Rockwell Testing

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The Rockwell testing method is the most commonly used for determining hardness in blades. The tester, shown below, consists of a penetrator that is pressed into the steel surface via a lever upon which is suspended the major load weights. The depth of penetration is accurately measured and indicated on the dial gauge at the front of the unit. Although it does have it's own distinct weak points, the Rockwell method can be very accurate due to the fact that a minor load is applied in order to firmly seat the penetrator into position for the major load and the measurements are displayed directly on the dial, eliminating much human error.


The procedure is as follows: The test piece is placed upon the anvil and the elevating unit is rotated by the handles at the bottom. This raises the anvil and test piece into position against the penetrator. The anvil is further elevated to lift the internal mechanism back through the main lever, the weight of which provides the initial minor load. This minor load adds or detracts nothing to the actual test penetration but firmly and accurately seats the penetrator for the test and thus compensates for any surface irregularities. The amount that this minor load is applied is indicated by the smaller secondary dial scale in the picture of the dial gauge below. When the small needle is at the lower red dot,the tester is set for the major load. At this point the main dial indicator should be at the 12:00 position (0 on the "C" scale).

Now the loading lever is pulled and the the major load of 150kg is applied to the main lever forcing the penetrator into the test piece. When full pressure has been applied the major load is removed by pushing the unloading lever. The distance that the penetrator has traveled from the point of the minor load to the end point of the major load is then accurately measured and indicated as a number value on the dial gauge.



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