Study of Wire-Cut Electro-Discharge Machining of Heat-Resistant Nickel Alloys.

This paper presents an analysis and theoretical model for assessing the quality and accuracy of wire-cut electro-discharge machining (WEDM) of products made from novel heat-resistant nickel alloys such as CrNi56KVMTYB. It is observed that WEDM processing of Ni alloy led to high surface roughness for the thick specimens, and electrical parameters such as pulse duration for the selected range depict an insignificant role in the value of surface roughness. On the other hand, the cut width of the machined surface decreases as the pulse duration increases, while the cut width is elevated for thick workpieces. Secondary discharges developed in WEDM have negative effects that cause sludge adhering and deterioration in the quality and productivity of processing. The regression model is developed to predict the surface roughness and cut width of machined surfaces, which holds significant importance in modern engineering. The workpiece is examined for surface integrity and material deposition. It is observed that an increase in the height of the specimen leads to the occurrence of secondary discharges, which in turn results in the formation of cracks on the surfaces of high-temperature nickel alloys. These cracks have a detrimental effect on the performance of critical products made from next-generation heat-resistant nickel alloys.

Investigation of Plasma-Electrolytic Processing on EDMed Austenitic Steels.

This study investigates the effect of electrolytic plasma processing on the degree of defective layer removal from a damaged layer obtained after manufacturing operations. Electrical discharge machining (EDM) is widely accepted in modern industries for product development. However, these products may have undesirable surface defects that may require secondary operations. This work aims to study the die-sinking EDM of steel components followed by the application of plasma electrolytic polishing (PeP) to enhance the surface properties. The results showed that the decrease in the roughness of the EDMed part after PeP was 80.97%. The combined process of EDM and subsequent PeP makes it possible to obtain the desired surface finish and mechanical properties. In the case of finishing EDM processing and turning, followed by PeP processing, the fatigue life is enhanced without failure up to 109 cycles. However, the application of this combined method (EDM + PeP) requires further research to ensure consistent removal of the unwanted defective layer.

Determination of Nanoindentation Behavior of HAZ on Glass Material Machined via ECSM Process through Simulation Approach.

The current study develops a numerical model to investigate the nanoindentation behavior of heat-affected zones (HAZ) on glass material produced via the electrochemical spark machining (ECSM) method. Initially, microchannels were created using the ECSM method on soda-lime glass. Following that, a nanoindentation test was conducted to quantify the Young's modulus and hardness of the glass sample. After that, a numerical model based on finite elements was created to characterize the changes in mechanical characteristics of HAZ. According to the findings, increasing the electrolyte concentration from 10 to 30% increases the intensity of electrochemical discharges, and thereby decreases the hardness of the work material by 16.29 to 30.58% compared to unmachined glass. The results obtained from the simulation are in close agreement with the experimental values. The maximum error obtained between simulation and experimental results is only 4.18%.

Energy Channelization Analysis of Rough Tools Developed by RM-MT-EDM Process during ECSM of Glass Substrates.

In the present work, the effect of tool surface roughness on energy channelization behavior was analyzed during the fabrication of micro holes by an electrochemical spark machining (ECSM) process. In this study, rough tools were fabricated by a rotary mode multi tip electric discharge machining (RM-MT-EDM) process. The electrical characterization was also carried out to investigate the electric field intensity over the surface of tool electrode, and it was found that the use of rough tools improves the electric field intensity by 265.54% in comparison to the smooth tool electrodes. The use of rough tools in the ECSM process forms thin and stable gas film over the tool electrode, and as a result the rough tools produced high frequency spark discharges. Energy channelization index and specific energy were considered as response characteristics. The use of rough tools improves energy channelization index by 248.40%, and the specific energy is reduced by 143.263%. The material removal mechanisms for both of the processes (RM-MT-EDM and ECSM process) have also been presented through illustrations.

Parametric Optimization of Electric Discharge Machining of Metal Matrix Composites Using Analytic Hierarchy Process.

The present study reports on the method used to obtain the reliable outcomes for different responses in electric discharge machining (EDM) of metal matrix composites (MMCs). The analytic hierarchy process (AHP), a multiple criteria decision-making technique, was used to achieve the target outcomes. The process parameters were varied to evaluate their effect on the material erosion rate (MER), surface roughness (SR), and residual stresses (σ) following Taguchi's experimental design. The process parameters, such as the electrode material (Cu, Gr, Cu-Gr), current, pulse duration, and dielectric medium, were selected for the analysis. The residual stresses induced due to the spark pulse temperature gradient between the electrode were of primary concern during machining. The optimum process parameters that affected the responses were selected using AHP to figure out the most suitable conditions for the machining of MMCs.

