The Knoop Hardness Tester is used to run microhardness tests. Since you only need to make a small indention to the material, you can use it to test thin parts or brittle and weak elements. This machine can perform tests at forces of between 10gf and 1000gf. Some materials or circumstances may make it necessary to use higher forces of up to 5kgf, but you should expect higher variations in the results at this level. The key advantage of using this tool is that it allows you to run the tests fast and easily. It is also worth noting that the materials that need to be tested can be very thin, which is another great advantage. The hardness scale conversions of this tester are all based on empirical data, and they are only meant to be used as estimates. The disadvantage of using this tool is that you will need a lot of time to prepare the sample.
How Do You Calculate the Knoop Hardness?
The Knoop hardness is calculated by taking the load in gf and multiplying it by 14229. The result here has to be divided by d squared, where d is the long diagonal. As mentioned earlier, these values are only meant to work as estimates, and the variations in the results will go up as you increase the load. The HK values usually range from 100 to 1000.