Machining responses of high-strength carbon/epoxy composites using diamond-coated brad spur drills.

Drilling of high-strength carbon/epoxy composites has been a critical procedure in the industry due to the need to create holes for mechanical assemblies. However, the inherent anisotropy and heterogeneity of the fibrous composites complicate the material removal process and induce tremendous challenges for the manufacturing sectors. The present paper addresses the machining issues of T700 carbon fibers reinforced epoxy laminates by using the diamond-coated brad spur drills. The cutting tools are featured by three protruding edge tips devoted to the minimization of drilling thrust forces for the composite laminates. The machining experiments were conducted under varying process conditions to investigate the parametric impacts on the machining responses. The cutting-induced delamination was studied using a novel quantification method. The work novelty is focused on revealing the machining characteristics of high-strength fibrous composites and evaluating the functionality of the specialized tools for the composite drilling. The process parameters greatly affect the drilling forces/temperatures and delamination factors. Delamination is shown to occur inside the inner plies of the composite and propagate rapidly toward the hole exit side. Moreover, surface cavities and fiber fractures dominate the failure of cut composite hole walls. [ABSTRACT FROM AUTHOR]