Investigation of Physical, Mechanical, and Drilling Machinability Properties of Nanoparticles Reinforced Carbon/Glass Fiber Hybrid Composites

This study aims to investigate the effects of nanoparticle reinforcement, fiber hybridization, and stacking sequences on the mechanical properties and drilling machinability of composite materials. For this purpose, 12-layered polymer composite plates reinforced with graphene nanoplatelets (GnPs) and boron nitride nanoparticles (BNNPs) were produced using the vacuum bagging method. Carbon fiber (CF), glass fiber (GF), and hybrid fiber (HF) with different stacking sequences were used as reinforcements. The samples were subjected to density and hardness measurements, as well as conventional drilling tests. Drilling operations were carried out on a CNC vertical machining center using Ø6.5 mm drills with point angles of 90°, 110°, and 130°, at a constant spindle speed (1000 rpm) and three different feed rates (200, 600, and 1000 mm/min). The results demonstrated that the neat CF specimen exhibited the highest hardness, whereas the incorporation of nanoparticles reduced hardness, with BNNP-reinforced specimens showing the greatest reduction of about 15%. Drilling machinability was significantly enhanced, as evidenced by the reduction in delamination, and the optimum hole diameter (Ø6.48 mm) was achieved in the GF-based composite reinforced with BNNPs using a 130° drill point angle and a feed rate of 200 mm/min. The effects of GnPs and BNNPs on the drilling machinability of fiber-reinforced composites have been investigated only to a limited extent in the literature, and this study provides new insights. These findings may contribute to improving the quality and efficiency of drilling processes in the aerospace and automotive industries.