|Rockwell Hardness (HRB or HRC)|
Definition:  Rockwell is a method of measuring the hardness of materials. Hardness, in this sense, means resistance to penetration. The test gets its name from Stanley P. Rockwell who devised the test and original machines, later selling the rights. The test measures the hardness by pressing an indentor into the surface of the steel with a specific load and them measuring how far the indentor was able to penetrate. While there are a number of Rockwell tests, the common is Rockwell B. Rockwell C is used on hard materials. When the material is very thin, lighter loads must be used. Resulting in Rockwell 30T, 1ST, Rockwell 15-N, 30-N scales. There are conversion charts which will allow conversion from one method of hardness to another, but it must be remembered that these conversion charts cannot precisely convert from one to another. Unfortunately, most customers do not recognize that there are different Rockwell test and/or do not realize that conversion charts are not totally accurate.