The Rockwell hardness scale is a macroscopic scale based on the indentation hardness of a substance or object. There are diverse scales that are symbolized by a single letter, which use different indenters or loads. The result obtained is a dimensionless number that denoted by HRX, wherein X stands for the scale letter. 




The testing method followed by Rockwell hardness indenters includes indenting of the material to be tested with the help of a diamond cone indenter. The determination of the hardness of a material based on Rockwell hardness testing system entails the application of a minor load and subsequently a major load. The permanent increase in the penetration depth, obtained as a result of application and subsequent removal of the major load is used to calculate the hardness number on the Rockwell scale. The harder the material, the higher will be the number obtained. 


The foremost advantage of Rockwell hardness testing system is its capability to exhibit hardness values directly. This prevents against tedious calculations that are required in other methods of hardness testing. Moreover, Rockwell hardness indenters are easy to operate and involve inexpensive set-up, making them extremely cost-effective. 


A Rockwell hardness indenter comprises a diamond cone set at an apex angle of 120 degrees with 200 micrometers radius of a spherical tip. This type of indenter most commonly finds application in engineering and metallurgy industries for testing the hardness of various metals and metallic equipments. Another reason as to why these Rockwell hardness indenters are popular commercially is because of their excellent speed, robust construction, fine resolution, small indentation area and most importantly, reliable results. 


Comet Engg. Co. manufactures a wide range of diamond indenters, including Rockwell indenters. With an Octahedron diamond mounted at an angle of 120 degrees, these indenters are guaranteed to provide accurate results without any scope for errors. The results obtained through the application of different indenters are compared along with the other tests, in order to derive at the hardness scale of a particular object.