Investigation of adsorption behaviour of lubricants in near-dry machining

Abstract

Near-dry machining (NDM) is a technology with many ecological and economic benefits that uses very small amounts of metal working fluid (MWF). In order to increase the applications of this technology, the tribological mechanism during this process needs to be better understood. To accomplish this, two experimental set-ups were configured. The first involved a vacuum chamber where changes of gas near the cutting area can be traced by a mass spectrometer. The second has an atmospheric chamber where practical cutting can be done for cutting-performance comparison. Three gases - argon, nitrogen, and oxygen - were used with and without an ester in a series of orthogonal cutting tests to understand their roles in lubrication. It was found that oxygen adsorbs best onto a newly generated work surface and plays a significant role in promoting adsorption of the ester and, in turn, creating a lubrication film. Therefore, it is important to supply an abundant amount of oxygen in NDM to provide good lubrication conditions.