Uncertainty evaluation of an optical system for on-machine measurement of microcomponents in a micromachining environment

Conventional inspection methods often fall short when applied to microcomponents, particularly in high-precision manufacturing environments. This study presents the characterization of an optical on-machine measurement (OMM) system integrated into a micromilling center, with a focus on evaluating its calibration uncertainty following the guidelines of the Guide to the Expression of Uncertainty in Measurement (GUM). The system employs a CMOS camera paired with two coaxial telecentric lenses, one using white light, the other green, to assess the impact of illumination type on measurements. Uncertainty was quantified for two cylindrical samples (1.4 mm and 0.5 mm diameters) using Taubin’s algorithm for circular fitting. Results reveal that exposure time significantly affects measurement reliability. Moreover, measurement uncertainty increases with sample size at a fixed exposure time, likely due to operator-dependent alignment and illumination settings. Importantly, the system showed higher precision for smaller features, making it well-suited for micromachining applications. This manuscript presents a systematic methodology for assessing measurement uncertainty in optical systems integrated within machining setups, highlighting their suitability for applications in the micromachining domain.