Numerical Modelling of Electro-Discharge Machining Process Using Moving Mesh Feature

Studying the variation of the electro-discharge machining (EDM) process outputs due to the change in shape of the generated pulse is one research aspect in the EDM process. In this study, the effects of voltage excitation of the pre-ignition spark pulse on the process outputs material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (Ra) have been investigated. Experiments were designed using design of experiments (DOE), and the results were analyzed using analysis of variance (ANOVA). Based on the results, it has become clear that applying voltage excitation of the pulse produces effective pulses, which in turn lessens EWR, increases MRR, and improves surface quality. Hence, the suitability of this method has been verified for EDM.

In this work, sparking electro-discharge machining (EDM) process parameters are optimized by using multiple criteria decision-making (MCDM) methods. The work piece utilized for the investigation was LM25 aluminum alloy reinforced with Vanadium carbide (VC), processed through a stir casting technique. The EDM process parameters that have been considered in this work are by peak current, pulse-on-time, and pulse-off-time, with the effects of each variable and their combinations on the performance metrics of EDM like material removal rate, electrode wearing rate, and surface roughness. In this study, three MCDM methodologies were applied to evaluate EDM performance. Then, the obtained MCDM scores were compared using two different objective verification mechanisms. In this case, the VIKOR technique delivered the best-desired results relative to TOPSIS method, and factorial analyzing method. Also, the factorial method is simpler than the other methods, though it produced nearly identical results as the sophisticated MDCM method.

Most of the components used in automobile and aerospace industries are replaced by advanced materials such as Metal Matrix Components (MMCs) and Inconel. So in this area, drilling is most popular method used for joining, bolting and riveting purpose. Inconel-718 is a high strength, temperature resistant (HSTR) nickel -based super alloy. It is extensively used in aerospace applications, such as gas turbines, rocket motors, and spacecraft as well as in nuclear reactors, pumps and tooling. Inconel-718 is difficult to machine, because of its poor thermal properties, high toughness, high hardness, and high work hardening rate. Therefore, many researchers have tried for an alternative source by many conventional and nonconventional machining processes. Electro discharge machining (EDM) is widely used non conventional machining process for such materials. Hence, in this paper some efforts are taken to investigate the effect of different EDM process parameters such as current, dielectric flow rate and pulse on time on the tool wear rate (TWR) and grading of deburred holes by visual inspection for burr removal in drilled holes of Inconel-718 material. In this study burr removal operation of drilled holes via EDM process is carried out. Two types of electrode materials such as Aluminum and Brass with cylindrical taper geometry at tip is used. The experiments are performed using Taguchi method of design of experiment and L27 orthogonal array. The results indicate that only current is most significant parameter affecting for tool wear rate (TWR) as well as grading of drilled holes by visual inspection. Secondarily, SEM photographs of deburred holes indicate that effective burr removal operation using Brass electrode compared to Aluminium provides better solution for Inconel-718 material.

In modern mechanical engineering, machine parts and mechanisms are made of new materials. These materials are characterized by enhanced mechanical properties. Expensive are products made from them. Deterioration of working surfaces leads to the need to replace the entire part. About 80% of the part is not subject to wear. The method of laser surfacing allows you to restore the part. The operability of the mechanism is returned. Cost-effectiveness is increasing. The processing of deposited surfaces is difficult. The properties of mechanical surfacing increases and cutting with a blade tool is not possible. Electroerosive technologies are beginning to be actively used in the processing of deposited parts. The study of the electro discharge machining (EDM) process of such details is now relevant. After EDM, the formation of the roughness of deposited surfaces has not been fully studied. The aim of the work is an experimental study of the EDM process of such surfaces. It is important to study the effect of EDM modes on the formation of roughness is important. A full factorial experiment was conducted during the study. EcoCut wire-cutting EDM machine selected as experimental equipment. Brass wire d = 0.25 mm is used as an electrode tool. The deposited material titanium VT-01 is selected for the experiment. An empirical model was obtained during the experiment. To establish the relationship between the EDM modes and the quality of the processed surface allows the model. An increase in the stress (U, mm) and the height of the workpiece (N, mm) leads to an increase in the roughness of the treated surface (Ra, μm) when processing titanium was found. The maximum roughness value for Ra = 3.3 μm is achieved at a voltage of U = 25 V, duty cycle q = 3.5, and a workpiece height of 10 mm.

