Experimental Studies on Effect of Process Parameters on Delamination in Drilling GFRP Composites Using Taguchi Method

Abstract

Currently composites are being used to replace conventional metallic materials in a wide range of industries including aerospace, aircraft and defense which require structural materials with high strength-to-weight and stiffness-to-weight ratios. GFRP composites are used in fairings, passenger compartments, and storage room doors due to their high mechanical properties. Out of all the machining operations, most commonly used operation is drilling. But drilling of these composite materials, irrespective of the application area, can be considered a critical operation, owing to their tendency to delaminate when subjected to mechanical stresses. With regard to the quality of machined component, the principal drawbacks are related to surface delamination, fibre/resin pull-out and inadequate surface roughness of the hole wall. Hence it is essential to understand the drilling behaviour by conducting a large number of drilling experiments and drilling parameters such as feed rate and spindle speed should be optimized. This paper presents the effect of speed and feed on delamination behaviour of composite materials by conducting drilling experiments using Taguchi's L25, 5-level orthogonal array and Analysis of variance by using three different tools namely Twist drill,End mill and Kevlar drill. ANOVA was used to analyse the data obtained from the experiments and finally determine the optimal drilling parameters in drilling GFRP composite materials. Results of these experiments revealed that increasing the spindle speed and reducing feed rate can reduce the delamination within limits of specified speed and feed rates. Too low feed rate and too high spindle speed can also increase the delamination. Results also revealed that feed rate is the more influential factor on delamination than spindle speed.