Comparative analyses of multi-pass face-turning of a titanium alloy under various cryogenic cooling and micro-lubrication conditions (original) (raw)

2018, International Journal of Lightweight Materials and Manufacture

Titanium alloys, despite their high strength-to-weight ratio, are considered as difficult-to-machine materials. Their poor machinability is attributed, among other reasons, to the accumulation of intense heat near the cutting edge that leads to brisk tool damage. The tool damage, in turn, causes deterioration of work surface quality, consumption of more energy and hike in machining forces. The paper focuses on application of innovative lubro-cooling approaches and variation in cutting parameters with a fixed material removal rate for the sake of impeding tool damage and improving associated performance measures. Two cryogenic coolants (liquid nitrogen and carbon dioxide snow), minimum quantity of lubrication (micro-lubrication) and hybridization of the two were tested for effective dissipation of heat in face-turning of a commonly used titanium alloy. Additionally, the effects of removing a given volume of the alloy in one and two cutting passes (with a fixed material removal rate) on tool wear, work surface roughness, cutting energy consumption and machining forces were also experimentally investigated. The double-pass approach was found to have performed better regarding surface roughness, cutting energy and machining forces. Hybrid application of liquid nitrogen and microlubrication, carbon dioxide snow, and hybrid application of snow and micro-lubrication yielded the best results regarding tool wear, cutting energy consumption, and work surface roughness, respectively. The solitary application of micro-lubrication yielded significant reduction in the cutting force component.