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Dense silicon carbide (SiC) composites with 0–30 vol% (ZrN-TiB 2) were fabricated by using liquid phase spark plasma sintering at a relatively lower sintering temperature (1800 °C) and shorter holding time (5 min). The effects of co-addition of ZrN and TiB 2 on densification, mechanical properties, and electrical conductivity of SiC ceramics were investigated. The reinforcement significantly enhanced density of sintered composites, while the phase analysis and microstructure confirm the suppression of β→α phase transformation in the SiC matrix. The fracture toughness ranged from 4.1 to 4.6 MPa·m0.5, hardness from 19.5 to 20.3 GPa, and electrical conductivity from 4.85 ×101 to 1.25 ×103 (Ω·cm)−1. Incorporating conductive reinforcements and nitrogen additives enhanced electrical conductivity. Successful wire-EDM cutting of SiC-ZrN-TiB 2 composites demonstrate the feasible alternative to conventional machining of non-oxide ceramics with a maximum material removal rate of 8.54 mm2/min. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigates the discharge energy distribution during Powder Mixed Electrical Discharge Machining (PMEDM) at different values of pulse duration, peak current and powder concentration. A finite element method (FEM) based numerical model has been developed to estimate the power distribution factor by reverse simulation. The developed model has been used for determining the fraction of discharge energy distributed to the electrodes. The model and experimental values of total fraction of discharge energy are in close agreement with the error varying between 0.47 % to 14.04 % for tool and 0.82 % to 9.82 % for workpiece. Parametric influence on components of discharge energy has also been discussed. • Study of discharge energy distribution during graphite powder mixed EDM. • Determination of power distribution factor using reverse simulation approach. • Development of FEM model using COMSOL Multiphysics. • Powder concentration, pulse duration, peak current are the process variables. [ABSTRACT FROM AUTHOR]

Being a manufacturing process based on thermal material removal, it has been known for decades that Electrical Discharge Machining (EDM) affects the properties of surface layers of machined workpieces, notably by inducing residual stresses. These stresses are undesirable as they can contribute to crack formation in ED machined parts in on-load operation. Thus, their minimization is preferable. In this research the influence of different combinations of EDM parameters (namely discharge duration and discharge current) on characteristics of residual stresses is studied and compared. However, industrial ED machining usually consists of a sequence of process regimes that each represents a thermal load for the material and consequently each causes an individual profile of residual stress. Therefore, the resulting effect of these combined loads is also investigated. The findings contribute to the knowledge of the process signature of Electrical Discharge Machining as well as they allow for improved planning of industrial EDM processes. [ABSTRACT FROM AUTHOR]

High electrical conductivity and low thermal conductivity are beneficial for the electrical discharge machining performance of ceramics. In this work, B 4 C–TiB 2 composites were prepared by spark plasma sintering of B 4 C–TiC–B powder mixture. The chemical reaction between TiC and B, together with subsequent selective matrix grain growth, expelled small in-situ generated TiB 2 grains to form conductive interlayers around large B 4 C grains. The unique microstructure significantly enhances the electrical conductivity of B 4 C–TiB 2 composites, especially at low TiB 2 content, while the ultrafine in-situ formed TiB 2 grains endow the composites with low thermal conductivity. The effects of TiB 2 content on the microstructure, mechanical properties, thermal & electrical conductivity of the composites were investigated. B 4 C–20 vol% TiB 2 composite exhibits excellent comprehensive performance, including a relative density, Vickers hardness, flexural strength, fracture toughness, room electrical and thermal conductivity of 98.6%, 28.15 GPa, 656 MPa, 5.46 MPa⋅m1/2, 1.08 × 105 S/m and 19.37 W/m⋅K, respectively. [ABSTRACT FROM AUTHOR]

The present work focuses on the impact of expanded graphite (EG) nano-powder along with spark-on-duration (T on) and spark-off-duration (T off), and current as factors on increasing material removal rate (MRR), reduction of surface roughness (SR), tool wear rate (TWR), dimensional deviation (DD), and surface defects for Ni 55.8 Ti. Taguchi's design having 4 factors at 3 levels was employed to perform the experimental trials. ANOVA has successfully validated the developed regression equations. EDM factors of PC, T off , current, and T off were found to be the largest contributing factors with the involvement of 76.91 %, 38.40 %, 34.36 %, and 44.54 % for MRR, TWR, SR, and DD respectively. TLBO algorithm was used in the present work to tackle the conflicting situation and to optimize the response variables. The simultaneous optimization conducted through the Teaching-learning-based optimization technique has yielded optimal parameters setting of T on at 7 µs, T off at 5 µs, PC at 1.5 g/L, and current at 10 A by giving optimal response values at MRR of 42.82 mm3/min, TWR of 0.4039 mm3/min, SR of 3.71 µm, and DD of 92.65 µm. Lastly, Scanning electron microscopy was utilized to check EG nano-powder significance on the machined parts' surface morphology. [ABSTRACT FROM AUTHOR]

Surface formation in electrical discharge machining (EDM) involves melting, evaporation, re-solidification and crater overlapping. However, almost all existing models concerning surface formation in EDM only consider the thermal process and ignore hydrodynamic phenomena during machining. Herein, a novel three-dimensional thermo-hydraulic coupling model incorporating the arbitrary Lagrangian–Eulerian scheme was developed to address the above problem. The model comprehensively considered the surface deformation caused by melt flow, temperature-dependent material properties, phase changes and the effects of practical forces on melt pools to simulate surface formation on an anodic workpiece at a discharge current of 2 A. Simulation results demonstrate that during single-pulse discharge, molten material flowed radially to the crater periphery. The radial melt flow was driven by evaporation recoil pressure and thermocapillary force. The effect of evaporation recoil pressure on melt flow was gradually counteracted by that of surface tension after discharge ignition, and thermocapillary force became the dominant factor that maintained the existence of bulges around craters. During multiple discharges, the bulges generated by different discharges underwent superposition owing to the flow of molten material and subsequently formed surface peaks. The simulation results also provide the measurements of crater diameter, surface roughness and recast layer thickness, which are consistent with experimental results. The proposed modelling method can provide a useful reference for further investigations on surface integrity in EDM with minimal computing resource requirements. • A novel 3D thermo-hydraulic coupling surface formation model for EDM was proposed. • The effects of evaporation recoil pressure and thermocapillary force on melt pool dynamics in EDM were investigated. • Simulation results of multiple discharges show good consistency with experiment results concerning surface properties. [ABSTRACT FROM AUTHOR]

This paper aims to enhance the machining characteristics of sinking electrical discharge machining by superimposing an impulse current on a conventional rectangular pulse. The material removal was found to be more significant when the time point of superposition was set earlier after the dielectric breakdown, as the plasma diameter is smaller. However, superimposition immediately after the discharge ignition leads to a higher tool wear ratio. Through experimentation and simulation, it was determined that the optimal time point to increase material removal while keeping tool wear low is approximately 12.5 μs when the rectangular pulse duration was 50 μs. [ABSTRACT FROM AUTHOR]

