INVESTIGATION AND OPTIMIZATION OF PROCESS PARAMETER FOR DRILLING MILD STEEL, STAINLESS STEEL AND BRASS FOR PREDICTING SURFACE ROUGHNESS

Abstract

The research study investigated and optimized the process parameters for drilling mild steel, stainless steel and brass for predicting surface roughness. The workpiece are of the same dimension measuring 200 mm by 80 mm. The process parameter with their values considered in the research were speed (1400 rpm, 1500 rpm, 1700 rpm), feed (0.11 mm/rev, 0.18 mm/rev, 0.75 mm/rev), depth of cut (0.25 mm, 0.50 mm, 0.75 mm) and drill bit diameter (6mm, 8mm, 10mm). The relationship between the process parameters and surface roughness was determined through the Response Surface Methodology (RSM), using linear regression model which revealed a high significant effect compared to linear square regression model, linear interaction regression model and quadratic regression model. Vertical pillar drilling machine (METALIK PK203 model) and ultrasonic thickness meter (TM-8810 model) were also used for drilling and measuring of surface roughness on the drilled workpiece. The findings revealed that the process parameters has a high significant effect in influencing the response variable at 5% significant level for mild steel, stainless steel and brass except for feed and depth of cut. Tool has no significant effect in influencing stainless steel and brass on 5% significant level. Optimum process parameters was achieved for surface roughness of mild steel, stainless steel and brass at a cutting speed of 1500 rpm, feed of 0.35 mm/rev, depth of cut of 0.5 mm and drill bit of 10mm. The response surface analysis also revealed that there exist a good agreement between the estimated and experimental results based on the analysis of variance