Effects due to the misalignment of build-up systems for force measurements in the Meganewton range

Calibration of force transducers in the Meganewton range is typically performed by comparison with reference build-up systems (BUS) under hydraulic presses for high loads. The centring of a BUS is a difficult operation due to its weight and dimension, and possible misalignments and the resulting effects are usually neglected. In this work the effect on force measurements due to a 3 mm misalignment of a 3 MN BUS was evaluated. Measurements were performed at INRiM and at LNE in hydraulic presses. It is shown that the relative measurement errors due to misalignment were lower than the declared CMC uncertainty, thus the shift of the BUS did not influence the measurements.