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In this study a multiphysics simulation model of the pulsed electrochemical machining (PECM) with oscillating cathode is shown. The focus of this study is on the implementation of machine tool-specific control characteristics in combination with physical phenomena and material removal. As a result, the implementation of the machine tool control cha...
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... geometry is derived by the design concept of the electrochemical manufacturing of external geometries which is shown in Fig. 2. Main components of this design concept are the cathode (yellow), the workpiece respectively the anode (gray), insulation (green), clamping devices (purple) and a flushing chamber which is hidden for better visualization. Fig. 3 shows the derived initial two-dimensional axial symmetric model geometry which consists of four domains and 16 boundaries. Domain I (blue) represents the electrolyte which is defined as water based solution with a mass fraction of 8 % sodium nitrate (NaNO 3 ). Domain II (grey) is defined as solid to represent the anode. The anode is a ...
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Micro electrochemical machining (ECM) is practicable for machining micro holes with internal features by adjusting machining parameters along with machining depths. However, it is difficult to maintain the shape accuracy due to dramatically varied electrolyte temperature (T) and gas void fraction (vol) caused by the parameter variations. Taking the...
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... Research efforts have been focused on ECM process modelling and simulation, primarily concerning tool geometry prediction and workpiece shape generation [3]. In the last ten years, the research in computer simulation and process optimisation techniques to predict and control the ECM process has increased by several factors [4][5][6]. Most simulation research uses COMSOL® [7] to deal with the multiphysics aspects of the process, which despite its many advantages, seems intrinsically limited in the accuracy of its results as its electrolyte flow solutions are based on finite element method (FEM) instead of its more adequate counterpart, the finite volume method (FVM), particularly suitable when dealing with computational fluid dynamics (CFD) [8]. ...
... Studies done so far on the design of ECM tools have to deal with approximations related to the fact that local physical effects create significant differences between the simulated design and the real one. Some of these discrepancies and their causes have already been addressed in the ECM simulation literature [5,6]. During the electric current pulse, material dissolution takes place. ...
... κ e = −82.96 + 0.336T (5) where T is the temperature in K. ...
Development of simulation models for electrochemical machining (ECM) is a widely researched challenge to avoid the traditional trial and error process, with potential resulting advantages in terms of time, cost, and sustainability. To this objective, it is crucial to utilise software that can accurately simulate the complex multiphysics aspects of ECM without being too computationally expensive and with a fast set up. This paper investigates an alternative finite element software to model ECM for industrial production. The specific features of this software make it attractive for industrial applications, and in this work, it is validated as suitable to model the electrolyte characteristics of flow rate and pressure. The model developed is the basis for determining local changes to electrolyte conductivity, current density, and efficiency as a function of gap spacing optimisation in order to achieve the desired geometry with dimensional accuracy and assure process repeatability for industrial production. Simulation results are in agreement with the experimental ECM carried out as part of this work.
... Higher temperature, hydrogen generation, and machining products affect the electrical conductivity of the electrolyte. 5 In the third step, the voltage is zero, and the tool moves up to the top zone of the oscillation range. Consequently, the IEG is bigger, and the electrolyte flushes away all the by-products of the machining and heat. ...
... Consequently, the IEG is bigger, and the electrolyte flushes away all the by-products of the machining and heat. 5 Choosing an optimum duty cycle and pulsed frequency is necessary for localized machining. 6 Furthermore, PECM results in an improved surface finish. ...
Electrochemical machining (ECM) is an important technology in machining difficult-to-cut materials. The contactless nature of ECM and anodic dissolution of the workpiece propound no tool ablation. Nevertheless, in a few studies, tool damages, namely the formation of pits and geometrical changes, have been observed, which is the investigative goal of this work. This study considers three hypotheses to investigate tool changes during pulsed electrochemical machining (PECM) which are hydrogen embrittlement, cavitation erosion, and cathodic corrosion. A systematic study of monitoring possible tool (1.4112 martensitic stainless steel) changes during ECM and PECM in aqueous NaNO3 electrolyte is performed. Experimental results of this study show that hydrogen embrittlement and cavitation erosion are not the reason for causing changes in the tool. Cathodic corrosion might be the reason for the changes in the tool in this study; however, more investigation is needed. The approach in this study is investigating the microstructure of the tool regarding different aspects before and after ECM and PECM, as the microstructure stores information regarding phenomena occurring during any process.
... Wang et al. [17] proposed a new tangential feeding ECM method for blade leading/trailing edges and studied the distribution of bubbles, temperature, and conductivity at the leading/trailing edges through multi-physical field coupling simulation. Schaarschmidt et al. [18] studied the characteristics of precision ECM with pulse and vibration coupling through multi-physical field coupling simulation. Chen et al. [19] predicted the ECM gap using a multi-physical field coupling simulation based on two-phase turbulence flow. ...