In recent years, several nature-inspired optimization methods have been proposed and applied on various classes of problems. The applicability of the recently developed socio-inspired optimization method referred to as multi-cohort intelligence (Multi-CI) is validated by solving real-world problems from manufacturing processes domain, viz. non-traditional manufacturing processes. The problems are minimization of surface roughness for abrasive water jet machining (AWJM), electro-discharge machining (EDM), micro-turning and micro-milling processes. Furthermore, the taper angle for the AWJM, relative electrode wear rate for EDM, burr height and burr thickness for micro-drilling, flank wear for micro-turning process, machining time for micro-milling processes were minimized. It is important to mention that for the micro-drilling and micro-milling process different tool specifications were used. In addition, for EDM the material removal rate was maximized. The performance of the algorithm has been validated by comparing the results with other variations of CI algorithm and several contemporary algorithms such as firefly algorithm, genetic algorithm, simulated annealing and particle swarm optimization. In AWJM, Multi-CI achieved 5–8% and 8–23% minimization for surface roughness and taper angle, respectively. For EDM, 47–80% maximization of material removal rate; 2–13% and 92–98% minimization of surface roughness and relative electrode wear rate, respectively, have been attained. Furthermore, for micro-turning 2% minimization of flank wear and for micro-milling, 2–6% minimization of machining time were attained. For micro-drilling, 24% and 16–34% minimization of burr height and burr thickness were attained. In addition, the performance is compared with the regression and response surface methodology approaches and experimental solutions. The analysis regarding the convergence of all the algorithms is discussed in detail. The contributions in this paper have opened up several avenues for further applicability of the Multi-CI algorithm for solving real-world problems.

In the present work, polanga oil has been used as the bio-dielectric for the machining of P20 steel by the electro-discharge machining (EDM) process with a tool made up of pure copper. As the pure polanga oil has a high viscosity (72cSt at 40 ℃), it has been chemically processed to make it suitable to be used as a dielectric fluid. The process parameters, viz. sparking current, pulse ON time (Ton) and pulse OFF time (Toff) have been used to investigate the EDM process. The material removal rate (MRR) and surface roughness (Ra) have been considered to evaluate the EDM process. The experiments were conducted using bio-dielectric polanga oil as well as the conventional dielectric fluid, i.e., kerosene. It has been observed that the MRR is improved by 0.08–0.77 times when machined with polanga oil as the dielectric. However, no significant improvement is observed in the surface finish when polanga oil is used as a dielectric.KeywordsEDMPolanga oilBio-dielectricMRRSurface roughnessP20 steel

The use of a foil tool in the electrodischarge machining (EDM) process has been shown to be effective for slicing, fabrication of micro slots, and various other applications. EDM with a foil tool has an advantage over wire-EDM as it allows the use of a foil tool with a thickness less than the wire diameter and to use higher discharge current due to the no risk of tool breakage. This work attempted to fabricate through-holes of various shapes on the D2 steel plate by removing material only from the periphery using a Cu foil tool, rather than the entire cross-sectional area. The thin foil tools are brought into respective shapes by wrapping them around Cu blocks having a cross-sectional area of the respective shapes. Gravity assistance is preferred to be employed as it has been experimentally found that it improves the linear material removal rate (LMRR) up to 24.86% compared to EDM without gravity assistance at various discharge current levels and pulse on time. Further, for a gravity-assisted EDM process using the foil tool, the LMRR has been improved up to 54.43%, with a selection of suitable duty cycle settings. The set of process parameters with the highest LMRR was chosen to fabricate through holes of circular, elliptical, square, and triangular cross-sections. The time required to machine through holes of various shapes was found to be proportional to the perimeter of the cross-section.

Drilling is one of the conventional methods of producing a hole of the desired shape by removing material with the help of a cutting tool named drill bit. The process of drilling a hole usually leaves behind an undesirable burr at the exit surface of the workpiece. In this experimental work, the design of experiment (DOE) has been carried out as per Taguchi’s L27 orthogonal array with an objective to minimize the height of burr (exit side) of stainless steel (SS) workpieces. The effect of process parameters like varied cutting speed, changes in feed and cutting fluid on burr height as well as machining time has been explored and the optimum condition for minimizing burr height under normal condition, using adhesive and with a backup support is determined by the entire experimental analysis. Response surface methodology and analysis of variance (ANOVA) have been performed to find out the optimum process parameters on burr height and machining time. With the progress of experiment, it has been observed that burr height is greatly influenced by the variation of speed, feed and cutting fluid whereas, cutting fluid has less impact on machining time reduction as compared to the varied speed and feed with adhesive and backup material condition.