In this study, the optimization of processing parameters of Inconel 718 using electrical discharge machining (EDM) with three kinds of renewable dielectrics (soybean oil, sunflower seed oil, and rapeseed oil) was studied. As input process parameters, pulse current, pulse duration, duty ratio, and dielectric type were all utilized. The machining performance indices of EDM were material removal rate (MRR), surface roughness (Ra), energy pulse ratio per volume (EEV), and exhaust emission characteristics (EEC). The response surface method (RSM) was used to carry out the central composite design of the EDM experiment, and it looked into how process parameters affected machining performance. In addition, the extreme learning machine (ELM)-improved integrated beta-distribution cuckoo search (IBCS) algorithm was used to optimize the EDM process, and the optimization results were verified by experiments. The research results demonstrate that the predicted results are generally better than the experimental results, and the maximum and average deviations of the experimental results are within the acceptable range (maximum deviation <20%, average deviation <15%). The effectiveness of the optimization algorithm was proved, which was helpful in improving the performance of EDM, reducing energy consumption and emissions, and improving the sustainability of EDM. • The mechanism of renewable dielectrics on EDM performances is explored. • The experimental design and analysis of EDM were carried out by using RSM. • ELM-IBCS to optimize the EDM processing (maximum error <20%, average error <15%). [ABSTRACT FROM AUTHOR]

Arc plasma is the heat source in electrical discharge machining (EDM), it affects the material removal and discharge crater formation directly, so it is necessary to clarify its characteristics. However, it is challenging to understand the physical mechanisms behind each pulse discharge through experimental methods, as it is a transient, multi-physical process that occurs in a very short time and small gap. In this paper, a two-temperature model was proposed to investigate the characteristics of the arc plasma and the energy distribution considering the multi-physics fields in the steady state. In this model, the electrons and the heavy species of the arc plasma were considered separately in the energy conservation equations, so that the temperature of the electrons and heavy species can be calculated separately. Besides, the velocity distribution, pressure distribution, electrical potential distribution, and diameter of the arc plasma, as well as the heat flux distribution and the energy distribution into the anode and cathode were analyzed. Then the variations in arc plasma properties and energy distribution with different discharge conditions were studied. The results showed that, at a lower discharge current, the electron temperature was higher than the heavy species temperature, which means that the arc plasma did not reach a local thermodynamic equilibrium (LTE) state under these discharge conditions. To validate the simulation results, the arc plasma was observed with a high-speed camera, and the diameter of craters on the surface of both the cathode and anode was measured with single-pulse discharge experiments. The experiment results were consistent with the simulation results. • A two-temperature model was established to study the arc plasma in EDM. • The temperature of electrons and heavy species of arc plasma was obtained. • The arc plasma did not reach the local thermodynamic equilibrium state under the given simulation conditions. • The energy distribution ratio into the anode, cathode, and dielectric were calculated, respectively. • The arc plasma characteristics and the energy distribution under different discharge conditions were studied. [ABSTRACT FROM AUTHOR]

In recently, titanium and its alloys have been used in a large number of medical implants due to their excellent biological qualities. However, infections brought on by their biological inertness have emerged as a challenging issue for clinicians across a range of specialties. On the other hand, improper use of antibiotics has increased bacterial resistance, which has made the issue of infections brought on by titanium implants worse. The preparation of implants with antimicrobial capabilities has emerged as a key research area in the effort to address this issue at its source. However, present techniques for preparing antimicrobial surfaces are pricy, ineffective, and harmful to the environment, thus cannot be used extensively in industrial manufacturing. In this study, the bionic shark skin's antibacterial rhombic surface was prepared in a single step using the WEDM processing. The samples were then described, and the outcomes were examined using XRD, FE-SEM, and EDS. By using the plate coating method and SBF immersion assays, the samples' bioactivity and antibacterial capacity were assessed. Due to the high temperature produced during the WEDM process, which enables the tool electrode to melt and metallurgically link with the titanium alloy substrate surface, the primary crystalline phase of the antibacterial surface is CuTi 2. After 1 h of incubation on the sample surface, the samples' antibacterial rate was 93%. The antibacterial property of the sample also attained an ideal 98.4% when acid etching was carried out using a 20%wt HNO 3 solution. The Ti on the sample surface had no discernible impact on the effectiveness of the antibacterial. Additionally, the simulated liquid immersion findings demonstrated that the sample pieces made using this approach exhibited good bioactivity. [ABSTRACT FROM AUTHOR]

Amorphous alloys are a new type of multi-functional advanced material with the properties of general metal materials and glass, which are also called metallic glasses. They have good comprehensive properties, such as a wide application range, low cost, and high reusability. Using reasonable process parameters, non-traditional machining can not only realize the machining of complex amorphous parts, but also avoid the crystallization and oxidation of amorphous alloys, realizing tasks that cannot be accomplished by traditional machining. Therefore, this review systematically summarizes the research status and development potential of amorphous alloys fabricated using non-traditional machining methods. First, we introduce the principles of laser machining, ultrasonic machining, electrical discharge machining, electrochemical machining, and other non-traditional machining methods for amorphous alloys. Subsequently, the influence of the machining parameters and other external conditions on the machining effect is summarized. The machining cost, machining efficiency, and environmental impact of these non-traditional machining methods were compared. Finally, non-traditional machining technology for amorphous alloys is summarized and discussed. • The processing principles of non-traditional machining methods are summarized. • The influences of processing parameters on the machining effect are reviewed. • Costs, effects, and pollution of non-traditional machining are compared. • The limitations or shortages of non-traditional machining methods are summarized. [ABSTRACT FROM AUTHOR]

In electrical discharge machining, in-process measurements of the induced mechanical stress are essential to develop process models for improving the fatigue strength of the machined part. For this purpose, high-speed digital speckle photography is introduced to measure the workpiece-side load fields with a lateral displacement resolution of 28 nm at a spatiotemporal resolution of 29 µm and 40 µs, respectively. As a result, the load effects of even individual 100 µs short discharge pulses are temporally resolved for the first time, and the occurring spatial load inhomogeneities and their dynamics are characterized to complement our understanding of the machining process. [ABSTRACT FROM AUTHOR]

Despite the widespread use of titanium alloys in various fields, surface defects that arise during the processing of Ti-6Al-4V can significantly reduce their service life. Therefore, developing a new approach to enhance the performance of TC4 alloys, particularly in challenging environments such as high-wear and wet conditions is crucial. This study proposes a novel method to create a hardened surface enriched with TiN using nitrogen gas-assisted electrical discharge machining (NA-EDM). The aim was to assess the impact of surface modification via NA-EDM on anti-wear and anti-corrosion performance across different peak currents and to explore the mechanism behind the surface's hydrophobic properties. The findings show that the NA-EDM process produces fewer surface defects compared to traditional EDM. Moreover, NA-EDM treatment significantly improves surface hydrophobicity, as evidenced by a 21.25 % increase in the contact angle (CA). Furthermore, the NA-EDM-treated surface exhibits enhanced resistance to wear and corrosion, with a notable 14.9 % reduction in wear rate and average friction coefficient. • Nitrogen gas assisted EDM machining results in better surface integrity. • The hydrophobicity was caused by the change of surface morphology and chemical composition. • The recast layer was the main reason for the improvement of tribological properties. • The surface treated with nitrogen gas assisted EDM had better corrosion resistance. [ABSTRACT FROM AUTHOR]

