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Microdimples as a typical surface texture has been widely used for improving the properties in tribology and heat transfer fields. Ultrasonically assisted electrochemical micromachining (USEMM) is a popular method for generating microdimples as it can reduce the overcutting and enhance electrolyte renewal to improve the machining localization and p...
Citations
... Non-conventional machining techniques, including micro-electrical discharge machining (EDM) [7][8][9][10], laser beam machining (LSM) [11][12][13][14], ion beam machining [15][16][17], and electrochemical micromachining (EMM) [18][19][20], have been applied to fabricate microstructures. Compared with other methods, EMM, characterized by the absence of tool wear, less thermal stress, mechanical stress and high material removal rate, has emerged as a leading micro manufacturing process [21][22][23][24]. Besides, the methodology of electrochemical micromachining has seen significant evolution and change, for example, in electrochemical jet machining, a cathodic nozzle is used to propel electrolytes at a high velocity towards the anodic workpiece. ...
Micro-pits are widely used in the aerospace and tribology sectors on cylindrical surfaces and electrochemical micromachining which are of great significance for the high material removal rate, absence of tool wear, and mechanical stress, while facing significant challenges such as stray corrosion and low machining efficiency. Aiming at the above problems, this paper proposes a comprehensive method called radial ultrasonic rolling electrochemical micromachining (RUREMM) in which an ultrasonic field has been added onto the cylindrical surface. First, a theoretical model was created to gain the rules of the formation and collapse of bubbles in the liquid medium. Second, to analyze the optimal size of the cathode electrode, the COMSOL5.2 simulation software was proposed to research the influence of the electric field on the different dimensions, and the influences of different parameters in RUREMM on material depth/diameter ratio and roughness are explored through processing experiments. Research results found that the cavitation bubble undergoes expansion, compression, collapse and oscillation, where the max deviation is less than 12.5%. The optimized size was chosen as 200 × 200 μm2 and an electrode spacing of 800 μm through a series of electric field model simulation analyses. Relevant experiments show that the minimum pits with a width of 212.4 μm, a depth of 21.8 μm, and a surface roughness (Ra) of 0.253 μm were formed due to the optimized parameters. The research results can offer theoretical references for fabricating micro-pits with enhanced surface quality and processing precision on cylindrical surfaces.
... Pulse electrochemical micromachining (PEMM) with periodic power supply reduces the electrochemical polarization behavior of anodic workpiece and improves the quality of machined surface [24,25]. Ultrasonic electrochemical micromachining (UEMM) enables the electrolyte to be rapidly renewed and promotes the disposal of products by applying micro-amplitude vibration to the tool cathode, thereby facilitating the electrolysis reaction and improving machining stability [26,27]. Available literature has indicated the benefits of ultrasonic, dynamic and pulsed on material removal, machining localization and surface quality in EMM. ...
High efficiency and high quality machining of micro-bulged arrays on metal surfaces is a major technical challenge in the field of modern industry. In this paper, ultrasonic rolling pulse electrochemical micromachining (URPEMM) technology is proposed to prepare micro-bulged arrays on 304 stainless steel. Focusing on the widely used circular micro-bulges, distributions of electric field, temperature field and evolution processes of the circular, square and triangular sectional micro-bulges in URPEMM were analyzed by finite element analysis method(FEM). The simulation process of micro-bulges forming was experimentally verified. The results show that the current density and temperature increase first and then decrease, and the error between the experimental and simulation results of the micro-bulges is within 10%. The array micro-bulges with a diameter of 503.3 μm, a height of 33.5 μm, a roughness of 0.216 μm, and a microhardness of 305 Hv can be prepared in URPEMM. Furthermore, the surface tribological properties of circular micro-bulges decreases first and then increases with the increase of micro-bulged height, which was obtained through friction and wear tests, and the friction coefficient is minimum when the micro-bulged height is 10 μm.
... Patel et al. [11] applied ultrasonic vibration in EMM, and successfully enhanced the part quality by reducing the surface roughness and taper angle of machined holes. Wang et al. [12] generated microdimples on SS304 surface by radial ultrasonic rolling electrochemical micromachining (RUREMM) and found that compared with EMM, the cross-sectional area of the machined dimple was increased by 31.2% and the bottom roughness was decreased by 23.9%. ...
Ultrasonic assisted electrochemical micromachining (UAEMM) is a promising method for its advantages in micromachining applications. It was conformed that more micro-bubbles can be produced and collapse in the proximity of an interface, resulting in high-speed micro-jet formation with surface erosion. This paper investigates the specific effect of cavitation micro-jet generated in a narrow gap in UAEMM on material corrosion. Firstly, the micro-jet impinging pressure was computed, erosion pits of chemical reaction by the micro-jet were simulated and verified, and the material was more easily removed in bulged areas by the analysis of electric field distribution around erosion pits. Furthermore, the variation of metallographic structure and electrochemical polarization characteristics of materials influenced by ultrasonic amplitude and processing time were studied in detail. Results show that the crystalline grain was refined with the increase of ultrasonic amplitude and processing time, which leads to a decrease in corrosion potential. Consequently, verification experiments were done in UAEMM and denoted that the material removal and surface precision improved significantly, and surface hardness was also increased.
