Laser-Assisted Machining of a Fiber Reinforced Metal Matrix Composite

Metal matrix composites due to their excellent properties of high specific strength, fracture resistance and corrosion resistance are highly sought after over their non-ferrous alloys, but these materials also present difficulty in machining. Excessive tool wear and high tooling costs of diamond tools makes the cost associated with machining of these composites very high. This paper is concerned with machining of high volume fraction long-fiber MMC’s, which has seldom been studied. The composite material considered for this study is an Al-2%Cu aluminum matrix composite reinforced with 62% by volume fraction alumina fibers (Al-2%Cu/Al₂O₃). Laser-machining is utilized to improve the tool life and the material removal rate while minimizing the sub-surface damage. The effectiveness of the laser-assisted machining process is studied by measuring the cutting forces, specific cutting energy, surface roughness, sub-surface damage and tool wear under various material removal temperatures. A multi-phase finite element model is developed in ABAQUS/Standard to identify and assist in selection of cutting parameters such as; tool rake angle, cutting speed and material removal temperature. The multi-phase model is also successful in predicting the damage depth on machining. The optimum material removal temperature is established as 300°C at a cutting speed of 30 m/min. LAM provides a 65% reduction in the surface roughness, specific cutting energy, the tool wear rate and minimum sub-surface damage over conventional machining using the same cutting conditions.