Tool life and wear mechanisms in laser assisted milling Ti-6Al-4V

Thermally assisted machining processes are gaining popularity among researchers and engineers as a method for improving the machinability of difficult-to-cut materials such as titanium. The process of artificially introducing heat to the cutting zone is reported to have many benefits; however, it remains unclear whether the process offers any tool life improvements during milling Ti-6Al-4V when compared to conventional milling processes. This paper compares the tool life during laser assisted milling, dry milling, milling with flood emulsion, milling with minimum quantity lubrication (MQL) and a hybrid laser+MQL process. It is found that conventional coolants offer superior tool life at the standard cutting speeds recommended by the tooling manufacturer, but at higher speeds the coolant deteriorates tool life due to thermal shock/fatigue. Despite this, laser assisted machining performed poorly and exacerbated thermally related tool wear mechanisms such as adhesion, diffusion and attrition. Hybrid laser+MQL substantially improved tool life by suppressing the thermal wear processes while also preventing thermal fatigue on the cutting tool. (C) 2014 Elsevier B.V. All rights reserved.