Machining distortion in asymmetrical residual stress profiles

This paper presents the results from a set of experimental and computational studies of the effect of asymmetrical residual stress on machining distortion of Al-7050 alloy. Aluminum coupons were physically bolted together for heat treatment to generate the asymmetrical residual stress profiles; which were measured using neutron diffraction method in the bulk of the samples after the heat treatment stage, and after the first machining stage to investigate the residual stress redistribution. A machining distortion model was successfully implemented to investigate comprehensibly the impact of the layer material removal in terms of depths of cut on the redistribution of the residual stress profile into the part, and how this redistribution influences the distortions in the coupon. This investigation allowed determining a robust machining approach capable of predicting the final desired distortion tolerance after clamping, irrespective of the highly asymmetric residual stress condition of the coupon. On machine inspection and CMM measurements were also done to validate the outcomes of the machining distortion model.