The Impact of Plain Waterjet Machining on the Surface Integrity of Aluminium 7475

Embedding of grit during abrasive waterjet (AWJ) is known to have an adverse effect on component fatigue life. To address this issue Plain Waterjet (PWJ) Machining, which does not make use of any abrasive material may be used as an alternative process. This paper presents an analysis of the impact of PWJ Machining on the surface integrity of Aluminium 7475 parts. Plates of Aluminium 7475 are subjected to PWJ surface machining. A range of machining parameters is considered, including traverse speed, stand-off distance, jet pressure, and number of passes. These plates are then subject to surface analysis to measure surface texture and residual stress, prior to fatigue life testing. This analysis allows conclusions to be drawn with regard to optimal machining conditions for fatigue life improvement. It is shown that waterjet induces compressive residual stress that benefits fatigue life.