EXPERIMENTAL INVESTIGATION ON SURFACE INTEGRITY IN MICRO-END MILLING OF NETWORK STRUCTURED TiBw/TA15 COMPOSITES

TiBw/TA15 composites with network architecture is a new class of metal matrix composites with superior mechanical properties. It has great potential to be applied in the aerospace and automotive fields. However, it is still a challenge to obtain the good surface quality in micro-machining of this kind of composite material. Compared with the micro-end milling experiments of non-reinforced TA15 alloy, this paper investigates the influences of cutting parameters and machining mechanism on the surface integrity in micro-end milling of the network-structured TiBw/TA15 composites, and the variations of cutting force, specific cutting energy, surface roughness and surface topography are analyzed. The results show that both brittle and ductile cutting mechanisms are involved in the machining process. The defects (such as voids, pits, microcracks, protuberance) on the machined surface are mainly distributed in a network-structured pattern. And then the detachment of the deboned or fractured reinforcements from matrix can generate the deep and meteor-like grooves emanating from the network-structured areas. It is suggested that the high spindle speed (not less than 30,000 rpm) and small feed rate (not more than 3 mu m/tooth) can deteriorate the machined surface quality.