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Factors Affecting Test Accuracy of Digital Magnetic hardness tester

Normally Digital Magnetic hardness tester model number PHR-200,PHB-200,PHBR-200 

need not arrange force calibration, for common use, only calibrate the hardness tester with test

block is available, and wrong operation or other factors will also affect test accuracy, please pay

attention to it.

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1. Surface of part: It will affect test accuracy if the surface of part is rough with scale, decarburized 

layer, rust and contaminant.

2. Operation: It will affect test accuracy if it is not operated skillfully or carefully, or force loading, 

time duration of test force and force releasing are not the same among several tests.

3. Total test force:The inaccurate loading total test force in testing will affect result accuracy. 

4. Test force measuring: After long time using, transducer or electric parts may drift, which may

 cause test force inaccurate measuring.

5. Time duration: Time duration of test force should be longer than 5 seconds when calibrating 

tester. In test parts, it could be 2 to 3 seconds which will not affect test accuracy despite of short 

holding time.

6. Hardness block: It will affect test accuracy if block is in following condition: uniformity out of 

tolerance; bad stability; beyond inspecting valid time; distance between indentation too close; 

indentation existed in supporting surface; block or iron steel dirty.

7. Calibration: It will affect test accuracy if hardness or test force calibration is not correct.

8. Environment: It will affect test accuracy if temperature changes in a large range; temperature 

difference between test and calibration is too big; vibration exists on site; dust exists.  

9. Scale: Error in HRA is bigger than in HRC when test.

10. Conversion: When converting the test hardness values into HBW or HV, error may occur.