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The production of electrical discharge machining (EDM) electrodes by conventional machining processes can account for over 50 % of the total EDM process costs. The emerging additive manufacturing (AM) technologies provide the possibility of direct fabrication of EDM electrodes. Selective laser sintering (SLS) is an alternative AM technique because...
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... manufactured EDM electrodes were also used to per- form a characterization of some properties such as density, porosity, and electrical conductivity. Table 3 summarizes the results from the characterization measurements performed. The measured porosity of the electrodes was similar to the estimated porosity discussed above, reaching an acceptable level of porosity when considering the pressureless nature of the sintering process involved in SLS. ...
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... Additive manufacturing (AM) can be utilized to manufacture EDM electrodes from materials that are either conductive or non-conductive [106,123]. In this subsection, a detailed description of relevant studies concerning conductive materials is provided. ...
... The electrodes were deemed unfit for industrial use due to the variation in copper coating thickness across the entire part. Amorim et al. [106] investigated the selective laser sintering (SLS) method for manufacturing tool electrodes. The materials used in the process were pure copper powder, DS20 steel alloy powder, bronze-nickel (Br-Ni) alloy powder and a mixture consisting of 50% pure copper and 50% standard bronze-nickel alloy powder. ...
In electrical discharge machining (EDM), the tool electrode is one of the substantial components of the system, and it ensures the success or failure of the EDM process. The electrode's role is to conduct electrical charges and erode the workpiece to the desired shape. Different electrode materials have different impacts on machining. Certain electrode materials remove metal quickly but wear out rapidly, while others degrade slowly but the material removal is too slow. The choice of the electrode has an influence on both the mechanical properties, such as metal removal rate (MRR), wear rate, surface finish, surface modification and machinability, and the electrical properties, such as sparking initiation, time lag, gap contamination and process stability. There are factors to consider when fabricating an electrode, which include the type of workpiece materials, the metallurgical alloying of the materials, the choice of fabrication techniques, the intended use of the electrode, and material cost. Considerable challenges in EDM electrode fabrication have been reported, which include excessive tool wear for green compact electrodes, high toughness for sintered electrodes, and poor rigidity for additively manufactured electrodes. To address these issues, researchers have explored different manufacturing methods, such as casting, conventional machining, electrodeposition, powder metallurgy and additive manufacturing. In this paper, the various techniques attempted and adopted in EDM electrode manufacturing are analyzed and discussed. This paper also sought to give insight into EDM, its various forms, the dielectric fluid's properties, EDM electrode's size and shape, the effects of the electrode on the EDM process, material removal, electrode wear, present technologies for electrode fabrication, and the limitations of these technologies. Finally, directions for future research are highlighted.
... Unfortunately, this coating or thin metal layer may be unreliable during EDM given the electrical load involved. Therefore, EDM tool manufactured by selective laser sintering (SLS) method from metal powder offers interesting opportunities in this area due to reduced tool wear and increased performance [7][8][9]. Similarly, researchers have investigated performance of different composite tools during EDM process [10][11][12][13]. Likewise, researchers have investigated on applications of RP tool in EDM process, where, RP tools have been fabricated by using nonconductive plastics and polymer materials with conductive coating of copper [2,[4][5][6][14][15][16]. ...
The present study explores the application of rapid prototyping (RP) for manufacturing tool electrodes in electro-discharge machining process. The performance of a metallic electrode built via selective laser sintering is compared to solid copper and brass tools during machining of D2 tool steel. In order to efficiently evaluate the influence of several parameters, Taguchi's L 18 design is adopted to plan the experimental layout. The machining parameters considered in this study are tool type, a categorical parameter and three quantitative parameters such as duty cycle, pulse-on-time and peak current. Multiple performance measures such as material removal rate, tool wear rate, surface roughness and radial over cut of the machined cavity are considered. The multiple performance responses are converted into an equivalent single response known as grey relational grade using grey relational analysis. A nonlinear regression model is developed to relate grey relational grade with process parameters with a coefficient of determination of 0.97. In order to obtain optimal parameter settings satisfying the performance measures, three meta-heuristic algorithms are used due to their computational elegance. The comparative study indicates that particle swarm optimization and simple optimization are effective in delivering the optimized results in substantially less time compared to teaching-learning-based optimization algorithms. It is found that RP tool can perform in a superior manner for simultaneous optimization of multiple responses when compared to copper and brass tools.
