Papers by Keyword: Electrochemical Discharge Machining

Abstract: The electrochemical discharge machining (ECDM) is a combination effect of electrochemical machining in which metal is removed through the electrochemical process and electrical discharge machining in which metal is removed by rapid current discharges between two electrodes which are separated by a dielectric liquid and subject to an electric voltage. Difficulty of machining nickel titanium alloys by conventional methods such as; the significant tool wear, the need of highly experienced operators, and an excessive degradation in the material performance due to the high thermal and mechanical effects of these methods. For these, reasons non-conventional methods such as electrical discharge machining and electro chemical machining are often used to fabricate NiTi alloys with better machining results. The experiments were conducted with various conditions of voltage (50,60,70 and 80)V, dielectric solution concentration (30 and 40% of NaOH) and nanoparticles silver, and copper content (0.5% Cu, 0.5% Ag, 0.5% Cu and Ag) in the (55% Ni-45%Ti) alloy samples. The machining experiments were designed according to Taguchi's design of experiments (L32). Grey relational analysis was used to optimize the responses of the ECDM process. Material removal rate (MRR), tool wear rate (TWR), and surface roughness (Ra) represent the response parameters for machining of the alloy samples prepared by the powder metallurgy route. To achieve the objectives of this research work MiniTab17 software was employed. The optimal conditions were: voltage of 50V, solution concentration of 40% and the sample (NiTi+0.5%Cu+0.5%Ag) have the highest effect on machining characteristics with MRR value of 0.04991mg/sec., tool wear rate value of 0.00125mg/sec., and surface roughness of 0.0117μm.

Abstract: In the case of electrochemical discharge machining (ECDM), the number of influence factors is very high, and the complete determination of a mathematic pattern is very complicated, as proved by the time passed since the application of this processing technology and absence (for the time being) of such a system. The paper presents the method of random balance which allows influence factors hierarchization, depending on the amplitude of the effect they have on the response variable. The main influence factors will be considered: current intensity, voltage, electrode-tool – workpiece pressure, electrolyte supply intensity, relative velocity between the electrode-tool and the workpiece, electrode-tool thickness. The following response functions (performance criteria) were determined: processing productivity, processed surface roughness, flatness deviation. The experiment was made on an electrochemical discharge machining (ECDM) processing machine with a electrode-tool, stratified disk by introducing the electrolyte in it. The semi-finished material is alloy steel X40CrMoV5-1, and the material of the electrode-tool is generally use steel S235JR.

Abstract: Electrochemical discharge machining (ECDM) is based on synergetic action of anodic dissolution with erosive effect of electrical discharges in material removal process. Drilling by ECDM can be applied for hard to be cut materials, when no drilling by cutting or no EDM machine is available.

Abstract: Micromachining techniques has increased the demand for precise and accurate instruments which are used in many industries. Glass materials offer higher challenges in micro machining as they are tough, non-conducting and difficult to machine with conventional machining operations. Electro Chemical Discharge Machining (ECDM) is a new non-conventional hybrid machining process which combines the features of Electrical Discharge Machining (EDM) and Electro Chemical Machining (ECM) to machine both conducting and nonconducting materials. In the present paper effect of various process parameters like voltage, concentration of electrolyte, duty factor and temperature on ECDM process are studied to obtain desired micro channels in soda lime glass. Design of Experiment (DOE) is used to plan and conduct the experiments. The Response Surface Modelling (RSM) is used for characterising non linear output responses in terms of material removal rate and surface finish. Modeled results are validated with experimental values.

Abstract: In the present study, a tungsten rod with diameter of 100μm is used as the tool to drill a quartz plate by Electrochemical Discharge Machining (ECDM). KOH solution mixed with different concentration of Ethanol is used as the electrolyte. The influences of different working parameters, such as electrolyte concentration, applied voltage, pulse frequency, and electrolyte level, on the gas film stability, gas film thickness, and machining accuracy are investigated. The experimental results show that the overcut and surface roughness is improved by the use of electrolyte with addition of 6.5wt% ethanol. The effect of gaseous bubbles is reduced during the machining, and the circulation of electrolyte is better. Compared with machining with pure KOH electrolyte, the overcut is reduced around 57% by the use of electrolyte with addition of 6.5wt% ethanol. The heat-effected zone on the machining is also largely reduced.

Abstract: The gap control problem in hole-machining of Pyrex® wafer by electrochemical discharge machining (ECDM) to obtain a smooth quality and acceptable material removal rate is studied. Analysis of the pulse signals shows that the average current pulse interval is constant, and it is mainly related to the ion translation conditions, such as the electrolyte concentration and the flushing strategy. The most steady and intense average current density can be obtained if the voltage on-time is around 3 times the average current pulse interval and the voltage off-time is 1/4 of the on-time for bubble film dissipation. The utmost allowable feed rate at each depth is recorded as the reference of the feed rate in real continuous machining to avoid the damage to the wafer. By applying 80% of the extreme allowable feed rate, 99.9% quality-proved holes can be acquired. The diametric error at the entrance or exit is within 6%. Besides, there is no crater-like problem around the hole that facilitates the succeeding bonding process. This study contributes to the successful production of reusable optical biological chips with integrated micro fluidic channels.