Drilling temperature and hole quality in drilling of CFRP/aluminum stacks using diamond coated drill

Abstract

Composite/metal stack materials, most often consisting of carbon fiber reinforced polymer (CFRP) composites and aluminum or titanium alloy (Al or Ti), have been widely used in the aviation industry. It is still a challenge to make holes on the composite/metal stack materials with high quality. This paper aims to investigate the influence of drilling parameters on the drilling of stack materials consisting of T800/X850 CFRP and 7075-T651 Al with regard to drilling force, drilling temperature, hole diameter and hole surface quality. Diamond coated drill bits with double point angles were employed in the drilling tests. The drilling temperature was measured utilizing a rotational motion temperature measuring system. It is indicated that maximum drilling temperature increases with the increase of spindle speed, while, it decreases with increasing feed rate. The thrust force and drilling temperature increase abnormally during drilling of the Al layer, which can be attributed to the evacuation difficulty of the long and flexible Al chips. It is found that sudden drops in the surface profile of CFRP are caused by the cavities owning to the resin degradation effects. The influences of different stack sequences on the drilling temperature and hole surface quality have also been discussed.

3D Finite Element Modelling of Cutting Forces in Drilling Fibre Metal Laminates and Experimental Hole Quality Analysis

“…At both -top and bottom-locations, the hole size increased with feed rate increase between f = 300 mm/min and f = 600 mm/min and decreased with it at f = 900 mm/min. It was also observed that the holes oversize was greater at bottom in most holes with the exception of holes drilled at n = 3000 rpm and f = 300 mm/min and f = 900 mm/min, and n = 3000 rpm and f = 600 mm/min, which be attributed to the cutting vibration and the instability of the workpiece as the feed rate increased [37]. It was reported in one of our previous studies that the hole size is likely to shrink with depth when drilling GLARE fibre metal laminates [19].…”

Comparative analysis of wobble milling, helical milling and conventional drilling of CFRPs

“…Abrão et al [57] showed that 56% of the tools used for drilling polymer composites have a special geometry. Some of the special drilling tools developed for CFRP cutting are as follows: (i) double point angle twist drills [58][59][60][61][62][63][64], (ii) brad and spur drills [21,[65][66][67][68][69][70], (iii) dagger drills (one-shot drills) [28,31,[67][68][69][70][71][72][73], (iv) step drills [67,68,[74][75][76][77][78][79][80], (v) core drills [81,82] and (vi) special core drills [83][84][85]. These special drilling tools are reviewed and discussed in detail by Geier et al [55].…”

Drill-exit temperature characteristics in drilling of UD and MD CFRP composites based on infrared thermography

“…15, have been studied to further elucidate the damage mechanisms within the large angle region of UD and MD [24][25][26][27][28][29][30][31][32][33][34][35][36][37] CFRPs. Fig.…”

“…[18,19,31], whereas infrared thermography [32,33] has been explored for non-contact measurement of temperatures with the infrared camera. In the drilling of CFRP, researchers have employed embedded thermal sensors on the flank faces of drills to monitor the temperature with varying processing parameters [3,6,34,35]. Due to the unique thermal properties of tool material and CFRP, and different heat distributions in tool, workpiece and chips, the measured temperature can only represent the average temperature within a wide zone rather than the specific temperature of the machined surface.…”