Performance Evaluation of Vegetable Oil-Based Cutting Fluids in Mild Steel Machining

Abstract

Vegetable oils are being investigated to serve as a possible replacement for non-biodegradable mineral oils, which are currently being used as base oil in cutting fluids during machining processes. In this present study, the performances of palm oil and groundnut oil were compared with that of mineral oil-based cutting fluid during machining operation of mild steel. Temperature of the workpieces as well as their chip formation rates using these vegetable oils as cutting fluids under different cutting speed (rev/min), feed rate (mm/rev) and depth of cut (mm) were compared with that of mineral oil and dry machining. The average temperatures of the workpieces were obtained at different depths of cut; 5mm, 10mm and 15mm under different cutting conditions. The temperature of the workpiece when groundnut oil was used as the cutting fluid was very close to that of the conventional oil, which was the lowest. Palm oil gave the overall highest chip thickness of 0.27 mm probably due to its better lubricating property. This was followed by that of the groundnut oil and the conventional oil as compared with dry machining of 0.17 mm thickness. Vitamin-C- rich-lemon fruit extract was used as an antioxidant to improve the oxidative stability of the vegetable oils. Viscosities of the various fluids were also analysed, and lowest average viscosity value of 28.0 Poise was obtained using groundnut oil. This shows that groundnut oil possesses better fluidity and faster cooling capacity than other oil samples. Samples lubricated with mineral-oil based fluid show fine microstructures, similar to what obtained using groundnut oil based cutting fluid. Fine surface morphology indicates improved surface roughness compared to using other cutting fluids. Based on these results, groundnut oil and palm oil are being recommended as viable alternative lubricants to the mineral oil during machining of mild steel.

Keywords: Vegetable oils, cutting fluids, drilling operation, mild steel, coolants.