Graphical abstract
... Pawariya [16] used ultrasonic vibration of tool electrode of ECDM to investigate and enhance deep microholes in difficultto-machine metal materials. Wang [17] reported that tool vibration improves machining the efficiency, surface quality, and gap environment of ECM. ...
Ultrasonic vibration-composited electrolysis/electro-discharge machining technology (UE/DM) is effective for machining particulate-reinforced metal matrix composites (MMCs). However, the vibration of the tool or workpiece suitable for holes limits the application of UE/DM. To improve the generating machining efficiency and quality of flat and curved surfaces, in this study, we implemented two-dimensional ultrasonic vibration into UE/DM and constructed a novel method named two-dimensional ultrasonic vibration-composited electrolysis/electro-discharge machining (2UE/DM). The influence of vibration on the performance of 2UE/DM compared to other process technologies was studied, and an orthogonal experiment was designed to optimize the parameters. The results indicated that the materiel remove rate (MRR) mainly increased via voltage and tool vibration. The change current was responsible for the MRR in the process. Spindle speed and workpiece vibration were not dominant factors affecting the MRR; the spindle speed and tool and workpiece vibration, which reduced the height difference between a ridge and crater caused by abrasive grinding, were responsible for surface roughness (Ra) and form precision (δ). Additionally, the optimized parameters of 1000 rpm, 3 V, and 5 um were conducted on MMCs of 40 SiCp/Al and achieved the maximum MRR and minimum Ra and δ of 0.76 mm3/min, 3.35 um, and 5.84%, respectively. This study’s findings provide valuable process parameters for improving machining efficiency and quality for MMCs of 2UE/DM.
... where P 0 is the standard atmospheric pressure, σ is the liquid surface tension, R 0 is the initial radius of bubble, P v is the vapor pressure of bubble, f is the ultrasonic frequency, κ is the adiabatic index, P A is the amplitude of the ultrasonic sound pressure, which is nearly 0.87MPa [21], and μ is the liquid viscosity. Substituting Eqs. ...
Micro-structure on metal surface can be created with high precision and good surface quality by ultrasonic-assisted electrochemical micromachining (USEMM). One of the prevalent material removal mechanisms in ultrasonic machining (UM) is cavitation erosion. However, the mechanism of material erosion is not clear and worth investigating. This study of the mechanical and chemical effects of the ultrasonic vibration on the 6061 aluminum alloy is targeted to reveal the material processing mechanism in USEMM. Based on the built model, the velocity of micro-jet produced near the workpiece surface by ultrasonic cavitation reaches up to 350 m/s when bubble collapses computed by software MATLAB. The impact of micro-jet produces plastic micro-pits on the metal surface and the convex peak around the edge of the pits, which is verified in ABAQUS software. The metallographic microscope and curves of the electrochemical polarization behavior results indicate a significant grain refinement and a marked increase of anodic dissolution current, as well as a weaker resistance than the original workpiece in NaNO3 electrolyte during UM. The current-time curve during machining demonstrates the passive layer forms on the metal surface and then breaks down at the time of less than 0.0066s in USEMM. Micrographs of scanning electron microscope (SEM) of the machined surface in different stages show that many uniform and flat pits are formed in USEMM, compared with the local uneven pits in EMM.
... Where P 0 is the standard atmospheric pressure, σ is the liquid surface tension, R 0 is the initial radius of bubble, P v is the vapor pressure of bubble, f is the ultrasonic frequency, κ is the adiabatic index, P A is the amplitude of the ultrasonic sound pressure, which is nearly 0.87MPa [21], and μ is the liquid viscosity. Substituting Eqs. ...
Micro-structure on metal surface can be created with high precision and good surface quality by ultrasonic-assisted electrochemical micromachining (USEMM). One of the prevalent material removal mechanisms in ultrasonic machining (UM) is cavitation erosion. However, the mechanism of material erosion is not clear and worth investigating. This study of the mechanical and chemical effects of the ultrasonic vibration in 6061 aluminium alloy is targeted to reveal the material processing mechanism in USEMM. Based on the built model, the velocity of micro-jet produced near the workpiece surface by ultrasonic cavitation reaches up to 350 m/s when bubble collapses computed by software MATLAB. The impact of micro jet produces plastic micro-pits on the metal surface and the convex peak around the edge of the pits, which is verified in ABAQUS software. The metallographic microscope and curves of the electrochemical polarization behaviour results indicate a significant grain refinement and a marked increase of anodic dissolution current, as well as a weaker resistance than the original workpiece in NaNO 3 electrolyte during UM. The current-time curve during machining demonstrates the passive layer forms on the metal surface and then breaks down at the time of less than 0.0066s in USEMM. Micrographs of scanning electron microscope (SEM) of the machined surface in different stages show that many uniform and flat pits are formed in USEMM, compared with the local uneven pits in EMM.
