Grace's Guide To British Industrial History

Registered UK Charity (No. 115342)

Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 149,755 pages of information and 235,473 images on early companies, their products and the people who designed and built them.

Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 147,919 pages of information and 233,587 images on early companies, their products and the people who designed and built them.

Rockwell

From Graces Guide

Stanley P. Rockwell invented the Rockwell hardness test.

He was a metallurgist for a large ball bearing company and he wanted a fast non-destructive way to determine if the heat treatment process they were using on the bearing races was successful. The only hardness tests he had available at time were Vickers, Brinell and Scleroscope. The Vickers test was too time consuming, Brinell indents were too big for his parts and the Scleroscope was difficult to use, especially on his small parts

To satisfy his needs he invented the Rockwell test method. This simple sequence of test force application proved to be a major advance in the world of hardness testing. It enabled the user to perform an accurate hardness test on a variety of sized parts in just a few seconds.

There are two types of Rockwell Tests:

  • Rockwell: the minor load is 10 kgf, the major load is 60, 100 or 150 kgf.
  • Superficial Rockwell: the minor load is 3 kgf and major loads are 15, 30, or 45 kgf.

In both tests, the indenter may be either a diamond cone or steel ball, depending on the characteristics of the material being tested.


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