• The feasibility of machining of CAHL composite using RTEDµD was established. • The machining time increased with the increase of aramid layers in the CAHL. • Better dimensional accuracy obtained at the exit of the micro-holes. • Material removal was assisted by pyrolytic carbon and copper deposition. This study reports the pioneering investigation on rotary tool-assisted electrical discharge micro-drilling (RTEDµD) of carbon-aramid hybrid laminate (CAHL). The machining times (MT) for fabricating one through-micro-hole (depth: 1500 µm) on the CAHL containing 1, 2, and 3 layers of aramid were 785 s, 800 s, and 840 s respectively. The MT increased by 20 % for the CAHL containing 3 aramid layers compared to carbon fiber reinforced polymer (CFRP). The diameter of the holes was within 730–900 µm and an overcut of 4.28 %–28.57 % was observed. [ABSTRACT FROM AUTHOR]

Superalloys, titanium alloys, stainless steels, and other difficult-to-cut materials have been widely used in aerospace and military due to their unique physical and chemical properties. Compared with conventional EDM and mechanical milling methods, the electrical discharge assisted arc milling (EDAAM) method can achieve efficient and stable machining when processing these difficult-to-cut materials. The oil-based dielectric fluid, which is often used in conventional EDM, may cause environmental problems if not recycled. In order to improve the environmental performance and study the influence of dielectric fluids, this paper studies the effects of different dielectric fluids on the machining performance of EDAAM. Deionized water and different gases including air, oxygen, nitrogen, and argon were used as the dielectric fluid, graphite was used as tool electrode, and iron-based superalloy A286 (GH2132) was used as the workpiece. Machining performance, including material removal rate, relative electrode wear rate, machining error, and surface properties, including recast layer, surface morphology, and element distribution, were studied. The experimental results show that the combinations of different dielectrics play a vital role in the processing effect. The mixed flushing method of using deionized water and gas medium can ensure the machining efficiency and improve the surface quality of the workpiece. [ABSTRACT FROM AUTHOR]

In sinking electrical discharge machining (EDM), tool electrode wear is crucial for an economical production. The tool electrode wear affects the process efficiency and determines the number of required tool electrodes for a specific machining process. Therefore, the relative tool wear, describing the relation of removed material volume between tool and workpiece electrode, needs to be minimised. The tool wear characteristics in sinking EDM depend strongly on EDM processing parameters and the applied electrode materials. Especially in micro-EDM, a significant increase of relative tool wear is representative. Because of its thermophysical properties tungsten carbide-cobalt (WC-Co) is a suitable material for the application as sinking EDM tool electrode. The economical production of WC-Co form electrodes for EDM sinking is enabled by recent advancements in precision milling of hard materials. Due to non-existent research on which composition of WC-Co is most advantageous for the application as sinking EDM tool electrode material, previous investigations have been intensified to describe correlations between material properties, EDM processing parameters and EDM processing results concerning material removal rate and relative tool wear. Therefore, various WC-Co grades with differing grain size and cobalt content were analysed in sinking EDM experimental studies. It was observed that the factor grain size showed an ambiguous effect concerning the process results. An increasing cobalt content led to a reduction of relative tool wear, which can be explained by the microstructure of the cobalt binder phase with its higher electrical conductivity. The WC-Co grades with beneficial EDM processing results have been further investigated in EDM parameter studies with differing tool electrode geometries. The experimental results concerning relative tool wear, with a minimum of 3 % for macro- and 5 % for micro-sized geometries, proved the suitability of specific WC-Co compositions as tool electrode material for sinking EDM. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) has been widely utilized in manufacturing for decades because of its remarkable advantages of noncontact machining and machining conductive materials of any hardness over traditional manufacturing technologies. However, the original EDM mechanism prevents the further improvements of surface qualities in precision manufacturing. In fact, although current and pulse duration were commonly set to be small to obtain small discharging energy in precision EDM, conventional EDM tools still employ single-channel discharging mechanism to form precise surfaces. This kind of machining concentrates the whole pulse discharging energy on one area, leaving the created crater wide and deep, and surface qualities are difficult to be improved. If the energy of the pulse is separated into several plasma channels, the craters generated by these small energies on the machined surface will be smaller. This kind of machining is called electrical multi-channel discharge machining. It was observed that multi-channel discharging can be formed only when transient arc pulses were generated in the gap. Nevertheless, in precision EDM, it is high probabilities to form stable arc pulses from transient arc pulses damaging machined surface. Therefore, an intelligent strategy should be exploited to realize electrical multi-channel discharging and avoid stable arc pulses occurred as well. To this end, a new adaptive control system of electrical multi-channel discharge machining was studied. Arcing ratio was chosen to be a controlled index and gap-servo voltage was a control variable. Because discharging pulses were transient arc pulses and crates were generated almost in the whole pulse duration, the integrity of the machined surface can be obtained. Experiments demonstrated that surface roughness (SR) on machined 1mm depth can reach up to Ra 0.2μs with a copper electrode of diameter 30mm around 2 hours. The significance of the study is that multi-channel discharging is a new perspective of discharging phenomenon and breaks through the inherent awareness of EDM precision machining in the past years. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the effects of working surface temperature on the material removal rate and tool electrode wear rate in sinking electrical discharge machining (EDM) process in order to clarify machining phenomena referred to as the area effect. First, the material removal rate, tool electrode wear rate and effective discharge frequency were measured for a 5mm-square rod tool electrode, and measured results were compared with those for 10mm-square rod tool electrode and 15mm-square rod tool electrode. Although the area effect is conventionally explained as the effect of discharge frequency, the measured results could not be explained in terms of only the dischargef requency. Then, the material removal rate and tool electrode wear rate for butt machining were compared with those of sinking machining, and the working surface temperature of the tool electrode were estimated using the measured temperature. It was found that the material removal rate and tool electrode wear rate are affected not only by the discharge frequency but also by the working surface temperature. It was also found that the tool electrode wear rate in a small working area can be reduced by lowering the working surface temperature. [ABSTRACT FROM AUTHOR]

Surfaces that were machined by Electrical Discharge Machining (EDM) inevitably exhibit a thin layer of resolidified material, commonly called "white layer". It is usually regarded as disadvantage of ED machining as it induces tensile residual stresses to the parent material and therefore facilitates the formation of cracks. It therefore was subject to a number of scientific investigations that often dealt with its (non-)crystalline structure or the stress induction. Some research groups have also focused on the thickness of the white layer. However, the variation of its thickness has not yet been investigated comprehensively and therefore constitutes the focus of this work. Experiments were conducted on a conventional sinking EDM machine. A heat-treatable steel was used as a workpiece material and graphite was used for the tool electrode. The influence of the discharge duration t e as well as the discharge current i e on the white layer formation were investigated. Results show that significant thickness variations occur on every ED machined surface and that increasing discharge energy leads to an increase of both, white layer thickness as well as its variation. [ABSTRACT FROM AUTHOR]

Big data (datasets accessible through the Internet) coupled with machine learning arrangements constitute big data analytics, which is heavily resource-depended and creates inequality-only large organizations can sustain or utilize big data analytics, and medium and small organizations fall behind. This article presents a novel inequality-free big data analytics for process planning in medium and small enterprises. Big data, search mechanism, control and evaluation variables relevant datasets, uncertainty quantification using possibility distributions, and decision rules are the components of the proposed analytics. This article reports the characteristics of the analytics applied to optimizing dry electrical discharge machining conditions of stainless steel. [ABSTRACT FROM AUTHOR]

