Investigation of Waterjet Phases on Material Removal Characteristics

Abstract

Abrasive waterjet (AWJ) controlled depth machining, often referred to as abrasive waterjet milling, has proven to be one of the most flexible non-conventional production techniques for difficult-to-machine materials. However, the prediction of process results is challenging since existing process models are limited and the jet tool consists of fluid-, solid- and gas-phases i.e. multiple physical processes occurring simultaneously. In this paper, the influence of the distinguished phases of waterjet machining on the material removal characteristics was investigated. In accordance with mechanical properties of the work piece, the process interference was considered at different structural modifications of 42CrMo4 steel, prior to processing and afterwards. With the help of different waterjet systems, the physical phenomena of the respective phases and their machining results were analyzed. Subsequently, a two-phase suspension jet containing water and solids and industry-standard 3-phase injector jet containing water, air and abrasives were used to machine a kerf pattern. Finally, a two-phase injection waterjet of sucking air without solids was used for post processing. A comparison was made by the geometrical features of the machining results. The applied understanding of the waterjet erosion process can lead to a better prediction and optimized waterjet results. Furthermore, the consequences may complete process models for simulation and support future applications of waterjet machining technique.