Unconventional Machining Processes Research Articles

A mathematical modelling of Abrasive Waterjet Machining on Ti-6Al-4V using Artificial Neural Network

Ti-6Al-4V is classified among the most commonly used Ti-alloys and is extensively used in aerospace and medical industries where low-density, high strength and outstanding corrosion resistance are required. This material cannot be processed by conventional machining methods because of its high strength. Abrasive Waterjet Machining, abbreviated as AWJM, is an unconventional machining process suitable for machining Ti-6Al-4V as it generates less heat affected zone. The quality of AWJM is governed by process parameters, the selection of these parameters is critical in this technology to achieve the desirable output measures. This paper provides an experimental investigation for the performance analysis of process parameters on machining Ti-6Al-4V using abrasive waterjet technology. In order to select appropriate parameters, a mathematical equations were developed using Regression Investigation Method (RIM) Artificial Neural Network (ANN) procedures. Based on the input and output data collected from the experiments, modelling is done and tested for the different set of data to ensure the accuracy. These mathematical models can be used to identify the static and dynamic behavior of the process. These models will further help in simulating the process, expanding the design facilities and studying the physical and chemical variation in the process. Models provide understanding the operations, control methods and the possible optimization. The developed models also help in documenting the performance of the existing system.

Optimization of Machining Parameters of EDM Of Al6061-Sic MMC Using Firefly Algorithm

In recent years, unconventional machining processes are the commonly used for machining the complex shapes over the hard materials with high precision. Among these processes, Electrical discharge machining is producing the better surface finish and easy to control the machining parameters. In this research, EDM process had used to drill the blind holes on the Al6061 SiC metal matrix composite to obtain the good surface finish, higher material removal rate and lesser tool wear by optimizing the pulse on time, current and flushing pressure using firefly algorithm. The identified optimal and feasible parameters had been used to fabricate the product and the characterization of machined work pieces were done using SEM and mechanical testing. In this machining process optimization, the relations between the machining parameters and the output performance have been developed through SPSS software and this relation had been utilized as the objective function for the firefly algorithm. Firefly algorithm is one of the emerging algorithms used to identify the optimal values for the NP-hard problem with multiple objectives and constraints. The obtained machining parameters through the firefly algorithm have been experimented and the test results are in the satisfactory level. So the research concluded that the firefly algorithm can be best suitable to identify the optimal EDM process parameters.

Vibration-assisted electrical arc machining of 10% B4C/Al metal matrix composite

To shape advanced engineering materials, many unconventional machining processes have been developed. Electrical discharge machining is such an unconventional machining process which is very popular nowadays but it is limited by poor material removal efficiency. Electrical arc machining is another unconventional machining process which is quite similar to electrical discharge machining and is now gaining attention from research fraternity due to its high material removal efficiency. In the present research, an innovative unconventional machining process known as vibration-assisted electrical arc machining has been developed. The performance of vibration-assisted electrical arc machining has been evaluated during machining of Al–B4C metal matrix composite by considering peak current, flushing velocity of dielectric and tool vibrations as input control factors. The quality characteristics considered were material removal rate, tool wear rate, relative electrode wear rate and surface roughness. It has been observed that vibration-assisted electrical arc machining results in approximately 3000% more material removal rate as compared to conventional electrical discharge machining during machining of Al–B4C metal matrix composite. The effects of various input control factors on output parameters have also been discussed. Further modelling and optimization of the process parameters has also been done by artificial intelligence approach.

Machine Ability Characteristics of PWEDM Process

The traditional machining consists of a specific contact between the tool and work piece. As a result of this contact the tool may wear out after a few operations. In addition to that, the MRR (Material Removal Rate), Surface Finish, etc. is also lowered. As a result of these drawbacks, traditional or conventional machining processes cannot be used to machine ceramic based alloys and thus we opt for unconventional machining process. The Electrical Discharge Machine contains of two spaces one is Electrode and other is Work piece. In this concept the among the tool wear rate is moderate and the surface roughness is to be poor. The tool cost is so high. Hence continuously tool modification is not possible. So in the work main objective of the problem is reduced the tool wear rate and increase the MRR. (Material removal rate). So in the case we are consider in the surface roughness. The surface roughness is to be high is the taken in industrial application. So we have focus with surface roughness. These are the considering with in our problems. In our aim is reducing the toll wear and improve the Material Remove rate. In order to addition of graphite in Electrolyte. When added the electrolyte in Graphite the Toll wear rate decrease and increase a material Removal Rate. Finally we have disc the DOE process

