Papers by Keyword: Electrochemical Machining (ECM)

Abstract: The Pulse Electrochemical Machining Process is an innovative, non-conventional process, based on the Electrochemical Machining process. Herein, pulsed current instead of constant current and a feed overlaid mechanical vibration of the tool electrode allows a higher precision and copying accuracy in contrast to the well-established ECM process. Yet, in this context the pulse-pause time and the length of the pulse on-time used in the process cause changes in the material removal while processing and therefore influences the processing result as well as cycle times and other industry relevant criteria. Understanding these pulse- and process specific changes is a key to the process design for industrial applications, since different sets and variations in parameters also change the final form and surface topography. This contribution shows, at the example of two materials 1.4301 and electrolytic copper, how a machining process can be designed and calculated based on material specific data. The way to acquire the necessary material data sets using industrial equipment, as well as the use and information which can be drawn from the data will be addressed.

Abstract: Properties of workpieces, like residual stress in the rim zone, cannot be predicted for manufacturing technologies reproducible in advance. This lack of predictability shall be solved by a new approach, called Process Signatures. These Process Signatures will combine the material loadings forced by the manufacturing process with the change of state variables, e. g. the variation of residual stress in the surface layer. As the Process Signatures shall achieve comparability for different processes with same physical working principle, it is necessary to describe the transition from material loadings to the change of material properties in a uniform way. Consequently an energy based approach is chosen that considers these transitions by the dissipation of the several kinds of energy brought into the manufacturing process and especially in the respective working area.A first step for the development of such Process Signatures is the identification of all process specific material loadings. This paper presents several material loadings generated during the electrochemical sinking process. In a further step the contribution of the individual material loadings to the material removal process are estimated. Finally first approaches for the combination of the main material loadings and the change of material properties are presented.

Abstract: Monel 400 is a cuprous nickel alloy which is very well-known for its resistivity towards physical and chemical strength. It is probably one of the hardest and most non-corrosive materials known in industrial as well as research field. These properties have enhanced its applications in various fields such as aerospace industries, marine industries, automotive industries etc. Monel 400 alloys are too hard to machine using conventional machine tools and methods as it work hardens rapidly on its surface. Authors concluded that electrochemical machining is the choice of machining of these materials. The present work is carried out to analyze the impact of ECM process parameters such as applied voltage (V), inter-electrode gap (IEG) and electrolyte concentration (EC) on material removal rate (MRR) and surface roughness (R_a). An aqueous sodium nitrate (NaNO₃) is used as basic electrolyte in the electrochemical machining of Monel 400 alloys. Response surface methodology (RSM) based central composite design (CCD) is used as experimental strategy. Effects of process parameters as well as their interactions are analysed and the process parameters are optimized.

Abstract: In this paper technological and economical capabilities of manufacturing titanium- and nickel-based alloys via unpulsed Electrochemical Machining (ECM) are presented. A standardized test to receive typical workpiece material removal properties according to its electrochemical machinability is introduced. First of all the experimental setup of this test is described in detail. The test results for the materials Ti-6Al-4V and Inconel 718 are presented and discussed. Here the feed rate – current density- and surface roughness – current density curves are in focus. With help of these two functions as an example out of many possible applications the capability of blisk manufacturing by electrochemical machining is quantified. Therefore the theoretical machining times for both materials of substituted blisk geometry are calculated. Finally on this basis an economical comparison between ECM and milling as rough estimation is executed.

Abstract: The long spiral tube with its deep rifle groove make a long duration for Electrochemical Machining (ECM) and mass of floccule precipitate, esulting in bottleneck to maintain cleanliness of electrolyte in sedimentation basin at machining. The design scheme of duplex vertical flow electrolyte basin was proposed. The surface hydraulic power, available cubage, flooding area, sludge blanket level (SBH) and sludge tank height were calculated in terms of the electrical current, sinking speed of Fe(OH)3, flux of electrolyte. The streamline in the basin were simulated by COMSOL based elementary draft. The flow speed at intake of sludge blanket and the exit of clarified were analyzed with diameter of cone-meatus of center tube being altered and the space between it and baffle-board shifted, and the sedimentation basin is optimized.

Abstract: Most recently automobile pumps contain intersecting holes. However, there has been no efficient method for burr at intersecting holes. The theory of electrochemical deburring for high pressure pump body is firstly introduced. Then math model of ECM deburring and cathode model are built. Experiment results indicate that the technique can effectively remove the burrs of the hole and regulate the corner radius of injection holes. The smooth transition circle could be obtained around the conjunction of the hole, thus ECM deburring method can effiectively increase cleanliness of injector body and make the whole injector more stable.

Abstract: Electrochemical machining is one of the widely used non-traditional machining processes to machine complicated shapes for electrically conducting but difficult-to-machine materials such as superalloys, Ti-alloys, alloy steel, tool steel, stainless steel, etc. Use of optimal ECM process parameters can significantly reduce the ECM operating, tooling, and maintenance cost and will produce components of higher accuracy. This paper investigates the effect and parametric optimization of process parameters for Electrochemical machining of EN-31 steel using grey relation analysis. The process parameters considered are electrolyte concentration, feed rate and applied voltage and are optimized with considerations of multiple performance characteristics including material removal rate, overcut and cylindricity error. Analysis of variance is performed to get contribution of each parameter on the performance characteristics and it was observed that feed rate is the significant process parameter that affects the ECM robustness. The experimental results for the optimal setting show that there is considerable improvement in the process. The application of this technique converts the multi response variable to a single response Grey relational grade and, therefore, simplifies the optimization procedure.

Abstract: In this paper, in order to make the simulation of the whole process of electrochemical machining(ECM), the characteristic of electric field and flow field is made detailed analysis in the gap of ECM. Mathematical-physical models of ECM simulation is set up based on the basic theories of electrochemistry, electric field and flow field. And the method of model solution is discussed and researched. So the theoretical base is established of the full process of ECM simulation.

Abstract: Gears’ accuracy has important influences on its working performance and life. Electrochemical mechanical finishing (ECMF) was applied to finish cylindrical gears. The influence of the generative type of ECMF was studied theoretically and experimentally on the shape of gear teeth, and on the dimensional accuracy between teeth, and that in the tooth thickness direction. The results indicate that the generative type of ECMF can improve the accuracy between teeth, as well, the dimensional accuracy of gear tooth and that in the thickness direction may be also improved.

Abstract: This paper studies the electrochemical machining on the surface of nickel-based alloys with a tubular electrode and analyses the effect of electric field distribution and current distribution to the shape of concave holes during the processing. It is concluded that the maximum distance between the positive and negative poles in the reaction of electrochemical machining. It is analyzed that order of electrochemical machining surface holes in the direction of hole radius and hole depth and the variation laws of reaction speed.