Electrochemical discharge machining for micro fabrication of insulating brittle material: State of the art and future directions

Electrically non-conductive advanced engineering materials, such as glass, ceramics, quartz, and composites, pose significant challenges for conventional machining methods. Electrochemical discharge machining (ECDM) emerges as a notable hybrid non-conventional technique specifically tailored for brittle, hard-to-machine, nonconducting materials. This technique achieves a delicate balance between thermal energy and chemical interactions. Variations of ECDM have been developed to enable the fabrication of complex miniature profiles. However, prevalent issues such as unstable electrolyte conditions and inadequate flushing within the machining zone compromise the process accuracy and repeatability, thereby undermining the industrial viability, sustainability, and stability of the ECDM process. To address these limitations, researchers have developed hybrid ECDM variants. Despite this advancement, challenges persist, particularly in maintaining high surface integrity and robust process stability. This review aims to provide a comprehensive overview of recent developments in the mechanism underlying ECDM and its variants. It examines the influence of process parameters and triplex hybridisation on the performance matrices. Additionally, the review outlines potential research directions across various aspects of ECDM, highlighting areas for further exploration.