Analysis of Sub-processes Specific to Hybrid Non-conventional Machining Methods

Hans-Peter Schulze,Oliver Kröning

doi:10.25518/esaform21.2709

Abstract

In principle, all non-conventional machining processes can be viewed as the sum of various sub-processes, the separate analysis of which influences the effectiveness of this machining process. The first question to answer is the criteria by which these sub-processes can analyzed. Since the non-conventional processes work exclusively based on electrical energy, voltage and current determine the character of the sub-process. The second focus is the time constant with which voltage and current influence the process, from which the measurement of the corresponding parameters result. The third group of influencing parameters is the working medium and its change due to the main removal process. In the summary, these three groups are consider with regard to a process model with which a process control (technology), a process regulation (process stability) and a safety control (limit value exceeded) are guide.

Highlights

It can be assumed that all non-conventional, hybrid-machining processes consist of a limited number of sub-processes, and that their specifics are only changed by the boundary conditions [1]
The basic sub-processes are spark erosion (EDM) and electrochemical removal (ECM), which essentially depend on which working medium is used
For the pulsed ECM (PECM), the connection impedances are decisive, which working current is established when a voltage source is used as process energy source (PES)

Summary

Introduction

It can be assumed that all non-conventional, hybrid-machining processes consist of a limited number of sub-processes, and that their specifics are only changed by the boundary conditions [1]. A correct process analysis of the sub-processes can determine which removal mechanisms, wear rate, and surface topologies are to be expected. The process analysis is mainly possible due to the current and voltage curves directly at the working gap, whereby the main problem is the measurement of these electrical quantities. Since it is usually not possible to measure the gap voltage, the “real” gap voltage must be determined using an equivalent circuit diagram and the measurement of the various impedances that occur. The article deals with the individual sub-processes and names the boundary conditions that lead to the transition between the sub-processes

Basic sub-processes and their current and voltage curves

Sub-processes in the group of electro-chemical processes

High-Speed Wire-EDM

Conclusions