Parameter Optimization of Wire EDM in a Range of Thickness for EN8 Die Steel

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INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY VOLUME 5 ISSUE 2 – MAY 2015 - ISSN: 2349 - 9303

Parameter Optimization of Wire EDM in a Range of Thickness for EN8 Die Steel S.Vignesh1

M.Sivakumar2

R.Shanmugaprakash3

Department of Mechanical Engineering, Bannari Amman Institute of Technology, 1 Anna University vignezmech@gmail.com

Department of Mechanical Engineering, Bannari Amman Institute of Technology, 2 Anna University muthusivaa@gmail.com

Department of Mechanical Engineering, Bannari Amman Institute of Technology, 3 Anna University summugaa1691@gmail.com

Abstract— Wire Electrical Discharge Machining (WEDM) is also known as an electro thermal production process in then, nor electricity) allows the wire to cut through the metal by the use of heat from electrical sparks. The present work process approach to parameter optimization in wire electric discharge machining of EN-8 die steel (of thickness 50 and 75mm) using Taguchi method which optimizes four process parameters (factors) such as pulse ON time, pulse OFF time, current, voltage and two important response such as material removal rate (MRR) and in surface roughness (Ra –average roughness) of machined workpiece is considered in this study. Taguchi is an efficient search technique, is used to obtain the optimal setting of the desired responses and to avoid the conflicting nature of response. Taguchi designs focus on reducing variability, as well as setting the mean to target. Index Terms— EN8 die steel, Thickness, Material removal rate, Surface roughness, Taguchi technique. ————————————————————

1 INTRODUCTION Wire EDM is a non-traditional thermo-electric process which erodes material from the workpiece by a series of discrete sparks by continuously moving wire electrode. The horizontal movement of the worktable controlled by computer numeric controlsystem, which determines the path of the cut. During the machining operations, dielectric medium is to stabilize the spark erosion path by increasing the conductivity of the medium and to flush-out the eroded metal from the cutting zone. There is virtually no cutting force to the machining parts during the process, because the wire electrode and workpiece never make contact. WEDM is a special form of thermal machining process used for precision machining of conductive materials with varying hardness and complex shapes.

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LITERATURE REVIEW

Chattopadhyay et al. have used Taguchi’s design of experiment (DOE) approach to conduct experiment on rotary EDM using EN8 steel and copper as work piece-tool combinations and developed empirical relations between performance characteristics (MRR and EWR) and process parameters such as peak current, pulse-on-time and rotational speed of the tool electrode.It is found

that peak current and rotational speed of the tool significantly on both the responses[1].

electrode

influence

Selvakumar et al have used Taguchi experimental design method for the selection of the most optimal machining parameter combinations for wire electrical discharge machining (WEDM) of 5083 aluminium alloy. A series of experiments were performed by considering pulse-on time, pulse-off time, peak current and wire tension as input parameters. The surface roughness and cutting speed

were considered responses. The cutting speed has been found to have an increasing trend with the increase of pulse-on time and peak current. The surface finish decreases, namely Ra increases, with the increase in pulse-on time and peak current [2]. Mevada et al investigated the wire wear rate at different machining parameter Such as peak current, pulse on time, pulse off time, based on a full factorial design of experiment method.Different setting of peak current, pulse on time and pulse off time with three levels. Molybdenum wire of 0.18 mm diameter with and medium strength EN-8 steel material was used as a tool and work piece material.From the experimental work, results and study shows that peak current, pulse on time, pulse off time are the main parameter for the wire wear. With the increase in peak current, wire wear increases, but it is slowly. With the increase in pulse on time, wire wear increases rapidly. Pulse off time is not much effects on the wire wear rate [3]. Singh et al in their paper have discussed about the effect of various process parameters of WEDM like pulse on time (TON), pulse off time (TOFF), gap voltage (SV), peak current (IP), wire feed (WF) and wire tension (WT) to reveal their impact on MRR of hot die steel (H-11). The optimal set of process parameters is identified to maximize the MRR, using one variable at a timeapproach [4]. Kanlayasiri et al have studied the effect of machining parameters on surface roughness of wire EDMed DC53 die steel. The investigated machining parameters were pulse-on time, pulse-off time, pulse-peak current, and wire tension. Results of ANOVA shows that pulse-on time and pulse-peak current are significant variables to surface roughness of wire-EDMed DC53 die steel [5]. From the literature several researchers have been applied Taguchi method to optimize the performance parameters in wire edm process [6]. From the literature survey, the gap identified was different materials were machined using wire electrical discharge machining

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