How the Electrical Conductivity of Water Fluids Affects Micro-EDM in the Short-Pulse Regime

Area of Science:

• Materials Science
• Manufacturing Engineering
• Surface Engineering

Background:

• Micro-electro discharge machining (micro-EDM) is a precision machining process.
• The choice of dielectric fluid significantly impacts micro-EDM performance.
• Understanding fluid properties like electrical conductivity is crucial for process optimization.

Purpose of the Study:

• To investigate the effect of deionized and tap water as dielectric fluids on micro-EDM performance.
• To analyze material removal rate (MRR), tool wear ratio (TWR), radius overcut, and surface roughness.
• To compare experimental results with numerical simulations.

Main Methods:

• Numerical analysis using COMSOL Multiphysics to simulate plasma channel and melted material.
• Experimental micro-EDM of hardened thin steel plates using varying voltages and currents.
• Measurement of MRR, TWR, radius overcut, and surface roughness.
• Evaluation of crater morphology and size using confocal microscopy.

Main Results:

• Increased voltage and current led to decreased MRR and TWR with higher electrical conductivity.
• Tap water (higher conductivity) reduced radius overcut, contrary to common assumptions.
• Micro-EDM process stability was affected by electrical conductivity at lower voltages and currents.

Conclusions:

• Electrical conductivity of the dielectric fluid is a critical parameter in micro-EDM.
• Tap water can offer advantages in reducing overcut despite potential process stability challenges.
• Numerical simulations provide valuable insights into the micro-EDM plasma and material interaction.