THE INFLUENCES OF VARYING FEED RATE ON HOLE QUALITY AND FORCE IN DRILLING CFRP COMPOSITE

Abstract

The selection of drill geometry and drilling parameters has high importance due to thermo-mechanical formations in drilling of carbon fiber reinforced polymer (CFRP) which has anisotropic structure. This study focused on the effects of drilling parameters on thrust force and hole quality in drilling of CFRP composites by applying constant and varying feed rate with uncoated WC drills having different point angles. Surface roughness, delamination factor and diameter plays a crucial role in the production of close-tolerance holes in hole quality. The quality of the hole surface was examined via surface roughness measurements and surface damage by scanning electron microscopy (SEM). Machinability experiments were performed with three different levels of drilling parameters that are point angle, cutting speed and feed rate. It was determined that thrust force (Fz), delamination factor (Fd) and surface roughness (Ra) values obtained in drilling processes by varying feed rate in hole exit are lower than that of constant feed rate with average of 21%, 14% and 36%, respectively. On the other hand, hole diameter (d) values obtained with varying feed rate in hole exit were higher than that of constant feed rate. The effects of drilling parameters on Fz, Fd and Ra were determined by analysis of variance with 95% confidence level and feed rate was found as the most significant parameter on them.

Keywords

• CFRP,Drilling,Varying feed rate,Hole quality,Anova

References

1. [1]. İsbilir, O., Ghassemieh, E., “Numerical investigation of the effects of drill geometry on drilling induced delamination of carbon fiber reinforced composites”, Composite Structural, 105: 126-133, (2013).
2. [2]. Soutis, C., “Fibre reinforced composites in aircraft construction”, Progress in Aerospace Sciences, 41(2) 143–51, (2005).
3. [3]. Liu, D., Tang, Y., Cong W.L., “A review of mechanical drilling for composite laminates”, Composite Structures, 94(4) 1265–79, (2012).
4. [4]. Singh, I., Bhatnagar, N., Viswanath, P., “Drilling of uni-directional glass fiber reinforced plastics: experimental and finite element study”, Materials and Design, 29(2) 546-553, (2008).
5. [5]. Faraz, A., Biermann,D., Weinert, K., “Cutting edge rounding: An innovative tool wear criterion in drilling CFRP composite laminates”, International Journal of Machine Tools and Manufacture, 49 1185-1196, (2009).
6. [6]. Fan, Y., Zhang, L., “New development of extra large composite aircraft components application technology”, Advanced of Aircraft Manufacture Technology, 30(3) 534-543, (2009).
7. [7]. Ahmad, J., “Machining of polymer composites”, Boston, MA: Springer-Verlag, (2009).
8. [8]. Xu, J., Mkaddem, A., Mansori, M., “Recent advances in drilling hybrid FRP/Ti composite: A state-of-the-art review”, Composite Structures, 135 316–338, (2016).

9. [9]. Abrão, A. M., vd, “Drilling of fiber reinforced plastics: A review”, Journal of Materials Processing Technology, 186(1-3) 1-7, (2007).
10. [10]. Pecat, O., Brinksmeier, E., “Low damage drilling of CFRP/Titanium compound materials for fastening”, 2nd CIRP 2nd CIRP Conference on Surface Integrity (CSI) Procedia CIRP 1–7, (2014).