Powder-mixed Electric Discharge Machining (PMEDM) of Inconel 625

In recent times, nickel-based super alloys are widely used in aerospace, chemical and marine industries owing to their supreme ability to retain the mechanical properties at elevated temperature in combination with remarkable resistance to corrosion. Some of the properties of these alloys such as low thermal conductivity, strain hardening tendency, chemical affinity and presence of hard and abrasives phases in the microstructure render these materials very difficult-to-cut using conventional machining processes. Therefore, the aim of the current research is set to improve the productivity and surface integrity of machined surface of Inconel 625 (a nickel-based super alloy) by impregnating powder particles such as graphite, aluminum and silicon to kerosene dielectric during electric discharge machining (EDM). Initially, temperature distribution, material removal rate (MRR) and residual stress were predicted through numerical modelling of powder-mixed EDM (PMEDM) process. In the experimental investigation, particle size analysis of the as-received powder particles was carried out to identify the distribution of particles. X-ray diffraction (XRD) analysis of particles indicated the presence of various phases including small amount of impurities. An experimental setup was developed and integrated with the existing EDM system for carrying out PMEDM process. The experiments were planned and conducted by varying five different parameters such as powder concentration, peak current, pulse-on time, duty cycle and gap voltage according to the central composite deign (CCD) of response surface methodology (RSM). Effects of these parameters along with powder concentration were investigated on various EDM characteristics such as material removal rate (MRR), radial overcut (ROC) and surface integrity aspects including surface crack density (SCD), surface roughness (SR), altered layer thickness (ALT), microhardness of surface and sub-surface regions, chemical and metallurgical alterations of the machined surface and residual stress. Results clearly indicated that addition of powder to dielectric has significantly improved MRR and surface integrity compared to pure dielectric. Among the powders used, graphite has resulted in highest MRR, lowest SCD, least ALT, least microhardness of surface and sub-surface regions. Least ROC, lowest surface roughness and least residual stress were obtained using silicon powder. Aluminum performed well in terms of MRR at low concentration range (upto 6 g/l).Therefore, optimal process performance under a given operating condition depends on judicious selection of powder materials, their size, concentration and process parameters

Modeling and Optimization of Micro-EDM Operation for Fabrication of Micro Holes

Based on the experimental results, an analysis was made to identify the performance of various electrodes during fabrication of micro holes considering Inconel 718 as well as titanium as workpiece materials. It was found that that platinum followed by graphite and copper as electrode material exhibited higher MRR for both the workpiece materials but on the other hand platinum showed higher values of OC, RCL and TA respectively when compared to graphite and copper. The variation of temperature distribution in radial and depth direction with different process parameters has been determined for Inconel 718 and Titanium 5. Theoretical cavity volume was calculated for different process parameter settings for both workpiece materials and it was found that Titanium 5 exhibited higher cavity volume then Inconel 718. This research work offers new insights into the performance of micro-µ-EDM of Inconel 718 and Titanium5 using different electrodes. The optimum process parameters have been identified to determine multi-objective machinability criteria such as MRR, angle of taper of micro-hole, the thickness of recast-layer and overcut for fabrication of micro-holes

Studies on Some Aspects of Multi-objective Optimization: A Case Study of Electrical Discharge Machining Process

Electrical Discharge Machining (EDM) finds extensive application in manufacturing of dies, molds and critical parts used in the automobile and other industries. The present study investigates the effects of different electrodes, deep cryogenic treatment of tools subjected to different soaking duration and a hybrid approach of powder mixed EDM of cryogenically treated electrodes on machinability of Inconel 718 super alloy. Inconel 718 has been used as the work material owing to its extensive application in aerospace industries. A Box– Behnken design of response surface methodology (RSM) has been adopted to estimate the effect of machining parameters on the performance measures. The machining efficiency of the process is evaluated in terms of material removal rate (MRR), electrode wear ratio (EWR), surface roughness, radial overcut and white layer thickness which are function of process variables viz. open circuit voltage, discharge current, pulse-on-time, duty factor and flushing pressure. In this work, a novel multi-objective particle swarm optimization algorithm (MOPSO) has been proposed to get the Pareto-optimal solution. Mutation operator, predominantly used in genetic algorithm, has been introduced in the MOPSO algorithm to avoid premature convergence and to improve the solution quality. To avoid subjectiveness and impreciseness in the decision making, the Pareto-optimal solutions obtained through MOPSO have been ranked by the composite scores obtained through maximum deviation theory (MDT). Finally, a thermal model based on finite element method has been proposed to predict the MRR and tool wear rate (TWR) when work piece is machined with variety of electrode materials. A coupled thermo-structural model has been also proposed to estimate the residual stresses. The numerical models were validated through experimentations. Parametric study is carried out on the proposed model to understand the influence of important process parameters on the performance measures. The study offers useful insight into controlling the machining parameters to improve the machining efficiency of the EDMed components

