Unconventional Machining Processes Research Articles

Surface and subsurface investigation of Al-Mg-MoS2 composite on performing wire electrical discharge machining

Metal matrix composites (MMCs) give challenges during machining because of the reinforcements present in them as this ultimately leads to increased tool wear and a poor surface finish. Considering this, Al-Mg-MoS2 composite samples prepared using powder metallurgy process are employed under unconventional machining process like wire electrical discharge machining (WEDM), since the composites prepared to possess a higher hardness and strength compared to that of pure aluminium. The machining is done under 3 different factors operated at 3 levels, peak current (10 A, 15 A & 20 A), pulse on time (60 μs, 90 μs & 120 μs), and gap voltage (40 V, 45 V & 50 V) to analyze the material removal rate (MRR), surface roughness (SR) and overcut (OC). The surface texture of the machined samples is analyzed with scanning electron microscopy (SEM) and the recast layer so formed has also been analyzed. It is detected that the recast layer is found larger for larger surface roughness due to the higher spark energy at high-level peak current. Also, an optimal parameter of 15 A peak current, 45 V gap voltage and 90 μs pulse on time and 4% of MoS2 is determined through main effect plots for better machinability of the samples to obtain a better MRR, SR and OC. A better MRR, an improved surface finish and a reduced OC is seen in Al − 4%Mg - xMoS2 composite samples than that of pure Al and Al − 4% Mg materials.

Feasibility analysis of novel Maglev EDM by comparing with conventional micro EDM

EDM is the most popular unconventional machining process. The present technology of EDM consists of a pulsed or capacitive type power supply in which the pulsed type power supply is more popular and effective. The following essential component of an EDM is its servo mechanism, which controls the gap between the electrodes and maintains the gap voltage. A low machining speed, complex power supply, and servo mechanism increase the cost of machining and the maintenance cost of an EDM machine. To resolve the above issues from the EDM, a novel servo mechanism has been developed, which is simple in design and low in cost and has the capacity to use direct current as a power source. The current work elaborates a brief description of the novel servo mechanism and its feasibility analysis. Pure DC power is employed with the conjunction of Maglev lucidity to refine the shortcomings of conventional micro EDM. The novel technology addresses the prime concerns of conventional micro EDMs and deficiencies such as the delayed response of mechanical actuators and a servo mechanism. The novel technology uses the logical arrangement of permanent magnets and electromagnets to address inadequacies such as short circuiting and arcing. The work outlook is to establish the viability of the novel Maglev EDM by a comparison with a similar range of parameters. The results on the novel technology showed an improved material removal rate (MRR), which was in the range of 76.6 μgm/min, whereas the specific energy and surface roughness were 33.4 Joule/microgram and 4.3 μm, respectively, while machining commercially pure titanium.

Advanced Processing and Machining of Tungsten and Its Alloys

Tungsten is a refractory metal with the highest melting temperature and density of all metals in this group. These properties, together with the high thermal conductivity and strength, make tungsten the ideal material for high-temperature structural use in fusion energy and other applications. It is widely agreed that the manufacture of components with complex geometries is crucial for scaling and optimizing power plant designs. However, there are challenges associated with the large-scale processing and manufacturing of parts made from tungsten and its alloys which limit the production of these complex geometries. These challenges stem from the high ductile-to-brittle transition temperature (DBTT), as well as the strength and hardness of these parts. Processing methods, such as powder metallurgy and additive manufacturing, can generate near-net-shaped components. However, subtractive post-processing techniques are required to complement these methods. This paper provides an in-depth exploration and discussion of different processing and manufacturing methods for tungsten and identifies the challenges and gaps associated with each approach. It includes conventional and unconventional machining processes, as well as research on improving the ductility of tungsten using various methods, such as alloying, thermomechanical treatment, and grain structure refinement.

