The Development Of 100 Nm Torque Standard Machine At Nim

A set of 100 Nm torque standard machine is newly developed at National Institute of Metrology (NIM). By adapting the air bearing with low friction as the arm lever fulcrum, the low expansion alloy (INVOR) as the arm lever material and the accurate machining and adjustment technology, the uncertainty of 100 Nm torque standard machine is minimized. This machine is capable of realizing torque from 1 Nm to 100 Nm both in clockwise and anticlockwise direction. The working principle and mechanical structure of the machine are introduced, the uncertainty assessment and results of performance test are described. The results show that the repeatability of 100 Nm torque machine is better than 2x10(-5), the uncertainty is smaller than 2x10(-5) (k=2).