Development of 2 N dead-weight type force standard machine

Abstract A 2 N dead-weight type force standard machine (2 N DWM) equipped with a balancing mechanism to cancel out the gravitational force acting on the loading frame is developed by National Metrology Institute of Japan (NMIJ), AIST. Removable standard weights are selected in accordance with the calibration force steps and placed onto a weight-loading mechanism. The minimum force that can be realized is 10 mN. The relative expanded uncertainties of the realized forces with coverage factor k = 2 are evaluated as 5.8 × 10−4 and 2.9 × 10−5 at force steps of 10 mN and 200 mN, respectively. Repeatability is evaluated in the range of 100 mN–2 N with the use of a 2 N force transducer. With the development of this standard machine, the force standards disseminated from NMIJ extend down to 10 mN. We believe that our work can further contribute to developments in force standards.