Non-traditional machining using pulsed water jets

Abstract

This paper discusses water jet machining of selected materials using a non-traditional way of delivering water jets in the form of a series of discrete pulses. The theory of water jet impact has been used to demonstrate the principle of removing material by exploiting the existence of a Rayleigh wave that excites the formation of surface cracks and the lateral outflow of water that extends the cracks and removes material. A mathematical model has been developed that predicts changes in the response characteristics of materials owing to an idealised representation of a finite jet of water impacting a plane surface. The analytical approach used is applicable to the first stages of impact where the compressibility of water in the droplet is significant. The predicted response characteristics are compared with experimental data generated using controlled water jet impacts produced by a specially constructed pulsed water jet machining centre. The predicted response of selected materials compare well with experimental data. The results presented in this paper illustrate the importance of using pulsed water jets as a way of machining materials in a non-traditional manner.