In many manufacturing applications, the hardness of a metal is critical for quality control. A rockwell hardness tester for sale provides the means to accurately determine a sample’s level of stiffness and strength using a standard method. Hardness testing is accomplished by applying a force to the sample and measuring the size of the indentation left behind. This method is particularly useful for determining the hardness of steel parts.
Grainger offers a wide selection of dependable analog and digital hardness testers to meet a range of needs. For instance, select models are capable of measuring a hardness value of metal alloys with either a Brinell or Rockwell method. In addition, you can shop for Leeb and Vickers hardness testers to evaluate the hardness of small precision parts or thin materials. These portable units are designed for non-destructive evaluations on the go.
The type of indenter used in a hardness test is another important factor to consider. For example, for higher hardness levels (above 650 HB), it is recommended that you use a diamond indenter. For lower hardness ranges, a steel indenter may be more suitable. A hardness tester’s accuracy depends on the level of contact between the indenter and the surface of the material, as well as the cleanliness of the indentation.
While the Rockwell scale is a common choice, other hardness measurement methods exist. For instance, the Brinell method uses a steel ball indenter with a diameter that varies according to the hardness of the sample. This method can be difficult to perform on rough samples, as the indentation marks are often hard to read and require a microscope or other measuring instrument.
Finally, a Knoop hardness tester is another microhardness testing technique that is suited for all solid and metallic materials. The method utilizes a narrow diamond-shaped indenter for tests with very light loads.
A hardness tester’s accuracy level also depends on the level of contact between the indenter, the material being tested, and the support surface. It is important to ensure that the supporting surface is free of dirt, grease, and other impurities. Otherwise, deformation may occur when the test load is applied and the measurement will be erroneous.
Regardless of the method you choose, it is essential to calibrate your equipment at least once per year. For the highest level of accuracy, you should consider using a master calibration set. This set contains the actual master diamond indenter or carbide ball penetrator that was used to calibrate your tester. This eliminates the possibility that the tester itself is the source of a bad test result. Moreover, these sets are inexpensive, making them an excellent investment for your quality assurance program.