Machinability study of Incoloy using different wire electrode in Wire-Cut EDM

Increase in the usage of nickel-based superalloys in the field of aviation, marine industry, nuclear reactor due to its excellent mechanical properties like corrosive resistance, carburization resistance especially at elevated temperature. Nickel based superalloys are very tedious to machine in conventional because of high strength, less conductivity of thermal, strain hardening property. In this study, one of the best Unconventional machining processes i.e., Wire electric discharge machining is used for machining of Inconel 800 (Incoloy). Zinc coated brass wire; Cryogenic cooled zinc coated brass wire electrodes are used in Wire cut EDM. RSM technique is used to plan experiments with Wire tension, Pulse on time and Wire feed as varying parameters, keeping Servo voltage and Wire feed as constant. Material removal and Roughness of surface are compared for Zinc treated brass and Cryogenic cooled (LN2) Zinc treated brass and optimizing responses i.e., by using lower the better and higher the better criteria.

Experimental investigation of Machining of stellite alloy

In recent days, the applications of advanced alloys in manufacturing industries have been increased due its superior substance properties. Stellite alloy comes under the category of cobalt-chromium super alloys. In this paper the machinability performance of stellite using different unconventional machining process such as spark erosion (SE) and laser beam (LB) technique were discussed. The fine holes were produced on the surface of the stellite 1 alloy. The comparisons of rate of material removal (RMR) were analyzed using different input constrains. The interaction and contribution of process factor on material removal rate were determined. Finally, it was concluded that laser machining was provided high metal removal than spark erosion process. More than 25% of metal removal was achieved through laser machining process.

Effect of wire materials on performance during WEDM of SS304

Traditional machining methods are being replaced by unconventional machining processes as the need for high surface quality, and machining of complicated form geometries grows, and Wire electric discharge machining (WEDM) is one of the unconventional machining processes. Stainless Steel 304 (SS304) is widely utilized in the aerospace, medical, electronic, and semiconductor sectors, as well as tool and die manufacturing. However, because of limited heat conductivity and a high built-up edge (BUE) affinity, industries encounter substantial complexities during traditional machining of SS304, such as excessive tool wear and high surface roughness values.Current study analyses the influence of current (I), pulse on time (Ton), pulse of time (Toff), and voltage (V) using two different electrode wire materials (Brass and Zinc coated brass), considering the numerous uses and obstacles in conventional machining of SS304 alloy. The material removal rate (MRR) and kerf of the machined surfaces were determined after each trial to determine the SS304’s machinability.Employing Taguchi's L18 orthogonal array, WEDM experiments were carried out in a WEDM machine using I (1, 3, 5 Amps), Ton (105, 110, 115 µs), Toff (25, 35, 45 µs), and V (20, 30, 40 V).From the experimental results, it was found that the coated brass wire had a higher material removal rate than the uncoated brass wire in the experimental trial. Low kerf was detected in an uncoated brass wire of the machined surfaces at the same time. Finally, grey relational analysis (GRA) was used to reduce the kerf and maximize the MRR simultaneously.

Investigating the effect of cryogenic treatment of workpieces and tools on electrical discharge machining performance

<abstract> <p>In this competitive world, manufacturers must embrace new technology in order to differentiate their products and capture market leadership. This can be achieved using advanced materials; however, these materials are difficult to machine by using traditional machining processes. A very viable and practical unconventional machining process is electrical discharge machining (EDM). EDM processes need proper selection of input parameters to get optimum productivity aspects, namely, the material removal rate and tool wear rate. Thus, the present study aims at investigating the effect of cryogenically treated work pieces and tools, gap currents, gap voltages, pulse on time and pulse off time on the material removal rate and tool wear rate during EDM of Nitinol (NiTi) alloy, Monel (NiCu) alloy and beryllium copper (BeCu) alloy. The experimental results showed that cryogenic treatment significantly improved the electrical conductivity of the workpieces and tool electrodes, which resulted in an enhanced material removal rate and reduced tool wear rate.</p> </abstract>

Development of a process signature for electrical discharge machining

Electrical discharge machining (EDM) is a versatile unconventional machining process allowing high precision manufacturing. Due to the thermal main active principle, the process-induced heat affected rim zone always needs to be particularly considered regarding its characteristics as the resulting surface integrity has to fulfill the needed functional properties for advanced applications. Today, no deterministic model is available especially for the residual stress prediction. As consequence, current process design is based on experience and heuristic optimization. The paper therefore mechanistically links the material modification and the process-induced load. Inversion of the according process signature component finally allows model-based process design.

