Improving coordinate measuring machine inspection efficiency through inspection-jig redesign: a lean-kaizen action research case study

Coordinate Measuring Machines (CMMs) are widely used in precision manufacturing to verify dimensional accuracy and product conformity. Most studies on CMM efficiency focus on measurement strategy, probe-path optimisation, scanning, orientation, or digital inspection planning. Less attention has been given to the effect of fixture batch capacity on repeated loading and unloading. This study examines whether increasing inspection-jig capacity can reduce that handling requirement using a Lean-Kaizen, Plan-Do-Check-Act (PDCA), and action-research approach. The case study was carried out at a precision manufacturing company in Malaysia. Three jig concepts with capacities of 5, 20, and 49 cavities were assessed for capacity, CMM table fit, part location, probe accessibility, loading practicality, and fabrication feasibility. With the sampling requirement fixed at 216 parts per shift, the required loading/unloading cycles fell from 44 with the five-cavity jig to five with the 49-cavity jig, an 88.6% reduction in required handling cycles. Measurement-system adequacy was supported by prior Gage Repeatability and Reproducibility studies on the same CMM, with Total Gage R&R values of 5.97% and 9.56% of tolerance and 23 and 32 distinct categories for two representative characteristics. A targeted positional study was then conducted using the same reference part, removed and reseated at eight representative fixture locations (four corners, centre, and three intermediate positions) over five repeated rounds, giving 40 measurements. All readings were within the 3.310-3.330 mm drawing limits, and a randomized complete block analysis found no statistically significant fixture-position effect at alpha = 0.05 (F(7,28) = 2.177, p = 0.0676). The positional result applies to the eight tested locations and does not establish equivalence across all 49 cavities. Under an illustrative constant-cycle-time assumption of eight minutes per loading/unloading cycle, handling time would change from 352 to 40 minutes per shift. Because actual cycle duration was not measured after the redesign, this scenario does not establish whether handling time scales linearly or non-linearly with fixture density. The study therefore separates the direct cycle reduction from metrological evidence and scenario-based capacity implications.