Accuracy enhancement of a horizontal machining center by real-time error compensation

A real-time error compensation system was developed to improve the geometric-thermal volumetric accuracy of a T-16 machining center by using sensing, metrology, modeling, and computer control techniques. Including thermal errors, 32 error components are formulated asa four-dimensional error field in the time-space domain. Fifteen thermal sensors are used to characterize the temperature field of the machine. A compensation controller based on the IBM/PC has been linked with an Acramatic-950 CNC controller to compensate for machine errors in real time. The maximum linear displacement error in four body diagonals was reduced from 140 mu m to 34.5 mu m with this compensation system, and the spindle thermal drift in space was reduced from 147.3 mu m to 16.8 mu m.