Acoustic emission sensing as a tool for understanding the mechanisms of abrasive water jet drilling of difficult-to-machine materials

For drilling difficult-to-machine materials, abrasive water jet (AWJ) drilling provides several advantages not offered by other machining methods, such as the capability to achieve higher depth-diameter ratios, the absence of a heat-affected zone, and no thermal distortion. An acoustic emission (AE) sensing technique is used to study the material removal mechanisms involved in the AWJ drilling process. The feasibility of using r.m.s. acoustic emission (AE(RMS)) to monitor the AWJ drilling depth on-line is also investigated. Stochastic modelling of the time domain AE signal provides more insight into the physics of the process.