WORKING AND CHECK STANDARDS FOR NIST SURFACE AND MICROFORM MEASUREMENTS

摘要

Different working and check standards are used in the NIST surface and microform measurement laboratory for calibrating instruments, establishing our measurement traceability and controlling measurement uncertainty. In this paper, we describe the definitions, characteristics and uses of working and check standards. Some examples demonstrate the selection and use of these standards in surface and microform measurements. With the help of these standards and a calibration procedure using a commercial stylus instrument, the calibration uncertainty for measurement of least-squares radius of the Rockwell diamond indenters was reduced from micrometers to sub-micrometers. In addition, we were able to identify an unsuitable Rockwell diamond indenter and avoid using it in the Rockwell hardness calibration laboratory.