Abstract

High Speed Wire EDM (HSWEDM) is characterized by high relative velocities between its electrodes which appear in almost no other field of electrical discharge machining (EDM). Also, it previously has been described as a hybrid process. Consequently, material removal mechanisms show significant differences compared with other EDM processes. In this research, single discharge craters of HSWEDM processes were examined, and their geometrical features were associated with the underlying parameters. Discharge crater geometries on the workpiece electrode (anode) could be investigated by measurements whilst those on the wire electrode (cathode) were calculated. Results show that the high wire velocity leads to moving foot points on both electrodes. Pulse duration and the type of working medium influence the generation of discharge craters and thus their geometry and the modes of material removal. Static discharges and anodic dissolution could also be identified as material removal mechanisms and characterized in their geometrical properties. However, they are of secondary importance.

Highlights

  • High Speed Wire Electrical Discharge Machining (HSWEDM) has been described as a hybrid machining process in which different types of electric pulses lead to material removal [1]

  • It was previously mentioned that the high relative velocity of the electrodes in HSWEDM has to lead to movements of the plasma channels’ foot points on at least one of the electrodes

  • Experiments were conducted with two different discharge durations and two different working media (“dry”: air; “wet” standard HSWEDM working medium with σ = 2.1 mS/cm)

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Summary

Introduction

High Speed Wire Electrical Discharge Machining (HSWEDM) has been described as a hybrid machining process in which different types of electric pulses lead to material removal [1]. Due to the high velocity of the wire electrode, a significant relative movement of the plasma channel foot points on the electrodes occurs This phenomenon has been observed before in the context of other EDM processes. Kunieda and Kameyama [9] have presented an exhaustive study on EDM material removal between moving electrodes They investigated discharges and discharge craters for both working media, air and mineral oil. Short circuit pulses (type 5) presumably can be observed when mechanical contact takes place or a current flow occurs for other reasons In this case, discharge craters are not likely to be created. No clear distinction between open circuit pulses and ECM pulses can be defined

Methods
Craters of moving foot points due to discharges
Other material removal phenomena
Estimation of crater length on the wire electrode
Conclusions
Compliance with ethical standards
Full Text
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