Delamination Analysis in Drilling of Carbon Fiber Reinforced Polypropylene (CFR-PP) Composite Materials

Abstract

Abstract Carbon Fiber Reinforced Polymeric (CFRP) composite materials are widely used in the fabrication of major structural parts in aerospace engineering application owing to their specific stiffness and high strength to weight ratio. The drilling process is often used machining operation in order to assemble the parts made by Fiber Reinforced Polymeric (FRP) composite materials. In this work the effect of drilling process variables such as spindle speed and drill feed rate on the drilling induced delamination at exit during drilling of Carbon Fiber Reinforced Polypropylene (CFR-PP) thermoplastic composite is studied in detail. For this study, CFR-PP laminates are fabricated using hot compression molding machine with film stacking technique. The fabricated laminates are tested for physical and various mechanical properties as per the relevant ASTM standards. To analyze the machining performances, the drilling experiments are conducted on a CNC Vertical Machining Center (VMC) using three type of twist drill made with high speed steel (HSS), tipped carbide (TC) and solid carbide (SC) of 6mm diameter. The main objective of this work is to analyze the influence of spindle speed and drill feed rate with respect to drilling induced delamination of drilled hole in CFR-PP composite materials. The empirical relation between machining variables and process responses are developed to predict the process outcome. The observations indicted that the developed regression model is highly suitable to predict the process responses during drilling of CFR-PP composite material. The developed mathematical model may be helpful to reduce the delamination damage which is the most significant undesirable failure during the drilling of CFR-PP material. The influence of machining parameters and their interactions are examined. The significance role of tool materials on the machining characteristic is also discussed in detail.