Comparative study of copper and graphite electrodes performance in Electrical Discharge Machining (EDM) of die steel

Electro discharge machine (EDM) is one of the unconventional machining process used to remove material difficult to machine. Its unique characteristic is to machine that type materials which are hard and electrically conductive materials using electro-thermal energy that is difficult to machine using traditional machining methods like turning and milling etc. Die-steel has a wide range of practical applications, including punching tools, mandrels, mechanical press forging die, mould manufactureand so on. In this work, high carbon high chromium die-steel used as workpiece, electrolytic copper and pure graphite are used as a tool. In addition, parametric analysis have been completed by conducting a set of experiment using kerosene oil as dielectric medium. Impact on the surface roughness (SR), Material Removal Rate (MRR), and white layer (WL) due to the discharge current or peak current (I or Ip), pulse on time (Ton), pulse off time (Toff), and voltage have been studied. The experimental results reveal higher MRR for copper and graphite for sample having the same input parameters. However, MRR, SR, and WL all decreases when the pulse on duration (Ton) is prolonged.

Study of Machine Characteristics During Rotary EDM Machining using Tools Made of Aluminium Alloy 6061

Electro discharge machining (EDM) is an unconventional machining process that uses spark energy to remove material from the workpiece. EDM process is extensively being used in die/mould making industries, automobile industry, aerospace industry etc. for generating complex and intricate shape on hard material. Numbers of research works have been carried out using EDM process in order to improve the performance. Further, different variant of EDM process like dry EDM, orbital EDM, powder mixed EDM, ultrasonic assisted EDM and rotary EDM etc. have also been studied. Rotary EDM process is very promising process that helps to improve surface finish, overcut as well as out of roundness. In the present paper, a extensive review has been presented on rotary EDM process. Significance of several input parameters has been observed on output characteristics like overcut and out of roundness.

An investigation on gas emission concentration and relative emission rate of the near-dry wire-cut electrical discharge machining process.

Wire-cut electrical discharge machining (WEDM) is the highly essential unconventional electrothermal machining process to cut the contour profile in the hard materials in modern production industries. The various environmental impacting contaminants (by evaporating and reacting liquid dielectric fluid) have been produced during the conventional WEDM process and are harmful to the machine operators. These wastes have been minimized by the near-dry WEDM process in which the pressurized air mixed with a small amount of water is used as a dielectric medium. In this research, influences of machining parameters (air pressure, flow rate mixing water, spark current, and pulse width) on gas emission concentration (GEC), material removal rate (MRR), and relative emission rate (RER) of near-dry WEDM process have been optimized by the Taguchi analysis. RER has been determined to analyze the variations of gas emission concentration per unit quantity of material removal by changing the process parameters. It was revealed that the maximum air pressure and flow rate of mixing water have been predicted as significant parameters on GEC and RER. While comparing wet and near-dry WEDM processes, the material removal rate of near-dry process is comparable to that of wet WEDM with minimum GEC and RER.

Graphene applications in Unconventional Machining Processes –A review

Graphene is being involved widely in research worldwide because of its unique properties such as high thermal conductivity and electrical conductivity, which are very important in machining the hardest materials by Unconventional Machining Processes. Due to the unique properties of Graphene, the researches focusing on improving the performance of Unconventional Machining Processes diverts their researchers to analyze Graphene applications in those processes. Many types of research carried out in the analysis of Graphene as a wide variety of applications in Electrical Discharge Machining and Wire Cut Electrical Machining. In this paper, the applications of Graphene as a different role are reviewed and summarized.

