Machining performance optimization for electrodis

Authors: Rahul Kumar Abhishek Saurav Datta Bibhuti Bhusan Biswal Siba Sankar Mahapatra

Publish Date: 2016/11/05

Volume: 39, Issue: 9, Pages: 3499-3527

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Abstract

Nickelbased super alloy such as Inconel is widely used in aerospace nuclear and chemical industries because of its excellent mechanical and chemical properties at elevated temperatures Inconel comes under the category of “difficulttocut” materials Difficulty is faced whilst machining of Inconel because of its poor thermal conductivity high toughness high hardness and extremely high work hardening behaviour Moreover it contains highly abrasive carbide particles which tend to stick on the tool surface resulting in inferior surface finish Moreover enormous heat is generated during machining which leads to reduction in tool life Hence machining and machinability aspects of Inconel have become a predominant research agenda today Technological advances have led to an extensive usage of high strength high hardness materials in manufacturing industries In course of machining of “difficulttocut” materials conventional manufacturing processes are increasingly being replaced by the advanced techniques such as electrodischarge machining EDM ultrasonic machining electrochemical machining and laser machining Amongst these EDM has found widespread application in microelectromechanical systems tool and die automobile and aerospace industries Therefore promoting the quality of the EDMed product and thereby achieving satisfactory machining performance a thorough understanding of the relationship between the EDM parameters and the machined surface integrity in consideration with the toolwork combination has become an important research focus EDM is an electrothermal machining process where electrical energy is used to generate electrical spark and material removal mainly occurs due to thermal energy of the spark It has become an excellent option to machine “difficulttocut” materials and high temperature resistant alloys super alloy Inconel in the present case An experimental investigation on assessing machining performance during EDM of Inconel 625 718 601 and 825 has been delineated herein Attempt has been made on evaluating optimal machining parameters setting to achieve satisfactory machining yield Based on 5factor4level L16 orthogonal array experiments have been carried out by varying gap voltage peak current pulseon time duty factor and flushing pressure each varied at four discrete levels to examine the extent of machining performance in terms of material removal rate electrode wear rate surface roughness and surface crack density of EDMed end products obtained by utilizing different parameters settings for Inconel of different grades respectively An integrated optimization route combining satisfaction function approach fuzzy inference system in conjugation with Taguchi’s philosophy has been proposed for simultaneous optimization of aforementioned multiple performance indices The most favourable machining parameters setting have been obtained as gap voltage = 90 V peak current = 5 A pulseon time = 200 µs duty factor = 70 flushing pressure = 06 bar for Inconel 625 gap voltage = 90 V peak current = 5 A pulseon time = 200 µs duty factor = 85 flushing pressure = 04 bar for Inconel 718 gap voltage = 80 V peak current = 7 A pulseon time = 500 µs duty factor = 80 flushing pressure = 03 bar for Inconel 601 and gap voltage = 80 V peak current = 5 A pulseon time = 300 µs duty factor = 85 flushing pressure = 04 bar for Inconel 825 In addition to that analysis of SEM micrographs has been carried out to understand surface irregularities in terms of surface cracks white layer for EDMed Inconel end products of different gradesAuthors gratefully acknowledge the support rendered by Dr Francisco Ricardo Cunha EditorInChief Journal of the Brazilian Society of Mechanical Sciences and Engineering BMSE Special thanks to the anonymous reviewers for their valuable constructive comments and suggestions to prepare the paper a good contributor

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