Melting and Evaporation Phenomena During Electrical Erosion

1975 ◽  
Vol 97 (4) ◽  
pp. 576-581 ◽  
Author(s):  
M. Toren ◽  
Y. Zvirin ◽  
Y. Winograd

A modeling method is presented for the evaluation of the eroded crater during electrical discharge machining. The method is based on the propagation of the melting crater when other effects such as evaporation can take place. Calculations are performed for a point heat source on the surface of copper and steel electrodes. An experimental technique for the measurement of the amount of eroded material is described: the method consists of extraction of the metal from the dielectric fluid by chemical reactions and measurement of the resulting color intensity.

Author(s):  
Sampath Boopathi

Abstract Electrical discharge machining (EDM) is very essential unconventional electro-thermal machining process to machine the contour profile of hard materials in modern production industries. The liquid dielectric fluid has been replaced by the gas and minimum quantity of liquid mixed with gas (gas-mist) to encourage the green machining processes. The various gases and gas-mist have been used as the working fluid in dry and near-dry EDM respectively. The research-contextual, various dielectric fluids, sustainable and innovative developments, process parameters, machining characteristics, and optimization techniques applied in various dry and near-dry EDM have been illustrated through an extensive literature survey. Future research opportunities in both dry and near-dry EDM have been summarized to promote eco-friendly EDM research activities.


Author(s):  
Murahari Kolli ◽  
Adepu Kumar

Surfactant and graphite powder–assisted electrical discharge machining was proposed and experiments were performed on titanium alloy in this investigation. Analysis was carried out to observe changes in dielectric fluid behaviour, material removal rate, surface roughness, recast layer thickness, surface topography and energy-dispersive X-ray spectroscopy. It was found out that the addition of surfactant to dielectric fluid (electrical discharge machining oil + graphite powder) improved the material removal rate and surface roughness. It was noticed to have reduced the recast layer thickness and agglomeration of graphite and sediment particles. Biface material migrations between the electrode and the workpiece surface were identified, and migration behaviour was powerfully inhibited by the mixing of surfactant. Surfactant added into dielectric fluid played an important role in the discharge gap, which increased the conductivity, and suspended debris particles in dielectric fluid reduced the abnormal discharge conditions of the machine and improved the overall machining efficiency.


2014 ◽  
Vol 3 (2) ◽  
pp. 212
Author(s):  
M. Durairaj ◽  
A.K.S. Ansari ◽  
M. H. Gauthamkumar

Wire Electrical Discharge Machining is a manufacturing process whereby a desired shape is obtained using electrical discharges (or) by repetitive spark cycle. Precision and intricate machining are the strengths. Machining parameters tables provided by the machine tool manufacturers often do not meet the operator requirements. Selection of optimum machining and machining parameters combinations is needed for obtaining higher cutting efficiency and accuracy. In this present study, machining is done using Wire-Cut EDM and optimization of surface roughness is done using Taguchis design of experiments. Experimentation was planned as per Taguchis L16 orthogonal array. Each experiment has been performed under different cutting conditions of gap voltage, pulse ON time, and pulse OFF time and Wire feed. Dielectric fluid pressure, wire speed, wire tension, resistance and cutting length are taken as fixed parameters. Inconel 800 was selected as a work material to conduct the experiments. From experimental results, the surface roughness was determined for each machining performance criteria. Signal to noise ratio was applied to measure the performance characteristics deviating from the actual value. Finally, experimental confirmation was carried out to identify the effectiveness of this proposed method. Keywords: Optimization; Taguchis L-16 Orthogonal Array; Surface Roughness; S/N Ratio.


2020 ◽  
Vol 996 ◽  
pp. 131-136
Author(s):  
Yao Li ◽  
Cheng Cui ◽  
Bengang Lin ◽  
Li Li

Inconel718 has been widely used in various fields for its good performance, but it is difficult to machine with traditional machining methods. Electrical discharge machining is an alternative competitive process to machine Nickel-based alloys by electrical erosion. In order to improve reduce the electrode loss and improve the machining efficiency, the horizontal ultrasonic vibration of the workpiece and the cryogenic cooling of the tool electrode were applied into the EDM process. Material removal efficiency, surface roughness, surface topography, and microhardness have been characterized.