The combination of high chemical and thermal durability with high hardness and strength is the main reason for the increasing use of ceramics in industry. However, these benefits lead to serious challenges for conventional manufacturing processes, which are often limited due to the mechanical properties of the workpiece material. Because of its working principle, electrical discharge machining (EDM) is almost independent from the mechanical workpiece properties. Nevertheless, the thermal loadings, which are caused by electrical discharges, result in different modifications on the surface and in sub-surface layers. These induced modifications define the surface integrity, which in turn determines the functional properties of a workpiece. Besides the intended rim zone modifications damages also occur. For a more detailed understanding of the occurring damages within the arising heat affected zone (HAZ), a heat transfer simulation for a single discharge on an alumina/zirconia/tungsten carbide ceramic was conducted in this work. [ABSTRACT FROM AUTHOR]

The goal of this work is to shed light on the importance and application of FDM (Fused Deposition Modelling) in the production of electrodes for die-sinking EDM (Electrical Discharge Machining). A literature-based survey is conducted, and it is discovered that the applicability of FDM for manufacturing EDM electrodes has received little attention. The quantity of articles on this issue is exceedingly low in conventional data bases such as Web of Science and Scopus. The purpose of this study is to offer relevant investigations and demonstrate the convenience, merit, and limitations of the method used. The review offered in this work is intended to assist researchers, practitioners, and scientists in making informed decisions on which method to use to meet their needs. The authors have been inspired by the study trend to encourage scholars and researchers to investigate the applicability of the FDM technique in the fabrication of EDM electrodes further. The review is based on the most recent database from Web of Science, Scopus, and Google Scholar, using the keywords FDM/Fused Deposition Modeling and AM/Additive Manufacturing. [ABSTRACT FROM AUTHOR]

• Long-term assessment of EDM bath influence on Ti6Al4V corrosion in simulated body fluid. • EDM in water and HA bath significantly enhanced long-term corrosion resistance of Ti6Al4V. • Long-term temporal evaluation of corrosion mechanisms in EDMed Ti6Al4V in simulated body fluid. • EDM in HA bath shows potential for enhancing Ti6Al4V biointegration. Ti-6Al-4V (Ti64) alloy is a widely used bioimplant material due to its excellent properties. However, long-term exposure to body fluids can lead to corrosion, a concern given increasing lifespans. Electrical discharge machining (EDM) can improve Ti64 corrosion resistance at long term. This study investigates the long-term corrosion behaviour of Ti64 in simulated body fluid (SBF) after EDM treatment using different bath compositions (oil, water, and hydroxyapatite dissolution (HA)). Electrochemical and microscopy techniques were used to analyse corrosion mechanisms over immersion periods ranging from 2 h to 3 months. Results show that EDM-treated samples in water exhibited the highest corrosion resistance, while those processed in oil possessed the lowest. Especially, the corrosion resistance of samples treated in water and HA remained constant over time, unlike the non-EDMed and oil-treated samples. Furthermore, all samples exhibited evolving corrosion mechanisms over time, with faster deposition of SBF elements observed on oil and HA-treated samples, suggesting enhanced biointegration potential. The thicker deposited SBF layer on these samples further supports the potential of these EDM treatments to improve the biointegration of Ti64 implants. [ABSTRACT FROM AUTHOR]

Sinking electrical discharge machining (EDM) is a vital machining technology used in modern mechanical manufacturing. However, the conventional sinking EDM, which utilizes an oil-based working medium, presents disadvantages such as low machining efficiency, harmful gas emissions, and fire hazards. Although researchers have attempted to use pure water as the working medium, pure water cannot replace oil and has not yet been industrially applied as a working medium because of its low machining efficiency and thick surface recast layer. Herein, we propose sustainable and green sinking EDM utilizing foam water (SEDM-FW) as the working medium, a method that uses pressurized foam water, ultrastrong energy discharge, and upward electrode feeding. The proposed method is cost effective, and its machining efficiency is more than three times higher than that of the conventional sinking EDM at the same peak current. The use of foam water instead of oil as the working medium solves environmental pollution problems associated with the conventional sinking EDM. In terms of environmental performance, the SEDM-FW produces gas byproducts that do not contain any harmful components, including 1,3-butadiene and benzene, which are present in the conventional sinking EDM. Compared with using pure water, using foam water as the working medium in conjunction with an appropriate gas-to-liquid ratio can double the machining efficiency, reduce the thickness of the recast layer by more than half, and reduce the size of surface microcracks. Using gas-dominated foam water, surface microcracks can be eliminated, and a zero-thickness recast layer can be achieved. [Display omitted] • A sustainable and green sinking EDM method (SEDM-FW) is proposed. • Foam water is used as the working medium, which replaces conventional oil and pure water. • Gas byproducts of SEDM-FW are completely harmless to humans and environment. • A proper gas-to-liquid ratio has higher MRR, lower REWR, and good surface integrity. • Gas-dominated foam water can eliminate microcracks and achieve zero-thickness recast layers. [ABSTRACT FROM AUTHOR]

This study investigated the machinability of AISI H13 hot work tool steel with a hardness of 54 HRC, which has been deep cryogenically treated using the electro-erosion machining technique, one of the unconventional manufacturing methods. The machinability parameters used in the study were determined as current (4, 8 and 12 A), pulse time (200, 300 and 400 µs) and three different electrodes (Copper, Graphite and Tuncop). The experimental design was designed according to the Taguchi L 27 model, and machinability tests were carried out to examine the results obtained from the experimental study both experimentally and statistically. When the literature was examined, it was seen that cryogenic treatment was generally applied to electrode materials, and only surface roughness and material wear amounts were examined as output parameters. The original value of the study is the interpretation of the results by applying cryogenic treatment to the test material and exploring the surface roughness and material wear amount, as well as the hole diameters and criterion diameters formed on the treated surfaces after the EDM process. As a result of the study, it was observed that the surface roughness value, the hole diameter, the amount of material wear, and the crater diameter increased with the increase in ampere and impact time. The lowest surface roughness value was 2.266 µm in the graphite electrode material at 4 amps and 200 µs impact time and the highest wear amount was realized as 0.555 g in the copper electrode material 12 amps and 400 µs impact time. The smallest hole diameter was 12.254 mm with a tuncop electrode with a pulse duration of 4 amps and 200 µs, and the lowest crater diameter was 127.301 µm with a graphite electrode at a current of 4 amps and a pulse duration of 200 µs. When the signal-to-noise ratios were examined, the optimum machining parameters for surface roughness, hole diameter, material wear amount, and crater diameter were determined as A 2 B 1 C 1 , A 1 B 3 C 3 , A 3 B 1 C 1 , and A 3 B 1 C 1 , respectively. When the ANOVA results are examined, it is determined that the most effective parameter for the surface roughness is of the current value with 86.54%, the most effective parameter for the hole diameter is the electrode material with 85.20%, the most effective parameter for material wear amount is the electrode material with 45.67% and the most effective parameter for the crater diameter is current value with 75.35%. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond is widely used in many fields including ultra-precise machining, optical material and semiconductor electronic devices due to its excellent physical properties. However, traditional mechanical processing methods of polycrystalline diamond leads to severe tool wear, low efficiency and high costs. Although electrical discharge machining can overcome some limitations, it usually exhibits a low material removal rate and poor surface quality. This study aims to explore the effect of graphene powder and ultrasonic vibration on polycrystalline diamond by electrical discharge machining. It was found that the synergistic effect of graphene powder and ultrasonic vibration can achieve a good surface quality. The results show that ultrasonic-assisted powder mixed electrical discharge machining can obtain the smallest surface roughness (1.98 μm) at low parameter and the biggest material removal rate (0.773 mg/min) at high parameter compared with ultrasonic assisted electrical discharge machining and powder mixed electrical discharge machining. In addition, after ultrasonic-assisted powder mixed electrical discharge machining, the minimum value (0.807) of I D /I G is obtained. For polycrystalline diamond, this study also proposes a removal mechanism that diamond converts into graphite and is peeled under tensile stress. [Display omitted] • The U-PMEDM for PCD benefits from the synergistic of ultrasound and graphene. • Ultrasonic vibration acts on the chemical bonds in the graphene layers. • Graphitization of diamond occurs and graphene is peeled off under tensile stress. [ABSTRACT FROM AUTHOR]