Experimental study on surface roughness by using abrasive jet machine

Abstract A machining operation is basically termed a material removal process, where material is removed in the form of chips. In a machining operation, the output parameter is achieved by controlling various input parameters. Abrasive jet machining process is an unconventional machining process. In this process a high velocity of abrasive particles directed to hit on the work piece to remove the material. Abrasive jet machining process is especially useful to perform operations on brittle materials, ductile materials. This process is mainly used for producing intricate shapes and also perform deburring and cleaning operations. Abrasive materials like aluminum oxide, silicon carbide etc. In this paper measuring the surface roughness on ductile materials like mild steel and also studying how aluminum oxide, silicon carbide abrasive particles effected on work piece.

A REVIEW ON VIBRATION-ASSISTED EDM, MICRO-EDM AND WEDM

Electrical discharge machining (EDM) is an unconventional machining process used for machining of hard-to-cut materials. Both EDM and micro-EDM processes are extensively used for producing dies and molds, complex cavities, and 3D structures. In recent years, researchers have intensively focused on improving the performance of both micro-EDM and EDM processes. This paper reviews the research work carried out by the researchers on vibration-assisted EDM, micro-EDM, and wire EDM. The consolidated review of this research work enables better understanding of the vibration-assisted EDM process. This study also discusses the influence of vibration parameters such as vibration frequency and amplitude on the material removal rate (MRR), electrode wear rate (EWR), and surface roughness (SR). The important issues and research gaps in the respective area of research are also presented in this paper.

Material synthesis, characterization, and machining performance of stir cast beryllium copper alloy composites

Copper alloys have important industrial roles due to their excellent properties. Beryllium copper is one of the copper-based alloys with the highest strength and excellent metal working and machining properties. Beryllium copper alloy composite is fabricated by the stir casting method. Its characteristics are studied with scanning electron microscopy and energy dispersive analysis of X-rays. The material properties of the stir cast beryllium copper alloy composites are evaluated. Hardness can be increased by the addition of silicon carbide particles. Abrasive water jet machining is an effective unconventional machining process, in which high pressure water jet and abrasive particles are used to remove material. Response parameters such as material removal rate and circularity of holes are considered. Response parameters of abrasive water jet machining are compared to electrical discharge machining. The most influential factor for the responses is determined by analysis of variance. Optimization of machining parameters is performed with the Taguchi method.

Electrical arc machining: Process capabilities and current research trends

Electrical arc machining is the thermal energy-based unconventional machining process, which utilizes energy of arc to melt and vaporize workpiece material. Electrical arc machining has the capability to machine advanced materials such as metal matrix composites, superalloys, and conductive ceramics effectively. The process is considered to be efficient than most of the other unconventional machining processes in terms of the material removal rate. But it has got limitations because it results in a very poor surface finish. Tool wear rate, recast layer formation, surface and subsurface cracks, and geometrical inaccuracy are other limitations up to a certain extent. In this paper, the comprehensive review of research carried out so for in the area of electrical arc machining has been presented. The paper discusses the detailed experimental and theoretical studies done on electrical arc machining to elucidate the effects of various input control factors on different quality characteristics. The paper also contains modeling and optimization studies done so far in electrical arc machining and finally discusses the future research possibilities in the area.

