Commonly used hardness tester classification and matters needing attention
Hardness tester classification Leeb hardness tester, Rockwell hardness tester, Brinell hardness tester, Shore hardness tester, Shore hardness tester, Barcol hardness tester, micro hardness tester, Mohs hardness tester, Vickers hardness tester, fruit hardness Meter, cement hardness meter, etc. In addition to the special precautions for the use of various hardness testers, there are some common issues that should be noted as follows: 1 Hardness tester classification Leeb hardness tester, Rockwell hardness tester, Brinell hardness tester, Shore hardness tester Hardness Tester, Shore Hardness Tester, Barcol Hardness Tester, Micro Hardness Tester, Mohs Hardness Tester, Vickers Hardness Tester, Fruit Hardness Tester, Cement Hardness Tester, etc. In addition to the special precautions for the use of various hardness testers, there are also some common problems that should be paid attention to. Here are listed as follows: 1. The hardness tester itself will produce two kinds of errors: one is caused by the deformation and movement of its parts. The second is the error caused by the hardness parameter exceeding the specified standard. For the second type of error, the hardness tester needs to be calibrated with a standard block before measurement. For Rockwell hardness tester calibration results, the difference is qualified within ±1. A stable value with a difference of ±2 can be given a correction value. When the difference is outside the range of ±2, the hardness tester must be calibrated and repaired or measured by other hardness testing methods. Each scale of Rockwell hardness has a de facto applicable range, which should be selected correctly according to regulations. For example, when the hardness is higher than HRB100, the HRC scale should be used for testing; when the hardness is lower than HRC20, the HRB scale should be used for testing. Because the accuracy and sensitivity of the hardness tester is poor when it exceeds the specified test range, and the hardness value is not accurate, it is not suitable for use. Other hardness testing methods also have corresponding calibration standards. The standard block used to calibrate the hardness tester cannot be used on both sides, because the hardness of the standard surface and the back surface may not be the same. It is generally stipulated that the standard block is valid within one year from the date of calibration. 2. When replacing the indenter or anvil, pay attention to the contact parts to be wiped clean. After the replacement, test several times with a steel sample of certain hardness until the hardness value obtained twice in succession is the same. The purpose is to make the contact part of the indenter or anvil and the testing machine be pressed tightly, and the contact is good, so as not to affect the accuracy of the test results. 3. After the hardness tester is adjusted, when starting to measure the hardness, the first test point is not used. For fear of bad contact between the sample and the anvil, the measured value is not accurate. After the first point of the test is completed, the hardness tester is in the normal operating mechanism state, and then the sample is formally tested, and the measured hardness value is recorded. 4. When the test piece allows, generally choose different parts to test at least three hardness values, take the average value, and take the average value as the hardness value of the test piece. 5. For specimens with complex shapes, use correspondingly shaped cushion blocks and fix them before testing. The round specimen is generally tested in a V-shaped groove. 6. Before loading, check whether the loading handle is in the unloading position. When loading, the action should be light and steady, and do not use too much force. After loading, the loading handle should be placed in the unloading position to prevent the instrument from being under load for a long time and plastic deformation, which will affect the measurement accuracy.
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