プレス部品板厚測定器の機能性評価

抄録

Functiona evaluation for transactions was applied to choose a plate thickness gauge to be introduced into an automotive production process. The plate thickness gauge is a type of measuring machine used to periodically measure the plate thickness of pressed parts during the manufacture of vehicle bodies. When the plate thickness is found to be out of tolerance, the press conditions are controlled to prevent cracks and other defects caused by plate thickness variations before they occur. A simple ultrasonic gauge was being used to measure plate thickness, but an optical gauge based on a new measurement principle had been developed and was available for application to the body pressing process. The merits of the two types of gauges were compared from the viewpoint of the buyer. First, a measurement S/N ratio was obtained from the relationship between items measured and measurement results, and the cost of measurement errors was obtained from a loss function. A gauge was then chosen from a total cost comparison including loss cost, purchase cost, measurement cost, and rework cost. This clear breakdown of the total cost of each gauge led to the establishment of rational criteria for product selection.