An experimental investigation on the effects of combined application of ultrasonic assisted milling (UAM) and minimum quantity lubrication (MQL) on cutting forces and surface roughness of Ti-6AL-4V

Ti-6Al-4V is widely used in aerospace, medical and defense industries where materials with superior characteristics are needed. However, Ti-6Al-4V is categorized as a difficult-to-cut material, and machining of this alloy is highly challenging. Ultrasonic Assisted Milling (UAM) is a quite recent method to facilitate the machining of difficult-to-cut materials. This method has numerous advantages over the Conventional Milling (CM) method, such as reduced cutting forces and increased surface quality. Besides, Minimum Quantity Lubrication (MQL) is an alternative cooling method to enhance the process efficiency with respect to conventional cooling methods. Cutting force and surface roughness are essential measures to evaluate the cutting performance of a machining process. However, the simultaneous effects of implementing MQL and ultrasonic vibrations in milling operations are not much researched yet. In this study, the combined effects of UAM and MQL on cutting forces and surface roughness during the machining of Ti-6AL-4V are investigated. Results show that the combination of MQL and UAM enhances the cutting forces in rough cutting operations and the surface roughness in both finish and rough cutting operations significantly compared to conventional processes. Consequently, it is concluded that simultaneous implementation of UAM and MQL enhances overall cutting performance in end-milling operation of Ti-6Al-4V.