Force and Torque Measurement Traceability

The term “measurement traceability” is mentioned often in the world of metrology. Certain companies tend to look for a calibration provider with a traceable measurement chain that originates from a National Metrology Institute (NMI). The purpose of this paper is to explain why this approach is misleading at best, and to illustrate that Test Uncertainty Ratios (TUR’s) should instead be calculated using the reference calibration laboratory’s expanded uncertainty for the measurement, divided by the Type A uncertainty component for the unit they calibrated, or the Unit Under Test (UUT).