OPTIMIZING THE MACHINING PARAMETERS FOR SURFACE ROUGHNESS IN CNC TURNING OF HYBRID METAL MATRIX (Al-RHAGSA) COMPOSITES

Abstract

In manufacturing industries, for determining the quality, surface finish of a product is very important. This study focuses on analyzing cutting parameters based on Taguchi method, a powerful tool to design optimization for quality, is used to minimize surface roughness. Taguchi method of design of experiments, the signal-to-noise (S:N) ratio, analysis of variance (ANOVA) and regression analysis are employed to investigate the cutting characteristics of three different metal matrix composites in varying proportion of reinforcements i.e. MMC (Al 7075-2%RHA2%GSA), MMC (Al7075-3.5%RHA-3.5%GSA) and MMC (Al7075-5%RHA-5%GSA) using carbide cutting tools. Different cutting parameters have different influence on the surface finish. The cutting speed, feed and depth of cut are considered using the suitable range recommended; which were 50.57m/min, 72.25m/min and 93.93m/min for cutting speed, 0.10mm/rev, 0.14mm/rev and 0.18mm/rev for feed and lastly 0.20mm, 0.35mm and 0.5mm for depth of cut. The specimen was turned under different level of parameters and was measured the surface roughness using a Taylor Hobson’s Surtronic 3+. According to the ANOVA analysis, feed is the dominant factor by 55.073% for MMC (Al7075-2%RHA-2%GSA) and depth of cut is the dominant factor by 28.056% for MMC (Al7075-3.5%RHA-3.5%GSA) and feed is the dominant factor by 55.073 for MMC (Al7075-5%RHA-5%GSA). The optimum cutting parameters which produce minimum surface roughness for MMC (Al7075-2%RHA-2%GSA) are 50.57m/min, 0.10mm/rev and 0.20mm. The optimum cutting parameters which produce minimum surface roughness for MMC (Al7075-3.5%RHA-3.5%GSA) are 93.93m/min, 0.10mm/rev and 0.50mm. The optimum cutting parameters which produce minimum surface roughness for MMC (Al7075-5%RHA-5%GSA) are 50.57m/min, 0.18mm/rev and 0.50mm. From tensile test it is concluded that in MMC (Al7075RHA-GSA), as the percentage of reinforcement increases up to certain value tensile strength decreases after this increase in reinforcement will improve tensile strength. From hardness test it is concluded that metal matrix composites (Al-RHA-GSA) have higher hardness value than pure Al 7075 alloy and as the percentage of reinforcement increases, hardness value also increases.