Ecofriendly inclined drilling of carbon fiber-reinforced polymers (CFRP)

Abstract

Key composite made aerostructures such as fuselage inner walls, flap support fairings, empennage ribs, and the vertical fin ribs are comprised of non-vertical inclined and radial holes that join with other key metallic and non-metallic structures. Carbon fiber reinforced plastics (CFRP) are also used in the aerospace, automotive, marine, and sports-related applications due to their superior properties such as high strength to weight ratio, better fatigue, and high stiffness. CFRP drilling operation is different than the homogenous materials as the cutting-edge interacts with fiber and matrix simultaneously. Flank face of the tool rubs on the workpiece material and develops high frictional contact due to the elastic recovery of broken fibers. Lubrication during CFRP cutting can reduce the friction involved at tool-workpiece interface to enhance cutting performance. Dry cutting, cryogenic machining, and minimum quantity lubrication (MQL)-based strategies are termed as ecofriendly cooling/lubrication methods when machining high performance materials. The abrasive nature of carbon fiber is responsible of producing cutting forces which leads to different types of imperfections such as delamination, uncut fiber, fiber breakout, and fiber pullout. The integrity of CFRP drilled hole especially at the entry and exit of the hole plays a significant role towards the overall service life. The presented paper aims to characterize the interrelationships between hole inclination, lubrication/cooling methods, tool coating, and drill geometry with inclined hole bore surface quality and integrity during drilling of CFRP laminates. In dry cutting, thrust forces were found 2.38 times higher in the 30° inclination when compared with the reference 90° conventional inclination angle. Compressed air provided lowest increase (1.46 times) in the thrust forces for 30° inclination.

State of the art review on the sustainable dry machining of advanced materials for multifaceted engineering applications: progressive advancements and directions for future prospects

“…The increase in thrust force observed for both CFRP and Al during dry drilling using uncoated tools may due to high wear [103]. In compressed air environment, lowest thrust forces were found (1.46 times) for 30°inclination as compared to dry cutting in drilling of CFRP reported by Parvez et al (2020) [104]. Cryogenic fluid between-the-holes shows favorable results with respect to drilling of CFRP concerning hole quality, thrust force and energy consumption while a reduction in surface roughness and energy consumption in case of drilling of titanium alloy [105].…”

Fiber-reinforced composites in milling and grinding: machining bottlenecks and advanced strategies

“…The lubrication mechanism of MQL is analyzed, that is, the pressurized directional transportation of oil mist makes oil droplets that penetrate into the pore network on the workpiece and grinding wheel effectively. The G-ratio of MQL grinding is 115.38% higher than that of dry grinding [188]. Pervaiz et al [189] found different rules and believed that the MQL strategy in external configuration could not provide favorable performance.…”

“…However, 1%vol SWCNT + MQL has the optimal effect on improving the surface roughness of CFRP and Al composites. Table 3 [30,100,154,156,162,187,188,191,207,208,210,211] lists the processing results of different MQL conditions and dry processing.…”

Impact damage assessment in patch‐repaired carbon fiber‐reinforced polymer laminates using the nonlinear Lamb wave‐mixing technique

“…Carbon fiber-reinforced polymer (CFRP) laminates are a new type of composite material that are extensively applied in aerospace, manufacturing, military industries and other high-tech fields due to their high specific strength, relative thermal stability, and low weight. [1][2][3] However, in aircraft CFRP structures, barely visible impact damage (BVID) may easily occur while facing complicated harsh environments with impacts such as hail strikes, lightning strikes, and tool drops. BVID is a kind of damage that originates inside the material, without significant signs on the surface of the structure.…”