Final report on APMP.M.H-S3: Comparison on hardness measurement Rockwell scale A and B

Abstract

The APMP.M.H-S3 Rockwell hardness intercomparison was initiated by NIMT, Thailand and the required protocol was prepared by NIMT and checked by Dr John Man, MNIA, Australia, in 2009. PTB, Germany, Standards and Calibration Laboratory (SCL), Hong Kong, National Physical Laboratory (NPLI), India, and Korea Research Institute of Standards and Science (KRISS), Korea, participated in this comparison.This comparison exercise was focused on the measurement range of 25 to 100 HRBW scale and 35 to 85 HRA scale. The round robin test was done during the period from April 2010 to October 2010. The participating laboratories have demonstrated the capability of the machine and the operating conditions according to ISO 6508 Part 3 to perform the measurements. However, SCL, Hong Kong, could demonstrate their capability to perform the measurements only according to ISO 6508 Part 2.The CMCs declared by the different laboratories lie in the range of 0.30 HRA to 0.40 HRA and 0.40 HRBW to 0.75 HRBW. The CMC declared by SCL for the Rockwell B scale is 1.5 HRBW for the reason described above. It is observed from the results that the measurement uncertainty is estimated not less than the CMCs declared by the laboratories.From the measurement results provided by all the participating laboratories, the En ratio was determined to establish the degrees of equivalence. The En ratio was calculated by including as well as by excluding the results of the laboratory which has performed the test according to ISO 6508 Part 2 in order to make sure that it does not affect the overall results. It is noticed that the En ratio was still found to remain less than 1.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the APMP, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).