scholarly journals Micro-Structuring on Cylindrical Inner Surface Using Whirling Electrical Discharge Texturing

2012 ◽  
Vol 565 ◽  
pp. 430-435 ◽  
Author(s):  
Vitchuda Lertphokanont ◽  
Takayuki Sato ◽  
Minoru Ota ◽  
Keishi Yamaguchi ◽  
Kai Egashira
Keyword(s):  
Friction Coefficient ◽  
Electrical Discharge ◽  
Area Ratio ◽  
Crater Depth ◽  
Tool Electrode ◽  
Textured Surface ◽  
Feed Speed ◽  
Total Removal ◽  
Crater Diameter ◽  
Micro Structuring

The authors developed Whirling Electrical Discharge Texturing (WEDT) in order to reduce friction coefficient of cylinder-shaped parts. In previous research, the authors verified fundamental characteristics of WEDT by observation of textured surface. It was found that a crater shape and texture-area ratio can be controlled by WEDT. The texture-area ratio depends on feed speed of tool electrode. In this research, crater depth, crater diameter, texture area ratio and total removal volume of craters were investigated to confirm characteristics of WEDT in detail. In addition, tungsten wire was used as a whirling shaft in order to improve stability of whirling phenomenon. Moreover, a textured surface was finished by lapping-film in order to remove protrusions around craters and reduce friction coefficient. As a result, it was verified that the texture-area ratio slightly increased with decreasing feed speed and it was confirmed that crater depth, crater diameter, and total removal volume of craters were also related to feed speed.

Effect of Discharge Duration and Pulse Frequency on Surface Characteristics Using Whirling Electrical Discharge Texturing

2014 ◽  
Vol 8 (4) ◽  
pp. 561-568 ◽  
Author(s):  
Vitchuda Lertphokanont ◽  
◽  
Masahiro Oi ◽  
Takayuki Sato ◽  
Minoru Ota ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Electrical Discharge ◽  
Surface Characteristics ◽  
Pulse Frequency ◽  
Area Ratio ◽  
Textured Surface ◽  
Optimum Conditions ◽  
Total Removal ◽  
Crater Diameter ◽  
Discharge Duration

Discharge duration and pulse frequency are studied to determine the optimum conditions for creating a single crater. In addition, the relationships between pulse frequency and surface characteristics using Whirling Electrical Discharge Texturing (WEDT) are determined. It is confirmed that the texture-area ratio and the total removal volume of craters, but not crater diameter or crater depth, can be controlled by adjusting pulse frequency. Moreover, after honing, surface characteristics decrease owing to the removal of protrusions. With honing, the surface roughness of the textured surface leads to a reduced friction coefficient as expected.

Friction Characteristics with Pin-on-Disc Friction Test on Microstructured Surface Using Whirling Electrical Discharge Texturing

2014 ◽  
Vol 1017 ◽  
pp. 417-422
Author(s):  
Vitchuda Lertphokanont ◽  
Takayuki Sato ◽  
Masahiro Oi ◽  
Minoru Ota ◽  
Keishi Yamaguchi ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Electrical Discharge ◽  
Area Ratio ◽  
Mixed Lubrication ◽  
Optimal Conditions ◽  
Friction Test ◽  
Crater Diameter ◽  
Microstructured Surface ◽  
Pin On Disc ◽  
Lubrication Condition

A microstructured surface was created on a steel surface by whirling electrical discharge texturing (WEDT) since it was considered that the microstructures could act as lubricant reservoirs to assist the formation of a lubricating film, resulting in reduced friction. In this study, friction tests under engine oil were carried out over a range of loads and sliding speeds. In addition, the surface characteristics of the microstructured surface were also investigated to optimize the friction characteristics of the textured surface through pin-on-disc friction tests. It was found that under the mixed lubrication condition near the boundary condition, textured surfaces with texture-area ratio of approximately 6% and a mean crater diameter of 35 μm were considered as the optimal conditions for reducing the friction coefficient. However, a texture-area ratio of approximately 4% and a mean crater diameter of 35 μm were considered as the optimal conditions for reducing the friction coefficient under the mixed lubrication condition near the elastohydrodynamic lubrication condition. It was considered that when the normal load decreased, the lubrication region changed from the mixed lubrication condition to the hydrodynamic lubrication condition, which meant that the actual contact surface area decreased. The decrease in the actual contact surface area with decreasing texture-area ratio led to a reduction in the friction coefficient. Finally, it was clarified that the friction coefficient was reduced under the optimized conditions of the microstructured surface through a pin-on-disc friction test.

