Error qualification for multi-axis BC-type machine tools

Multi-axis machining processes are often used to fabricate complex components with tight geometric tolerances. Thus, the need for highly accurate 5-axis machine tools is imperative in high precision industries such as aerospace and mold and die. Often, construction errors result in geometric errors within the machine tool. These errors must be identified and compensated in order to guarantee accuracy of the machine. In this work, kinematic equations of motion for a BC-style machine tool were derived while incorporating the 8 distinct kinematic error constants associated with a 5-axis machine tool. A method is presented to derive these kinematic error constants from eccentricity values obtained using 3-axis simultaneous tests for table-table style 5-axis machine tools. To validate this method, error constants were input into the kinematic simulation. Eccentricity values were then output from the simulation and error constants were derived and compared to the input values. It was shown that if the procedure is followed, the error constants can be correctly derived and compensated. This method was then implemented on a BC-style machine tool and error constants were derived.