INTEGRATED PLANNING FOR PRECISION MACHINING OF COMPLEX-SURFACES .3. COMPENSATION OF DIMENSIONAL ERRORS

This paper presents an approach that compensates machining errors in b all-end milling processes using the control-surface strategy. In the p roposed approach, machining errors induced by cutter deflections are p redicted from a surface generation model so that actual machining expe riments and dimensional inspections are not required. Therefore, the p roposed approach can be integrated into an integrated framework for ma chining planning in which prediction and compensation of dimensional e rrors take place in the process development phase rather than in the m anufacturing phase of the production cycle. Based on the predictive ca pability of the surface generation model, a sensitivity function is de fined so as to characterize the variations of the machining errors whe n perturbing the control surface. Using the defined sensitivity functi on, a compensated control surface can be constructed, based on which n ew cutting paths can be planned and ''near-zero'' surface dimensional errors can be accomplished. In order to verify the proposed strategy, actual production of a turbine blade die using a CNC machining center was conducted. By using the control-surface strategy with the sensitiv ity function approach, the maximum surface dimensional error is reduce d from +/- 340 to +/- 10 mu m. (C) 1997 Elsevier Science Ltd. All righ ts reserved.