INFLUENCE OF POINT AND HELIX ANGLE ON THRUST FORCE AND DELAMINATION FOR ONE-SHOT DRILLING OF CARBON FIBER REINFORCED PLASTIC (CFRP)
Drilling operation for CFRP parts in the aircraft industry assembly line is unavoidable. Delamination frequently occurs during drilling holes in CFRP and reduces the ability of CFRP parts to carry loads and affects its service life spend. Drill reamer is enhancing the drill bits option for one-shot drilling to save time and cost. This article aims to investigate the influence on the variation of point and helix angle of drill reamer to thrust force and delamination damage. Different drills with the variation of point and helix angle were used to drill unidirectional CFRP laminates panel separately. From the thrust force curve graph, drilling using drill reamer can be divided into three main stages. Point angle geometrical feature influence in stage I while, helix angle in stage III, whereas stage II act as an opener for the drilled hole. Its found that point angle in drill reamer act as pilot drill and helix angle significantly affect to drilled holes quality. Variation of point angle features affected the thrust force measurement for stage I of drilling. The minor right-hand side helix angle reduces the delamination compared to straight flute but negatively affected when major helix angle applied. The suitable combination of drill reamers' geometry features will enhance overall drilling qualities.
 A. Faraz and D. Biermann, “Subsequent drilling on pilot holes in woven carbon fibre reinforced plastic epoxy laminates: The effect of drill chisel edge on delamination,” Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, vol. 225, no. 9, pp. 1493–1504, 2011.
 M. Pirtini and I. Lazoglu, "Forces and Hole Quality in Drilling", Interntaional Journal of Machine Tools and Manufacture, vol. 45, no. 2, pp. 1271-1281, 2005.
 I. S. Shyha, D. K. Aspinwall, S. L. Soo, and S. Bradley, “Drill geometry and operating effects when cutting small diameter holes in CFRP,” International Journal of Machine Tools and Manufacture, vol. 49, no. 12-13, pp. 1008-1014, 2009.
 C. C. Tsao and H. Hocheng, “Parametric study on thrust force of core drill,” Journal of Materials Processing Technology, vol. 192, no. 193, pp. 37–40, 2007.
 Y. Bai, Z. Y. Jia, F. J. Wang, R. Fu, H. B. Guo, D. Cheng and B. Y. Zhang, “Influence of drill helical direction on exit damage development in drilling carbon fiber reinforced plastic,” IOP Conference Series: Materials Science and Engineering, vol. 213, no. 1, pp. 1-10, 2017.
 F. Su, L. Zheng, F. Sun, Z. Deng, and X. Qiu, “Theoretical modeling for the exit-delamination morphology of the unidirectional CFRPs,” The International Journal of Advanced Manufacturing Technology, vol. 102, no. 1–4, pp. 533–544, 2019.
 A. Dogrusadik and A. Kentli, “Comparative assessment of support plates’ influences on delamination damage in micro-drilling of CFRP laminates,” Composite Structures, vol. 173, no.8, pp. 156–167, 2017.
 J. Babu, T. Sunny, N. A. Paul, K. P. Mohan, J. Philip, and J. P. Davim, “Assessment of delamination in composite materials: A review,” Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, vol. 230, no. 11, pp. 1990–2003, 2016.
 I. P. T. Rajakumar, P. Hariharan, and L. Vijayaraghavan, “Drilling of carbon fibre reinforced plastic (CFRP) composites - a review,” International Journal of Materials and Product Technology, vol. 43, no. 4, pp. 43–67, 2012.