EVALUATION AND OPTIMISATION OF SURFACE ROUGHNESS AND TOOL WEAR IN TURNING AISI 304 ALLOY STEEL USING FORMULATED CUTTING FLUIDS

Abstract

Cutting fluids play a major role in machining operations. They have shown to be instrumental to achieving better machining performance–minimal tool wear, minimal surface roughness and better machining finished product. These characteristics can be attributed to their ability to act as coolant, lubricant and flush away chip formation. The recent trend in the development of cutting fluids is tending towards use of non-edible vegetable based-oil which could be seen as satisfying requirement imposed by health, safety and environmental pollutions and food scarcity. In this work, the development, characterisation and machining parameter optimisation of two non edible oil base cutting fluid is reported. The non-edible oil extracted from Jatropha and Neem seed –here in referred to as Jatropha seed oil (JSO) and Neem seed oil (NSO) were extracted through cold press process. The characterisation of JSO and NSO showed a viscosity values of 21.30 and 25.10 respectively; pour point values of 260 and 238, and specific gravity of 0.907 and 0.919. In addition, the analysis of Fatty Acid Composition (FAC) of JSO showed a composition approximately 21.6% with Palmitic acid (14.2%) as constituent, while NSO showed composition of 37.0% constituted by palmitic acid (18.0%) and stearic acids (18.0%). The characterisation of Jatropha oil-based cutting fluid (JBCF) and Neem oil-based cutting fluid (NBCF) (hereafter referred to as vegetable cutting fluids) were conducted to establish the physicochemical properties and FAC. JBCF and NBCF showed pH value of 8.36 and 8.67 respectively and viscosity value of 0.52 mm2 /s and 0.50 mm2 /s. The anticorrosion test (which was based on iron filling method) as well as stability test showed good resistance to corrosion and good stability respectively. The performance of the JBCF and NBCF on turning of AISI304 alloy steel using tungsten carbide cutting tool was further evaluated and optimised using Grey Relational Analysis (GRA). The S/N result showed that an optimal surface roughness of 0.740µm were reached at cutting speed of 1250 m/min (level 5), feed rate of 1.15 mm/rev (level 5), depth of cut of 0.65mm (level 3) for JBCF, and at cutting speed of 1000 m/min l4, feed rate of 0.52 mm/rev (level 1), and depth of cut of 0.1mm (level 1) for NBCF. Similarly, the optimum tool wear of 0.800mm was reached at cutting speed of 500 m/min (level 1), feed rate of 1.15 mm/rev (level 5), depth of cut of 0.65mm (level 3) for the JBCF, and at cutting speed of 630 m/min (level 2), feed rate of 1.0 mm/rev (level 4), depth of cut of 0.10 mm (level 1) for the NBCF. Based on the ANOVA, the cutting speed and depth of cut had significant contribution of 62.73% and 37.26% respectively on the surface roughness and 70.83% and 40.41% respectively on tool wear under both JBCF and NBCF. The experimental result s show NBCF compare favourably to JBCF and MBCF, however, JBCF exhibit minimal surface roughness, minimal tool wear and overall better performance when compared to NBCF and MBCF.