A novel comprehensive thermal error modeling method by using the workpiece inspection data from production line for CNC machine tool

The workpiece accuracy has always been a top priority for manufacturers. In mass production, variations in the workpiece accuracy are mainly affected by thermal errors, which cause unacceptable process capability index (Cpk) and often require frequent manual adjustment of cutting tool location when machining errors exceed tolerances. In this work, a novel comprehensive thermal error model is proposed by utilizing the workpiece inspection data and Cpk from production line. The Cpk is employed in the modeling, and Cpk influence analysis is conducted to select the thermal key points (TKPs). Thermal errors predicted using the proposed model are then compensated in real time during machining. The proposed method is proved to be feasible and effective; the produced workpiece in both the verification test and mass production all meet the specification. The workpiece Cpk is improved from 0.56 to 1.35. Manual adjustment of the cutting tool is no longer necessary as a result of thermal error compensation and 100% workpiece inspection can be replaced by sampling inspection. This work contributes to the workpiece quality improvement and the cost savings for the factory.