... 9 Besides, porosity remains a major problem in electrodes fabricated by SLS due to which strength of the produced electrode is low. 14,15 FDM produces electrode of acrylonitrile-butadiene-styrene (ABS) and to make it suitable for EDM application its metallization is done using wellestablished techniques reported in the literature. [16][17][18][19] Hence, FDM has great potential for the production of EDM electrodes but is relatively less explored. ...
In the present study machining performance of a novel ABS P400 based EDM electrode is experimentally investigated. Three EDM parameters that is, current ( I), pulse on time ( T on ) and pulse off time ( T off ), each at three levels, are considered, and mild steel is machined using these electrodes according to the response surface methodology (RSM) based face-centred central composite design (FCCCD). Machining performances such as material removal rate ( MRR), tool wear rate ( TWR) and surface roughness ( SR) are measured. Experimental results are analysed using analysis of variance (ANOVA), response graphs and 3D surface plots. Current is found to be the dominating parameter for MRR, TWR and SR. The optimal combination of EDM parameter for multi-performance is determined using teaching-learning based optimization (TLBO) algorithm. The effectiveness of the new electrodes is established by comparing their machining performances with the already developed electrode at the same machining parameter setting. MRR resulting from the new electrode and also its TWR are found to be in good agreement with those of already produced electrodes. However, SR of the machined surface using new electrodes is found to be relatively higher.
... The application of this force generates a series of discontinuous electrical discharges (called sparks) that produce local temperatures sufficiently high to melt or vaporize the metal in the immediate region of the discharge. During machining, the EDM process by penetration involves nine stages: (1) The nearing of a charged electrode towards the part, producing a discharge between the nearest surfaces (the dielectric liquid avoids the formation of premature discharges, cooling the machined area and removing metal chips); (2) The generation of an "energy column" in the fluid (perforation of the medium) when the electric potential difference is large enough, such that a discharge path is created between the electrode and the workpiece (at this stage the voltage reaches the maximum value, but the current intensity is still zero); (3) The starting of the activation time or impulse time (ti), defined as the time where the machining takes place-the higher ti, the higher the surface roughness of the part (vaporization begins); (4) The heat increases at the same rate as the current intensity (vaporization continues); (5) During this stage, the instant in which vaporization stops, fusion begins, increasing the contamination of the dielectric; (6) Near the end of the process, the current and voltage are stabilized, the heat and the pressure inside the vapor bubble reach the maximum, and part of the metal starts to be removed from the base part; (7) The system is disabled, both the voltage and current intensity drop to zero (this is the deactivation time or pause time, t0, defined as the time between two impulses), the temperature decreases and the melted metal is removed; (8) The collapse of the vapor bubble in the previous stage generates a void which is filled with fresh dielectric, decreasing the contamination and cooling the base part, while the remaining melted metal solidifies forming the so-called "white layer" on the base part; (9) Once the contaminants and damaged dielectric are removed, a small crater is observed on the base part, as well as a slight wearing in the electrode. After this stage a new cycle begins. ...
... Due to the relevance of a high electrical conductive material as part of the EDM electrode, several studies were carried out with copper as part of the composition. For example, Czelusniak et al. [7,8] used PBF to sinter a composite formed by a metallic matrix (Cu-Ni) and a ceramic (ZrB2, TiB2). Both ceramics are known to be ultrahigh-temperature materials. ...
Atomic Diffusion Additive Manufacturing (ADAM) is an innovative Additive Manufacturing process that allows the manufacture of complex parts in metallic material, such as copper among others, which provides new opportunities in Rapid Tooling. This work presents the development of a copper electrode manufactured with ADAM technology for Electrical Discharge Machining (EDM) and its performance compared to a conventional electrolytic copper. Density, electrical conductivity and energy-dispersive X-ray spectroscopy were performed for an initial analysis of both ADAM and electrolytic electrodes. Previously designed EDM experiments and optimizations using genetic algorithms were carried out to establish a comparative framework for both electrodes. Subsequently, the final EDM tests were carried out to evaluate the electrode wear rate, the roughness of the workpiece and the rate of material removal for both electrodes. The EDM results show that ADAM technology enables the manufacturing of functional EDM electrodes with similar material removal rates and rough workpiece finishes to conventional electrodes, but with greater electrode wear, mainly due to internal porosity, voids and other defects observed with field emission scanning electron microscopy.
