Reduction of machining errors of a three-axis machine tool by on-machine measurement and error compensation system

This paper suggests a method to reduce the machining errors of a three-axis machine tool by implementing an on-machine measurement with a touch probe. Probing errors of a touch probe and positioning errors of a machine tool, inevitably included in the measurement data, are compensated for to obtain the true machining errors for the repeated machining process. Positioning errors of a tool/probe tip are modelled by approximating error components as polynomial functions and considering the effects of backlash errors. To estimate the unknown model parameters, a cube array artifact composed of eight cubes is proposed and calibrated on a CMM. Simulation results and verification experiments showed that the measured and predicted positioning errors agree well within less than 10 μm for all axes. The actual cutting test of a simple block and two-dimensional curves showed that the machining errors are reduced to within 10 μm after error compensation.