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This research discusses the effect of typical characteristic dimensions of electrodes on electric arc electrochemical composite machining (EAECM). The flow rate and debris removal capability of electrodes with different characteristic dimensions were investigated by flow field simulation. Single-factor machining experiments were conducted. The discharge characteristics, process indicators and machined surfaces of electrodes were analyzed it was found that the tubular electrode has a demarcation phenomenon that affects the surface quality. The results indicate that the use of electrodes with large inner diameters is favorable to improve the surface consistency. The use of electrodes with small outer diameters improves the overall surface quality but increases the electrode wear. Finally, the fracture mechanism of thin-walled electrodes was revealed by stress field simulations and experiments. In conclusion, in order to improve the machining effect of EAECM, large-diameter (inner and outer diameter) electrodes with wall thickness greater than 2 mm should be selected. [ABSTRACT FROM AUTHOR]

In this paper, a novel efficient and sustainable electrical discharge machining method, referred to as short electric arc machining (SEAM), is proposed to solve the problems of low efficiency, severe tool wear, and high cost of Ti2AlNb machining by traditional methods. The mechanism of SEAM with different voltages and tool electrode materials (W70Cu30, high-purity graphite, copper-plated graphite, and 304 stainless steel) is studied using a DC power supply, and the workpiece material removal rate (MRR), surface roughness (Sa), and relative tool wear rate (RTWR) are analyzed. In addition, the surface morphology, cross-sectional morphology, elemental distribution, and microhardness of Ti2AlNb after processing are investigated. The experimental results show that under 28 V, the W70Cu30 electrode achieves the highest MRR of 2571 mm3/min, which is higher than that of the other three electrode materials. It has also the lowest RTWR of the electrode and a relative electrode loss of only 0.0974%. The lowest surface roughness and heat-affected layer of the workpiece after machining are 53.2 and 56.54 µm, respectively. The absolute difference of the width of the cross-section of the workpiece is the smallest, and the hardness of the recast layer of the workpiece is close to the hardness of the base metal, which is conducive to further processing. [ABSTRACT FROM AUTHOR]

Short electric arc machining (SEAM) is a highly efficient, environmentally friendly, and developing manufacturing method that does not depend on the physical properties of the workpiece. However, there is still a gap in research on the arc ignition mechanism for DC short electric arc machining. This paper proposed an arc ignition mechanism with Joule-arc heat transition and verified its validity by machining current waveforms and a high-speed camera. In addition, the performance of different aerospace materials (Inconel 718, TC4 titanium alloy, and 7075 aluminum alloy) in SEAM was investigated. Experiments revealed the mechanism of arc ignition in DC-SEAM. It was found that machining efficiency, surface roughness, and dimensional accuracy were strongly dependent on the melting points of workpiece materials. In addition, the poor thermal conductivity of the workpiece material accelerated electrode loss. Experiments showed that SEAM of aluminum alloys driven by DC voltage performed better depending on the thermal properties of the material. [Display omitted] [ABSTRACT FROM AUTHOR]

SKD11 has a wide range of applications in the tooling industry. However, due to its high mechanical strength and hardness, it is a difficult material to machine. To address the issues of low machining efficiency, severe tool electrode wear, and environmental pollution caused by traditional EDM, this paper proposes a more efficient and sustainable method of EDM production called short electric arc machining (SEAM). This paper discussed the mechanism of material removal by a short electric arc and then conducted experiments on SKD11 machining with various voltage parameters using a self-designed short electric arc milling machine, analysing the material removal rate (MRR), relative tool electrode wear ratio (REWR), and specific energy consumption (SEC) of the machined workpiece. The experimental results indicate that the maximum removal rate is 15,745 mm3/min, the REWR is significantly reduced to 1.4 %, and the energy consumption ratio is 76.84 KJ/cm3. Finally, the microscopic morphology and elemental composition of the workpiece and tool electrode were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), and the variation of cross-sectional grains was analyzed by electron backscatter diffraction (EBSD).It can be concluded that the short-arc milling method discussed in this paper can provide an efficient machining method for difficult-to-machine materials. [ABSTRACT FROM AUTHOR]