The significantly increased stability of third-generation semiconductors, both mechanically and chemically, presents a significant challenge to traditional wafer grinding. This study develops pure electrical discharge machining as an alternative for non-contact wafer grinding and thinning to achieve high precision and low cost. This method employs a copper-made rotary cup wheel as the tool electrode to replace the conventional diamond wheel to realize electrical discharge grinding. A prototype is built to evaluate the new process with single-crystal SiC. Aiming at ultra-precision machining, the material response of SiC to both single and consecutive discharge is elucidated. The influencing mechanism of pulse conditions on hard, brittle crystalline SiC material is demonstrated via experiments and simulation. Further, the material removal behavior, grinding stability, surface integrity, wafer shape accuracy, and process-induced subsurface damage are comprehensively investigated via single and consecutive discharge experiments under various conditions. In addition, the extreme precision that is achievable by contemporary EDM technology is explored. As a result, a 30 μm thin Φ 20 mm SiC wafer with a subsurface damaged layer <1 μm was obtained, showing the potential of EDM for the processing of third-generation semiconductor wafers. • A non-contact wafer grinding/thinning method by pure EDM is first presented. • The material response of SiC to both single and consecutive discharge is elucidated. • Ultra-short-pulse enhances the wafer grinding efficiency and surface integrity. • The grinding precision and thinning limit by contemporary EDM technology are explored. • EDM shows high potentials for processing next-generation ultra-hard semiconductor wafers. [ABSTRACT FROM AUTHOR]

Boron carbide (B 4 C) composites containing 0–10 wt.% graphene nanoplatelets (GNPs) were consolidated using hot pressing at 1950 °C for 60 min under 30 MPa in an argon atmosphere. Their electrical discharge machining (EDM) characteristics were evaluated for the first time. Additionally, the effects of GNPs on the microstructure, electrical conductivity, material removal rate (MRR), and surface roughness (R a) of B 4 C composites were investigated. The results show that the B 4 C composite containing 10 wt.% GNPs exhibited the highest electrical conductivity of 4997 S·m−1 because of the formation of GNPs conductive networks. Under a fine machining condition, the MRR of the B 4 C composite was enhanced by 43.5 % (from 6.55 to 9.40 mm3 min−1) compared with that of monolithic B 4 C. Furthermore, the R a decreased to 1.12 μm, which was significantly lower than that of pure B 4 C (2.44 μm). Scanning electron microscope and energy disperse spectroscopy analysis of the EDM surfaces were used to determine that the main material removal mechanisms for B 4 C composites with less than 2 wt.% GNPs were spalling and melting. As the GNPs content increased, B 4 C grain fallout, melting, and evaporation became more dominant. The other mechanisms, including thermal shock and oxidation, are also discussed in detail. [ABSTRACT FROM AUTHOR]

A micro rod machining method which can switch between electrical discharge machining (EDM) and electrochemical machining (ECM) by attaching/detaching a diode to/from a bipolar pulse generator in parallel to the working gap was newly developed using a wire electrode made of tungsten. The problem of the wire electrode wear was eliminated by the use of the wire electrochemical turning (WECT) method in which the tungsten wire electrode is continuously running. The ultra-short bipolar pulse current was generated by the electrostatic induction feeding method where a pulse voltage is coupled to the working gap through a feeding capacitance. The machining characteristics of three types of wire guide; disk-shaped WC guide, laminated wire guide and cylindrical acrylic guide, were studied. The experimental results showed that the cylindrical acrylic guide has the best machining characteristics without the influence of guide wear and with less stray current flowing through the working gap. Using the cylindrical acrylic guide, the influences of the feeding capacitance C 1 , and the total amplitude of the pulse voltage on the machining characteristics were studied. Finally, a stainless steel SUS 304 micro-rod with a high aspect ratio of 14 was fabricated efficiently by using the EDM and ECM modes for rough and finish machining in sequence with the same setup, pulse generator, and neutral electrolyte. • EDM and ECM modes can be switched in neutral electrolyte by attaching/detaching a diode in parallel to the working gap. • The problem of the tool electrode wear was eliminated by the use of the WECT method. • The machining characteristics of different types of wire guide are studied. • Micro-rod of high aspect ratio is machined using the EDM and ECM in same neutral electrolyte. [ABSTRACT FROM AUTHOR]

The surface modification of Ti–6Al–4V alloy was achieved by using an electrical discharge machining (EDM) surface modification technology under the action of pulsed discharge to induce an in-situ synthesis reaction between the molten metallic material and the ionized elements in the atomized medium. In this study, nitrogen and urea solutions are used as the gas-liquid phases of the atomization medium. ANSYS simulation software was used to simulate and analyze the interpolar pressure and flow field of the different electrodes. The effect of different electrode forms on the EDM surface modification layer was investigated by designing comparative trials. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and other detection methods were used to characterize the process indicators, such as surface morphology, roughness, hardness, and wear resistance of the reinforced layer. It was found that a thick and uniform continuous layer can be obtained on the Ti–6Al–4V alloy substrate using multi-channel electrode machining, and the thickness is about 65 μm. XRD analysis indicates that the reinforced layer mainly contains TiN, Ti 2 N, Ti 2 AlN, Ti 2 O, and CuO phases. The samples with reinforced layers were shown to have higher hardness (1578 HV) and better wear resistance than the titanium substrates. The main wear mechanism is spalling wear and light oxidation wear. • Near-dry EDM surface modification using different channel electrodes. • Evaluating the effect of electrode forms on the state of the interpolar flow field distribution. • The multi-hole electrode contributes to the formation of modified layers. • The modified layer of multi-hole electrode has better surface morphology and performance. [ABSTRACT FROM AUTHOR]

