Modeling of micro tool fabrication process using wire electro discharge grinding

Abstract

Fabrication of micro tools made from tungsten carbide and polycrystalline diamond is a difficult and time consuming process. Quality of the tool directly affects the dimensional integrity of the fabricated micro products. In this thesis, fabrication of micro end mills using wire electro discharge grinding (WEDG) process, a variation of electro discharge machining process, is considered. The advantage of this process is that very small micro tools (less than 0.1 mm diameter) can be produced by eroding the tool material through electrical discharges. It is preffered over traditonal grinding process since no forces are transmitted to the tool body during fabrication. However, it takes a very long time to fabricate micro tools with this method. Therefore, it is important to understand the influence of process parameters on material erosion rate in order to be able to model the process. In this study, the relationship between process input parameters and process outputs (material erosion rate and surface roughness) is investigated using experiments. A parametric formulation which allows the estimation of tool fabrication time as a function of WEDG process parameters and given tool geometry has been developed. The developed model can be used in tool geometry design optimization studies.