By introducing a high concentration of electrolyte into the working medium of conventional short electric arc machining (SEAM), we have realized the removal of surface defects of SEAM using electrochemical machining (ECM) during the discharge of SEAM. This process is called short electric arc-electrochemical (SEAM-ECM) combined machining. The forms of power excitation mainly use pulsed and constant voltage DC. Therefore, this research first reveals the arc-breaking and action mechanism of SEAM-ECM combined machining under two excitation forms by single-pulse simulation and experiment. The results show that DC excited arc-breaking is an adaptive arc-breaking over the discharge gap; the intensity and duration of ECM action of DC excitation are higher than that of pulsed excitation; at the same current strength, the arc-breaking time of DC excitation is about three times more than that of pulsed excitation (duty cycle of 55%). In addition, continuous discharge experiments are conducted to verify the machining effect of SEAM-ECM combined machining. The results show that DC excitation tends to form a continuous arc during machining, aggravating copper electrode loss and reducing the workpiece's dimensional accuracy and the material removal rate. The concentrated discharge energy also produces deeper discharge pits, making the workpiece surface rougher relative to the pulsed excitation. The machining differences between the two excitation methods at different voltages are compared, showing that a balance exists between SEAM and ECM under suitable machining conditions. [ABSTRACT FROM AUTHOR]

In order to solve the problems of poor dimensional accuracy, high-specific energy consumption (SEC), and poor surface integrity in DC short electric arc machining (SEAM), this paper proposes to use W-Ag alloy as the electrode material for machining nickel-based alloy (Inconel 718). Firstly, the effect of voltage and electrode material (graphite and W-Ag alloy) on the material removal rate (MRR), relative electrode wear rate (REWR), surface roughness (Sa), and SEC were investigated, and current and voltage during machining were measured by a multichannel data acquisition system. In addition, the surface morphology, cross section, and element distribution after machining were analyzed. The experimental results showed that W-Ag alloy as a tool electrode can obtain better performance in SEAM; its MRR reach 6314 mm3/min at 30 V which is twice as high as graphite electrode. The SEC of W-Ag alloy electrode is 32.64 kJ/cm3, significantly lower than that of graphite electrode with 84.16 kJ/cm3. The surface roughness is lower after machining with W-Ag alloy electrode, and the thermal damage layer is only half of that machined with graphite electrode. [ABSTRACT FROM AUTHOR]

[Display omitted] • Theoretical model of EAECM material removal mechanism was developed. • Experiments showed that the feed rate is the decisive factor regulating the percentage of EAM/ECM action in EAECM. • Waveform and surface integrity measurements showed that the structural evolution of the machined surface transitions from a black recast layer covered surface to a brightly finished material matrix. • Cross-sectional experimental results showed that EAECM can obtain good surface quality at low discharge energies and high electrolyte concentrations with no recast layer. In this study, a theoretical model about the conversion mechanism of material removal by electric arc electrochemical machining (EAECM) was derived. The limiting conversion rate of ECM-EAECM was measured on this basis. The current waveform, surface integrity, shape accuracy and process indexes during machining were measured and evaluated. The results showed that when the limiting conversion rate of ECM was exceeded, the material removal consisted of alternating effects of electric arc machining (EAM) and ECM. The proportion of EAM increased and the surface structure evolved into discharge defects, verifying the correctness of the theory. In addition, parametric crossover experiments were performed to clarify the degree of parametric response to EAECM modulation. Finally, the optimal combination of parameters resulted in a material removal rate of up to 5452 mm3/min, a relative electrode wear rate of 1.39 %, and a surface roughness of only 4.62 μm. [ABSTRACT FROM AUTHOR]