In current manufacturing science and engineering application, material selection is an important criterion. Hybrid metal matrix composite (MMCs) has emerged as an important growing demand for manufacturing field like aerospace, automotive and electronic engineering due to its excellent mechanical, physical and thermal characteristics in comparison with convectional materials. The distinctive features of electrodischarge machining (EDM) and high exhaustiveness lead to improve the machining characteristics of MMCs. In this current research work, EDM technique has been applied in order to machine hybrid Al-7075 composite to obtain the high product quality and improve the performance level. The impetus of this research paper is to investigate the optimum parameters to reduce the machining time with high material removal rate (MRR), low surface roughness (SR), low tool wear rate (TWR) and frequency by varying the input parameters such as current, voltage and pulse-on time(Ton), pulse-off time (Toff) and arc gap. Several experimental runs are conducted by using L16 orthogonal array (OA), and prime parameters were predicted by ANOVA technique with effective parametric contributions. From the result, it is found that Grey–Taguchi method gave better optimization result with error percentage as compared to simple Taguchi method and also found current and voltage, Ton gave higher contribution in the time of machining in comparison with other parameters.KeywordsEDMMMCsMRRSRTWRTaguchiANOVAGrey–Taguchi

Study of Micro-groove Generation on Titanium Alloy (Ti6Al4V) using Novel WEDM and WECM Sequential Electro Micro Machining (SEMM) Technique

Systematic investigation on the use of cylindrical tools for the production of 3D complex shapes on CNC EDM machines

Electro discharge machining (EDM) is a process that uses an electric sparks to generate the high temperature and melt the workpiece. One of the EDM process is drilling. In EDM drilling, an electro thermal mechanism is introduced between the electrode and work piece to create the hole. The hole size is dependent on the diameters of electrode used during the drilling process. The present study performs Taguchi method to investigate the optimal process parameters for high-speed EDM super drill machine that is used to make a small hole. The workpiece used is made from titanium alloy (Ti-6: ASTM B348 Grade 5) and the copper electrode is 2.0 mm in diameter. In this experiment, the process parameters that were selected to be optimised are: current pulse off, maximum current and standard voltage levels. An orthogonal array L9 were employed to analyze the hole enlargement and material removal rate (MRR) depending on 2.0 mm diameter hole penetration. The optimum EDM parameters for hole making process was established and verified with the acquired results.

Nickel based alloys have found their wide range of applications in the automotive, oil and gas, and aerospace industries due to their excellent mechanical and thermal properties. However, these alloys impose greater challenges to conventional machining techniques due to their extreme hardness. Therefore, non-traditional machining process like micro-electro discharge machining, which is a non–contact machining process, comes into consideration. In this study, the machinability of Ni based X-alloy was investigated using micro-EDM process with the aid of coated and uncoated tools. From the experimental results, it was evident that the machining time was reduced with the increase of discharge energy for both the coated and uncoated tools. Increase in discharge energy also resulted in enlargement of entrance diameter and overcut. However, the non-conductive nature of coating caused in the reduction of overcut for machining using coated tools. The tool wear was found to reduce with the increase of discharge energy due to shorter machining time at higher discharge energy. Finally, crater size also increased with the increased discharge energy. The coated tools resulted in bigger crater sizes than uncoated tools at 1000 rpm, however, for higher tool rotation the difference was not significant.

