Study on some Effects on Shore Hardness Number : 4 th Report) The Effect of Both of Specimen Thickness and Pressing Force

In this report, the behaviour of the effect of both of specimen thickness and pressing force 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 velocity of the operating handle with consideration of the results of the 1 st. report, using many specimens which were different in hardness or in material, hardness numbers were measured with varieties of thickness of specimens from 10 to 0.1 mm and of pressing force from 0 to 60 kg. As the results, the behaviour of this effect is influenced strongly by specimen thickness and pressing force acts supplementarily upon it. Critical pressing force is constant over a certain thickness of the specimen, and decreases according to thickness under that thickness, and still more, such a special point as called critical pressing force vanishes soon in successive range. The range of specimen thickness and pressing force to gain constant hardness numbers in this condition was represented. But, from a practical point of view, it is desirable to apply critical pressing force and critical thickness represented in the 2 nd. and the 3 rd. reports respectively.