Water-jet guided laser drilling of SiC reinforced aluminium metal matrix composites

Laser drilling of monolithic materials like metals and alloys is a well-established process and used extensively in a wide range of applications in many sectors including aerospace, medical and automotive. However, conventional laser drilling of materials like metal matrix composites is challenging due to the differences in the chemical and physical properties of the hard ceramic reinforcement particles and the soft-metal matrix. The water-jet guided laser process has the potential to machine advanced materials such as an aluminium metal matrix composite reinforced with silicon carbide particles (Al MMC), with exceptional quality. The main objective of this research is to understand the material removal mechanism associated with water-jet guided laser drilling of Al MMCs and compare this with conventional laser drilling of Al MMC. Experimental results showed that the water-jet guided laser process is an excellent technique for drilling holes in composite materials like metal matrix composites. During water-jet guided laser drilling of Al MMC, the material has been removed by cold ablation, without leaving any residual melt layer within the bulk material. Both soft-matrix and hard-particles are removed by the same process of cold ablation, which is completely different to the conventional laser drilling process in which the solid SiC are ejected without melting, along with the molten aluminium.