Study on Certain Effects on Shore Hardness Number : (3 rd Report) On the Effect of Thickness and Weight of the Specimen

Abstract

In this report, the effect of thickness and weight of the specimen on Shore hardness number was investigated. Under the general requests for the testing with the Shore scleroscope being satisfied and especially attending to free from the effect of the operating handle and of pressing force with consideration of the results of the preceding reports, using many specimens which were different in hardness or in material, hardness numbers were measured with verieties of thickness from 10 to 0.1 mm. As a result, the effect of thickness and weight of the specimen on hardness number was made clear. That is ; the effect of thickness is due to (1) spring effect, (2) deformation effect, and (3) anvil effect. However, these effects may be classified to three main types according to the material, whose hardness undergoes the test, as follows : a type containing (1), (2) and (3) effects (iron and steel), a type containing (2) and (3) effects (nonferrous Ist. type). and a type containing only (3) effect (non-ferrous 2 nd. type). Critical (minimum) thicknesses immune from this effect were decided according to the above mentioned types, as about 5 mm for iron and steel, about 2 mm for non-ferrous Ist. type, and about 0.5 mm for non-ferrous 2 nd. type. Above mensioned results are also applicable to the effect of weight of the specimen. According to the results, specimen weighing 0.1 kg or even less give no effect on hardness number, if sufficient pressing force is applied.