Micro-Drilling of Sapphire using Electro Chemical Discharge Machining

Area of Science:

• Materials Science
• Manufacturing Engineering
• Electrochemistry

Background:

• Electrochemical discharge machining (ECDM) is a non-traditional method for machining hard, brittle, non-conductive materials.
• Traditional ECDM efficiency improvements via increased voltage or electrolyte concentration lead to overcutting and surface roughness.
• Need for advanced ECDM techniques to overcome limitations in precision and efficiency.

Purpose of the Study:

• To propose and evaluate an innovative combinational machining assisted method for ECDM.
• To enhance machining efficiency and surface quality on non-conductive materials.
• To investigate the effect of a self-developed coaxial-jet nozzle combined with tool electrode rotation.

Main Methods:

• Developed a coaxial-jet nozzle to combine tool electrode rotation and coaxial-jet assistance simultaneously.
• Maintained a low liquid level and continuous renewal of electrolyte in the machining area.
• Controlled and reduced machining energy output prior to machining and micro-drilling.
• Conducted experiments on 640 μm thick sapphire specimens using 5 M KOH electrolyte and varying voltage parameters.

Main Results:

• The combined method concentrated spark discharge at the tool electrode-material interface.
• Achieved efficient material removal with improved precision compared to traditional methods.
• Demonstrated feasibility of machining thin sapphire specimens with controlled parameters.

Conclusions:

• The proposed combinational ECDM method with coaxial-jet and tool rotation significantly improves machining efficiency and precision.
• This technique offers a viable solution for high-quality machining of non-conductive hard and brittle materials.
• Further research can explore optimization of parameters for various materials and applications.