Accuracy and Profile Analysis of Cylindricity Measurement Methods Using Coordinate Measuring Machines

This study investigates the evaluation of cylindricity in precision components using coordinate measuring machines (CMMs), which are increasingly adopted as alternatives to conventional roundness testers. Although roundness testers provide reliable measurements, their applicability is constrained by part size, geometry, and weight. CMM-based cylindricity methods are often selected arbitrarily in industrial practice, which causes variations in measurement characteristics and results. To address this, three CMM-based methods, namely, cross-section, generatrix, and helix, were applied. Their accuracy was evaluated with reference to mechanisms recommended in KS and ISO standards, which consider instrument structure and principles to minimize error, whereas their precision was assessed based on Type A uncertainty derived from repeated measurements, focusing on statistical dispersion. The results indicated that cylindricity values varied between axial (generatrix) and circumferential (cross-section, helix) directions. Profile analysis further revealed subtle distortions associated with machining and clamping, which enables workpiece deformation prediction and suggests directions for process improvement. This study provides experimental data on method-dependent differences in CMM-based cylindricity evaluation, thereby offering practical guidance for industrial applications and supporting more reliable quality assessment.