Rockwell scale Rockwell scale The Rockwell scale is a hardness scale based on indentation hardness of a material. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload. There are different scales, denoted by a single letter, that use different loads or indenters. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale (see below). When testing metals, indentation hardness correlates linearly with tensile strength. This important relation permits economically important nondestructive testing of
Measuring cup be read from an external scale; metal ones only from a dipstick or scale marked on the inside. Measuring cups usually have capacities from 250 mL (approx. 1 cup) to 1000 mL (approx. 4 cups = 2 pints = 1 quart), though larger sizes are also available for commercial use. They usually have scale markings at different heights: the substance being measured is added to the cup until it reaches the wanted level. Dry measure cups without a scale are sometimes used, in sets typically of 1/4, 1/3, 1/2, and 1 cup. The units may be milliliters or fractions of