Factors influencing the performance of a roundness measuring instrument - Development of an empirical model

Roundness/Circularity is commonly measured using dedicated Roundness Measuring Instruments. In this study, an attempt has been made to quantify the effect of potential factors causing measurement uncertainty in such instruments. Number of sampling points, method of initial setup, rotary table speed, diameter and form error of the specimen selected for measurement are the factors which have been studied. The specimen chosen for the measurement was the poppet valve for four stroke internal combustion engines. A designed experiment was carried out and an empirical model to predict the measurement uncertainty arrived at.