Study of Lapping and Polishing Performance on Lithium Niobate Single Crystals.

Recently, the range of crystal materials used in industrial microelectronics has significantly increased. Lithium niobate single crystals are most often used in integrated optics, due to the high values of optical and electro-optical coefficients. An integral-optical circuit based on a lithium niobate single crystal is a key element in the production of local high-precision fiber-optic gyroscopic devices used in civil and military aviation and marine technologies. In the process of production of an integral-optical circuit, the most labor-intensive operations are mechanical processing, such as lapping and polishing. Technological problems that arise while performing these operations are due to the physical and mechanical properties of the material, as well as target surface finish. This work shows the possibility to achieve the required surface quality of lithium niobate single crystal plates by mechanization of lapping and polishing process in this article.

Cubic Lattice Structures of Ti6Al4V under Compressive Loading: Towards Assessing the Performance for Hard Tissue Implants Alternative.

Porous Lattice Structure (PLS) scaffolds have shown potential applications in the biomedical domain. These implants' structural designs can attain compatibility mechanobiologically, thereby avoiding challenges related to the stress shielding effect. Different unit cell structures have been explored with limited work on the fabrication and characterization of titanium-based PLS with cubic unit cell structures. Hence, in the present paper, Ti6Al4V (Ti64) cubic PLS scaffolds were analysed by finite element (FE) analysis and fabricated using selective laser melting (SLM) technique. PLS of the rectangular shape of width 10 mm and height 15 mm (ISO: 13314) with an average pore size of 600-1000 µm and structure porosity percentage of 40-70 were obtained. It has been found that the maximum ultimate compressive strength was found to be 119 MPa of PLS with a pore size of 600 µm and an overall relative density (RD) of 57%. Additionally, the structure's failure begins from the micro-porosity formed during the fabrication process due to the improper melting along a plane inclined at 45 degree.

Analysis of Wire-Cut Electro Discharge Machining of Polymer Composite Materials.

This study presents the analysis of wire-cut electro-discharge machining (WIRE-EDM) of polymer composite material (PCM). The conductivity of the workpiece is improved by using 1 mm thick titanium plates (layers) sandwiched on the PCM. Input process parameters selected are variable voltage (50-100 V), pulse duration (5-15 µs), and pause time (10-50 µs), while the cut-width (kerf) is recognized as an output parameter. Experimentation was carried out by following the central composition design (CCD) design matrix. Analysis of variance was applied to investigate the effect of process parameters on the cut-width of the PCM parts and develop the theoretical model. The results demonstrated that voltage and pulse duration significantly affect the cut-width accuracy of PCM. Furthermore, the theoretical model of machining is developed and illustrates the efficacy within the acceptable range. Finally, it is concluded that the model is an excellent way to successfully estimate the correction factors to machine complex-shaped PCM parts.

Impact of Magnetic Field Environment on the EDM Performance of Al-SiC Metal Matrix Composite.

In the present work, a hybrid magnetic field assisted powder mixed electrical discharge machining had been carried out on the Aluminum-Silicon Carbide (Al-SiC) metal matrix composite. The aim of the study was to obtain higher surface finish, and enhanced material removal rate. The dielectric mediums employed were plain EDM oil, SiCp mixed and graphite powder mixed EDM oil for flushing through the tube electrode. The magnetic field intensity, discharge current, T-on/off duration and type of dielectric were the control variables used for present investigation. From the results, it was observed that the machining variables for instance, discharge current, T-on/off duration and type of dielectric conditions remarkably affected the material removal rate, micro-hardness and surface roughness of the machined composite material. The MRR augmented considerably with an increase in the magnetic field intensity along with peak current. Subsequently, the composite with lesser vol.% of SiC particulates witnessed sharp rise in MRR in maximum magnetic field environment (0.66T). In addition, quality of the machined surface improved significantly in graphite powder mixed dielectric flushing condition with intermediate external magnetic field environment. Besides, an enhancement of micro-hardness was quantified as compared to base material due to the transfer of the material (SiCp) during powder mixed ED machining.

A review on alloy design, biological response, and strengthening of ß-titanium alloys as biomaterials.

