A new concept for automatic measuring of mass production parts with a profile laser-mounted cobot: CFMM

Every car comprises thousands of parts, is expected to operate reliably for many years, and this reliability depends on the production process. Measuring production is complex and costly; measurement times often exceed part production time. Statistical Process Control (SPC) enables reliability monitoring rather than measuring entire parts, and the fundamental instruments for this method are 3D Coordinate Measuring Machines (CMMs). However, the CMMs’ requirement for a vibration-free floor necessitates that measurements be taken in specialized laboratory conditions, away from the production line. This requirement poses a significant challenge for manufacturers, who often require their own “control fixtures” (CFs) for their production lines. However, these CFs, custom-built for each mass-produced part, can be complex and relatively expensive. This article introduces operator-assisted automated part measurement near the production line using a cobot-mounted profile laser and simplified CFs fixtures. The system automatically performs measurement and data collection after the operator simply loads/unloads the part and scans the QR code. The proposed system, a hybrid of a CMM and a control fixture, is termed the Control Fixture Measuring Machine (CFMM). In this research article, the basic working principles of CFMM are explained, and as a “Gage,” its reliability and repeatability are evaluated through a Type 1 Gage Study. During the experiments, the prototype is placed near a machine tool. The results show that the measurements obtained with this new concept of checking control points on a simplified control fixture with a profile laser are satisfactory under shop floor conditions, aided by a simple Kalman filter.