Review on machining process optimization for metallic aerospace parts affected by distortions induced by residual stresses

Metallic alloys are widely used in the aerospace industry; however, residual stresses (RS) present a significant challenge, particularly in monolithic components. These stresses can lead to significant distortions, increasing manufacturing costs and material waste. For instance, a 2001 Boeing report attributed $290 million in rework and scrap costs to RS-induced distortions across four aircraft types. This paper reviewed various approaches from the literature proposed to account for these deformations and optimize the machining process. The review covered the state-of-the-art in so-called offline and online methods used to mitigate RS-induced distortions, which were further classified into 9 categories. The analysis found that while current strategies, such as stress relief, machining offset, and sequence optimization, showed promising results, they often fell short when applied to complex geometries or materials like titanium alloys, with most research focusing on simple aluminum test cases. It was concluded that significant potential exists in developing hybrid offline-online methods, advanced in-situ monitoring, and adaptive machining strategies to address these persistent gaps.