Telebrineller Hardness Testing
The test bars are labeled with their known Brinell Hardness Number (BHN). For the most accurate calculations, try to select a reference bar that is within 15 percent of the hardness of the test object. Some research will need to be done to find out the approximate hardness of the material that is to be tested. Then, compare the approximate hardness of the test object to the known hardness of the test bars in order to find a bar with a comparable hardness.
However, there are some situations in which the material of the test object is unknown. How can you choose a test bar that is within 15 percent of the hardness of the test object when you do not even know the material of the test object? An advantage of the Telebrineller Hardness Testing procedure is that you do not need to select a bar that has a hardness within 15 percent of the hardness of the test object. It is better if you are able to, but the results will not be affected dramatically if you can not. When the material of the test object is unknown, it is best to choose a bar with an average hardness.
After you select a test bar, place it inside the bar holder. Be sure to not use an area that already has an indentation in it. Making indentations over top of other indentations in the reference bar will alter the results of the test. The next step is to perform the test.