Soft computing technique based modelling of ceramics mix electric discharge machining on LM-25/SiC composites

Silicon carbide mixed electrical discharge machining (SCM-EDM), an unconventional machining process that utilizes an electrolyte mix additive, combines the advantage of various energies (abrasive, heat). The aim of these articles is to investigate the impact of control variables on the machining performance of SCM-EDM using LM-25/SiC MMC. The major variable of SCM-EDM is identified as current intensity, pulse duration. The experimental run has conducted as per Box- Behnken design which produces statistical data solely based on the experiment run and estimates the measurement error. Artificial neural network (ANN) technique implemented to estimate experimental inputs and modelling of measure response such as material deletion rate (MRR), tool wear (TW), and surface roughness (SR). It is observed that predicted results from ANN model are compared with experimental result are quite satisfactory. The chemical composition and analysis of variance show the percentage contribution of each parameter on machining performance.

Modeling of hole geometrical features in laser drilling of AISI316L sheet

Micro-drilling of AISI316L is very challenging task. Unconventional machining process may be used for such type of operation. Laser beam drilling is a best for micro drilling. High thermal energy and converging-diverging property of laser beam affects the quality of laser drilled holes. In present work Nd:YAG laser beam has been used and investigate effects of laser input parameters on responses. To minimize number of experiments, get extreme information for experimental trials. Central composite rotatable design approach has been adopted. Analysis of variance is used to find reliable input parameters, are affecting responses. From this paper, it is found that current and gas pressure are significant for hole circularity at top. Current and pulse frequency are significant for bottom side circularity. Current and cutting speed are significant parameter for hole taper.

Experimental investigation and optimization of machining performance characteristics during WEDM of inconel 718: On evaluation of wire electrodes and advanced parameter techniques

Wire Electrical-Discharge-Machining (WEDM) is a well-known unconventional machining process to produce intricate shapes. However, obtaining a satisfactory WEDM cutting performance is indeed a challenging task during precision cutting. Hence, this investigation aims to attempt a favorable machining parameter setting in order to corner-cutting during WEDM for In-718. Here, machining performance characteristics have been considered based on corner deviation (CD) along with Material Removal Rate (MRR) and surface roughness (SR). Taguchi’s experiment design technique (L16) has been considered to run the experiments. The controllable process parameters are considered as Spark-on-time (Son), flushing-pressure (Fp), wire-tension (Tw), and discharge-current (Id). The aforesaid machining performance characteristics have been achieved through the two most popular wire electrodes, i.e., Zinc-coated brass electrode (Zn-BE) and Brass Wire Electrode (BWE), and compared the results. The comparison of performances by the wire electrodes on CD, MRR, and SR varied from 0.0286 mm to 0.0844 mm, 0.0045 g/min to 0.0214 g/min and 3.12 µm to 4.80 µm for BWE and 0.0218 mm to 0.0783 mm, 0.0090 g/min to 0.0342 g/min and 2.58 µm to 4.40 µm for Zn-BE respectively. However, machining with Zn-WE yields reduced CD, SR, and increased MRR value and shows less defect on the WEDMed surfaces than its counterpart. The present study developed the mathematical model based on non-linear regression for correlating the machining parameters with the machining responses. The next step of this study is that a unique optimization strategy, namely grey relation analysis (GRA) integrated with Teaching Learning-Based Optimization (TLBO), has been implemented for achieving optimal parametric setting. The satisfactory machining setting obtained from GRA-TLBO has been compared with GRA-JAYA and GRA-genetic algorithm (GA). The proposed methodology appears more fruitful in terms of computational time and effort.

