- The hardness tester itself will produce two kinds of errors: one is the error caused by the deformation and movement of its parts; the other 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 the calibration result of the Rockwell hardness tester, the difference is qualified within ±1.
Each scale of Rockwell hardness has a practical scope of application and should be selected correctly according to the 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 are poor and the hardness value is inaccurate when it exceeds its specified test range, it is not suitable for use.
Other hardness testing methods also stipulate corresponding calibration standards.
The standard block used for calibrating the hardness tester cannot be used on both sides, because the hardness of the standard surface and the back may not be the same. It is generally stipulated that the standard block is valid for one year from the date of calibration.
- When replacing the indenter or anvil, pay attention to cleaning the contact parts. After the replacement, use a steel sample with a certain hardness to test several times until the hardness value obtained twice in a row is the same. The purpose is to press the indenter or the anvil and the contact part of the testing machine tightly and make good contact, so as not to affect the accuracy of the test results.
- After the hardness tester is adjusted, when starting to measure the hardness, the first test point is not used. For fear of poor contact between the sample and the anvil, the measured value is inaccurate. After the first 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.
- 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.
- For the specimen with complex shape, the corresponding shape of the spacer should be used, which can be tested after being fixed. The round specimens are generally placed in the V-groove for testing.
- Before loading, check whether the loading handle is placed 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 in a loaded state for a long time, resulting in plastic deformation and affecting the measurement accuracy.
For more information on this source, please visit TITLTEST.COM If you need to know more details, please contact support@titltest.com
1 comment
Charlotte Fleet
I am interested in all of the information you provided on hardness testers. It is good to know that it is important to pay close attention to cleaning the contact parts after you replace an anvil. I think it would be essential to invest in a quality and durable anvil in the first place to promote accurate results. https://westportcorp.com/pages/british-thread-gages