The analysis of craters in electrical discharge machining (EDM) can help improve the understanding of the basic theory and predict the process indexes; thus, the research on craters has been a popular topic in this field. However, a novel low-voltage, high-current EDM technique based on a constant-voltage power supply, namely short electric arc machining (SEAM), is almost completely unexplored. To fill this gap and reveal the basic theory of SEAM, in this work, the influences of the voltage and pulse duration under different polarities on the crater diameter, the width, depth, and thickness of the recast layer, and the bulge height are investigated by single-factor experiments using single-pulse discharge, and the differences between the surfaces and cross-sections of craters are further analyzed. The experimental results demonstrate that as the voltage and pulse duration increase, the discharge channel expands, the energy density of the discharge channel increases, and the crater diameter, the width and depth of the recast layer, and the bulge height all increase. It is also found that negative-polarity machining tends to form large and shallow craters with lower surface roughness, while positive-polarity machining tends to form small and deep craters with higher machining efficiency. [ABSTRACT FROM AUTHOR]

Short electric arc machining (SEAM) is an efficient method for difficult-to-machine materials and is characterized by low voltage and high current. In this study, graphite is used as the tool electrode and titanium alloy (Ti6Al4V) as the workpiece. The process parameters, including voltage, duty cycle, flushing pressure, electrode rotation speed, and milling depth were analyzed at different electrode polarities on SEAM of titanium alloy Ti6Al4V. The maximum material removal rate (MRR) is 479.4 mm3/min, the minimum surface roughness (SR) is 30.61 μm, and the minimum relative tool wear rate (RTWR) is 2.9% during SEAM of titanium alloy. The grey correlation analysis method is used to explore the correlation of process parameters to MRR, RTWR, and SR, and sort according to the order of correlation. Further, when the voltage is 30 V and other process parameters are the same, the specific energy consumption (SEC) of electrode negative and positive polarities were 133.56 kJ/cm3 and 431.42 kJ/cm3, respectively. The experimental results show that the MRR, RTWR, and workpiece SR are higher in negative polarity machining, and the SEC is higher in positive polarity machining because of a significant difference in the energy distribution of different electrode polarities that affects the material removal mechanism and the machining current. Moreover, the dimensional accuracy, surface morphology, cross-section, chemical composition, and micro-hardness of Ti6Al4V after machining were also investigated. [ABSTRACT FROM AUTHOR]

Short electric arc milling (SEAM) is an efficient electrical discharge machining method, especially for the efficient removal of difficult-to-machine conductive materials with high hardness, high toughness, and wear resistance. In this study, titanium alloy Ti–6Al–4V is used as the research object to conduct machining experiments. The material removal mechanism of SEAM technology is studied using a DC power supply and different tool electrode materials (copper, graphite, Q235 steel, and titanium). The energy distribution of the discharge gap is analyzed using a data acquisition system and a high-speed camera. The arc is found to move with the spindle rotation in the process of arc discharge, and multi-point discharge occurs in the process of single-arc discharge. The voltage and current waveforms and the radius of the etched particles during the experiment are measured; the material removal rate (MRR) and relative tool wear rate (RTWR) are calculated; and the surface and cross-section micromorphology and hardness are analyzed. The experimental results show that when the electrode material is graphite, the maximum feed rate is 650 mm/min; the MRR can reach 17268 mm3/min; the ideal maximum MRR is more than 65,000 mm3/min; and the RTWR is only 1.27%. When the electrode material is Q235 steel, the minimum surface roughness is 35.04 μm, and this material has good stability under different input voltages. When the electrode material is copper, the hardness of the resolidified layer is close to that of the base material, which is beneficial for further processing. The lowest specific energy consumption is 18.26 kJ/cm3 when titanium is used as the electrode material. [ABSTRACT FROM AUTHOR]

