Development of Whirling Electrical Discharge Texturing on Inner Surface of Small Hole

Abstract

The tribological characteristics of sliding parts can be controlled by creating a microstructure on their surface. However, the effect of microstructures on the surface of a small hole of an inner sliding part or a hardened part has not been investigated. Thus, an efficient method, electrical discharge texturing (EDT) was previously developed to create a microstructure using a single discharge. In this study, whirling electrical discharge texturing (whirling EDT: WEDT) was developed as a method of creating microstructures on the inner surface of small holes and mechanical parts made of high-hardness materials. It was examined whether the WEDT equipment can be used to texture the inner surface of small holes and high-hardness materials. In addition, the fundamental characteristics of WEDT were studied. It was verified that, it is possible to create microstructures via the whirling phenomenon and single discharge of WEDT. The shape and texture-area ratio can also be controlled by WEDT, where the texture-area ratio is controlled by varying the feed speed.

Development of EDT Equipment Using Wire Tool Electrode

“…A textured surface consisting of dimples is known to be effective for improving the lubrication condition and reducing the friction coefficient [1]. The authors developed whirling electrical discharge texturing (WEDT) [2]. This method can process textures on the inner surface of cylinders of high-hardness materials.…”

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

“…Since a long time is required to popularize new energy sources, energy problems can be mitigated by improving energy efficiency. It is considered that friction reduction is necessary to improve fuel consumption and reduce environmental impact [1,2]. Surface texturing by creating microstructures on a surface is an attractive method of decreasing the friction coefficient and maintaining a good lubrication condition for sliding parts in vehicles [1][2][3][4][5][6][7][8][9][10].…”

“…It is considered that friction reduction is necessary to improve fuel consumption and reduce environmental impact [1,2]. Surface texturing by creating microstructures on a surface is an attractive method of decreasing the friction coefficient and maintaining a good lubrication condition for sliding parts in vehicles [1][2][3][4][5][6][7][8][9][10]. It is expected that microstructured surfaces can not only act as reservoirs to engender persistent lubrication by increasing the quantity of lubricant during sliding but also act as trapping sites of wear debris and increase the fluid dynamic effect [1][2][3][6][7][8][9][10].…”

“…However, it is difficult to apply these methods to high-hardness materials and on the inner surface of small cylindrical parts. Therefore, the authors developed whirling electrical discharge texturing (WEDT) as a method for creating microstructures by single-pulse discharge on the inner surface of a cylinder [2,4]. The surface characteristics of a textured surface, such as the texture-area ratio, the total removal volume of craters, crater diameter and crater depth, can be controlled by adjusting the electrical conditions in WEDT [2,4,5,9].…”

“…Therefore, the authors developed whirling electrical discharge texturing (WEDT) as a method for creating microstructures by single-pulse discharge on the inner surface of a cylinder [2,4]. The surface characteristics of a textured surface, such as the texture-area ratio, the total removal volume of craters, crater diameter and crater depth, can be controlled by adjusting the electrical conditions in WEDT [2,4,5,9]. The purpose of this study is to investigate the effect of the lubrication region, the actual contact surface area and the surface characteristics of the textured surface on friction characteristics through pin-on-disc friction tests.…”