Image processing method for delamination and fiber pull-out assessment during drilling of natural fiber composites

Natural fiber-reinforced composites are promising alternative materials in the manufacture of modern moderate-to-high-technology products. However, their heterogeneous structure causes processing defects uncommon with metallic parts. Drilling of composites is an essential machining process to facilitate assembly and fastening of composite components. The occurrence of delamination damage around the drilled hole and fiber pull-out within the hole are critical factors that affect the performance of these parts when assembled. A new image processing method using digital scanning and tracing for characterizing delamination and fiber pull-out induced by drilling has been developed to address the limitations in the existing methods of quantifying drilled hole qualities. The capability of the proposed method as a delamination and fiber pull-out assessment tool was verified using simulated and real images of drilled holes. The method was also used to investigate the effect of drilling parameters on delamination and fiber pull-out in jute reinforced epoxy composite produced via resin transfer molding. The results show that drill bit diameter, feed rate, and spindle speed have varying effects on both delamination areas and fiber pull-out within the drilled hole.