Abrasive Waterjet Profile Cutting of Thick Titanium/Graphite Fiber Metal Laminate

Fiber Metal Laminates (FML) are one of the most advanced engineered materials used in aerospace industry. The combination of metallic sheets interspersed in composite laminates in one hybrid material system provides higher impact and corrosion resistance when compared with their monolithic counterparts. However, due to the difference in machining responses for different material phases, conventional machining often induce damages and defects, affecting the cost and structural performance of the part. This research study investigates the machinability of thermoplastic Titanium Graphite (TiGr) FML. The feasibility and machinability of contouring thick (7.6 mm–10.5 mm) TiGr through Abrasive Waterjet (AWJ) process was studied in terms of machined kerf characteristics — taper ratio and surface quality. The effect of a wide range of process parameters was investigated such as geometric variables (mixing tube aspect ratio and orifice bore size), kinetic variables (water pressure, jet traverse speed) and abrasive load ratio on the machining quality. Predictive mathematical regression models were developed through Analysis of Variance (ANOVA) in order to optimize the process. Alongside, machined surface was examined to inspect the topological characteristics, material removal mechanism, and machining induced damage (micro-defects) and distortion through Surface Profilometry, Scanning electron and optical microscopy. A comparison was drawn between conventional and AWJ trimming of TiGr to demonstrate the superiority and high speed machining of AWJ with less damage.