The establishment of 1N·m torque standard machine at NIM
1 N·m torque standard machine was established at National Institute of Metrology (NIM) in 2013. The torque standard machine adopts deadweight and moment-arm type. The static air bearing with low friction is used to support the moment-arm, the invar alloy with the low expansion coefficient as the material of the moment-arm, the specially designed weight suspension part and weight loading system may ensure the applied force by small weights accurately and reliably. The mechanical structure of the machine is introduced, the results of performance test and uncertainty assessment are described. The expanded uncertainty (k = 2) is smaller than 5 × 10-5 in the range of 100 mN·m - 1 N·m, smaller than 1× 10-4 in the range of 10 mN·m - 100 mN·m.
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