Several common methods for checking during the testing machine period

The material testing machine is a commonly used testing instrument in physical property experiments, and its importance ranks particularly high among various instruments. Therefore, the issue of periodic verification of material testing machines is particularly important. Below, I summarize several common methods for periodic verification of testing machines as follows:
Firstly, explain the concept of periodic verification:
Periodic verification: also known as“operational check”, or“Intermediate verification”. During the time interval between two calibrations or verifications, the measuring equipment should be checked multiple times using appropriate technical verification methods to ensure that the measuring equipment is“serve in the military”Activities that maintain a good state throughout the period.
The commonly used methods for determining criteria are as follows:
1Transmission comparison method
2Multiple comparison method
3Two comparison methods
4Sample retention measurement method
One; Transmission comparison method:
Purchase standard force measuring instruments to conduct periodic checks on the testing machine, and verify the basisJJG139-1999The verification records can use the original records in the appendix of the regulations, and data calculation and processing can also be carried out in accordance with the regulations. Advantages: Its verification results have the lowest uncertainty and the lowest quality risk. Disadvantage: The cost is too high. If several testing machines are used, multiple force measuring instruments may need to be purchased, and the force measuring instruments used for periodic verification must be traced before they can be used.
Multiple comparison and two comparison:
Test the uniform and stable tested material, compare the results, and confirm the service status of the testing machine. This verification method is not very suitable for mid-term verification of the testing machine. We don't have in-depth discussions.
Three; Sample retention measurement method:
After the calibration of the testing machine is qualified, two sets of tested materials with uniform and stable performance are found, one set is retained and the other is tested. Based on the calibration data of the testing machine, the experimental results are corrected and saved. After a period of time, the retained samples are tested, and the experimental results are compared to confirm the performance of the testing machine. Generally, metal samples are selected for material verification.
Check control limits:
Verification control limit:
ΔB=2|Y-y|/(Y+y)≤U (UIt should be determined according to the level of the testing machine)
in the formula: Y——*Average value of group sample results
y ——The average result of the second group of samples
U ——The uncertainty of the testing machine.