To improve the processing deformation, low efficiency, tool wear, surface burrs and other problems of aluminium alloy thin-walled parts, a study on 7075 aluminium alloy using short electric arc milling (SEAM) technology is proposed. Using the material removal rate, relative tool wear ratio, surface roughness and side taper of workpiece as technical indexes, the effects of voltage, duty cycle, frequency and electrode material on aluminium alloy processing performance were studied. The surface morphology, chemical composition, microstructure and microhardness of 7075 aluminium alloy were analysed, and the machining mechanism of 7075 aluminium alloy was further revealed. Comparing the processing results of different electrode materials, the copper electrode can process aluminium alloys with an efficiency of up to 14940 mm3/min, good surface finish and high dimensional accuracy. This work lays a foundation for high efficiency and high quality SEAM of 7075 aluminium alloy. [ABSTRACT FROM AUTHOR]

In this study, the machining characteristics of pulse short arc milling (SEAM) Ti6Al4V alloy were studied. In this regard, the influence of SEAM parameters on the material removal rate (MRR), relative electrode wear ratio (REWR), and surface integrity of Ti6Al4V is studied. A wide variety of processing parameters, including different voltages, frequencies, duty cycles, flushing pressures, electrode rotation speeds, and electrode feed rates, are considered in the investigation. Scanning electron microscope (SEM), energy dispersive spectrograph (EDS), and micro-hardness analysis are applied to analyze results. Moreover, a multichannel data acquisition system is used to measure gap voltage and gap current. Obtained results cover the variation of MRR, REWR, surface roughness (Ra), average resolidified layer thickness, and average heat-affected zone thickness with different processing parameters. Furthermore, the electrode surface morphology and chemical composition of the negative growth of REWR are studied. Based on the obtained results, the microstructure of the resolidified layer and heat-affected zone of the workpiece cross-section is confirmed. This study provides a basis for the high-quality pulse SEAM technology of difficult-to-machine (DTM) materials to enter the semi-finishing field. [ABSTRACT FROM AUTHOR]

A favorable flow field enhances the product transport capacity and also increases the electrochemical mass transfer rate. In this paper, an end-side connected electrode suitable for electric arc electrochemical composite milling was proposed based on the existing flushing form. The aim is to simultaneously enhance the machining of the groove surface and the side. The flushing form was optimized by the flow field, and it was shown that the internal flushing increased the area of the high flow rate zone of the bottom gap. In the experiments, it was found that the internal flushing reduced the secondary discharge probability, the accumulation of re-solidified material on the groove surface was decreased, and the surface dissolution was uniform with low oxidation. However, the central jet is lost along the course and a zero velocity zone exists at the corners of the groove. Therefore, the sidewall open flow field is proposed to reduce the sidewall recast layer. It was verified that the sidewall slots of the positive flow type improved both the surface quality of the groove surface and the side wall. It was also found that the increase in the number of open grooves facilitates the generation of uniform debris removal. [Display omitted] • A gas-liquid-solid three-phase flow model was developed for flow field optimization. • The flushing form was optimized and the important role of internal flushing was demonstrated. • An end-side connected electrode with improved surface and sidewalls quality was proposed. • The optimized end-side connected electrode can be adapted to more complex working conditions. [ABSTRACT FROM AUTHOR]

The current application of short electrical arc discharge machining (SEAM) for cemented carbide removal is limited by its surface quality. In this study, tungsten-copper (W-Cu) alloy materials with different proportions as electrodes were studied by experimental methods. The mechanism of electrical parameters and composition content affecting the processing performance of SEAM was investigated, including surface roughness (Ra), material removal rate (MRR), micro-morphology, and the recast layer thickness (RLT). The results showed that the maximum MRR with W50-Cu electrode was 41 g/min, and the processing performance was the best with W90-Cu electrode in the U of 25 V, F of 2.3 KHz, and D of 55%. The W90-Cu electrode could provide good processing, and a thinner and more uniform recast layer was found on the workpiece surface. Therefore, W-Cu alloy tools are recommended when the hard surface materials machined by SEAM requires higher accuracy and surface finish. [ABSTRACT FROM AUTHOR]