2014 ◽  
Vol 554 ◽  
pp. 643-647 ◽  
Author(s):  
Minhat Ade Erawan ◽  
Khamis Nor Hisham ◽  
Azli Yahya ◽  
Andromeda Trias ◽  
Juli Purwanto Nugroho Kartiko ◽  
...  

Electrical Discharge Machining (EDM) is a advanced machine that can control electrical spark to erode metal on the workpiece. In manufacturing, EDM is used on hard material parts that are extremely difficult to machine by conventional machining processes. EDM system consists of a shaped tool and the work piece, which are connected to a power supply and placed in a dielectric fluid. EDM pulse power generator applies voltage and current pulses between the electrode and workpiece to generate sparks through the gap. To obtain the optimum metarial removal rate (MRR), a good alternative is to improve the gap voltage and gap current. A proposed solution to these issue is combining ultracapacitor bank to the main power supply circuit for EDM machines. The control feedback of this research is designed to make sure that the current on DC bus is maintained at current setting during the machining processes.


2014 ◽  
Vol 592-594 ◽  
pp. 416-420 ◽  
Author(s):  
Singaravelu D. Lenin ◽  
A. Uthirapathi ◽  
Ramana Reddy P.S. Venkata ◽  
Muthukannan Durai Selvam

The present paper describes the influence of pulse-on-time on performance features such as Metal Removal Rate (MRR), Kerf width, Surface Roughness (SR) on cutting Titanium alloy (Ti-6Al-4V) in wire electrical discharge machining (WEDM) using zinc coated brass wire. The deionised water is used as dielectric fluid. The process parameters such as wire tension, wire speed, flushing pressure, discharge current, sparking voltage and pulse off time have kept constant at appropriate values throughout the experiment and the pulse on time is varied at nine different intervals. It was found that pulse-on-time is the most significant factor which greatly influences MRR, kerf width, and SR. It was also observed that taper at the end of cutting zone which is unavoidable occurrence for the machined part. This is due to the erosion of wire material. The surface roughness increases with increase in pulse on time also with higher rate of MRR.


2014 ◽  
Vol 611-612 ◽  
pp. 650-655 ◽  
Author(s):  
Laurenţiu Slătineanu ◽  
Margareta Coteaţă ◽  
Hans Peter Schulze ◽  
Oana Dodun ◽  
Irina Besliu ◽  
...  

Electrical discharge machining uses the pulse electrical discharges generated between the closest asperities existing on the workpiece surface and the active surface of the tool electrode in dielectric fluid. Essentially, some distinct electrical discharge machining schemas could be used in order to obtain cylindrical external surfaces; within this research, one preferred a machining schema based on the use of a cooper plate in which there were small diameter holes, by taking into consideration the existence of a ram electrical discharge machine. The results of the machining process analysis were presented. A thin copper was considered to be used as tool electrode, in order to diminish the spurious electrical discharges, able to generate shape errors of the machined surface. Some experimental researches were developed by changing the sizes of the process input parameters. As output factors, the test piece and tool electrode masses decreases were considered. Power type empirical mathematical models were determined, in order to highlight the influence exerted by the pulse on time, off time and machining process duration on the output parameters values.


Author(s):  
S. Nallusamy

Electrical Discharge Machining is a machining method primarily used for hard metals or those that are impossible to be machined with traditional techniques. The experimental investigation of material removal rate and tool wear rate during machining of oil hardened non-shrinking steel with brass and copper electrodes using EDM machine was carried out in this paper. This investigation presents the analysis and evaluation of heat affected zones and surface finish of the work piece using different tool electrodes and varying the machine parameters. The commercial grade kerosene oil has been used as dielectric fluid. The effect of various important EDM parameters such as discharge current (Ip) 2 to12A, pulse duration (Ton and Toff) and sparking voltage (V) of 80±5% have been used to yield the response in terms of Material Removal Rate (MRR) and Tool Wear Rate (TWR). Further a detailed analysis of the heat affected regions was also been carried out by using scanning electron microscopy.


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