Influence of machining parameters and tool structure on cutting force and hole wall damage in drilling CFRP with stepped drills

Recent advances in drilling of carbon fiber–reinforced polymers for aerospace applications: a review

“…The same investigation was found by [113]. This is because lower feed rates contribute in decreasing the cutting depth per revolution and the drill bit does not require to cut more material volumes per revolution and to break more fibers [52]. Therefore, the feed rate also shows impact on the drilled hole quality of CFRP [114].…”

“…Hocheng and Tsao [116] also performed drilling of CFRP using different drill bits each having 10 mm diameter and in all experimental drill bits at lower thrust force the drilling-induced delamination was minimum. Recently, Qiu et al [52] also reported that higher feed rate generated high thrust force is responsible for increase in delamination. For more detail about the acknowledgement of feed rate and cutting speed, readers are recommended to references [15,22,24,26,27,58].…”

“…The most common helix angle ranges between 12 to 38 depending on the application [117]. Moreover, the contact area of the drilled hole increases as the drill's diameter increases which subsequently, increases the thrust force and more delamination [52]. Generally, drill holes in aerospace machined structures range between 4.8 and 6.4 mm [16].…”

“…Twist drills [45,46,53,52,48,118] Brad & spur drills [119] Step drills [52,120] Straight-flute drill bit [121,122] Slot drill bit [65] Saw drills [116] Dagger drill [123] Candlestick drill [116] Core drills [109] Core-twist drill [124] Core-saw drill [124] Step-core-candlestick drill [124] Core-candlestick drill [124] Step-core-twist drill [124] Step-core-saw drill [124] Countersink drill [51] Tapered drill reamer [125] Reamer drill with four cutting edges [126] Figure 10: Drill tool geometries used in CFRP For instance, Brad & spur drills were recommended by [119], step drills were used by [52,120], dagger drills by [123], saw drills by [116] , core drills by [109], Slot drill bit by [65], candlestick drill by [116], core-twist drill, core-saw drill, step-core-candlestick drill, core-candlestick drill, step-core-saw drill, and step-core-twist drill were used by [124], countersink drill by [51], and tapered drill reamer was used by [125]. Figure 7 shows some of them schematically [127].…”

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].…”