Micro-hole structures are widely used in aircraft engines, but they are difficult to fabricate because of stringent machining quality requirements. Electrochemical discharge drilling (ECDD) is a hybrid machining method for fabricating small holes in nickel-based superalloys that uses low-conductivity salt solution as the working fluid. Electrical discharge and electrochemical dissolution occur simultaneously in the ECDD process. ECDD is expected to achieve micro-holes with high machining efficiency and without any recast layer, but little research has been carried out on the surface integrity. In this study, the surface morphology, element composition, residual stress, microhardness, and recast layer properties of the ECDD machined holes were analysed. The results show that the surface integrity of the holes improves by the ECDD method, and there is no recast layer, no melted debris, and no tensile residual stress. Moreover, with an increase of the working fluid conductivity from 0.005 to 3.6 mS/cm, the residual stress of the ECDD machined hole becomes compressive, the microhardness of the wall no longer decreases significantly, and the surface roughness of the wall decreases to Ra = 1.69 μm. Furthermore, the average diameter and the taper angle of ECDD machined hole increase with the increase of machining time. In addition, the entrance of the ECDD machined hole has a round corner without a sharp edge, and its radius-of-curvature is approximately 150 μm. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) of electrically conductive ceramics offers the possibility to manufacture customized ceramic components from sintered blanks. In this study two different yttria neodymia co-stabilized TZP materials containing 28 vol% niobium carbide were manufactured by hot pressing at 1275 °C–1400 °C and axial pressure of 60 MPa and compared to a 3Y-TZP based reference. The co-stabilized ceramics offer a strength up to 1250 MPa and a hardness of 14 GPa. The fracture resistance can be tailored between 7.4–9.7 MPa√m by variation of the yttria/neodymia ratio and the sintering temperature. These composites, however, require an exact setup of machining parameters. Die sinking EDM experiments revealed that the dominant material removal mechanism is melting. Machined surfaces can achieve low roughness Ra =0.3 μm combined with material removal rates of 1.5 mm³/min. The choice of excessively high energy parameters in EDM may lead to crack formation, spallation and phase accumulation during re-solidification. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of a short circuit on machined surface quality in the electrical discharge machining (EDM) of carbon fiber reinforced plastics (CFRP) in order to obtain a machined surface with good quality. In the EDM of CFRP, short circuits caused by the attraction of frayed carbon fibers on the machining surface to the tool electrode frequently occur and has adverse effects on the quality of the machined surface. In this study, die-sinking EDM of CFRP using deionized water was carried out, and the influence of duration of stable state in which short circuit does not occur on quality of machined surface was investigated. The occurrence of short circuits was determined from the fluctuation of the z-axis position. The machined surface was investigated using an optical microscope and the quality of the machined surface was judged on the basis of the presence or absence of frayed carbon fibers. The experimental results show that each stable state continues for 50 seconds or less when elapsed time is from 0 to 20 minutes. On the other hand, when the elapsed time is from 20 to 40 minutes, the duration of each stable state becomes longer than 50 seconds. It was found that when the machining process was stopped during unstable state in which short circuits occur, the quality of the machined surface was poor. On the other hand, when the machining process was stopped after stable states for a certain amount of time, the quality of the machined surface was good. [ABSTRACT FROM AUTHOR]

In commercial micro electrical discharge machining (micro-EDM) a high process-stability is required, which is mainly determined by the dynamic characteristics of the kinematic system and the process control. To reduce inefficient processing such as open circuits, arcing and short circuiting and thereby increase removal-efficiency, an additional feed-system is required when using industrial EDM machines, since detailed knowledge about the kinematic parameters and the parameters of the electrical control system is limited and usually only comprehensible by analysing voltage and current characteristics. In this study, the dynoMat module as an additional system is presented, which is based on statistical analyses to control the gap between the tool electrode and the work piece by help of a piezo module. A separate monitoring system was realized for process analyses, which is used for fast and direct control of the piezo actuator. The maximal feed of the piezo actuator is less than the minimal step size of the basic feed system, which ensures the applicability in the EDM machine. The fundamental functionality of the dynoMat module is described in this study. Based on an experiment for machining micro-channels, it will be shown that the piezo module ensures a high process-dynamic and thus reduces the number of removal-inefficient pulses, which is verified by analyses of the voltage and current characteristics. From the experimental results it can be determined that the process-efficiency, characterised by the material removal rate and the tool wear rate, as well as the machining precision, characterised by the sparking-gap, are significantly improved. [ABSTRACT FROM AUTHOR]

Wire electrical discharge grinding (WEDG) is an attractive alternative to traditional grinding technologies for machining tapered micro rods. However, controlling the shape and diameter of the micro rods can be challenging using conventional WEDG. A new approach of WEDG using two static brass wires (TS-WEDG) is proposed in this paper for reducing the complexity in fabricating tapered micro rods. Following this approach, tapered micro rods can be fabricated by feeding a rotating micro rod along the centreline between two inclined wires. A prototype device for TS-WEDG processing has been developed. This device allows to adjust the position of one wire, thus changing the relative angle and distance between the two wires. This way the size and taper of the micro rods can be controlled. The feasibility of the proposed TS-WEDG approach has been experimentally verified. The results have shown that TS-WEDG is a promising method for efficiently fabricating micro rods having either a positive or a negative taper. [ABSTRACT FROM AUTHOR]

In this study, Fe-based metallic glass was machined by the Electrical discharge machining process with the ultrasonic vibration assisting and conductive aluminum powder adding. Fe-based metallic glass possess high strength, high hardness, and very brittle characteristics. The processing parameters include peak current, duration time, ultrasonic power, and aluminum powder concentration. After completing the experiments, the quality characteristics such as surface roughness, processing time and electrode wear quantity were also analyzed. Compared with experimental results without the ultrasonic vibration-assisting and conductive aluminum powder adding, the surface roughness and processing time is reduced by 48.8% and 40.3% after UV-assisted EDM at the aluminum powder concentration of 1.0 × 10 -2 wt% respectively. The machined Fe-based metallic glass is still an amorphous material without the crystal structures generation under XRD identification. [ABSTRACT FROM AUTHOR]

The electrical discharge machining (EDM) process with inner and outer flush is effective for drilling film cooling holes on the blades of aeroengines and gas turbines. Due to the hollow structure of the blades, the break-out status needs to be accurately detected in order to control the position of tool electrode end to prevent the back strike. Currently, the break-out detection is mainly realized based on the change of electrical signals and tool electrode velocity. The previous research shows that the machining stability of the process can be improved by optimizing the outer flush. However, in this case the break-out status is difficult to be detected using the existing methods. In this research, a novel break-out detection method using audio signal is proposed. The audio signals of the process are firstly collected and analyzed through time and frequency domain methods to provide the basis for algorithm design. Then a filter of the audio signals is designed based on the comparison of original signals collected before and after break-out to reduce the impact of noise. And the feature extraction algorithms are designed to reflect the characteristics of break-out with less dimension. Next a recognition model using artificial neural network is established by the features of audio signals, which are classified as before or after break-out. The recognition model is validated by test data acquired by machining experiments and the results verified that the break-out detection using audio signal is feasible in drilling film cooling holes. [ABSTRACT FROM AUTHOR]

