Investigation of surface roughness and chip formation on peck drilling of mild steel

Abstract

Drilling is one of the fundamental machining processes and most frequently performed in the last step of material removal process. Furthermore, the machining parameter has significant influence to the surface finish and quality of machined part. The aim of this experiment is to study the effect of drilling cutting condition on the surface roughness and chip formation of mild steel. Drilling test at different cutting speed of 7.53, 8.48, and 9.42 m/min and a constant feed rate of 0.15 mm/rev were conducted in order to investigate the effect of the above parameters on the surface roughness and chip formation. The average surface roughness for each hole was measured using a portable surface roughness device (HandySurf) and the chips were measured under Scanning Electron Microscope (SEM). It is observed that high cutting speed (9.42 m/min) generates smoother surface finish but produces lesser hole due to tool wear. The size and shape of chips for new tool is small and completely broken while the worn tool produces long sizes of chips. As a result, the quality of machined surface and chip formation in a product is definitely affected by cutting parameters, such as cutting speed, and feed rate.