Hardness Testing

Metals and Polymers can be tested for hardness.

Rockwell B & C Hardness tests are run on metal. The purpose of this test is to obtain approximate strength of the material. Rockwell B is performed with a load of 100kg, and Rockwell C with a load of 150kg. 

Rockwell Superficial N & T tests are also run on metal. This is similar to the B & C hardness tests but a much lower load is used, so it is useful for thin samples and coatings. The loads may be 15kg, 30kg, or 45kg. 

Knoop Microhardness 
Microhardness testing uses a low load, typically 500g, resulting in small indentations (pictured right) which are measured to determine the hardness of the material. 

Knoop Microhardness can be performed as a survey, with many readings taken in a line. This can determine the depth of case hardening, or can inspect for embrittlement across weld heat affected zones (HAZ). 

Knoop Microhardness is useful for determining hardness of very small parts or multi-component parts.

This testing is performed on metal samples that have been sectioned to small size, then mounted in epoxy and polished to a mirror finish. 

Shore A hardness tests are run on rubbers and Shore D tests are run on plastics.