Parametric optimization in modified air abrasive jet machining

PurposeThe choice of best machining parameters is an extremely basic factor in handling of any machined parts. The purpose of this paper is to exhibit a multi-objective optimization technique; in view of weighted aggregate sum product assessment (WASPAS) technique toward upgrade the machining parameters in modified air abrasive jet machining (MAAJM) process: injecting pressure, stand-off distance (SOD), and abrasive mesh size measure with 100 rpm rotatable worktable on Nickel 233 alloy material. Three conflicting destinations, material removal rate (MRR), surface roughness (SR) and taper angles (Ta), respectively, are considered at the same time. The proposed procedure uses WASPAS, which is the examination of parametric optimization of the abrasive jet machining (AJM) process. The results was used any scopes of reactions in MAAJM process is the ideal setting of parameters are resolved through investigations represented. There is wide utilization of Nickel 233 in aviation enterprises; machining information on producing a hole utilizing MAAJM for the first time is given in this work, which will be helpful different industries.Design/methodology/approachThis paper exhibits a multi-objective optimization technique; in view of WASPAS technique toward upgrade the machining parameters in MAAJM process: injecting pressure, SOD, and abrasive mesh size measure with 100 rpm rotatable worktable on Nickel 233 alloy material.FindingsAs an outcome of using the tool in any ranges of responses in the AJM process, the optimal setting of parameters is determined through experiments illustrated. The machining data of generating a hole using AJM are studied for the first time in this work, which will be useful for aerospace industries, where Nickel 233 is used broadly.Originality/valueA new material in unconventional machining process and also a multi-objective optimization technique are adopted.

Influence of inner-spraying rotating tool during electrochemical milling of Nimonic-263 alloy

ABSTRACTElectrochemical milling (EC milling) has great possibility in consequence of its flexibility and applications in the various manufacturing industries, especially in defense and biomedical industry. In future, it is likely to be one of the most capable, successful, and commercially used unconventional machining processes in the up-to-date manufacturing industries. In this research work, an attempt has been made to develop a versatile in-house EC milling setup to study the impact of inner-spraying rotating tool on the different responses of EC milling. Experiments have been performed on a special type of nickel-based (nickel–cobalt–chromium–molybdenum) superalloy commonly known as Nimonic-263 alloy specially developed for high-temperature and high-strength applications to identify the impact of major process parameters, e.g., feed rate and milling layer depth with and without tool rotation, on the responses like machining depth, side angle, surface roughness, and quality of machined profile. During EC milling of Nimonic-263 alloy, excellent surface finish ranging from 0.06 to 0.08 μm has been attained by employing mixed electrolyte, i.e., NaCl (1 M) and NaNO3(1 M). With the incorporation of inner-spraying rotating tool, flushing can be improved to a large extent which improves the accuracy of machining.

Uticaj brzine rezanja i dubine reza na geometriju prednje linije reza pri obradi abrazivnim vodenim mlazom

Abrasive water jet machining is an unconventional machining process, which is increasingly being used. It is suitable for cutting complex contoured elements, in all types of materials. The major disadvantages of this machining technique are ununiform quality of the machined surface at different depths of cut, lagging of the cut front of the machined surface from the vertical plane and the phenomenon of striation patterns on the cut surface. The striation patterns on machined surface are the trail of the abrasive water jet through the material, and as such, they represents the cut front. Striation may result in different flaws occurring at cutting closed contours and may cause irregularities at cutting angles. The objective of this paper was to determine traverse speed and depth of cut effect on the cut front geometry i.e. on the striation geometry. The experiments were carried out on 6 mm and 10 mm thick samples of aluminum alloy AA 6060 (EN AW-6060; ISO AlMgSi). Samples were machined with several traverse speeds. The lagging of the cut front, at different depths of cut, was measured and analyzed. The obtained results enabled us to define the influence of traverse speed on striation geometry.

A review on optimization of machining performances and recent developments in electro discharge machining

Electro discharge machining (EDM) is a popular unconventional machining process widely employed in die-making industries. Careful selection of process parameters such as pulse current, voltage, on and off time, etc. is essential for machining of hard and conductive materials using EDM. Previous researchers working in the area of EDM have extensively analyzed the machining performance through experimental study, modeling, and simulation and also by theoretical analysis. This article discusses the significant summary of the work performed by earlier researchers through a detailed literature survey. Relevant literature on EDM and impact of process parameters on performance measures such as surface quality, tool wear rate and material removal rate are reviewed. The challenge and limitation of EDM process are also highlighted in this article. It is observed that optimization of process parameters is essentially required for effective and economical machining. So, this article addresses the various issues related to EDM and also provides brief insight into some of the current generation applications of EDM process explored in various industries.

