Closed Loop Dimensional Error Correction for 5 Axis Flexible Part Milling

Abstract

Because of deflection due to cutting forces, the surface of machined thin, flexible parts will be dimensionally incorrect. Although offline simulation can be used to predict a corrected tool path, significant data must be collected in advance to calibrate the process model. This paper presents a self-calibrating, closed loop correction strategy. The initial, climb milling pass is executed assuming no tool or part deflection. An inspection touch probe is then used to measure the dimensional errors. The process model is then used to calculate a second, 5 axis corrective pass. For subsequent parts, parameters are incrementally adjusted with the goal of achieving in tolerance dimensional errors after one pass. An RS232 serial connection between the machine tool controller and the process model microcomputer allows the system to run without operator intervention.