Background: The fabrication of microstructures with high machining quality is always difficult
when it is concerned with non-conductive hard and brittle materials such as glass and engineering
ceramics. It is reported in related papers and patents that Electrochemical Discharge Machining
(ECDM) process is a good choice for machining non-conductive, hard and brittle materials. However,
the machining performance of ECDM process, especially in the aspect of geometric accuracy and surface
quality, needs to be greatly improved.
Objective: The purpose of this study was to improve the machining quality of conventional ECDM
process by introducing ultrasonic vibration to ECDM process, develop an Ultrasonic Vibration Assisted
Micro Electrochemical Discharge Machining (UAECDM) tool, and investigate the improvements of
the machining performance by means of comparative experiments.
Methods: Firstly, the machining principle of UAECDM was investigated, and the effects of ultrasonic
vibration are discussed with the analysis of the micro process. Secondly, the hardware system, which
consists of a machine tool body, XY and Z axes, an ultrasonic spindle system and motion control system,
was established; and the software system was developed based on the analysis of the overall
workflow of the machining process. Finally, comparative experiments, including ECDM drilling,
UAECDM drilling, ECDM milling and UAECDM milling, were carried out to reveal the improvements
of the machining quality.
Results: In the UAECDM group, a micro-hole with the inlet diameter of 133.2µm as well as the 3 × 3
array of micro holes was fabricated on the glass workpiece with 300µm thickness, and a microgroove
with the width of 119.2µm was successfully milled on the glass workpiece. It is shown in both microscopic
photographs and optical measurements that the microstructures fabricated by UAECDM have
better machining quality compared with similar microstructures fabricated by ECDM.
Conclusion: Based on comparative experiments and discussions of the results, it has been proved that
the machine tool can meet the requirement of the ultrasonic vibration-assisted micro electrochemical
discharge machining and can improve the geometric accuracy and surface quality significantly.