The effect of cutting fluid chemistry during aluminium cutting using limited volume lubrication

摘要

Limited volume lubrication (LVL) is a technique that can be applied to metal-working operationsrnwith benefits ranging from direct savings in volumes of cutting fluid used, to improved hygienernin the workplace, reducing the occurrence of skin ailments that result from skin contaminationrnby the lubricant. In addition, no recycling and cleaning of used lubricant is necessary as most ofrnthe applied lubricant evaporates from the chips that are produced during the metal-workingrnprocess. Since the chips are basically dry, chip recovery is much easier. Disposal of used cuttingrnfluid is also not an issue, since there is none. The cutting fluid is used once and has little chancernof prolonged exposure to the atmosphere; thus the chances of bacterial growth in the cutting fluidrnare considerably reduced. The probability that unwanted work-piece stains will occur is alsornreduced by the use of limited volumes of cutting fluids. Several studies have been publishedrnindicating that the quality of cuts obtained when using LVL, are often as good, or better, thanrnthose obtained with flood lubrication.rnIn this study, a shaper, a tungsten carbide tool and a LVL applicator that applied a jet of mist ofrncutting fluid were used for the machining of T6 6082 aluminium. Samples of cutting fluids thatrnwere tested included esters, alkanes, a poly-isobutylene, carbon tetrachloride (CCl_4) and dryrncutting - the latter two for reference purposes.rnThe results obtained were used to establish a performance methodology to rank lubricants usedrnfor cutting operations. It was possible to distinguish between the effects that various cutting fluidrnchemistries had on the cutting process. Each fluid used generally provided consistent andrnnoticeably unique effects on the cutting process. This was useful in quantifying the effect that arnchange in chemistry of the lubricant produced. The tests have potential to be extended so as tornevaluate the effect of different additives to the cutting fluid. It was observed that some of therncutting fluids have better ability to penetrate the surface layer of atoms of the work-piece,rnthereby enhancing the ductility of the aluminium to form a chip. This ability is thought to bernrelated to electronegativity, polarity, molecular geometry and molecular size of the lubricantrnconstutuents. This information should be of significant value when cutting fluids are developedrnfor specific applications, including the effect of cutting fluid on tool life, tool costs andrnminimisation of down-time during cutting operations as well as decreasing secondary machiningrntime, like polishing to attain a desired surface finish, or to remove stains.