Optimization of Coordinate Measurement Machine Performance Through Measuring System Analysis and Full Factorial Design

In the industry, a recurring issue has been identified wherein both machining part manufacturers and customer factories utilize Coordinate Measuring Machines (CMM) for dimensional inspection prior to product delivery and acceptance. The most frequent measurement discrepancy arises in hole size assessment. The root cause was found to be the difference in probe sizes used by the manufacturers and the customer’s CMMs, leading to inconsistencies in measurement results. This discrepancy raised concerns, prompting a research study to investigate the factors influencing hole size measurement accuracy in CMM systems. A Full Factorial Experimental Design and Measurement System Analysis (MSA) employing Gauge Repeatability and Reproducibility (GR&R) testing was performed to identify the primary factors affecting CMM measurement performance. The analysis revealed that all selected factors substantially affected measurement accuracy. The adjusted coefficient of determination (R-sq(adj)) was calculated to be 0.974, indicating a strong correlation between the specified variables and the measurement outcomes. The GR&R result was recorded at 0.76%, indicating it is within a good range and validating the measurement system's acceptability. The ideal measurement settings were determined by experimental design and response optimization as follows: (1) a probe diameter of 4.0 mm, (2) measurement points established at five locations, (3) a square probing trajectory, (4) a measurement depth of 5.0 mm, and (5) a counterclockwise probing orientation. Five repeated measurements were made using the optimal factor levels to support the experimental findings. The results showed an extremely low error rate of 0.0036%, demonstrating exceptional accuracy and dependability. By successfully establishing the enhanced parameters as a standard in CMM measurement processes, industrial applications can benefit from increased measurement accuracy and consistency.