Short electric arc milling (SEAM) is an electrical discharge machining method characterized by low voltage and high current. This method has high machining efficiency, and the eroded material is quickly discharged from the discharge gap by a high-speed rotating tool electrode and a certain pressure of the gas-liquid mixed medium. In this paper, the effects of tool polarity, working medium, voltage, duty cycle, frequency, and flushing pressure on the performance of short electric arc milling were investigated by using the material removal rate (MRR), tool mass wear ratio (θ), and surface roughness (SR) as technical indicators. Moreover, the surface morphology, cross-section morphology, chemical composition, and micro-hardness of GH4169 after machining were also studied, and the machine mechanism was further revealed. This work lays a foundation for more efficient and high-precision short electric arc milling. [ABSTRACT FROM AUTHOR]

To solve problems such as insufficient energy and effective arc burning during the injection of a working medium in a short arc discharge channel, the application of a W-Cu alloy as the electrode material in short electrical arc machining (SEAM) is explored in this paper. Using the surface roughness, material removal rate, and tool electrode wear rate as technical indices, the effects of voltage, frequency, and duty cycle on W-Cu alloy materials are studied to explore machining characteristics in SEAM. Contrast experiments on a graphite electrode were conducted using a SU8010 scanning electron microscope and energy spectrum analysis to study the erosion mechanism of the W-Cu alloy material. This paper addresses applications of copper-based composites in SEAM and provides a theoretical basis for the development of electrode materials in the SEAM. [ABSTRACT FROM AUTHOR]

Short electric arc machining (SEAM) technology is a complex process involving arc physics, heat and mass transfer, metal melting, and solidification, which is characterized by locality, instantaneity, and unsteady states. The energy distribution as well as both the shape and size of the molten pool has an important influence on the quality of surfaces machined with SEAM. This paper presented a mathematical model of the short electric arc molten pool built via scientific method to conduct a quantitative analysis of the heat transfer of the molten pool. The model was conducted via discretization based on ANSYS and obtained change pattern of the quasi-steady state temperature field in the short electric arc molten pool via solving the set up mathematical model. Furthermore, the short electric arc discharge removal process was simulated via element birth and death technology. The temperature increase in SEAM was monitored with the A40 infrared thermal image instrument, the thermal cycling curves of the three critical nodes were analyzed, and the result shows that the maximum error between the simulated and the actual values was smaller. This verified that the setup model and adopted software method are appropriate and feasible. The surface microstructure of the nickel-based super-alloy GH4169 shows that the strong thermal effect of the arc in the molten pool causes the material near the eroded zone to instantaneously reach the melting point, and cool rapidly. This resulted in a strong temperature gradient, which had a significant effect on the microstructure, properties, and residual stress of the erosion zone. [ABSTRACT FROM AUTHOR]

A higher energy-efficient and safe-environment-friendly method named ultra short electric arc machining (US-EAM) was proposed to meet the imperative needs of cleaner production. Low loop circuit resistance, long discharge time, and continuous energy output ensured highly stable and low energy output at low voltages in US-EAM. Voltage-current (V-A) analysis and single-point experiments investigated the machining stability. Typical US-EAM characteristics, such as the material removal rate (MRR), specific energy consumption (SEC), relative electrode wear rate (REWR), and surface characteristics, were investigated as a function of the electrode rotation speed, gas pressure, and milling depth. Moreover, the optimal parameters were obtained through the grey correlation situation decision method, showing that the MRR reached 17100 mm3/min, SEC was limited to 27.296 kJ/cm3, and the REWR was limited to 1.487%. • Stable and high energy output can achieve higher energy and efficiency. • Appropriate voltage meets both efficiency and safety. • Non-electrical parameters have a significant effect on machining. • Grey correlation decision theory estimated the non-electrical parameters. [ABSTRACT FROM AUTHOR]