Uncertainty evaluation of shore hardness testers

To understand the uncertainties in the calibration of Shore hardness testers, it is necessary to evaluate the main factors contributing to the uncertainty in Shore hardness measurements. These factors are: the uncertainty of the force transducer used for the calibration process, and its long term instability (drift), temperature variation effect on the force transducer response, Shore hardness resolution, durometer inclination error, the permissible calibration error, the repeatability effect, indenter form error and other geometric parameters. In this study the calibration process is explained, the uncertainty elements are identified and directly verified. Elements that could not be directly verified are analysed or assessed using the available information. A numerical example shows how to estimate the uncertainty budget for the Shore D hardness tester is given.