Experimental study on drilling temperature and hole quality in drilling of carbon fiber reinforced plastic/titanium stacks

Abstract

Carbon fiber reinforced plastic/titanium stacks are widely used in aviation field due to the superior properties such as high strength-to-weight and high yield strength. Drilling these stacks in single shot is still challenging because of the disparate properties of two stack constituents. Various hole defects occur during drilling stacks, especially for stacking sequence titanium alloy to carbon fiber reinforced plastics. Cutting parameters of titanium alloy, compared to those of carbon fiber reinforced plastics, have more significant influences on hole quality of stacks. The contribution of this work is to research the influence of cutting parameters of titanium alloy on hole qualities during drilling of stacks including drilling temperature, hole diameter deviation, titanium burrs, and interface damage. A novel assessment approach is developed to character the interface damage area based on the greyscale of digital image. Interface damage factor is proposed to evaluate interface damage quantitatively. Experimental results indicate that maximum drilling temperature reaches the peak value when drilling of the interface region. Hole diameter of titanium layer is always lager than that of the carbon fiber reinforced plastic layer. In the same layer, the deviation of hole diameter increases as spindle speed of drilling titanium layer increases. In addition, the damage areas obtained through damage assessment method show a good correlation with the experimental damage results in shape and distribution. Interface damage increases with the rise of the spindle speed of drilling titanium layer.