... By using the SLS process, one can produce a complex shaped electrode in a cost-effective and timely manner. SLS is a powder based technique in which parts are sintered in layers using a laser beam 4,5 . However, not all materials are amenable to SLS which makes it a bit difficult to adopt any material to be fabricated by SLS. ...
Electro-discharge machining is an extensively used manufacturing process. The process requires a tool electrode but the selection of the right material for preparing the tool continues to remain an engineering puzzle. This work makes use of a hybrid intelligent algorithm for selecting the right electrode out of three tool electrodes such as AlSi10Mg, copper and graphite for efficient electro-discharge machining of Ti6Al4V. The work began by constructing a Taguchi's L27 experimental design and then collecting the output data such as the material removal rate, tool wear rate, surface roughness, surface crack density, white layer thickness and micro-hardness. A simultaneous multi-objective optimization was performed to maximise the workpiece material removal rate while minimizing the remaining variables. For this purpose, a hybrid grey-TOPSIS based quantum-behaved particle swarm optimization was chosen and additional data gathered from scanning electron microscopy and energy dispersive spectroscopy techniques revealed new insights into the post-machining material behaviour such as the use of graphite electrode makes the machined surface far harder due to the dissociated carbon.
... The performance of Mo-CuNi tool electrode is found to be poor. Czelusniak et al. [8] have prepared ZrB 2 -CuNi metallic composite tool electrode by SLS process and studied its performance during electrical discharge machining of AISI H13 tool steel. The porosity of the electrodes increases with increase in laser scan speed, layer thickness and scan line spacing. ...
Nowadays, additive manufacturing (AM)-based rapid prototyping (RP) is used as a convenient route for making tool electrodes required in electrical discharge machining (EDM). AM enables direct fabrication of complex shaped EDM electrode in comparatively less time in contrast to subtractive machining processes. In this study, an EDM electrode is prepared directly by selective laser sintering (SLS) process using metal matrix composite of aluminium (Al), silicon (Si) and magnesium (Mg). To study the performance of the prepared RP tool electrode in electrical discharge machining, titanium is used as workpiece material and EDM-30 oil as dielectric medium during machining. The performance of the prepared tool electrode is compared with conventional copper and graphite tool electrodes. Experiments have been conducted changing EDM process parameters viz. open circuit voltage (V), peak current (Ip), duty cycle (τ) and pulse duration (Ton) along with three tool electrodes such as RP, graphite and copper tool electrodes. The performance measures considered during the experimental study are material removal rate (MRR), tool wear rate (TWR), average surface roughness (Ra), white layer thickness (WLT), surface crack density (SCD) and micro-hardness (MH) on white layer. SEM and EDX of the machined surface reveal that tool material is generally eroded and deposited on the machined surface with formation of metal carbides. However, tool erosion is more pronounced in case of RP tool electrode. XRD analysis reveals the formation of titanium carbides on the machined surface resulting in increase in the micro-hardness of white layer. Discharge current and tool type are found to be significant parameters influencing the performance measures considered in the study. The surface produced when machined with RP tool electrode exhibits superior surface characteristics while graphite tool electrode produces better MRR and TWR.
... In recent years, considerable researchers have been focusing on EDM for ZrB 2 -based UHTCs [16][17][18][19]. Due to high melting points of ZrB 2 -based UHTCs, they were used as electrode to reduce electrode loss and achieve precision structure [20][21][22][23]. On the other hand, for ultra-high temperature applications, they were machined into high temperature terminal components to measure physical and chemical characteristics in ultra-high temperature surroundings [4,5]. ...
