Carbon fibre reinforced plastics (CFRP) and titanium (Ti) stacks have been steadily replacing metals as choice for engineering materials in aerospace applications. Although materials can be manufactured separately and stacked together to attain a near-net shape, it still involves post processing operations such as trimming and drilling. In order to drill holes efficiently without defects (delamination, circularity, variation in hole diameter) in the CFRP/Ti stacks, it is essential to understand the machining behavior of stacks. An experimental study on the drilling of CFRP/Ti stacks was conducted using K20 carbide drill. The drilling characteristics were evaluated for drilling force and torque, delamination in CFRP, drilled-hole quality (hole diameter and circularity) and exit burr height in Ti. This paper describes an attempt made to maximize the hole quality parameters by employing multi-objective optimization using weighted sum method.
CFRP/Ti6Al4V stacks are widely used in aerospace and automobile industries as structural components. The parts are made to near net shape and are assembled together. Aerospace standards demand rigid tolerance for the holes. While drilling stacks, during the exit of drill from CFRP and entry into Ti6Al4V, there is a change in the overall behavior of the drilling process due to changes in the mechanical properties of the two materials. Hence, stacks should be drilled under their optimal machining conditions in order to achieve better hole quality. The machining parameters and tool geometry are different for CFRP and Ti6Al4V. This requires knowing the thickness of the CFRP and Ti6Al4V layers beforehand so that at the time of drill tool transition from CFRP to Ti6Al4V the machining parameters can be altered. But in aircraft bodies the cross-section varies along the profile and the thickness of the individual layers at different locations. The current study proposes the use of acoustic emission (AE) signals to monitor the drill position while drilling of CFRP/Ti6Al4V stacks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.