Large size TiAl alloy blade is one of the important parts to reduce the weight of advanced aero-engines. However, the precision manufacturing of such blades is a challenge due to their large size, low ductility at room temperature, and high hardness of the TiAl alloy. Electrochemical machining (ECM) is a very promising method for the precision manufacturing of such blades, considering its unique advantages. In this study, a very comprehensive multi-physical field coupling simulation and pulse ECM experiments on large size TiAl alloy blades are carried out. Geometric and theoretical models involving electric fields, gas-liquid two-phase flow, heat transfer, and anodic dissolution are developed. The variation of bubble, temperature, electrolyte flow rate, and electrical conductivity at the outlet and the different areas on the blade surface with the processing time and distribution along the flow channel in the machining gap are revealed by simulation. It is found that the influence of electrolyte temperature on electrical conductivity is more dominant than that of bubble concentration. Finally, the experiments of pulse ECM on large size TiAl alloy blade are carried out, and the experimental results are analyzed in detail. The high efficiency and high surface quality of large size TiAl alloy blades are realized. The surface roughness and machining accuracy of the blade are about Ra 0.9 μm and 0.18 mm, respectively.
... For further information, reference is made to previous publications were the multiscale and multiphysics simulation model of PECM with oscillating cathode is described in detail [10][11][12]. The implementation of the machine tool specific current and voltage control characteristics in multiphysics simulation and the effect on the formation of the side working gap is described in [13]. ...
Pulsed electrochemical machining (PECM) with oscillating cathode is a non-conventional manufacturing technology to machine complex precision geometries independent from the mechanical properties of the workpiece material. PECM with oscillating cathode is an advanced development of conventional ECM by applying a pulsed electric current in conjunction with an oscillating movement of the cathode. Result is electrochemical precision machining with a more stable process combined with better accuracy and quality.
This work focuses on the analysis of the resulting side working gap in electrochemical precision machining of external geometries by applying PECM. Therefore, the height of a ring cathode was varied to adjust the cathode inner surface. The resulting side working gap was studied through multiscale multiphysics simulation applying COMSOL Multiphysics as well as experiments applying a PEMCenter 8000. As main result, the increase of the resulting side working gap as consequence of an increasing cathode inner surface will be analysed in detail.
Counter-rotating electrochemical machining (CRECM) is a novel electrochemical machining (ECM) method, which can be used to machine convex structures with complex shapes on the outer surface of casings. In this study, the evolution of the convex structure during CRECM is studied. The complex motion form of CRECM is replaced by an equivalent kinematic model, in which the movement of the cathode tool is realized by matrix equations. The trajectory of the cathode tool center satisfies the Archimedes spiral equation, and the feed depth in adjacent cycles is a constant. The simulation results show that the variations of five quality indexes for the convex structure: as machining time increases, the height increases linearly, and the width reduces linearly, the fillets at the top and root fit the rational function, and the inclination angle of the convex satisfies the exponential function. The current density distributions with different rotation angles is investigated. Owing to the differential distribution of current density on workpiece surface, the convex is manufactured with the cathode window transferring into and out of the processing area. Experimental results agree very well with the simulation, which indicates that the proposed model is effective for prediction the evolution of the convex structure in CRECM.
The process principle of electrochemical machining (ECM) is based on anodic material dissolution at the interface between the workpiece surface and an electrically conductive solution without any mechanical or significant thermal impact on the workpiece surface. As the material removal mechanism is contact- and force-free it is independent of mechanical properties of the workpiece material such as strength or hardness. In this paper, a methodology to perform the process design of pulsed electrochemical machining (PECM) for manufacturing a three-dimensional geometry based on a sequence of standardized material characterization experiments, data processing and multiphysics simulation is shown. As a part of parameter studies, the machining parameters cathode feed rate and process voltage were varied to determine their influence on the resulting workpiece geometry. Resulting process conditions as for example the working gaps and electric current density distributions were analyzed and compared with experimental results.
In this chapter, the electric-magnetic-mechanical coupling methods and related research progress of precision machine tools are discussed. The electromagnetic machine complex of guideway and spindle and the influence of electromagnetic machine parameters on precision machining equipment are discussed respectively based on the key functional parts of precision machine tools. Then, the electromagnetic coupling, motor coupling, and magnetic machine coupling are analyzed respectively to study the coupling of three technical directions, and the method involves the finite element analysis method and electromagnetic machine test method of electromagnetic machine. Based on a specific machining process example, this chapter discusses the theoretical analysis of the influence of three parameters of electromagnetic machine on precision machining machine tools. Finally, the summary analysis of this chapter needs to study the systematic theoretical system of the coupling of three directions of electromagnetic machine on the accuracy and reliability of machine tools, so as to promote the development of precision or ultra-precision machining equipment and supply machining process basic theory.
