I. Introduction
Water Jet and abrasive water jet (WJ/AWJ) technology presents some particular characteristics that make it suitable in application fields where particular manufacturing operations on special material are required; machining activities such as cutting hard to machine materials (e.g., steels, titanium alloys, aluminum alloys, brittle materials) or carrying out operations such as turning and milling as well as surface treatments such as peening, cleaning, decoating, and descaling represent some of the possible applications of WJ/AWJ technology.