Continuous chip formation in drilling

The formation of coil continous chips in drilling often leads to chip disposal problems. This paper investigates the drill chip formation process of continuous chips (spiral chips and string chips). Chip removing motions and forces are analyzed. Two models are developed to predict the spiral and string chip formation, respectively. Based on the level of bending due to the chip generation at the cutting edge and deflection by the flute, these models qualitatively investigate relationship of the point angle and flute helix angle on the average chip length. Drilling experiments validate the chip length for spiral and string chip predicted by both models.