Surface Roughness Optimization in Drilling Process Using Response Surface Method (RSM)

This paper presents the effect of drilling parameters on surface roughness and surface appearance by applying response surface method (RSM). The mathematical model for correlating the interactions of drilling parameters such as spindle speed, feed rate and drill diameter on surface roughness was developed. RSM methodology was used as it is a technique that most practical and effective way to develop a mathematical model. In addition, this method also can reduce trial and error in experiment. Since the number of factors are three; spindle speed, feed rate and drill diameter, by applying RSM the total numbers of experiment involved are 20 experimental observations. From the experimental result, it is found that the minimum surface roughness on the hole was 1.06 µm from combination of 2000 rpm spindle speed, 78 mm/min feed rate and 2.5 mm drill diameter. While the maximum surface roughness 2.59 µm was the combination of 250 rpm spindle speed, 153 mm/min feed rate and 3.5 mm drill diameter. A mathematical equation was developed with percentage of error are 0% to 29%. Thus, from the result we understand that to find the smooth surface in drilling process, it needs higher spindle speed with lower feed rate and smaller diameter.