Micro-Electro Discharge Machining: Principles, Recent Advancements and Applications

Micro electrical discharge machining (micro-EDM) is a thermo-electric and contactless process most suited for micro-manufacturing and high-precision machining, especially when difficult-to-cut materials, such as super alloys, composites, and electro conductive ceramics, are processed. Many industrial domains exploit this technology to fabricate highly demanding components, such as high-aspect-ratio micro holes for fuel injectors, high-precision molds, and biomedical parts.Moreover, the continuous trend towards miniaturization and high precision functional components boosted the development of control strategies and optimization methodologies specifically suited to address the challenges in micro- and nano-scale fabrication.This Special Issue showcases 12 research papers and a review article focusing on novel methodological developments on several aspects of micro electrical discharge machining: machinability studies of hard materials (TiNi shape memory alloys, Si3N4–TiN ceramic composite, ZrB2-based ceramics reinforced with SiC fibers and whiskers, tungsten-cemented carbide, Ti-6Al-4V alloy, duplex stainless steel, and cubic boron nitride), process optimization adopting different dielectrics or electrodes, characterization of mechanical performance of processed surface, process analysis, and optimization via discharge pulse-type discrimination, hybrid processes, fabrication of molds for inflatable soft microactuators, and implementation of low-cost desktop micro-EDM system

Proceedings of the 4th International Conference on Innovations in Automation and Mechatronics Engineering (ICIAME2018)

The Mechatronics Department (Accredited by National Board of Accreditation, New Delhi, India) of the G H Patel College of Engineering and Technology, Gujarat, India arranged the 4th International Conference on Innovations in Automation and Mechatronics Engineering 2018, (ICIAME 2018) on 2-3 February 2018. The papers presented during the conference were based on Automation, Optimization, Computer Aided Design and Manufacturing, Nanotechnology, Solar Energy etc and are featured in this book

Experimental Investigation and Modelling of Surface Integrity, Accuracy and Productivity Aspects in EDM of AISI D2 Steel

Electrical Discharge Machining (EDM) is one of the most popular non-traditional machining process for “difficult to machine” conducting materials and is quite extensively and successfully used in industry owing to its favourable features and advantages that it can offer. In EDM, the objective is always to get improved Material Removal Rate (MRR) along with achieving better surface quality of machined component. Furthermore, the essential requirements are as small a thermally affected region of the workpiece surface as possible and a lower radial overcut with minimal tool wear. The quality of a machined surface is becoming increasingly significant to satisfy the increasing demands of superior component performance, longevity, and reliability thus preserving the integrity of the surface is essential. In order to sustain and/or improve reliability of the components, it is always necessary to have knowledge of the effects of the manufacturing parameters on the surface integrity, precision and productivity of the EDMed components

Nuclear Fusion Programme: Annual Report of the Association Karlsruhe Institute of Technology (KIT)/EURATOM ; January 2009 - December 2009 (KIT Scientific Reports ; 7548)

The Karlsruhe Institute of Technology (KIT) is working in the framework of the European Fusion Programme on key technologies in the areas of superconducting magnets, microwave heating systems (Electron-Cyclotron-Resonance-Heating, ECRH), the deuterium-tritium fuel cycle, He-cooled breeding blankets, a He-cooled divertor and structural materials, as well as refractory metals for high heat flux applications including a major participation in the preparation of the international IFMIF project