Hugh Rockwell and Stanley Rockwell were granted a patent for the Rockwell hardness tester on February 11th 1919, a device for measuring the resistance of metallic materials to force. At the time both men worked for the New Departure Company and although they shared the Rockwell name, they were not related. The company was a major manufacturer of ball bearings and later became part of General Motors.
Determining the Rockwell hardness of a material involves the application of a minor load followed by a major load. The minor load establishes a zero position, the major load is applied, then removed while still maintaining the minor load. The depth of penetration from the zero position is measured, a harder material gives a higher number.
The major advantage of the Rockwell test is that it displays the hardness directly without the need for measuring the indentation and calculating the hardness.
Its commercial success stems from its reliability, robustness, and small indentation size. The standard Rockwell test is only valid on samples over ten times the indentation depth, precluding its use in foils and small wire. The Rockwell superficial test was developed test materials too thin or small for the regular scales
UK Calibrations Limited are a UKAS accredited Laboratory, (No. 0201), authorised to carry out UKAS verification to the latest BS EN ISO requirements on Rockwell hardness testing machines. We can Service and maintain machines from ALL manufacturers. Contact us now to discuss your requirements.
If you're interested you can view the full patent application.