AFS Foundry Sand Testing Equipment Operating Instructions Manual

RIDSDALE-DIETERTCORE HARDNESS TESTERIGENERAL PRINCIPLESThis instrument is used to determine accurately the surface hardness of cores. The surfaceof the core is subjected to controlled abrasion by a four-point penetrator and the depth ofpenetration measured on a horizontally mounted dial gauge.IIDESCRIPTIONIt consists of a probe or penetrator which can be rotated by means of an external knurledring, indexed so that the number of rotations can be counted, and a horizontally mounteddial gauge which measures the depth of penetration of the probe.IIITEST PROCEDURE(a)(b)(c)Hold the curved section of the tester body with the thumb and forefinger. Turn theknurled index ring assembly until the line on the index ring is opposite the referenceline on the housing projection. Do not move the dial indicator bezel.Press the base of the instrument firmly against the core and rotate the ring assemblyclockwise through two revolutions, until the lines are again matched. Read thehardness directly from the indicator. As long as the reference lines are together nofurther resetting of the unit is required for the next test.For routine testing two revolutions may be considered as the standard procedure. Toincrease the sensitivity of the instrument when testing harder cores, three or morerevolutions should be employed, and for very weak cores it may be desirable to useonly one revolution. The number of revolutions should be recorded along with thehardness value.125