shore hardness testers at hardness values other than those calibrated with a tolerance of ±1.0 Hs is examined and is proved to be less than ±1.8 Hs.