Journal of the Japan Society of Electrical-machining Engineers 

About: Journal of the Japan Society of Electrical-machining Engineers is an academic journal. The journal publishes majorly in the area(s): Machining & Electrical discharge machining. Over the lifetime, 244 publications have been published receiving 1069 citations.

Research on Removal Amount Difference between Anode and Cathode in EDM Process

Abstract: The pulse duration of discharge current greatly influences the removal amount of anode and cathode in EDM process. The purpose of this research is to find out the reason for such a phenomenon. At first, the energy distributed into anode and cathode in the case of the single discharge process is obtained by means of measuring the temperature rise and removal amount of electrodes. Then the influence of the carbon adhesion onto the anode surface on the anode removal amount is investigated. It is found that the energy distributed into the anode is more than that into the cathode, and the influence of pulse duration on the energy distribution is small. Besides, it is concluded from the experimental results that the removal amount difference between anode and cathode in the EDM process is mainly caused by carbon adhesion, not by the energy distribution.

Surface Generation Mechanism in Electrical Discharge Machining with Silicon Powder Mixed Fluid

Abstract: The surface generated by electrical discharge machining (EDM) appears to be generally mat. However, the machined surface in EDM with silicon powder mixed fluid becomes glossier and has a smaller surface roughness than that in conventional EDM with kerosine type fluid, which leads to the omission of finish hand lapping of metal mold. The quality of machined surface significantly depends on the kind of workpiece material, but the surface generation mechanism has not yet been made clear sufficiently.In this study, the effect of silicon powder mixing on the surface generation mechanism is experimentally investigated, analyzing the shape of crater generated by a single pulse discharge, the surface roughness, the machined surface and so on. Main conclusions obtained are as follows:(1) The gap distance in EDM with silicon powder mixed fluid is larger than that with kerosine type fluid, because of the lower resistivity of the former and the influence of silicon powder arrangement in the gap.(2) EDM with silicon powder mixed fluid leads to smaller undulation of a crater, because of the smaller impact force acting on the workpiece due to evaporation and expansion of machining fluid.(3) The more the precipitated carbides in the workpiece are, the larger the surface roughness is, since the carbides come off because of crack propagation due to the frequent heat impact during EDM.(4) EDM with silicon powder mixed fluid results in the stable machining without short circuit between the electrode and the workpiece.

Study on the Distribution of Scattered Debris Generated by a Single Pulse Discharge in EDM Process

Abstract: Dielectric liquids such as kerosene based oils are generally preferred in the EDM process because such liquids are regarded as indispensable for material removal. As environmemtal hazards, cost, etc., are demerits with those liquids, the EDM without any such medium was thought to be important to explore. With this intention, the present study was formulated in which debris formation and their distribution on the working surface due to single pulse discharge in the EDM process under air and liquid (gelatin) were examined. Specifically, the EDM gap after single pulse discharge was monitored and during the process, total debris volume removed was measured. The position of scattered debris and their size distribution were also obtained.In air, almost all the debris removed were scattered on the electrode surface, got attached there and solidified. In liquid, the scattered debris were, however, mainly distributed at the bound ary of bubble formed due to evaporation and disassociation of gelatin. The bubble formation in the liquid and their explosive expansion contributed to the material removal. Such contribution was found effective only when the pulse duration was less than 90μsec, whereas the material removal in liquid was almost the same as that of in air for a pulse duration longer than 90μsec. As far as the material removal is concerned, therefore, EDM may be performed in air provided the debris generated in the process be flushed out of the EDM gap before they get solidified on the electrode surface.

Numerical Analysis of Cross Sectional Shape of Micro-Indents Formed by the Electrochemical Jet Machining(ECJM)

Abstract: In this paper, the authors propose a numerical method to analyze the machined shape in the Electro-Chemical Jet Machining (ECJM) by calculating the distribution of electric potential in the electrolyte using the Finite Element Method (FEM). In this ECJM, a high pressure electrolyte is jetted from a fine nozzle whose position is numerically controlled against the workpiece, and a pulsating machining current is supplied in the working gap for micro-fabrication.At first, assuming the voltage drop in the electrolyte the theoretical machining current is calculated by means of integrating the current density, which can be obtained from the potential distribution, over the surface of the workpiece. Secondary, the assumed voltage drop is adjusted so that the theoretical machining current should coincide with the measured machining current. Then, the current density distribution over the surface of the workpiece is recalculated using the corrected voltage drop. Lastly, from the current density distribution the machined shape is found by taking the equivalent dissolution valence of the workpiece and the current efficiency, both of which are obtained from the measured relationship between the current density and the material removal rate, into account. It was found that the shape obtained by the numerical calculation coincided well with the experimental result.