Development of EDT Equipment Using Wire Tool Electrode

2016 ◽  
Vol 1136 ◽  
pp. 384-389
Author(s):  
Yasuhiro Takada ◽  
Mitsuru Shinozaki ◽  
Minoru Ota ◽  
Kai Egashira ◽  
Keishi Yamaguchi ◽  
...  
Keyword(s):  
Electrical Discharge ◽  
Small Diameter ◽  
High Hardness ◽  
Area Ratio ◽  
Tool Electrode ◽  
Feed Speed ◽  
Feeding System ◽  
Inner Surface ◽  
Cylindrical Parts ◽  
Novel Method

Whirling electrical discharge texturing (WEDT) was developed to process microstructures on the inner surface of cylindrical parts made of high hardness materials. However, the minimum processable diameter of the cylindrical parts was φ 5 mm and the equipment could not feed the new tool electrodes. Therefore, the authors devised a novel method of WEDT using a straight wire tool electrode for a cylindrical surfaces with a small diameter. It was confirmed that microstructures could be created on the inner surface of a cylinder of φ 1.1 mm diameter, and that the texture-area ratio could be controlled by the workpiece feed speed. Moreover, new EDT equipment with a feeding system for a wire tool electrode and a bending system for the tip of a wire tool electrode was developed. As a result, the equipment that can process microstructures on the inner surface of a cylinder with a small diameter and feed a wire tool electrode during texturing was successfully developed.

Surface Quality of Textured Surface on Cylindrical Inner Surface Using Whirling Electrical Discharge Texturing

2013 ◽  
Vol 797 ◽  
pp. 338-343 ◽  
Author(s):  
Vitchuda Lertphokanont ◽  
Takayuki Sato ◽  
Minoru Ota ◽  
Keishi Yamaguchi ◽  
Kai Egashira
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Friction Coefficient ◽  
Surface Quality ◽  
Electrical Discharge ◽  
Compressive Residual Stress ◽  
Textured Surface ◽  
Feed Speed ◽  
Good Surface

Whirling Electrical Discharge Texturing (WEDT) was developed to create microstructures. It was thought that textured surface with low surface roughness could reduce friction coefficient on the sliding parts. In this research, surface quality was studied to evaluate the quality of WEDT textured surface. Surface quality was evaluated in terms of the surface roughness and surface integrity which were characterized by microstructure, composition and residual stress of the textured surface. The value of Rp and Rv of textured surface after finishing with improved finishing method were obtained as expected for low surface roughness to reduce friction coefficient. In addition, it was clarified that microstructure and composition of textured surface after texturing with WEDT and finishing with lapping-film depend on feed speed. Furthermore, the compressive residual stress was presented on WEDT textured surface and depended on feed speed. It was confirmed that good surface quality of textured surface could be obtained by WEDT.

Automatic Stripping of Dielectric-Encased Wire Tool Electrode Used in Electrical Discharge Machining

2007 ◽  
Vol 129 (5) ◽  
pp. 973-978
Author(s):  
Seiji Kumagai ◽  
Naoki Sato ◽  
Koichi Takeda
Keyword(s):  
Control System ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Threshold Value ◽  
Electrode System ◽  
Tool Electrode ◽  
Feed Speed ◽  
Wire Electrode ◽  
Aspect Ratios ◽  
The Wire

A new electrical discharge machining (EDM) system using a wire encased in a dielectric jacket is proposed as an alternative to conventional hole-fabrication EDM systems. The jacket suppresses secondary discharges occurring between the sidewalls of the wire and the fabricated hole, which allows fabrication of holes with higher aspect ratios compared to those formed by a conventional EDM system using naked pipe electrodes. In this new system, the tip of the wire electrode is stripped by displacing the jacket, which produces continuous sparks for workpiece erosion and keeps the bore and shape of the fabricated holes constant. In the present study, we developed a control system to maintain the exposed length of the tip without the need for visual observation and without the assumption that wear is constant over time. The exposed length of the tip of the wire electrode is related to the feed speed (toward the workpiece) of the electrode system. The jacket was displaced when the feed speed of the electrode system exceeded a threshold value, which resulted in slowing of the electrode system feed. The feed speed was kept within the specified range by determining a threshold value, which led to maintenance of a constant exposed length of the tip. This control system was validated in actual drilling tests. Optimizing the threshold feed speed contributed to a higher machining speed.

scholarly journals Sub-Microstructure of Surface and Subsurface Layers after Electrical Discharge Machining Structural Materials in Water

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1040
Author(s):  
Sergey N. Grigoriev ◽  
Marina A. Volosova ◽  
Anna A. Okunkova ◽  
Sergey V. Fedorov ◽  
Khaled Hamdy ◽  
...  
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Structural Materials ◽  
12Kh18n10t Steel ◽  
Mean Deviation ◽  
Water Medium ◽  
Tool Electrode ◽  
Marquardt Algorithm ◽  
Subsurface Layers ◽  
Electrical Wear

