ASTM E-18 - We test our rockwell tester using calibrated test blocks

[dbulak]

I don't know if I am understanding ASTM E-18 correctly. Everyday we test our rockwell tester using calibrated test blocks. For example, the B and C scale get checked every morning. My question is, if we change from the B scale to the C scale during the course of the day do we have to retest the rockwell tester with the test block again? ASTM E-18 says when you check each scale, but nothing about using the rockwell tester for multiple scales. Anyone have any thoughts on this? As always many, many thanks in advance!

 

[andygr]

Para 13.5.1.5 has report by scale. I interpert this as you have to do it for each scale. If you do not change you machine over to each scale durring the verification process ( can be done with some digital units) and see what the actual is you are just performing interpolations for the other scales not verified with actuals as required by spec. I see it as covering all those pesky things called variables.
Maybe some of the calibration folks here can guide us?

 

[Kevin H]

What we did at the mechanical testing lab I ran in a steel mill was to test our Rockwell units at the start of each turn - most of the product we ran was on the "B" Scale, so we did an initial test on the B scale following the recomendations in section 14 for periodic checks by the User - if we had to change scales to either C or one of the superficial scales such as 15, 30, or 45 T or 15, 30, 45 N we would change the indenter if required, select the proper weight ranges on the machines, do two preliminary tests to ensure that the indenter was properly set and that the tester was working properly, and then check the test blocks per section 14 of ASTM E18. If we switched back to the B or other scale that we had already tested, we did not recheck that scale as described by section 14 again during that turn. However, we did do 2 preliminary tests to ensure that the indenter was properly seated and that the tester was working properly.

We'd log all of the periodic checks in a log book noting scale, date & turn, tester's initials, and actuall test results so that we could go back and troubleshoot if we had any test issues or complaints from a customer regarding Rockwell hardness test results. I never had any issues with our
A2LA assessor for ISO Guide 25 with our Rockwell testing in those areas. Only issue I ever had was to add to our procedure for Rockwell testing that the checks had to be 3 indentations apart and at least two indications in from the edge of the test block.

 

[SteelMaiden]

What we did at the mechanical testing lab I ran in a steel mill was to test our Rockwell units at the start of each turn - most of the product we ran was on the "B" Scale, so we did an initial test on the B scale following the recomendations in section 14 for periodic checks by the User - if we had to change scales to either C or one of the superficial scales such as 15, 30, or 45 T or 15, 30, 45 N we would change the indenter if required, select the proper weight ranges on the machines, do two preliminary tests to ensure that the indenter was properly set and that the tester was working properly, and then check the test blocks per section 14 of ASTM E18. If we switched back to the B or other scale that we had already tested, we did not recheck that scale as described by section 14 again during that turn. However, we did do 2 preliminary tests to ensure that the indenter was properly seated and that the tester was working properly.

We'd log all of the periodic checks in a log book noting scale, date & turn, tester's initials, and actuall test results so that we could go back and troubleshoot if we had any test issues or complaints from a customer regarding Rockwell hardness test results. I never had any issues with our
A2LA assessor for ISO Guide 25 with our Rockwell testing in those areas. Only issue I ever had was to add to our procedure for Rockwell testing that the checks had to be 3 indentations apart and at least two indications in from the edge of the test block.

What he said...we did document training and reference the standards in our procedures for testing. Once we calibrated for a shift, we only did a couple of "seating" tests prior to the documented hardness tests. We did two seating tests on each sample, not just when changing the indenter.