In the first half of 2007 ASTM Subcommittee E28.06 passed new versions of E18 for Rockwell testing. These new documents took several years to finish and are complete rewrites of the popular test method. There are many technical changes and new document requirements that can have a far reaching effect, especially when you have to satisfy the needs of an auditor. It may be that none of your Rockwell test results meet the new standards.
Rockwell Diamond Indenters:
E18-07 and later test methods require that Rockwell diamond indenters are to be geometrically and performance verified. The geometry verification of the indenter is now mandatory on E18-07 and later diamond indenters. The performance requirements of the indenters have been tightened and now there are separate classes of diamond indenters. (Class B, Class A and Reference diamonds).
- Class B diamond indenters have added performance verification on additional hardness scales and also the tolerances have been tightened compared to indenters previously calibrated to E18-07. These indenters are used for normal everyday hardness testing.
- Class A diamond indenters are a new requirement in the standard starting in the E18-07 version and have very tight performance specifications. These indenters are used to calibrate test blocks, testing machines and used to performance verify class B diamond indenters.
- Reference diamond indenters are indenters that have been calibrated by a recognized National level laboratory. Examples of recognized National level laboratories is NIST in the United States, NPL in the UK, PTB in Germany and INRIM in Italy.
These changes make all pre E18-07 indenters obsolete. In order to comply with the latest standard you can obtain new indenters that comply with the standard or you can send your old indenters to the Wilson Calibration Laboratory for recalibration.
Rockwell Testers:
With all of the above changes to test blocks and indenters your Rockwell tester will need to be reverified to E18-07 or later to ensure compliant test results.