What is a hardness tester?
Hardness Tester is one of the materials used to measure the resistance to pressure, polish and turning of materials. Therefore, Hardness tester have many ways to test but in the metallurgy Hardness measurement will test the metal's ability to resist permanent processing when the pressure from the indenter is applied to the specimen.
The methods of testing commonly used as follows Rockwell Hardness Test, Brinell Hardness Test, and Vickers Hardness Test.
In the present, Hardness tester have been developed. There are reading systems, such as old and new digital systems. Moreover, the newest of reading system is a digital system that can touch the screen. However, how do we know that the hardness tester is still good performance under ISO 17025 standard. The answer is hardness tester must be calibrated from accredited calibration laboratory ISO 17025 before using the instrument.
- Rockwell Hardness Test is the most commonly used method to measure the hardness of metals by measuring the indentation depth under constant pressure.
- Brinell Hardness Test is a measure of hardness based on the constant pressure exerted on the hardened steel ball on the specimen surface. The hardness is calculated from the pressure exerted per unit of surface area especially, the surface area is curved
- Vickers Hardness Test is a way to measure hardness by using the diamond indenter look like a rectangular pyramid at the end of the head, press the angle 136 degrees (the angle is the closest degree to the circular indenter) for 10-15 seconds. The hardness is calculated based on the pressure exerted per surface area unit, as well as the Brinell test. However, this method is a diamond, which has a very high hardness so, in the application, the hardness can be measured from very soft metals (HV about 5) to very hard metals. (VHN about 1500) without changing the indenter or change only the pressure, ranging from 1-120kgf depending on the hardness of the metal tested.