Surface integrity in drilling AA5052 + 3 %MoS2 + 9 %Si3N4 HAMMC and comparing the results with AA5052 + 9 %Si3N4 AMMC - experimental studies and optimization

Abstract

The purpose of this study is to compare the surface roughness (SR) achieved during drilling the fabricated aluminium metal matrix composite (AMMC) considering AA5052 as base matrix and 9 % silicon nitride (Si3N4) ceramic as reinforcing phase with hybrid aluminium metal matrix composite (HAMMC) added with 3 % of solid lubricant MoS2 (AA5052 + 3 %MoS2 + 9 %Si3N4) using carbide drill bit. The novel AMMC and HAMMC are fabricated by the traditional liquid casting technique. For investigation of the drilling process two groups were selected: an experimental group (AA5052 + 3 %MoS2 + 9 %Si3N4) and control group (AA5052 + 9 %Si3N4). Based on the sample size calculator, 20 samples were considered for each group for performance comparison. A CNC vertical machining center was adopted for performing the drilling process with a carbide drill bit without the application of coolant which is termed as green machining. From the outcomes of this research work it is identified that with the inclusion of solid lubricant MoS2, surface roughness is reduced because of friction reduction among workpiece and drill bit. The mean value of SR for the experimental group is 0.806 μm whereas for the control group it is 1.281 μm. During statistical analysis with Independent sample T-test, significance obtained is 0.008 which is below the ideal value of p < 0.05. Hence a significant variance exists among the considered groups. Within the limit of this study it is identified that AA5052 + 3 %MoS2 + 9 %Si3N4 developed superior surface finish during the machining process because of the inclusion of solid lubricant MoS2 against the fabricated AMMC.