The Difficulty of Measuring Low Friction: Uncertainty Analysis for Friction Coefficient Measurements

Abstract

The experimental evaluation of friction coefficient is a common laboratory procedure; however, the corresponding measurement uncertainty is not widely discussed. This manuscript examines the experimental uncertainty associated with friction measurements by following the guidelines prescribed in international standards. The uncertainty contributors identified in this analysis include load cell calibration, load cell voltage measurement, and instrument geometry. A series of 20 tests, carried out under nominally identical conditions, was performed using a reciprocating pin-on-disk tribometer. A comparison between the experimental standard deviation and uncertainty analysis results is provided.