Performance evaluation of carbide tools in drilling CFRP-Al stacks

Abstract

Composite-metal stack is an ideal combination of materials which unites the advantages of each dissimilar material in a substantial weight. However, drilling dissimilar materials has been a challenge since the composite-metal stacks are at demand in industries. It is important to choose the appropriate drill geometry regarding the stacking sequence and utilize proper machining parameters in order to achieve damage free and precession holes. This experimental study was conducted on dry drilling of CFRP/Al2024/CFRP (carbon fiber-reinforced plastic). Four types of twist drills with various geometries, both coated and uncoated, were utilized to study the effect of machining parameters on hole quality. It was observed that increasing feed rate entails an increase in entrance delamination, whereas exit delaminations and fiber fraying at 2nd CFRP exit diminished with increasing feed rate. It was also found that four facet tools performed better than two facet tools in terms of fiber delamination. Most accurate hole was attained on 2nd CFRP; however, it was found that increasing feed significantly affects the hole size on 1st CFRP.

An experimental study on drilling of unidirectional GLARE fibre metal laminates

“…The change in the cutting force varied considerably when the tool cut through the alternating layers of aluminium and glass fibre composites, and the thrust force and torque in aluminium sheets were always higher than that in S2/FM94 layers. This observation agreed with the findings reported earlier performed on drilling GLARE and aluminium/composite stacks [9,13,21,23,30]. This is attributed to the difference in their mechanical properties and behaviour when they are subjected to large cutting forces during the drilling process.…”

Examination on Mechanical Behavior and Drilling Analysis of Fiber Metal Laminates

“…Peel-up and pushout defects were made by the drill bit geometry (Brad and Dagger drills) and machining parameters higher velocity and higher feed rate, which are found at the entry and exit of drill hole of the composites and witnessed around the perimeter of the holes that are drilled [6]. These defects occur in FML due to the depression at the entry of the drill bit and protrusion at the exit of the first and last laminate respectively, and also fiber unravelling and fiber coming off were seeming on each of the side, at the entrance and the exit [7].…”

The drilling of carbon fibre composite–aluminium stacks and its effect on hole quality and integrity

“…The associated ANOVA also showed that feed rate had a dominant influence on resulting hole diameter and was statistically significant at the 5% level with respect to the Al section, with a percentage contribution ratio (PCR) of ~95%. In general, hole diameter in Al was marginally larger than the CFRP layer, as the former has a lower modulus of elasticity and higher thermal expansion compared to the latter [17]. Figure 8.…”