Drilling Strategy for Thick Carbon Fiber Reinforced Polymer Composites (CFRP): A Preliminary Assessment

Abstract

Carbon fiber reinforced polymer or CFRP composites are the epitome of high-performance materials in lightweight design. However, their machinability can be problematic due to non-homogenous and anisotropic material properties. This preliminary assessment emphasizes drilling strategy by using mechanical drilling and laser machining on 25.4 mm thick CFRP, which has not been investigated so far. In mechanical drilling, three drilling strategies were applied with the same parameters in order to assess the feasibility of drilling thick CFRP. The laser machining experiments were conducted to identify the potential of fiber laser machines to cut thick CFRP due to their superior laser beam quality. The results showed that choosing the appropriate drilling strategy in mechanical drilling is essential for reducing damage when drilling thick CFRP. Significant damage occurred in all experiments. The results are useful to define the relationships between machining parameters related to mechanical/laser drilling and hole/cut quality.

Sequential Laser–Mechanical Drilling of Thick Carbon Fibre Reinforced Polymer Composites (CFRP) for Industrial Applications

“…The highest S FDSR , as well as the unattended HAZ, was expressed by the sequential laser 8 mm-mechanical 8 mm for both tools and laser pre-drilled strategies (i.e., single-side (SS) and double-side (DS)). This observation is also present in the experimental work of Sobri et al [6]. This result could be due to the presence of the pre-drilled holes, because the drill bit tool diameter has the same diameter and therefore is unable to eliminate the HAZ contributed by the laser beam.…”

“…Experimental studies used a combination laser and mechanical technique creating 8 and 10 mm holes in 25.4 mm thick CFRP. All parameters in Tables 2 and 3 were identified based on the standard parameters obtained from previous research attempts [3][4][5][6][7][8][9][10][11][12][13][15][16][17][18][19][20][21][22][23] and modified to fit the current scenario based on machine and equipment capability. In this process, pilot holes were started with a 1 kW IPG fibre laser.…”

“…The optimum performance in the drilling of CFRP composites depends on the proper consideration of these conditions. Mechanical drilling requires the selection of optimum cutting operation parameters (i.e., cutting/spindle speed and feed rate) in order to avoid having any excessive forces affect the surface integrity of the CFRP composites [6]. Laser drilling depends on good thermal management or heat efficiency distribution towards the work piece, since the good thermal conductivity characteristics of CFRP make it prone to thermal damage at the surface (such as heat-affected zones (HAZ), porosity, etc.)…”

“…Laser drilling depends on good thermal management or heat efficiency distribution towards the work piece, since the good thermal conductivity characteristics of CFRP make it prone to thermal damage at the surface (such as heat-affected zones (HAZ), porosity, etc.) [4][5][6]. The proper selection of parameters in laser drilling (such as laser power, scanning speed, gas pressure, and type) can be optimized in order to achieve an optimum performance [7].…”