Investigations on the Effect of Tungsten Carbide and Graphite Reinforcements during Spark Erosion Machining of Aluminium Alloy (AA 5052) Hybrid Composite

Abstract

Reinforcements introduced to metal matrix composites are known for their inherent properties like corrosion resistance, wear resistance and machinability. This study deals with the investigation of the effect of adding tungsten carbide (WC) and graphite (Gr) reinforcements in aluminium alloy (AA 5052) hybrid composite material over the spark erosion machining performance. The composite material was fabricated using stir casting process. The tungsten carbide and graphite particles were introduced in various %-wt combinations to aluminium alloy (AA 5052) as per Taguchi robust experimental design and spark erosion machining was carried out on the composite specimens. Discharge current, voltage and discharge time were chosen as the process parameters and their effect on the output performance was measured using material removal rate (MRR) and average surface roughness (Ra). The optimal set of process parameters and the amount of these particulate reinforcements which either directly or indirectly impact the machining performance were predicted by signal-to-noise ratio analysis and the extent of such impact by each constraint were estimated by employing the analysis of variance (ANOVA). The experimental results showed that the effect of adding WC particles improved the MRR which is proportional to the peak current though surface roughness increases when there is a rise in the peak current at the regions where WC particles are concentrated. Also, compared to tungsten carbide, adding graphite as reinforcement influenced the machining of the composite to a greater extent.