An Experimental Comparative Analysis of Twist Drilling, Helical Milling and Pilot Hole Machining for Large Diameters in CFRPs

Carbon fiber-reinforced polymer (CFRP) large diameter hole drilling is certifiably not a broadly examined theme on account of their non-homogeneity and anisotropic highlights. In the scope of aerospace industrial uses of this material, thousands of holes have to be machined for purposes of assembly. The quality of this machined hole is influenced adversely by matrix grid cratering, thermal damage, spalling, surface delamination, and material debasement or fiber pullout. Among these different deformities, delamination is considered the most severe for CFRP composite. The main objective of this work is to compare twist drilling, helical milling and pilot hole machining technologies concerning unidirectional CFRP composite. In addition, the force modules were also discussed. In the scope of this work, numerous machining experiments were conducted in unidirectional CFRP composite: herein the impact of the type of cutting tool and of process parameters on the quality of machined holes are analysed and discussed (diameter of holes, circularity error and characteristics of uncut fibres). In other to achieve a better hole quality, the Scanning electron microscope (SEM) analysis and evaluation of acquired data were conducted. Experimental results show holes machined using twist drilling method present the lowest-quality, with damages present at the tool entry and exit as compared to the other studied methods. This study intended to help in assisting technicians working on assembly large structural parts in aircraft or automobile industries in choosing the best hole machining procedure when this three are in consideration.