The material removal mechanism, submicrostructure of surface and subsurface layers, nanotransformations occurred in surface and subsurface layers during electrical discharge machining two structural materials such as anti-corrosion X10CrNiTi18-10 (12kH18N10T) steel of austenite class and 2024 (D16) duralumin in a deionized water medium were researched. The machining was conducted using a brass tool of 0.25 mm in diameter. The measured discharge gap is 45–60 µm for X10CrNiTi18-10 (12kH18N10T) steel and 105–120 µm for 2024 (D16) duralumin. Surface roughness parameters are arithmetic mean deviation (Ra) of 4.61 µm, 10-point height (Rz) of 28.73 µm, maximum peak-to-valley height (Rtm) of 29.50 µm, mean spacing between peaks (Sm) of 18.0 µm for steel; Ra of 5.41 µm, Rz of 35.29 µm, Rtm of 43.17 µm, Sm of 30.0 µm for duralumin. The recast layer with adsorbed components of the wire tool electrode and carbides was observed up to the depth of 4–6 µm for steel and 2.5–4 µm for duralumin. The Levenberg–Marquardt algorithm was used to mathematically interpolate the dependence of the interelectrode gap on the electrical resistance of the material. The observed microstructures provide grounding on the nature of electrical wear and nanomodification of the obtained surfaces.

Relationships between Textures and Surface Roughness, Frictional Behavior, Erosion and Corrosion Properties of TiN Films

2004 ◽  
Vol 449-452 ◽  
pp. 781-784 ◽  
Author(s):  
Hee Dong Kim ◽  
In Soo Kim ◽  
Dong Young Sung ◽  
Min Gu Lee ◽  
S. Dost ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Friction Coefficient ◽  
Physical Vapor Deposition ◽  
Textured Surface ◽  
Corrosion Properties ◽  
Tin Films ◽  
Physical Vapor Deposition Method ◽  
Erosion Corrosion ◽  
Better Than

TiN coated films were prepared by a reactive ion physical vapor deposition method. In this research, we studied the relationships between textures and friction coefficient, erosion-corrosion resistance and corrosion resistance in textured TiN films. The surface roughness of (115) textured TiN films is lower than that of (111) textured TiN films. The friction coefficient of (115) textured surface is similar with that of (111) textured surface of TiN coated films. The erosion-corrosion and corrosion resistance of (115) textured surface is better than that of (111) textured surface of TiN coated films.

Effect of Arc Discharge Pressure on Discharge Current in EDM

2008 ◽  
Vol 381-382 ◽  
pp. 451-454
Author(s):  
Atsutoshi Hirao ◽  
S. Tai ◽  
H. Takezawa ◽  
Naotake Mohri ◽  
Kazuro Kageyama ◽  
...  
Keyword(s):  
Discharge Current ◽  
Electrical Discharge ◽  
Material Removal ◽  
Electrical Discharge Machining ◽  
Arc Discharge ◽  
Vibration Sensor ◽  
Work Piece ◽  
Tool Electrode ◽  
Discharge Pressure ◽  
Current Behavior

In electrical discharge machining (EDM), an electrical discharge occurs between a tool electrode and a work-piece, and removal of materials is carried out by vaporized explosion between the electrode and the work-piece. However, the mechanism of material removal in EDM is not well understood. In order to clarify this issue, the acoustic emission (AE) method has been applied to examine the force of explosion, and the Schlieren visualization method has been applied to observe the explosion. In this study, we investigate the effect of discharge current behavior on the occurrence of the AE waves by means of an optical fiber vibration sensor.

scholarly journals A Novel Process for Manufacturing High-Friction Rings with a Closely Defined Coefficient of Static Friction (Relative Standard Deviation 3.5%) for Application in Ship Engine Components

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 448
Author(s):  
Wojciech S. Gora ◽  
Jesper V. Carstensen ◽  
Krystian L. Wlodarczyk ◽  
Mads B. Laursen ◽  
Erica B. Hansen ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Friction Coefficient ◽  
Relative Standard Deviation ◽  
Static Friction ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Textured Surface ◽  
Fibre Lasers ◽  
Static Friction Coefficient ◽  
Relative Standard

In recent years, there has been an increased uptake for surface functionalization through the means of laser surface processing. The constant evolution of low-cost, easily automatable, and highly repeatable nanosecond fibre lasers has significantly aided this. In this paper, we present a laser surface-texturing technique to manufacture a surface with a tailored high static friction coefficient for application within driveshafts of large marine engines. The requirement in this application is not only a high friction coefficient, but a friction coefficient kept within a narrow range. This is obtained by using nanosecond-pulsed fibre lasers to generate a hexagonal pattern of craters on the surface. To provide a suitable friction coefficient, after laser processing the surface was hardened using a chromium-based hardening process, so that the textured surface would embed into its counterpart when the normal force was applied in the engine application. Using the combination of the laser texturing and surface hardening, it is possible to tailor the surface properties to achieve a static friction coefficient of ≥0.7 with ~3–4% relative standard deviation. The laser-textured and hardened parts were installed in driveshafts for ship testing. After successfully performing in 1500 h of operation, it is planned to adopt the solution into production.

Sign in / Sign up

Export Citation Format

Share Document