Research of Large-Area Electrical Discharge Machining for Insulating Si3N4 Ceramics with the Assisting Electrode Method

2014 ◽  
Vol 939 ◽  
pp. 76-83 ◽  
Author(s):  
D. Hanaoka ◽  
Y. Fukuzawa ◽  
K. Yamashita
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
High Resistivity ◽  
Surface Adhesion ◽  
Large Area ◽  
Resistance Surface ◽  
Electrode Method ◽  
Long Pulse ◽  
Assisting Electrode ◽  
Insulating Ceramics

Generally, all insulating materials were regarded as the non machinable workpiece for the electrical discharge machining (EDM) method. About twenty years ago, many insulating ceramics turned to the machinable materials for EDM using the assisting electrode method which was proposed by our research group. The machining mechanism was already explained with the surface adhesion phenomena [1]. In this process, many unstable discharge phenomena occurred such as concentrate, short circle and long pulse. It was clarified that they generated frequently on the high electrical resistance surface. The EDMed surface became rough and uneven on the unstable discharged area. In this paper, to obtain the good and even EDMed surface on the large removal area same as small area machining for Sinking-EDM, the effects of electrode size and shape were investigated. Considering the path of discharge supply energy on the high resistivity surface, new machining method was proposed which was named as the scanning machining method, and the ability of this method for practical use was confirmed with Si3N4 insulating ceramics. Using the new proposal method, better surface roughness and the sharp corner edge shape could be machined on the large area EDMed surface.

High Speed Wire Electrical Discharge Machining (HS-WEDM) Phenomena of Insulating Si3N4 Ceramics with Assisting Electrode

2007 ◽  
Vol 339 ◽  
pp. 281-285 ◽  
Author(s):  
Yong Feng Guo ◽  
Ji Cheng Bai ◽  
Guan Qun Deng ◽  
Ze Sheng Lu
Keyword(s):  
Electrical Discharge ◽  
High Speed ◽  
Electrical Discharge Machining ◽  
High Hardness ◽  
Single Pulse ◽  
Wire Electrical Discharge Machining ◽  
Electrical Parameters ◽  
Abrasive Resistance ◽  
Electrode Method ◽  
Assisting Electrode

Advanced engineering ceramics are more and more widely employed in modern industries because of their excellent mechanical properties such as high hardness, high compressive strength, high chemical and abrasive resistance. This paper investigates the high speed wire electrical discharge machining (HS-WEDM) of Si3N4-based ceramics by assisting electrode method. The theory of assisting electrode method is introduced. The machining phenomena under different electrical parameters were studied and the optimized machine pulse width was got. The material removal mechanisms change with the increase in the power of single pulse.

Electrical Discharge Machining (EDM) Phenomena of Insulating ZrO2 Ceramics with Assisting Electrode

2008 ◽  
Vol 375-376 ◽  
pp. 313-317 ◽  
Author(s):  
Yong Feng Guo ◽  
Guan Qun Deng ◽  
Ji Cheng Bai ◽  
Ze Sheng Lu
Keyword(s):  
Electrical Discharge ◽  
Material Removal ◽  
Electrical Discharge Machining ◽  
High Hardness ◽  
Single Pulse ◽  
Electrical Parameters ◽  
High Chemical ◽  
Abrasive Resistance ◽  
Electrode Method ◽  
Assisting Electrode

Advanced engineering ceramics are more and more widely employed in modern industries because of their excellent mechanical properties such as high hardness, high compressive strength, high chemical and abrasive resistance. These properties limited the machining to the insulated ceramics. This paper investigates the electrical discharge machining (EDM) of ZrO2-based ceramics by assisting electrode method. The theory of assisting electrode method is introduced. The machining phenomena under different electrical parameters were studied. The material removal mechanisms change with the increase in the power of single pulse. Some work-pieces have been machined successful through the assisting electrode method.

scholarly journals Investigation an assisting electrode powder mixed electrical discharge machining of nonconductive ceramic

2021 ◽  
Author(s):  
Dragan Rodic ◽  
Marin Gostimirovic ◽  
Milenko Sekulic ◽  
Borislav Savkovic ◽  
Branko Strbac
Keyword(s):  
Surface Roughness ◽  
Tool Wear ◽  
Material Removal Rate ◽  
Electrical Discharge ◽  
Material Removal ◽  
Metal Removal ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Positive Effects ◽  
Assisting Electrode

Abstract It is well known that electrical discharge machining can be used in the processing of nonconductive materials. In order to improve the efficiency of machining modern engineering materials, existing electrical discharge machines are constantly being researched and improved or developed. The current machining of non-conductive materials is limited due to the relatively low material removal rate and high surface roughness. A possible technological improvement of electrical discharge machining can be achieved by innovations of existing processes. In this paper, a new approach for machining zirconium oxide is presented. It combines electrical discharge machining with assisting electrode and powder-mixed dielectric. The assisting electrode is used to enable electrical discharge machining of nonconductive material, while the powder-mixed dielectric is used to increase the material removal rate, reduce surface roughness, and decrease relative tool wear. The response surface method was used to generate classical mathematical models, analyzing the output performances of surface roughness, material removal rate and relative tool wear. Verification of the obtained models was performed based on a set of new experimental data. By combining these latest techniques, positive effects on machining performances are obtained. It was found that the surface roughness was reduced by 18%, the metal removal rate was increased by about 12% and the relative tool wear was reduced by up to 6% compared to electrical discharge machining with supported electrode without powder.

