Experimental Investigation of Process and Response Parameters in Drilling Using Fuzzy Logic Approach

Abstract

Drilling is probably the most frequently used operation in industry. Sometimes, as many as 55,000 holes are generally required to be drilled as in a complete single unit production of the Airbus A350 aircraft. The carbon fibre reinforced plastics (CFRP), owing to their anisotropy and abrasive nature of their carbon fibre content, exhibit totally different drilling results as compared to those of drilling common metals and other materials. Different challenges faced in drilling CFRPs in particular, and machining FRPs in general could be classified on the one hand as the excessive tool wear, while on the other hand as workpiece material-related problems. The latter ones include part edge, surface anomalies and hole quality defects like material cracking and delamination. Delamination during drilling CFRP has been recognised as one of the major problems by almost all the researchers. It is an inter-laminar or inter-ply failure phenomenon. When occurred at the top surface around the drilled hole periphery, it is known as ‗peel-up delamination‘ or simply hole entry delamination. It is more severe at the bottom most surface- ply of the material—known as push-out delamination or hole exit delamination. The considerable amount of contribution in this field has been made and have been modeled analytically and validated (experimentally) the effect of various Process & Response parameters have been studied with their respective critical thrust force, torque values for the onset of the hole exit delamination. Moreover, the effect of chisel edge and a pilot-hole on to the critical thrust force and the resulting delamination has been studied. This work covered mathematical modeling of hole exit delamination with respect to the critical thrust force. The optimum value has been determined with the help of main effect plot and ANOVA Tables to findout which parameter has affected most for increasing thrust force and torque. The mathematical modeling has been carried out using Minitab 15 software and different models has been analysed with help of the taguchi design using orthogonal array. The Universal microscope has been used which determines delaminated diameter in GFRP specimens. The fuzzy logic approach has been adopted using MATLAB software which helped to find out Torque, Thrust Force graphs with different control factors like feed, speed etc. The failure criteria has been applied for finding delamination occurring in glass fiber composite around the drilled holes. The piezoelectric dynamometer has been used for measuring thrust forces and torque on varying the feed rate, speed, and drill diameters. The drill bit like High speed steel used for carrying out the experimental works in the Machine Tool Lab. The various process parameters like different diameters, feed, speed, depth of cut has been taken to record the various response parameters like torque, thrust force, tool wear. The thrust forces and torque were measured for different machining conditions.