What Is a Hardness Tester?
A hardness tester is an instrument used to determine the hardness of materials by measuring the size of deformation or marks left when a specific force is applied. Different hardness scales, such as Rockwell, Vickers, and Brinell, are used, and selecting a hardness tester that matches the test object’s characteristics is crucial.
While most hardness testers are stationary, there are also portable models for on-site testing.
Uses of Hardness Testers
Hardness testers play a vital role in product development and quality control, ensuring materials meet specific hardness requirements. They are used for quality verification, material comparison, research and development, and troubleshooting in product failure analysis.
Principles of Hardness Testers
Hardness testers use various measurement principles and should be chosen based on the material and its hardness. The types include Rockwell, Brinell, Vickers, Shore, durometer, pencil hardness, and Mohs Hardness methods, each with specific applications and measurement techniques.
1. Rockwell Hardness Tester
Uses a diamond indenter and measures hardness based on the depth of indentation. Variants like HRC, HRA, and HRB are used for different materials and applications.
2. Brinell Hardness Tester
Calculates hardness based on the indentation surface area created by a steel ball under load, suitable for objects with uneven hardness or rough surfaces.
3. Vickers Hardness Tester
Measures hardness from the diagonal length of the indentation made by a diamond square-weight indenter with a 136° facing angle and the load applied at the time of the indentation.
4. Shore Hardness Tester
Calculates dynamic resilience hardness by measuring the height of a diamond hammer’s bounce on the specimen.
5. Durometer
Used for softer materials like rubber and elastomer, measuring hardness based on the depth the indenter is pushed in.
6. Pencil Hardness Tester
Measures the surface hardness of coatings by applying a load to a pencil with a fixed tip shape and visually checking for scratches.
7. Mohs Hardness
Although not a hardness tester, there is a method for determining the hardness of minerals called Mohs Hardness, which uses standard minerals of known hardness levels for comparison.
Other Information on Hardness Testers
Notes on the Use of Hardness Testers
Hardness has no universal definition and varies based on the tester used. Regular inspections and calibrations are necessary to ensure accuracy. When comparing hardness values, using the same type of tester is recommended due to varying definitions of hardness across different devices.