Modeling and Optimization of Thrust force and Torque during Drilling of Aluminum 6061 Alloy Using Taguchi–Grey Analysis Approach

Abstract

Drilling, a hole producing process is especially important because it accounts for a large portion of overall machining operations. Amongst all machining operations, drilling using twist drill is the most commonly applied method for generating holes for riveting and fastening structural assemblies. It is well known that the drill point geometry has a significant effect of the thrust force of a twist drill. The present research initiative in an attempt to investigate the relative significance of the drilling parameters such as point angle, clearance angle, speed, feed rate and drill diameter on the thrust force and torque using Taguchi-Grey relational analysis. Drilling operations have been conducted over a wide a range of cutting condition. Spindle speed varied in the range 600 rpm to 1000 rpm in 3steps, Feed rate varied from 0.3 to 0.6mm /rev in 3 steps. High-speed steel (HSS) drills of 3 different diameters (8mm, 10mm and 12mm) and different point angles have been used for drilling of 27 through holes on 10mm depth with variable combination of soluble oil mixing with pure water on Aluminum 6061 alloy. A drill tool dynamo meter was used to record the thrust force and torque. In grey relational analysis can be used to represent the grade of correlation between two sequences so that the distance of two factors can be measured discretely. In the case where experiments are ambiguous or when the experimental method cannot be carried out exactly, grey analysis helps to compensate for the shortcoming in statistical regression .Grey relation analysis is an effective means of analyzing the relationship between sequences with less data and can analyze many factors that can overcome the disadvantages of statistical method. Most of manufacturing industries perform a huge number of drilling operations in machine shops. The drilling technology has been studied to improve the cutting performance with optimizing the cutting parameters and the tool geometry. However, burrs are sometimes formed when the drill exits the work piece and the exit burrs have to be removed in the deburring process. The control of burr formation, therefore, has been strongly required to reduce the post process of the drilling operation. Many researchers have been made on burr formation so far. The earlier works associated the burr shape with the cutting parameters experimentally. Some mathematical models based on the experiments were presented to determine the cutting conditions. A statistical analysis was presented to estimate the burr height in the drilling process. Some of researches tried to associate the drill geometries with burr formations. A drill shape, which removed the chisel edge and increased the wedge angle and the web thickness, was designed to suppress burr formation and evaluated in cutting of some materials . From the point of view of the cutting force, the thrust at the end of the cut promotes burr formation in drilling of the plates. When the cutting chip flows upward, a large burr is left at the edge of the hole. Therefore, the thrust and torque should be controlled to reduce burr formation.