Effect of Burr Height in Drilling Low Carbon Steels for Different Drill Point Angles

Abstract

In the present work low carbon steel have been used to observe the burr height at the exit end of the workpiece of a drilled hole under different machining conditions. Three uncoated 12 mm diameter HSS twist drills are used. These drills have different drill point angles, i.e., 118°, 100°, 80°. All the experiments are carried out on a CNC milling machine with and without the application of coolant. Cutting speed and feed are chosen within the range of 20–31 m/min and 0.032–0.08 mm/rev respectively. Ranges of cutting speed and feed are selected considering usual industrial practice for drilling mild steel with HSS drill bit. The result from these set of experiment reveal that the increase in cutting speed increases the burr height at given feed rates in both the cases of drilling without coolant and with coolant. An increase in feed rate generated less burr height values at a given cutting speed. It was observed that the drill bit having a point angle of 118° produced the least burr for the drilling with and without the use of coolant. The validation of the experiment results is done using ANN. The neural network algorithm with the three layers is applied to model the experimental burr height for the drill point angle The ANN values matched very well the experimental results.