Analysis of surface performance measures on WEDM processed titanium alloy with coated electrodes

Owing to its distinct physical properties, titanium alloy is usually machined using unconventional machining process. In the present study, an effort has been performed to enhance the machinability of titanium alloy using wire electrical machining process with coated wire electrodes. An experimental investigation has been done to evaluate the significance of wire coating such as zinc and diffused coating on surface performance measures. The compositional analysis of the machined surface has been made to analyze the effects of coating on material deposition. From the experimental results, it has been inferred that diffused type of electrode has produced better surface morphology than conventional wire electrodes.

Comparative Study on EDM of Ti-6Al-4V Using Circular and Convex Shaped Electrodes

As on today, Electrical Discharge Machining (EDM) is world famous unconventional machining process for electrically conductive materials. In this project work, Ti-6Al-4V is performed in electrical discharge machining using differently shaped (circular and convex) copper electrode. The machining parameters considered are the pulse on- time, pulse off-time, voltage and current to investigate machining characteristics like material removal rate and tool wear rate. Taguchi method is applied to frame experimental design. Ti-6Al-4V finds wide usage in industrial applications such as marine, aerospace, bio-medical and so on.

Numerical simulation of electric discharge machining of functional graded material

In the present scenario, advanced material is required for higher end applications whose material properties can be preassigned according to the performance demands. This lead to the development of functional graded material. These kinds of materials are divided into different layers with varying material properties. The Functionally Graded Materials are heterogenous in nature but in layer wise it can be considered homogenous in nature. The material properties can be calculated by using Rule of Mixture. However, this material possesses challenges during the machining process. Machining of these materials using conventional process is challenging due to its improved mechanical properties. However, such materials can be machined using unconventional machining processes. This work involves a development of finite element simulation model to simulate the Electric Discharge Machining (EDM) process on Functional Graded Material (FGM). The EDM is a material removal process through multiple occurrence of single spark on the workpiece. This single spark will create a crater due to the excess heat of the spark and the molten material can be removed by using the dielectric fluid. The heat input for a single spark can be defined by using the Gaussian distribution of the spark profile. The centre point will have maximum heat inputted and as the heat passes in the work piece it decreases. The size of the crater will vary with the varying the process parameters such as Discharge current, Discharge Voltage, Pulse on-time, off-time and Energy Partition. The effect of the process parameter on material removal rate (MRR) is evaluated using the FEM simulation. The predicted result shows that with increase of pulse on-time and discharge current, the crater size was found to be increased. This increase in the crater size attributes in the increment of MRR. The predicted results can enhance the machining process of FGM.

