Calibration of a torque wrench tester using a reference torque wrench

Torque wrench testers (TWTs) are used for periodical confirmation of graduations in both indicating and setting hand torque wrenches at calibration or testing laboratories. Weights, pulleys, wires and bars have been conventionally used as reference standards for calibrations of these TWTs. This paper shows another calibration method of TWTs using reference torque wrenches (RTWs). The RTWs are calibrated so as to keep the traceability to the national standard of torque, and are used as alternative reference standards for calibrations of TWTs. The authors experimentally verified the appropriateness of this calibration method by using some loading patterns, comparing with the conventional method.