Introduction to Rockwell Hardness Tester.

In rockwell hardness tester, an indenter of specified size, shape and material (diamond cone, steel ball or hardmetal ball) shall be forced into the surface of the specimen in two steps under specified condition. The permanent indentation depth, h under preliminary test force shall be measured after the removal of additional test force. From the value of permanent indentation depth, h and two constant number N and S, the rockwell hardness is calculated according to formula (1):
Rockwell hardness = N – h/s ………………………………………………………….(1)

 

Symbols and designation:

 

 

Scales of Rockwell hardness and Rockwell superficial hardness and related matters

 

Permissible repeatability and error of the testing machine

 

How to determine the relationship between Rockwell Hardness Tester and the minimum thickness of a specimen?

The relationship between Rockwell Hardness Tester and the minimum thickness of a specimen can be explained by diagram below:

 

Convex Cylindrical and Spherical Surfaces

For test on convex cylindrical surfaces and spherical surfaces, correction given in table C.1 to table C.4 and table D.1 shall be applied. The hardness after correction should be the hardness of the test piece. The hardness of the test piece should be obtained according to the formula below:

Hardness of test piece = reading + correction 

For test on concave surfaces, due to the absence of corrections, test on such surfaces shall be upon the agreement between the parties concern with delivery.
 

Correction to be added to Rockwell hardness values obtained on convex cylindrical surfaces

For tests on convex cylindrical surfaces, the corrections as given in table C.1 and table C.4 should be applied.

Hardness correction for scales A, C and D

 

Hardness correction for scales A, C and D

 

Above sharing just for your reference. When you’re interested in investing a hardness tester to improve your quality process, select a supplier who offer a quality service and meet your specific needs.

If you have any enquiry with hardness tester, welcome to contact us by email: enquiry@mspmetrology.com