Using water-based dielectrics and high-energy density electrical discharge machining for titanium alloy and superalloy has shown promising economic advantages. Combined with sinking-EDM, its finishing quality can be further enhanced. However, the relatively high tool wear rates restrict the use of water-contained working fluid in sinking-EDM. As EDM is widely used for the machining of slots and holes, it is necessary to study the tool wear in these situations. In this paper, the mechanism of electrode loss is studied in 6 kinds of dielectrics, including EDM oil, WEDM working fluid, tap water, deionized water, emulsion, and polyethylene glycol solution. Two kinds of graphite materials were compared to explain the tool wear mechanism. Electrolysis consumption and discharge erosion were evaluated by experiments. The aim of this study is analyzing the effect of electrolysis and spark explosion on the performance of tool wear as well as their relation with dielectric characteristics. According to slot machining and electrode electrolysis experiments, carbon content and conductivity are regarded as the main influence factors. It is found that the dielectrics with higher carbon content can effectively reduce the tool wear in the machining process and electrolysis can lead to thinning of the electrode which makes it crumbly. This work can help compound suitable dielectrics and choose appropriate graphite electrode materials with lower tool wear in EDM machining. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings (TBC) can significantly improve heat resistance of aero-engine hot-end components. The abrasive water jet machining (AWJM) and electrical-discharge machining (EDM) can be combined to drill holes at the TBC coated super-alloy. In this combined process, the AWJM is used to remove TBC material to form a pilot hole in the first step, and EDM is used to drill along the pilot hole at metal substrate in the second step. However, the residual TBC material at the bottom of the pilot hole after AWJM markedly influences the feasibility of the subsequent EDM drilling. The objective of this paper is to investigate the relation between metal exposure and EDM machinability for the combined process. The results reveal that the EDM machinability is highly related with metal exposure and the height of the residual TBC material. Larger exposed metal area results in greater discharge energy and subsequently can remove more volume of residual TBC, and improves the EDM machinability. A threshold of metal exposure percentage of approximate 18% for the EDM drilling was observed according to the present conditions. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) of biocompatible nitinol combines superelasiticity, high accuracy of fabrication and miniaturization capabilities, thus presenting a promising base material for flexible medical instruments in minimally invasive surgery. In order to remove cytotoxic surface contamination which is caused by brass wire in the standard EDM process, the effectiveness of a hydrofluoric acid and nitric acid based chemical etching process was tested. Here, Energy-dispersive X-ray spectroscopy proved the purity of the surface after etching, while cytotoxicity experiments showed great improvement in the reaction of human fibroblasts, shifting cell vitality to non-cytotoxic levels. [ABSTRACT FROM AUTHOR]

[Display omitted] • Deterministic cellular lattice structures of IN718 are fabricated through LPBF. • Through-holes EDM drilling is performed on LPBF-fabricated lattice structures. • Machined holes show dimensional variability due to pores, nodes, and lattice defects. • Near-circular through-holes machined by optimizing EDM parameters and electrode positioning. Additive manufactured (AM) metallic lattice structures are being largely explored for different engineering applications. The fastening, implantation, and installation of such lattice structures demand secondary processing. In the current work, through-hole drilling is performed using electrical discharge machining (EDM) on Inconel 718 (IN718) lattice structures fabricated by laser powder bed fusion (LPBF). The challenges in EDM hole drilling have been encountered and uncertainty in the machined holes owing to periodically open pores and nodes in the lattice structures sizes has been identified. Finally, an experimental strategy has been proposed for near-circular hole drilling by design optimization and tool positioning with respect to the cellular structures. [ABSTRACT FROM AUTHOR]

• Shock location correlation to direct contact condensation stability. • CFD analysis of nozzle features. • Stability study on chamfers and defects in DCC nozzles. • Stability regime maps for multiple types of nozzles including orifice, converging, and converging diverging nozzles. Direct contact condensation (DCC) is an efficient way of transferring heat between fluids' vapor and liquid phases by mixing them directly rather than using a device like a heat exchanger. However, in the field, DCC may produce destructive and unwanted vibrations due to the instability of the gaseous plume condensing in the process fluid under certain conditions. Previous research on this topic has focused on correlating the flow conditions of the liquid and vapor phases to engineering quantities, such as the heat transfer coefficient, plume length, stability, and the dominant frequency exhibited by the DCC process. The present study investigates the impact of nozzle geometry on plume stability. It was motivated by the drastic difference observed experimentally between the stability of two identically designed nozzles with slightly different microfeatures. Tests were performed with several nozzle geometries, including converging/diverging, straight, and converging nozzles. The results from these experiments show that a nozzle with a supersonic flow at the exit plane is more likely to be stable than one with a subsonic exit flow. It is, therefore, possible to correlate the pressure ratio across the nozzle and nozzle geometry to the stability of the plume. This understanding allows a DCC nozzle geometry to be analyzed and designed for high stability with relatively simple one- and two-dimensional compressible flow modeling tools capable of resolving only the single-phase, compressible flow in the nozzle itself [ABSTRACT FROM AUTHOR]

Titanium alloys, such as Ti6Al4V, are widely employed in the biomedical industry for implant applications due to their favourable properties. However, these alloys can experience long-term corrosion in the presence of bodily fluids, which is a critical concern for implants as it affects their timespan. Therefore, this study aimed to examine the corrosion resistance of Ti6Al4V in body fluid. Highly desirable electrical discharge machining (EDM) techniques used for Ti6Al4V sample preparation with three different conditions (oil, deionized water, and hydroxyapatite mixed in deionized water). Corrosion was assessed using electrochemical analyses, with microstructural analysis. Results indicated that the samples produced using water and oil had the best and lowest corrosion resistance, respectively. Protective oxide layer formed during the EDM in water while heterogeneous surface was produced for EDM in oil. The increase in capacitance leads to the thickening of the oxide layer, thereby enhancing the corrosion resistance. • Capacitance and bath influence on the corrosion resistance of the EDMedTi6Al4V in SBF. • The passive film was produced in aggressive environment (water and HA), increasing the Ti6Al4V corrosion resistance in SBF. • The capacitance increment generated thicker oxidised layer on Ti6Al4V, improving the corrosion resistance in SBF. • Corrosion mechanism of the EDMed and non-EDMed samples in SBF was influenced by EDM before and after transpassivation. [ABSTRACT FROM AUTHOR]

Crystallization fouling adhered on the heat transfer surface is a serious problem. Here, we report an anti-fouling heat transfer surface prepared by magnetron sputtering (MS) a-C film on an electrical discharge machining (EDM) Cu surface (MES). Microstructure, chemical composition, wettability and anti-fouling property of the resulting modified surface were analyzed by SEM, EDS, XRD, XPS, Raman, Contact angle measurement, Atomic Absorption Spectroscopy and homemade heat transfer performance testing device. The formation of CaCO 3 fouling and the anti-fouling mechanism of the as-prepared surface are also discussed. The results show that the surface prepared by EDM and MS displays a micro/nano structure with a-C film deposited on it. The combination of micro/nano structure and the low surface energy a-C film endows the MES with higher contact angles for both water and glycerol as well as superior anti-fouling property than the polished Cu surface (PS) and the EDM Cu surface (ES). This work offer an effective strategy and promising application for fabricating anti-fouling heat transfer surface. • Anti-fouling surface is modified by magnetron sputtering and EDM. • The modified surface is characterized with a-C film coated on micro/nano structure. • The modified surface shows remarkable hydrophobicity and oleophobicity. • The modified surface performs lower fouling resistance and longer induction period. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Superhydrophobic surface is fabricated on electrical discharge machining (EDM) surface by electrochemical etching. • EDM superhydrophobic surface is shown a hierarchical micro-nanostructure, where EDM surface is basement. • EDM is used as a pretreatment process for the fabrication of superhydrophobic surface, enhances the performance. • The superhydrophobic surface on EDM functional unit of parts shows better application. Abstract Fabrication of superhydrophobic surface (SHS) on metal can effectively enhance its utility value. Herein, electrochemical etching for the electrical discharge machining (EDM) surface of beryllium copper (Be-Cu) alloy is carried out in the hydrochloric acid electrolyte, to obtain a hierarchical micro-nanostructure. After modification by stearic acid, the contact angle is up to 167.1 ± 2.6° and the sliding angle to 2.4 ± 0.7°. The microstructure constructed by EDM improves the quality of the SHS availably. The corrosion and abrasion resistance tests show that the performance is significantly higher than that without EDM. EDM can be used as a pretreatment process for the fabrication of SHS. It can also be applied to the EDM functional unit of parts to achieve specific functions. In addition, EDM for hole, the inner wall of the superhydrophobic hole was obtained, confirmed the excellent self-cleaning performance. This method has a good application prospect in the fabrication of SHS of metallic engineering materials. [ABSTRACT FROM AUTHOR]

