Does a Vickers hardness tester inherently contain errors?

Taiwan Nakazawa Co., Ltd. answers for you: Yes, there will be [errors], generally divided into two types:
1. Each hardness scale is actually a range, depending on the selection. For example, if the hardness is greater than HRB100, the HRC scale should be used for testing; if the hardness is less than HRC20, the HRB scale should be used. Because outside of its predetermined testing range, the sensitivity of the hardness tester is poor and the hardness values are inaccurate, it should not be used. Other hardness testing methods also provide appropriate calibration standards. When calibrating a hardness tester, both sides of the standard block cannot be used because the hardness of the standard surface and the back surface is not necessarily consistent. Generally, the calibration block is required to be valid for one year from the date of calibration.
2. When replacing the indenter or the anvil, pay attention to wiping the contact areas of different parts clean. After replacement, test several times using a steel sample of a certain hardness until the hardness values obtained twice in succession are the same. The purpose is to ensure that the contact parts of the indenter or anvil and the testing machine are tightly pressed and in good contact, so as not to affect the accuracy of the test results.