A Study of Liquid Cooling Heat Sink Fabrication and Development in Notebook

2006 ◽  
Vol 505-507 ◽  
pp. 223-228
Author(s):  
A Cheng Wang ◽  
Kuo Zoo Liang ◽  
C.C. Liu ◽  
C.K. Yang
Keyword(s):  
Heat Sink ◽  
Electrical Discharge ◽  
Heat Dissipation ◽  
Electrical Discharge Machining ◽  
Liquid Cooling ◽  
Working Surface ◽  
Erosion Effect ◽  
Long Pulse ◽  
Cutting Path ◽  
Off Time

Liquid cooling heat sink has excellent heat dissipation ability at the personal computer. It can also produce the similar effect at the notebook when the same heat sink is used. However, under the installing space is limited in notebook, the size and weight of heat sink must be limited too. Therefore a novel liquid cooling heat sink was fabricated herein to understand the heat dissipation efficiency in the notebook. Wire electrical discharge machining (WEDM) uses heat erosion effect to remove material and only produces little cutting force on the working surface. Therefore, WEDM has excellent ability to fabricate the straight micro fins (high 1000 μm, width 250 μm, fin gap 400 μm). The WEDM parameters were used to find the precision micro fins in this experiment. The precision micro fins were made when the cutting path offset was 185 μm in WEDM. WEDM would produce over cutting during long pulse duration and it caused oblique micro fins. The appropriate off time in cutting process would promote the WEDM efficiency. However, a liquid cooling heat sink with uniform micro fins and slits was obtained using WEDM.

Expanding heat source model for thermal spalling of TiB2 in electrical discharge machining

1992 ◽  
Vol 7 (10) ◽  
pp. 2853-2858 ◽  
Author(s):  
A.M. Gadalla ◽  
B. Bozkurt
Keyword(s):  
Heat Source ◽  
Pulse Duration ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Source Model ◽  
Surface Erosion ◽  
Thermally Induced ◽  
Wire Cutting ◽  
Long Pulse ◽  
Heating Up

A model is presented to explain the recently reported mechanism of thermal spalling for shaping high melting point ceramics by electrical discharge machining. Since previous models fail to explain the experimental observations completely, an expanding circular heat source created by growth of plasma is assumed to act on the surface. Erosion of materials by spalling is caused by thermally induced compressive stresses during heating-up periods and tensile stresses during cooling-down periods. This model explains material removal for anodic erosion in general (wire-cutting machines) and for cathodic erosion (die-sinking machines) whenever long pulse duration is used. Simulation of the model for TiB2 provides a local melt front that penetrates to a depth of submicrometer, then recedes as pulse duration increases. Spalling develops flakes with thickness correlated to pulse duration. The results were verified by the experimental observations which showed that large flakes having the predicted maximum thickness as well as few quenched spherical droplets containing titanium were obtained.

Machining of Through Holes in Non-Conductive Aluminum Nitride Ceramic Using Electrical Discharge Machining Process

2020 ◽  
Author(s):  
Asif Rashid ◽  
Muhammad P. Jahan ◽  
Asma Perveen ◽  
Jianfeng Ma
Keyword(s):  
Aluminum Nitride ◽  
Electrical Discharge ◽  
Material Removal ◽  
Electrical Discharge Machining ◽  
Weight Ratio ◽  
Ceramic Materials ◽  
Machining Process ◽  
Machining Parameters ◽  
Eds Analysis ◽  
Electrode Method

Abstract Ceramic materials are known for their high hardness and strength-to-weight ratio, resistance to wear, and chemical inertness. These materials can be deployed at elevated temperature even to the limit where super alloys cannot be used. The distinctive properties of ceramics make them difficult to machine by conventional processes because of their brittleness. Electrical discharge machining (EDM) is a non-contact machining process that can machine any workpiece irrespective of its hardness, as long as the material is electrically conductive. Therefore, the challenge that comes with the EDM of ceramics is the electrical non-conductivity. In this study, an innovative method (modified assisted-electrode method) has been proposed, which can be used to successfully machine through holes in pure and non-conductive ceramic materials using the EDM process. The effect of machining parameters and conductive coating has been studied. In addition, the possible material removal method has been investigated using the scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis. It is found that multi-layer coating with conductive copper tape sandwiched with graphene and carbon nanotubes in between the tape worked as a successful assistive electrode method. The SEM and EDS analysis indicates melting and thermal spalling as possible material removal mechanisms during EDM of electrically non-conductive Aluminum nitride (AlN) ceramics. The deposition of carbon at the edge of the holes indicate generation of conductive carbon layer favoring continuous sparking during the machining process, and this makes the EDM of non-conductive AlN possible. The walls of the drilled holes become conductive and allow the machining to go through even beyond the conductive layer range. The performance characteristics depends on both the electrical parameters and assistive electrode method.

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