Prediction of the microstructure modifications during manufacturing processes will allow to deduce the functionality of a manufactured workpiece. Likewise, for manufactured workpieces by thermal processes, the prediction of the microstructure modifications within the characteristic heat affected zone will allow detailed conclusions regarding their functionality. In course of this work, a previous developed model is improved with higher temperature gradients. Using the phase field method, the developed model is performed for a 42CrMo4 steel, and is applicable for simulations of microstructure evolution during processes with main thermal active principle e.g. laser machining or electrical discharge machining. [ABSTRACT FROM AUTHOR]

The manufacturing industry commonly benefits from model-based understanding that correlates process data and physical process conditions. In many cases, this enables the identification of machining results. Electrical discharge machining (EDM) incorporates unique electrical signals that are used efficiently for process control and process stability documentation. Unfortunately, correlations of the data to actual physical conditions during the presence of each discharge that eventually yield material modifications are scarcely investigated. This paper addresses this issue through the compilation of concepts to establish a model-based understanding in EDM to accomplish the digital replication of machining results. [ABSTRACT FROM AUTHOR]

Abstract Electrical discharge machining is a significant non-traditional technique, widely used in the precise manufacturing field. However, the electrical discharge machining process possesses plenty of energy consumption and hazardous exhaust emissions. Since a sustainable machining technique, external magnetic field assisted, could dramatically develop sustainable machining performance of electrical discharge machining process, this paper presents a comparative study energy efficiency and environmental impact in magnetic field assisted electrical discharge machining and conventional electrical discharge machining. A novel thermo-physical model was proposed to calculate energy distribution under the single/continuous discharge, which was verified by a series of corresponding experiments. Then, based on simulation and experimental methods, a comparative study on the magnetic field assisted electrical discharge machining and conventional electrical discharge machining was conducted to analyze the discharge energy flowing and temperature distribution of workpiece, electrode tool and debris. Moreover, the effects of external magnetic field on the machining performance, environmental impacts and energy efficiency were presented. Eventually, it can be found out that the effect of magnetic field contributes to increasing energy utilization efficiency by 15.2%, material erosion efficiency by 22.6%, and material removal rate by 21.9%. To balance energy efficiency and surface roughness (Ra), the optimal parameter combination is obtained as below: magnetic field intensity: 0.2T, discharge current: 7–9A, and pulse duration: 300s. Highlights • Magnetic field assisted EDM improve energy efficiency and environmental impact. • A thermo-physical model is proposed to calculate energy distribution of MF-EDM process. • Sustainable machining performance of EDM and MF-EDM are comparatively investigated. • The optimal parameter is: magnetic field intensity: 0.2T, current: 7∼9A, and pulse duration: 300μs. [ABSTRACT FROM AUTHOR]

Abstract In micro-electrical discharge machining (micro-EDM), the minimum machinable size is determined by the material removal per pulse discharge. In this study, two types of single-crystal silicon tool electrodes with high electrical resistivity were used to fabricate the micro-rod by minimizing the material removal per pulse discharge, and to reduce the machinable size for micro-EDM. The EDM characteristics of micro-rods using silicon tool electrodes with high electrical resistivity were investigated. Based on the experimental results, it is found that the peak discharge current decreases with an increase in the electrical resistivity of the tool electrode. Consequently, the average diameter of discharge craters generated on the micro-rods is reduced to approximately 0.4 μm. The silicon tool electrode has also disadvantage of their higher tool wear ratio compared with that of copper, which is probably due to the brittleness of the silicon. Moreover, the material removal rate is significantly lower for the silicon tool electrodes compared with that for the copper tool electrode. Because the average diameter of the discharge craters generated by the silicon tool electrodes is small, an attempt is made in this study to fabricate a cemented tungsten carbide micro-rod with a diameter less than 1 μm using the silicon tool electrode with an electrical resistivity of 1.2 × 10−3 Ω m. The result is indeed promising since the diameter of the micro-rod is 0.8 μm, indicating that it is possible to fabricate micro-rods with a diameter within the sub-micrometer range by only using silicon tool electrode with high electrical resistivity in micro-EDM. Highlights • The peak discharge current decreases with an increase in the resistivity of the tool electrodes. • The diameter of discharge craters decreases by increasing the resistivity of the tool electrodes. • The tool wear ratio is higher for the silicon tool electrodes compared with that for copper. • The material removal rate is lower for the silicon tool electrodes compared with that for the copper tool electrode. • A cemented tungsten carbide micro-rod with a diameter of 0.8 μm is fabricated. [ABSTRACT FROM AUTHOR]

Abstract Polycrystalline diamond (PCD) is one of the most important wear-resistant materials. Electrical discharge machining (EDM) is often used to remove pieces with different sizes, shapes, and surface qualities from polycrystalline diamond compacts (PDC) in order to satisfy the demands of PCD tools. However, as the special properties of the PCD, the structure transformation and removal process of the PCD materials are different to that of the cemented carbide substrate. This paper proposes a removal mechanism for PCD considering the morphology of discharge craters and the micro-structural evolution of diamonds. It was observed that the tensile residual stress was contributed to a large diameter value and irregular shapes of discharge craters in cobalt-rich areas. The graphene was obtained through the peeling process of graphite under the action of tensile residual stress when the thickness of metamorphic layer was in a small level. The degree of graphitization and number of crystal defects increased with increasing the thickness value of metamorphic layer according to the Raman shifted analysis. A metamorphic layer containing graphite, cobalt, and cobalt carbide was observed by the XRD analysis, which increased in thickness with increasing discharge energy. The hardness of PCD layer was reduced due to the action of the metamorphic layer, which damaged the performance of PCD tools. The electrical conductivity of the PCD layer was increased with increasing the thickness value of metamorphic layer, which contributed to the high machining efficiency with enlarging the discharge areas. Meanwhile, the diamonds were removed in the graphite form due to the graphitization of diamonds were the mainly removal mechanism in electrical discharge machining. Graphical abstract Unlabelled Image Highlights • The removal mechanism and micro-structural evolution of diamonds in EDM are proposed in this paper. • The diamonds were transformed into graphite before the diamonds were removed. • The thickness of metamorphic layer was key factor to a non-linear relationship between the amount of feed and machining time. [ABSTRACT FROM AUTHOR]