Components having micro-holes find wide application in fields like aircraft, automobile, healthcare, power circuit boards and ink jet printing nozzles. Monel 400 alloy which is a mixture of nickel and copper is the prime material used for such components. Experiments were conducted by supplying pulsed atmospheric air to the electrolyte with a view to effectively remove the residual machined material. Micro holes were machined using (ECMM) and a single electrolyte. The machining factors namely the percentage of the electrolyte, applied voltage, duty cycle and frequency had been taken as dominant factors. Their optimal combination was arrived using standard optimization techniques, such as, Technique of Order Preference Similarity to the Ideal Solution (TOPSIS), VlseKriterijumskaOptimizacijaKompromisnoResenje (VIKOR) and Complex Proportional Assessment (COPRAS), using material removal rate (MRR) and overcut as response metrics. All the three methods indicated the same optimal parameter combinations. All three methods exposes the same optimal parameter combinations that 28 g/l, 13 V, 75 % and 90 Hz for the first position. Also, the ANOVA results revealed that electrolyte concentration and machining voltage contributes around 62 % and 41 % respectively on the ECMM performance. Further, the quality of micro-hole on work material with the use of pulsed air supply to electrolyte was studied by obtaining scanning electron microscopy (SEM) images and checking the finish of the hole circumference.
In this experiment, the work piece is electrochemically machined which finds its applications in brine heaters, heat exchangers, propeller shafts, and pumps. The process is carried out using sodium chloride electrolyte and copper beryllium wire as tool electrode which is heat treated in three different methods which are annealing, quenching, and normalizing. The response parameters like theoretical and experimental metal removal rate have been measured and studied by varying machining parameters like voltage, frequency, concentration of electrolyte, and duty cycle. Based on the values obtained from the experiment, it is found that quenched tool electrodes have better machining capabilities than the other heat-treated tool electrodes and untreated tool electrodes.
In the aerospace field, difficult-to-machine materials are used widely to improve engine performance. As a nickel-based material that performs well in all aspects, Inconel 625 is used for the blisks of aircraft engines, and electrochemical trepanning (ECTr) is used widely to fabricate such blisks because of its unique advantages regarding ruled surface parts. In this study, to investigate the performance of Inconel 625 in ECTr, measurements were made of the electrochemical characteristics firstly, specifically the anodic polarization curve and the actual volumetric electrochemical equivalent curve. Then, via dynamic electric-field simulations, the processes for forming Inconel 625 blades using ECTr were examined under direct voltage (DV) and pulsed voltage. The contours and current density distributions of formed blades at different times were obtained under different duty cycles. With decreasing duty cycle, the forming accuracy improved gradually and the stray current was reduced. To verify the simulation results, ECTr experiments with Inconel 625 were performed under different voltage conditions. With DV and 90% and 80% duty cycle, the taper angles of the machined blades were 7.784°, 6.278°, and 5.191°, respectively, and the surface roughness ( Ra) values were 0.95, 0.81, and 0.72 μm, respectively. With DV, there were obvious flow marks and gullies on the microscopic surface. With decreasing duty cycle, stray corrosion was reduced effectively and the state of the flow field was improved. Overall, the simulation results were verified effectively.
The radial ultrasonic rolling electrochemical micromachining (RUR-EMM) combined rolling electrochemical micromachining (R-EMM) and ultrasonic vibration was studied in this paper. The fundamental understanding of the machining process especially the interaction between multiphysics in the interelectrode gap (IEG) was investigated and discussed by the finite element method. The multiphysics coupling model including flow field model, Joule heating model, material dissolution model and vibration model was built. 3D multiphysics simulation based on micro dimples process in RUR-EMM and R-EMM was proposed. Simulation results showed that the electrolyte flowed into and out IEG periodically, gas bubbles were easy to squeeze out and the gas void fraction deceased about 16% to 54%, the maximum current density increased by 1.36 times in RUR-EMM than in R-EMM in one vibration period of time. And application of the ultrasonic vibration increased the electrolyte temperature about 1.3%-4.4% in IEG. Verification experiments of the micro dimple process denoted better corrosion consistency of array dimples in RUR-EMM, there was no island at the micro dimple bottom which always formed in R-EMM, and an aggregated deviation of less than 8.7% for the micro dimple depth and 4% for the material removal amount between theory and experiment was obtained.
