Debris and consequences in micro electric discharge machining of micro-holes

The tip shape of a blind micro-hole produced using micro electrical discharge machining varies with respect to the process parameters used during machining. The usual tip shape is a blunt geometry within the common range of applications, however, under specific machining conditions and machining depths, the tip shape changes drastically to an inverted concaved shape. The origin of such tip deformation in micro electric discharge machining of blind micro-holes was investigated. It was observed that debris particles produced during machining accumulated at the tip, formed a hill and functioned as a tool electrode especially when using fine machining conditions. The phenomena is elaborated experimentally with the affecting parameters to describe the wear mechanism. Open gap voltage, pulse energy and tool rotation speed are examined as varying parameters during the experiments.

► Tip shape geometry in micro electric discharge machining of blind micro-holes were examined.
► Unusual concaved tip shapes were encountered under specific operational conditions.
► It was observed that debris particles accumulated at the tip due to fluid vortex.
► The particles formed a hill and functioned as an electrode during machining.
► Finally, the phenomenon is elaborated experimentally with the affecting parameters.