Tool wear and surface roughness characterization during turning of Co-Cr-Mo alloy ASTM F75 with coated carbide tools

The cobalt chromium molybdenum (Co-Cr-Mo) alloy is widely used in biomedical applications such as implants and prostheses. However, due to its inherent properties, machining this alloy is challenging. This study aims to analyze the effects of cutting parameters on tool wear and surface roughness during turning. A complete factorial experimental design was conducted with two factors, levels, and replicas, in which the cutting speed varied from 60 to 90 m.min and the feed rate from 0.08 to 0.13 mm.rev. Tool wear was quantified using scanning electron microscopy (SEM) and confocal microscopy, while surface roughness was assessed using confocal microscopy. The results revealed the presence of crater and flank wear, with crater wear being predominant. The decrease in tool coating was found to have the most significant impact on the development of crater wear when adjusting feed rates. Additionally, changes in cutting parameters were shown to have a noteworthy effect on both the cutting tool’s wear and the workpiece surface’s roughness. Extreme cutting parameters resulted in significant differences in peak and valley heights on the turned workpiece surface, impacting the average roughness. Energy dispersion spectroscopy (EDXA) analysis identified the chemical elements on the worn tool and workpiece surfaces, revealing that the primary mechanism causing tool wear is workpiece material adhesion to the insert rake surface. Additionally, embedded carbides on the machined surface suggested abrasive action during cutting.