Stationary Hardness tests
There are 3 common hardness tests used with stationary hardness testing machines. Depending on your specific application and reporting standard, you may want to choose a machine that can use one or more of the testing methods below. There are machines that can be used with just 1 hardness test and machines that can handle all 3 hardness tests.
The Rockwell scale is a hardness scale that is based on the indentation hardness of a material. Meaning how far the indenter penetrates the material that is being tested. The depth is converted into a number on the Rockwell scale. The probe is usually either a 120o diamond spheroconical or a 1/16th (*1.588 mm) diameter steel sphere. One of the advantages of the Rockwell scale over other scale systems is the immediateness of the testing results as results are displayed in the Rockwell scale compared to Brinell and Vick which usually require calculations based on results.
The Brinell scale is based on hardness similar to the Rockwell scale. However, the indenter used in this scale is much larger than the one used in the Rockwell scale and poses a greater risk of damaging material being tested. The typical test uses a steel ball with a 10 mm (0.39 in) diameter as an indenter. You also need to convert the results of the test into a Brinell Hardness number.
The Vickers hardness test is an alternative test to the Brinell and is often easier to calculate as the necessary calculations are independent of the indenter used.
Portable Hardness Tests
There are many portable types of hardness testers available for hardness testing in difficult to reach areas. Depending on the application, you may choose one type over another.
Many portable testers on the market use the Leeb rebound hardness test. The hardness measurements are reported in the Leeb scale and can then be converted into other hardness scales depending on the instrument you use. Steel, alloy steel, stainless steel, bronze, aluminum, copper, and cast iron are all materials that are suitable for testing using a Leeb rebound instrument. However, they are not suited for testing the hardness of very thin or light weight parts.
Ultrasonic Contact Impedance (UCI) hardness testers are designed for rapid and non-destructive hardness testing. They can measure a multitude of products immeasurable by the Leeb testers including thin-walled structures, steel sheets, metal coatings, etc.). This testing runs on the principal of measuring hardness by detecting the frequency shift of a longitudinal oscillating rod fused to a Vickers diamond indenter. The indentation is then measured electronically be detecting a frequency shift.
Durometers are the international standard for testing the hardness measurement of rubber, plastic, and other non-metallic materials. There are different types of durometers based on the specific material that you want to test.