Impact of measuring devices: Whether the measuring device is qualified or not, and whether the operation of the measuring device is scientific or not, will cause significant errors. Therefore, it is necessary to use a Brinell hardness tester that has been verified by the metrological department as qualified, has not exceeded the verification period, and has not been damaged. When Brinell hardness testers must be regularly sent to the metrological verification department for periodic verification operations, the indenter should be slowly and smoothly pressed into the sample surface. During the process of applying a load, the tester can be moved or shaken at will.