From the past few years, developments of ß-Ti alloys have been the subject of active research in the medical domain. The current paper highlights significant findings in the area of ß-Ti alloy design, biological responses, strengthening mechanisms, and developing low-cost implants with a high degree of biocompatibility. It is evident that an astonishing demand for developing the low modulus-high strength implants can be fulfilled by synchronizing ß stabilizer content and incorporating tailored thermo-mechanical techniques. Furthermore, the biological response of the implants is as important as the physical properties that regulate healing response; hence, the optimum selection of alloying elements plays a curial role for clinical success. The paper also presents the evolution of patents in this field from the year 2010 to 2020 showing the relevant innovations that may benefit a wide range of researchers.

Surface Characterization and Tribological Performance Analysis of Electric Discharge Machined Duplex Stainless Steel.

The present article focused on the surface characterization of electric discharge machined duplex stainless steel (DSS-2205) alloy with three variants of electrode material (Graphite, Copper-Tungsten and Tungsten electrodes). Experimentation was executed as per Taguchi L18 orthogonal array to inspect the influence of electric discharge machining (EDM) parameters on the material removal rate and surface roughness. The results revealed that the discharge current (contribution: 45.10%), dielectric medium (contribution: 18.24%) majorly affects the material removal rate, whereas electrode material (contribution: 38.72%), pulse-on-time (contribution: 26.11%) were the significant parameters affecting the surface roughness. The machined surface at high spark energy in EDM oil portrayed porosity, oxides formation, and intermetallic compounds. Moreover, a pin-on-disc wear analysis was executed and the machined surface exhibits 70% superior wear resistance compared to the un-machined sample. The surface thus produced also exhibited improved surface wettability responses. The outcomes depict that EDMed DSS alloy can be considered in the different biomedical and industrial applications.

Enhancing Corrosion and Wear Resistance of Ti6Al4V Alloy Using CNTs Mixed Electro-Discharge Process.

This paper presents wear and corrosion resistance analysis of carbon nanotubes coated with Ti-6Al-4V alloy processed by electro-discharge treatment. The reported work is carried out using Taguchi's L18 orthogonal array to design the experimental matrix by varying five input process parameters i.e., dielectric medium (plain dielectric, multi-walled carbon nanotubes (MWCNTs) mixed dielectric), current (1-4 A), pulse-on-time (30-60 µs), pulse-off-time (60-120 µs), and voltage (30-50 V). The output responses are assessed in terms of microhardness and surface roughness of the treated specimen. X-ray diffraction (XRD) spectra of the coated sample reveal the formation of intermetallic compounds, oxides, and carbides, whereas surface morphology is observed using scanning electron microscopy (SEM) analysis. For the purpose of the in-vitro wear behavior of treated samples, the surface with superior microhardness values in plain dielectric and MWCNTs mixed dielectric is compared using a pin-on-disc type wear test. Furthermore, electrochemical corrosion test is also conducted to portray the dominance of treated substrate of Ti-6Al-4V alloy for biomedical applications. It is concluded that the wear-resistant and the corrosion protection efficiency of the MWCNTs treated substrate enhanced to 95%, and 96.63%, respectively.

On the machinability and properties of Ti-6Al-4V biomaterial with n-HAp powder-mixed ED machining.

Nano-hydroxyapatite powder was used in electric discharge machining to modify the surface of Ti-6Al-4V medical alloy. Herein, electric discharge machining was performed, with and without powder-mixed flushing for evaluation of the material erosion rate and surface roughness. In addition to dielectric type, several process parameters including current, pulse-on duration, pulse-off duration, and electrode hole diameter were considered. The experiments were planned by Taguchi design technique and conducted to analyze the material erosion rate and surface roughness. After machining, scanning electron microscope, energy-dispersive X-ray spectrometry, and X-ray diffraction techniques were used to evaluate the surfaces of the samples. Furthermore, wear and corrosion tests were also carried out on the Ti alloy with modified surfaces. The influential factors were identified based on analysis of variance results. Current and dielectric type were the significant factors, both for the material erosion rate and surface roughness. The scanning electron microscope images of Ti-6Al-4V samples highlighted that the process parameters exhibited a vital influence on the topology and microstructure of machined surface. Furthermore, energy-dispersive X-ray spectrometry and X-ray diffraction analyses confirmed the presence of hydroxyapatite on Ti alloy surface after machining. Moreover, the results of wear and corrosion tests revealed lower wear and corrosion rates of the surface-treated workpiece with nano-hydroxyapatite.