Innovation is the only pathway for manufacturer, visionary and scholars, to improve the quality of human beings daily life. This is where robotics and mechatronics engineering has been adopted since 1984, as one of the most pioneering solutions to many of our industrial challenges. The distinction about such resolution is its flexibility to meet the well-known innovation platforms, i.e. empowering, sustainable and efficient innovation. It's the creatively of applied research to implement some superintendent roles rather than creation ones. Industrial market has become very challenging to secure businesses, maintain products development, and sustain its growth, since it is not any more about knowledge and existing know-how. It is nowadays about what industrialist can embed into their evolving products using cutting edge emerging technology and how they manufacture it. This is where the International Journal of Robotics and Mechatronics (IJRM) will play a vital role, through the exchange of the innovative ongoing research and development in this area of intelligence and automation across the world. The first issue of the IJRM Journal presents selection of high standards research and development papers that bring together the latest ongoing and developed endeavours. The first paper by Takahiko Nakamura and Satoshi Suzuki (Tokyo Denki University, Japan) focused on childcare service and presented an automatic method to develop an indoor mapping system using the SLAM technique. The outcomes of this research introduce a novel automation system to maintain good childcare service and support kindergarten staffs using objective monitoring system. The paper by Masafumi Miwa and Sinya Marubashi (Institute of Technology & Science, The University of Tokushima, Japan) presents an innovative 3-axes Ducted Fan Flying Object (DFO3) for Radio Controlled Unmanned Aerial Vehicle (UAV). UAV is mainly used in aerial photography and aerial investigation. The newly developed DFO3 equipped with normal and reverse rotation ducted fan and is to cancel the Gyro moment effect and provide the necessary industrial safety standards required. The development presents a real breakthrough and succeeded to achieve a stable take-off, landing and hovering. The next papers deal with some of the existing industrial challenges in robotics and mechatronics engineering and provide a number of ground-breaking solutions, for instant: Takayuki Matsuo, et al, (Kitakyushu National College of Technology, Japan) presents a design method for a phase lag adjustment system using neural oscillators for a snake-like robot. The research offers a motion control system that enables a snake-like robot to adjust the phase lag of target joint trajectories according to changing environments. Mahmoud Shafik (College of Engineering and Technology, University of Derby, UK) presents the state of art of the latest development in Electro Discharge Machining (EDM) system technology. The paper covers the current and recent development using the electromagnetic and piezoelectric ultrasonic servo control feed drive technology. It also demonstrates how the ultrasonic technology renovates the EDM system and transfers its industrial applications into a new era. EDM process is one of the most common processes in automotive and aerospace industry. EDM is principally used to machine and process alloys and very hard materials for key manufacturing components, such as film cooling holes for Turbine Blades, engine strip sheets, steel sheets for automotive industry, outer vehicle body… etc. Murali Krishna (Intelligent Systems and Robotics Division, India) presents a biologically inspired Central Pattern Generator (CPG) based controller for a quadruped minimule robot. The CPG based minimule robot offers a real opportunity to realise both trot and walk gait by varying the phase relationship between the limbs and is stable due to the inherent property of CPG. Takahiko Nakamura (Tokyo Denki University, Japan) focused on childcare service and presented an automatic method to develop an indoor mapping system using the SLAM technique. The outcomes of this research introduce a novel automation system to maintain good childcare service and support kindergarten staffs using objective monitoring system. The final paper of this issue is focused in one of the 21st century renewable energy storage source challenge. It introduces a pioneering approach to optimise and minimise the cost of supercapacitor-battery. Chia Yen Yee, Niusha Shafiabady, Dino Isa (The University of Nottingham, Malaysia) presents an approach to optimise the size of a supercapacitor-battery hybrid energy storage system for solar applications using the Genetic Algorithm. The potential contribution of this approach is optimising the cost of the Supercapacitor-battery hybrid energy storage system in renewable energy system which cannot be solved in most of the commercial simulation tools, such as HOMER and HYBRIDS. We hope that all of you find the issue inspiring beneficial and has also given you a good on-site of the ongoing research and development in this fascinating fast-moving area of innovation and technology. We look forward to receive your contribution to the future journal issues. Mahmoud Shafik

In 5-axis machining, the initial orientation and position of the part in the fixture on the machine table are chosen to avoid collisions and to ensure that axes ranges are respected. However, kinematics of the machine is rarely considered for workpiece setup optimization although it affects the tool path execution and machining time. Indeed, for complex surfaces, actual feedrate is often lower than the programmed one and can present strong slowdowns, which are critical for the tool cutting conditions and therefore the part quality. This article investigates the use of kinematic manipulability criteria to determine the best orientation of the workpiece setup to maximize the actual feedrate and reduce machining time. The modelling of maximum velocity, acceleration, and jerk of each axis by means of polytopes makes it possible to take advantage of the whole kinematic space of the machine more intuitively. Simulations and experiments are carried out in 3 + 2-axis machining on test parts with a ball-end tool. For stretched surfaces, while the tool centre motion is given by the machining strategy, the tool axis orientation is optimized jointly with the workpiece setup. Experiments confirm that actual feedrate raises faster to better respect the programmed cutting conditions along each path. As feedrate is also higher, machining time is reduced significantly.