Zirconium diboride-silicon carbide (ZrB2-SiC) ceramics are considered to be potential candidates for ultra-high temperature (> 2200 °C) applications due to unique combination of properties. However, it is difficult to machine micro-hole in ZrB2-SiC with a high precision by traditional methods owing to its highly mechanical strength. Here, an effective method to machining micro-holes on ZrB2-SiC ceramics was presented, by using a magnetic suspension spindle system (MSSS) electrical discharge machining (EDM) which possesses high response frequency. The objective of this experimental work is to study effects of machining parameters of MSSS EDM on discharge percentage, material removal rate (MRR), electrode wear rate (EWR), and lateral surface quality. Experimental results reveal that compared to micro-holes machined by conventional EDM, with the application of MSSS EDM, discharge percentage increased by at least 28%, and arc percentage decreased by at least 16.3%. Hence, MRR increased by at least 35% and EWR decreased by at least 51%. The inlet and outlet diameters of the micro-holes and the lateral surface of the holes significantly improved with using MSSS EDM. The experimental results demonstrate that compared to conventional EDM, MSSS EDM can be used to fabricate micro-holes on ZrB2-SiC ceramics with a higher efficiency and quality.
... Kiyak and Cakir examined machining parameters on surface roughness in EDM of tool steel using pure copper tool and observed that surface roughness of tool and workpiece was influenced by pulse duration and current, by increasing them the roughness also gets increased [8]. Some authors developed ZrB 2 -CuNi tool for EDM and described its applications [9]. Review of electric discharge machining also shows that efforts are being made to lower the tool wear and increase material removal in EDM process [10]. ...
... Stucker et al. [124] by means of indirect SLS and normal sintering process, manufactured copper-based zirconium diboride electrode that achieved better results than copper, graphite and W-Cu electrodes regarding wear and material removal rate. Czelusniak et al. [157] applied SLS to directly manufacture ZrB 2 -CuNi EDM electrodes. The authors compared EDM performance at roughing, semi-finishing and finishing regime with LS copper electrodes and electrolytic copper. ...
Over the years, sinking electrical discharge machining has become one of the most important production technologies to manufacture very accurate three-dimensional complex components on any electrically conductive material. This article reports a literature review on the diversity of conventional and non-conventional materials that are used or have potential to be used as EDM electrodes. In addition, additive manufacturing of EDM electrodes are also reviewed. © 2018, The Brazilian Society of Mechanical Sciences and Engineering.
... The tribological properties of any engineering surfaces can be improved by many other methods like surface coating, surface cladding, and surface nitriding, which produce a layer of metal matrix composite, whose thickness varies within the range of few hundred micrometers [4][5][6][7][8]. Recently, metal matrix composites (MMCs) have been a topic of great interest as it has a variety of demands in numerous fields because of its vital properties, such as low density, high stiffness-to-weight ratio, non-corrosive nature, and wear resistant properties [9][10][11]. Titanium alloy is a notably expensive material as compared to the other common engineering materials, but it has wide applications in various fields as it possesses good corrosion resistance properties [12], excellent biocompatibility, low elastic modulus, high specific strength. ...
In the present research, direct metal laser sintering (DMLS) method was chosen to fabricate titanium nitride (TiN) reinforcedTi6Al4V alloy based metal matrix composites (MMCs) under an argon atmosphere using continuous wave (CW) fiber laser having a capacity of 400 W. Laser sintering process parameters, such as layer thickness (0.4 mm), laser beam spot diameter(0.4 mm), and hatching gap (0.2 mm) were kept constant throughout the experiments. Effects of input variable process parameters, such as laser power (50–65 W), scanning speed (3500–4500 mm/min), and volume % of TiN (5–15% v/v) on density, microhardness, and coefficient of friction of the fabricatedMMCs were analyzed. The obtained results show the improvement in the physical properties of the fabricated MMCs and FESEM images evidently confirm the presence of TiN particulates and also revealed the uniform distribution of the TiN reinforcement in Ti6Al4V matrix. It was found that the microhardness measured by Vickers test was improved from 388 to 590 HV0.2 with an increase in the volume percentage of TiN. The results showed the coefficient of friction for fabricated samples were in the range of 0.33–0.42. The density (3.40–4.10 g/cm3) of the MMCs was found to increase with increasing the volume percentage of TiN reinforcement in the powder mixture. X-ray diffraction (XRD)analysis of the fabricatedMMC confirmed the presence of different in-situ phases, such as Ti, TiN, TiO2, VN, AlV, Ti3Al2N2, andV6N2.7 as a consequence of a series of a chemical reaction between TiN and different elements of Ti6Al4V in the argon atmosphere.
