Wear characteristic on BAM coated carbide tool in drilling of composite/titanium stack

Abstract

This paper studied characteristics on a BAM coated carbide, which comes from a ceramic alloy of boron, aluminum, magnesium, etc., in drilling of CFRP and titanium (Ti) stacks. A series of drilling test was performed starting from drilling of CFRP (top) to Ti (bottom) in the stacks using uncoated tungsten carbide (WC) and BAM coated WC. The BAM coating, which is known for one of the hardest and slipperiest materials. In this regard, BAM coating can be used for cutting tool by reducing the adhesion of work material and interfacial friction. Tool surfaces were periodically measured during the drilling tests using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and confocal laser scanning microscope (CLSM) in order to analyze the tool wear evolution and metallurgical changes on the tool surface. From the experiment, it was observed that no major wear occurred on rake surface and center of the tool while flank wear was significant. The wear mechanisms on flank surface were abrasion and titanium adhesion. The abrasion wear took place by the hard carbon fibers in CFRP and the hard inclusions in titanium. On the other hand, the adhesive wear occurred by pulling out the carbide grains when the adhered titanium layers detached from the tool surface. BAM coated carbide tool showed substantially reduced Ti adhesion especially at high cutting speed. In addition, the lower flank wear was observed for BAM coated tool compared with for uncoated carbide tool.