Optimization of the Anodic Dissolution of the Superalloy Inconel 718

Due to its particular mechanical and thermal properties, nickel-based superalloys such as Inconel 718 are widely used for aerospace industry. They are known to be the among the most difficult-to-cut- materials[1], so that conventional machining methods such as milling are inefficient and hard to proceed[2]. Because of its ability to generate high quality surfaces and to reproduce complex shapes. Pulse or Precise ElectroChemical Machining (PECM), an unconventional machining process (no cutting tools), can be useful to manufacture those alloys. This technic is based on the anodic oxidation of metals through a strong applied pulse current. The electrical signal is synchronized to the oscillation of the cathode corresponding to a rectilinear translational movement. Throughout the process, the electrolyte is continuously renewed that allows the removing of the solid residues of the dissolved metal and guarantees a good dissolution efficiency. The PECM is characterized by a very low inter-electrode distance (gap), from 0.01 to 0.2 mm, which ensures the dimensional accuracy. First step was to understand the physical-chemical phenomena related to the anodic dissolution of the Inconel 718 in the usual electrolyte NaNO3. Thus, polarization curves associated with current constant dissolution have been studied in 2,35 mol/L (20 % wt) NaNO3. Energy dispersive X-ray spectroscopy analysis of cross-sections were used to highlight the solid anodic products formed during anodization. They are mainly constituted of Ni and Nb oxides as well as γ '' (Ni3Nb) inclusions. From ICP analyses of the electrolyte, the dissolved elements in solution are mainly those of the austenitic matrix. Consequently, in order to optimize the dissolution process, the individual anodic behavior of both main components forming the superalloy, namely the matrix and the γ'' phase were studied in a mixture of NaNO3 and EDTA as a chelating agent. Linear Sweep Voltammetry (LSV) was performed to study the global behavior of each phase in the chelating medium. Chronopotentiometry was carried out to determine the dissolution yield. Finally, electrochemical impedance spectroscopy (EIS) measurements were performed to evaluate the electrochemical interface following the anodization process. It appears that, in presence of EDTA, the hydroxides formation in the electrolyte is limited, whereas the charge transfer resistance and the anodizing layer resistance decrease. As a final step, the electrolyte containing the chelating agent was subsequently tested for Inconel 718 in PECM configuration using a home – made experimental set up in order to determine the influence of the gap, the electrolyte flow and the pulse time on anodic dissolution. In addition, metallographic sections and dissolution products analysis were also made to identify the material integrity. [1] D. Dudzinski, A. Devillez, A. Moufki, D. Larrouquere, V. Zerrouki, et J. Vigneau, « A review of developments towards dry and high speed machining of Inconel 718 alloy », Int. J. Mach. Tools Manuf, vol. 44, no 4, p. 439-456, mars 2004. [2] M. Burger, L. Koll, E. A. Werner, et A. Platz, « Electrochemical machining characteristics and resulting surface quality of the nickel-base single-crystalline material LEK94 », J. Manuf. Process, vol. 14, no 1, p. 62-70, janv. 2012.

Desirability-Based Multi-objective Optimization and Analysis of WEDM Characteristics of Aluminium (6082)/Tungsten Carbide Composites

Wire electrical discharge machining is a broadly recognized unconventional machining process capable of accurately manufacturing rigid components with compound contours. The present study is to optimize the machining parameters of Al (6082)/tungsten carbide composite. Peak current, pulse-on time, pulse-off time, wire feed rate and tungsten carbide percentage were used as variables to study the material removal rate and surface roughness. Analysis of variance technique is used to study the effect on material removal rate and surface roughness. Material removal rate is primarily influenced by % tungsten carbide followed by peak current, pulse-off time, feed rate and pulse-on time, respectively. Surface roughness is highly influenced by peak current followed by % tungsten carbide, pulse-off time, pulse-on time and feed rate respectively. Scanning electron microscopic structures of the machined surfaces were characterized by the presence of hillocks, fine and deep craters, microcracks, protrusion, recast layers and debris. Desirability-based multi-objective optimization was employed to optimize the process parameters. The developed mathematical model has a good level of adequacy and can be used to predict the responses with minimum error. The experimental results along with the mathematical model and optimization will serve as a technical database for aerospace, automotive, military and commercial applications.

Hybrydowe procesy obróbki ubytkowej. Definicje, zasady tworzenia i znaczenie w przemyśle

Some important trends in the development of advanced machining processes with potential applications in Production/Manufacturing 4.0 are presented. In general, both conventional and unconventional machining processes are characterized in terms of potential technological possibilities related to their hybridization allowing the performance of more productive and effective machining processes. This is due to the fact that hybrid processes considerably enhance the advantages of individual processes and minimize potential disadvantages in individual processes. Possible classification systems of hybrid processes including the CIRP terminology are overviewed and some representative examples are provided. In particular, the hybrid machining processes based on the simultaneous and controlled interaction of process mechanisms and/or energy sources leading to the synergic effect (1 + 1 = 3) on the process performance are taken into account. Some conclusions and future trends in the implementation of hybrid processes are outlined.