Experimental application of a laboratory equipment for micro-electroforming using models manufactured with additive technology

One of the manufacturing processes applications on a microscopic scale, consists in modifying parts or components´ surfaces to improve their properties. Unconventional machining processes are needed to generate complex geometries, high details reproduction, and excellent finished surfaces at that scale. Micro sinker electrical discharge manufacturing (μ-SEDM) process could be one good option. The electrode manufacturing is one of the main drawbacks. It supposes a big resources waste before starting to manufacture. In this way, working on a microscopic scale becomes a challenge to obtain different shapes and textures on functional surfaces. In this work, combined use of micro-electroforming and digital light processing (DLP) additive manufacturing is presented. These two additive techniques are completely different and unrelated in their applications, materials, and technological fundamentals. However, their combination is a low-cost option to obtain good results in the manufacture of μ-SEDM electrodes. Therefore, it was necessary to develop a micro-electroforming equipment to meet the challenge. Furthermore, device had to have the ability to adapt the process parameters to the needs of the parts. As a result of this experimental application, we got high-quality parts, which could have an industrial application.

An extensive review on sustainable developments of dry and near-dry electrical discharge machining processes

Abstract Electrical discharge machining (EDM) is very essential unconventional electro-thermal machining process to machine the contour profile of hard materials in modern production industries. The liquid dielectric fluid has been replaced by the gas and minimum quantity of liquid mixed with gas (gas-mist) to encourage the green machining processes. The various gases and gas-mist have been used as the working fluid in dry and near-dry EDM respectively. The research-contextual, various dielectric fluids, sustainable and innovative developments, process parameters, machining characteristics, and optimization techniques applied in various dry and near-dry EDM have been illustrated through an extensive literature survey. Future research opportunities in both dry and near-dry EDM have been summarized to promote eco-friendly EDM research activities.

An overview on role of unconventional machining processes on different materials

In present days, the development and applications of unconventional machining processes got rapidly increased in modern industries. The quality and performance of the product are improved through unconventional machining processes. Hard materials are preferred to obtain high dimensional accuracy. The machining of complex shapes, super finishing, micro machining and surface is possible by unconventional machining process. The efficiency of production and machining precision were enhanced. The different types of machining methods were utilized to remove the materials. The different metal removal parameter such as erosion, Ionic dissolution, vaporization were analysed etc. The medium of energy were been transferred through electrolyte, electron and high voltage particles. This review article clearly describes the unconventional machining and hybrid machining processes on different materials.

EXPERIMENTAL INVESTIGATION OF MICRO-EDM OPERATION IN INCONEL 718

The increasing trends towards miniaturized and lightweight components for various engineering and aerospace applications by unconventional machining the demand for micro-electrical discharge machining (EDM) have become increasingly wide. Micro-EDM is one of the most promising unconventional machining processes as compared to other unconventional machining due to its lower cost, ease of operation, and accuracy. This research explores the experimental investigation of micro-EDM operation on hard and difficult to machine material Inconel 718. The micro-holes were fabricated on an Inconel 718 workpiece with a copper electrode. The influence of input process parameters on material removal rate (MRR), machining time, and quality of the fabricated micro-holes were studied. Overcut and taperness of the fabricated micro-sized through holes were measured to address the accuracy of the fabricated micro-holes in micro-EDM operation. Experimental results reveal that the increase in current and voltage increases the MRR, and reduced machining time but at the cost of dimensional accuracy of the fabricated holes. The high value of current and voltage resulted in poor surface quality. The optimum machining condition that gives higher MRR with higher machining precision was obtained by experimenting while machining Inconel 718.

Fabrication and Machining of Fiber Matrix Composite through Electric Discharge Machining: A short review

The Fiber Refinement Polymer Composites (FRPCs) are of great interest nowadays. Composites are employed in diverse areas such as automobiles, aerospace, and the military due to their multiple advantages for better mechanical, thermal, and fracture toughness features. Several researchers have constructed FRPCs using different natural fibers and matrix materials. However, to complete the assembly of the components or pieces, FRPC's actual applications require some secondary activities. Very few scientists discussed the machinability of these FRPCs. The main problems in fiber-reinforced composite plastic machining were discussed in this review concerning the most recent research in this field. In contrast, the unconventional and conventional machining processes were considered, this paper includes annual research in production, traditional machining, unconventional machining, and hybrid MMC machining. The final part of the paper addresses conclusions and future scope.