Shore Or Rebound Hardness Test by Scleroscope

The shore scleroscope consists of a small diamond pointed hammer of very small weight ( about 2.4 g) which is allowed to fall freely from a height of 250 mm down a glass tube graduated into 140 equal parts . The height of the rebound is taken as the index of the hardness. This test is used for testing rolls and other machine components, and the instrument can be carried about in workshop. Shore value multiplied by 6 gives roughly the BHN on steels.

The scleroscope is very useful for testing the hardness of case - hardened surface which provides a very small hardness of the skin of the surface of the material.

Micro hardness test by Vickers Test Method

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ELECTRICAL COMPARATORS AND ITS WORKING

Electrical Comparators are used as a means of detecting and amplifying small movements of a work contacting elements. An electrical comparator consists essentially of a pick-up head or transducer for converting a displacement into a corresponding change in current and a meter or recorder connected in the circuit to indicate the electrical change, calibrated to show in terms of displacement. Generally, an amplifier is needed to provide the requisite sensitivity and to match the characteristics of different parts of the circuit. Electrical comparators can be classified according to the electrical principle used in the pick-up head. Most of the comparators use either a differential transformer, an inductance bridge, a strain gauge or a capacitor as a means of detecting movement of the gauging element. There are different types of electrical comparators. One kind called an electrolimit gauge is used to check or measure the outside diameter of a roll. The object to be checked is place

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Mechinopedia For Mechanical Engineers

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