Case Study 2.1: Detection and Compensation of Workpiece Distortions During Machining of Slender and Thin-Walled Aerospace Parts

Abstract

In machining of thin-walled large parts in aerospace industry, workpiece distortions occur during and after the processes due to residual stresses which are introduced or set free by the material removal process. These distortions lead to an inacceptable shape and geometric errors of the produced components and, thus, to deficient products. Considering that milling operations at large aerospace structural parts take several hours and that often expensive workpiece materials (such as titanium alloys) are used, these critical deformations cause high costs in the manufacturing companies. In some cases, post-treatments such as shot peening is applied in order to reduce the influence of residual stresses. This also means a significant increase of production costs of the parts. With the aim to overcome these challenges of part deformations, in this case study an intelligent fixture was developed which detects the tendency of workpiece distortions within sequenced processing steps and which allows an active adjustment of the clamping conditions in order to compensate for the influences of residual stresses on the final shape of the part.