Investigation of dimensional accuracy and chip formation on through hole drilling of mild steel

Abstract

Drilling process is among the last proses in manufacturing were highly focused in the industry due to huge impact on the final product. Therefore, a method for determining appropriate drilling techniques and parameters for any particular drilling condition is greatly needed. In this study investigated the dimensional accuracy and chip formation on through hole drilling under dry cutting condition using Computer Numerical Control (CNC) when drilling mild steel. Uncoated High Speed Steel (HSS) cutting tool and three different machining speed of 7.54 m/min, 8.48 m/min, 9.42 m/min and constant 0.15 mm/rev feed rate used in this experiment. Dimensional accuracy and chip formation are measured by the achievement of 0.2 mm tool wear onto cutting tool. However, chip formation which focused on new tool and worn tool condition based on speed 9.42 m/min only. The result from this study shows that the dimension on upper part of hole drilled becomes larger and smaller when reaching the bottom meanwhile chip formation on new tool are thicker and shorter rather than chip on worn tool. In conclusion, the dimensional accuracy is increase as the depth of cut decrease and chip formation on new tool gives significantly great chip formation which can easily removes during drilling operation and increase tool life to the cutting speed.