Microfabrication and Functionalization of an Aluminum Gas-Phase Micro-Reactor via Through-Mask Electrochemical Micromachining

Gas-phase micro-reactors have been the focus of much research related to their use for the distributed and decentralized production of chemicals and electricity [1]. Micro-reactor applications include the production of hydrogen-rich synthesis gas from fuels (steam reforming), CO removal from fuel cell feedstocks (Water-Gas-Shift reaction, preferential CO oxidation), and the synthesis of hydrocarbons (Fischer-Tropsch reaction), methanol, dimethyl ether, and ethanol. The advantages of micro-reactors in these applications stem from their small characteristic dimensions leading to a high specific surface area and low volume [2]. As a result, the driving forces for heat and mass transfer increase by several orders of magnitude, mixing times lie on the order of milliseconds, and both product selectivity as well as process safety are vastly improved. Among the available metals and alloys, aluminum is frequently chosen for the fabrication of gas-phase micro-reactors [1]. Despite its low melting point (660°C), aluminum may be safely used for the Water-Gas-Shift reaction, preferential CO oxidation, or the Fischer-Tropsch reaction, as these processes typically operate below 400°C. Advantageously, its high thermal conductivity (237 W/m·K) assists in removing excess heat released by these exothermic reactions. In addition, the surface structure of aluminum surfaces may be altered via the formation of porous oxide films, which subsequently serve as protective coatings, nano-structure templates, or catalyst support layers [3,4]. In particular, this enables noble metal catalysts, such as palladium and gold, to be deposited within the pores via wash-coating or electrodeposition methods [4,5]. The combination of photolithographic masking with electrochemical dissolution processes, termed Through-Mask Electrochemical Micromachining (TMEMM), is an unconventional machining process enabling localized material removal from conductive substrates [6]. Compared to conventional micro-machining techniques utilizing chemical etchants, reactive plasmas, cutting tools, or laser beams for micro-structuring, TMEMM offers several advantages: (i) enhanced process safety, (ii) improved surface finish, (iii) accelerated machining rate, (iv) and increased machining selectivity [6-8]. In the case of aluminum, concentrated phosphoric acid at elevated temperatures is a suitable electrolyte for TMEMM. This is because anodic dissolution proceeds due to the random removal of metal cations through a thin barrier oxide film, resulting in a polished surface finish [9]. In this way, the fabrication of an aluminum micro-mixer was successfully demonstrated, avoiding issues related to electrolyte reactivity, flammability, and stability [10]. In the present work, results on TMEMM of an aluminum gas-phase micro-reactor are presented (Figure 1). To this end, square aluminum platelets were dissolved through a photoresist mask in 85% phosphoric acid at 75°C using a custom-made, jacketed glass cell. In the process, the uniformity of mass transfer along the mask was studied using different designs for the photoresist mask as well as agitation. The use of surfactants as electrolyte additives was examined to retain a polished surface finish over the whole mask design. Using the same set-up, TMEMM was compared with chemical etching in several aluminum wet etchants. The machined micro-reactor structures were subsequently examined via light microscopy, scanning electron microscopy, and profilometry to investigate their surface structure, roughness, and shape profile. This work is complemented by a preliminary study of the formation of catalyst support layers via anodization as well as of gold catalyst nanoparticles via electrodeposition along the channel walls of the micro-reactor.

Machinability of nickel based alloys using electrical discharge machining process

The high temperature materials such as nickel based alloys and austenitic steel are frequently used for manufacturing critical aero engine turbine components. Literature on conventional and unconventional machining of steel materials is abundant over the past three decades. However the machining studies on superalloy is still a challenging task due to its inherent property and quality. Thus this material is difficult to be cut in conventional processes. Study on unconventional machining process for nickel alloys is focused in this proposed research. Inconel718 and Monel 400 are the two different candidate materials used for electrical discharge machining (EDM) process. Investigation is to prepare a blind hole using copper electrode of 6mm diameter. Electrical parameters are varied to produce plasma spark for diffusion process and machining time is made constant to calculate the experimental results of both the material. Influence of process parameters on tool wear mechanism and material removal are considered from the proposed experimental design. While machining the tool has prone to discharge more materials due to production of high energy plasma spark and eddy current effect. The surface morphology of the machined surface were observed with high resolution FE SEM. Fused electrode found to be a spherical structure over the machined surface as clumps. Surface roughness were also measured with surface profile using profilometer. It is confirmed that there is no deviation and precise roundness of drilling is maintained.