Methodology for prediction of distortion of workpieces manufactured by high speed machining based on an accurate through-the-thickness residual stress determination

Abstract

After high-speed machining of rolled and stretch straightened aluminium sheets, out-of-plane distortion is found. This is especially true for complex machined shapes in thin-gauge and high-strength aluminium alloys. This kind of sheets are mostly found in the aeronautical industry, where thin-weight-optimised aluminium shell designs are used for skin applications. Usually, in the aeronautical sector, low-thickness sections are used wherever possible, and higher thicknesses are used only where additional strength is required. In the present work, a methodology of predicting workpiece distortion based on the residual stress present in the workpiece is presented, which can be applied by machining companies without further investment in measurement equipment. A method for accurately determining through-the-thickness residual stresses was adapted to the special requirements of this industrial sector. The measured residual stresses were used in a finite element model capable of approximately calculating the shape distortion of simple and complex high-speed machined parts. Promising results have been obtained.