Abstract
The role of cutting fluids in metal cutting processes is fundamental to achieving high performance machining. However, the use of conventional cutting fluids necessitates post-machining cleaning, typically involving hazardous organic solvents, which pose significant risks to both human health and the environment. Our recent findings have highlighted the potential of alcohol as a viable alternative in the cutting of aluminum alloys. When alcohol is introduced at the cutting point during aluminum alloy machining, it undergoes a reaction with the freshly exposed aluminum surface, resulting in the formation of an “alkoxide” reaction product. This alkoxide exhibits exceptional lubricating properties, effectively reducing cutting force and improving the surface finish quality. Given the high volatility of alcohol, its application as a lubricant in aluminum alloy cutting could eliminate the necessity for post-machining cleaning processes. In this study, two-dimensional cutting experiments were conducted on an AL7075 alloy using isopropyl alcohol (IPA) to assess the potential of alcohol as a lubricant in aluminum alloy cutting. The results from the cutting experiments presented the evidence that the supply of IPA effectively reduced cutting force by approximately 50%, surpassing the performance of conventional oil-based cutting fluids in certain cutting conditions. Employing high-speed in-situ imaging and particle image velocimetry (PIV) provided critical insights, revealing that dry machining without any use of lubricants in cutting of AL7075 led to the cyclic formation and removal of a built-up edge due to severe friction between the tool-chips interface. In contrast, the supply of IPA facilitated the chip flow along the tool rake face, resulting in the formation of a continuous, laminar-type chip flow. These findings clearly illustrate the significant enhancement in the tool-chip lubrication condition enabled by the application of IPA. Moreover, the effects induced by IPA supply were not observed in the cutting of Cu, indicating that the improvement in cutting performance due to IPA is not caused by the lubricating effect of IPA itself, but rather by the formation of alkoxide. Additionally, the cutting experiments with different types of alcohols were also performed to investigate the relationship between their physical properties and their impact on cutting performance. The results indicated that alcohols with lower viscosity and a higher ability to penetrate the tool-chip interface exhibited superior cutting performance. These results unequivocally support the assertion that alcohols possess substantial potential as effective lubricants for achieving high-performance cutting in aluminum alloys. This breakthrough could significantly mitigate the environmental and health hazards associated with conventional cutting fluids, offering a promising, sustainable alternative in metal machining practices.
