Issues Associated With MQL Implementation: Effect on Peripheral Milling Process Performance and Impact on Machining Economics

Abstract

The copious use of metal working fluids in machining applications carries with it worker health, environmental, and cost concerns. Driven by these concerns, minimum quantity lubrication (MQL) technology has been proposed as an intermediate alternative between flood and dry machining applications. However, widespread use of MQL is inhibited by worries related to unknown costs, thermal distortions, chip flushing problems, flammability of airborne metal dust, and system reliability/repeatability. More information is needed on the effects of lubricant flow rate and droplet characteristics on the cutting performance. One challenge associated with implementing MQL technology has been the difficulty in reconfiguring dedicated transfer line systems. To address some of the above issues, tests have been conducted to investigate the effects of lubricant flow rate and droplet characteristics on cutting performance in terms of cutting force, workpiece temperature, surface finish, and air quality. Comparisons are made among dry, MQL, and fluid flood applications to show that MQL and flood application provide similar benefit in terms of work temperature. Machining cost analysis for both multistage and single-stage operations provides insight into the relative difference between transfer line and FMS machining systems in terms of costs for different fluid applications.