An Experimental Investigation of Enhancement Surface Quality of Micro-holes for Be-Cu Alloys Using Micro-EDM with Multi-diameter Electrode and Different Dielectrics

Be-Cu alloys are known as high-reliability engineered materials because of their high fatigue strength and hardness, excellent wear and corrosion resistance and non-magnetic characteristics. So they are used in the field of the micro liquid floated gyroscope. Micro-EDM provides a cost-effectively methods to machine micro-holes for Be-Cu alloys because of their good thermal and electrical properties. The surface quality directly influences the micro-fluid circulation in liquid floated gyroscope. The robustness of the liquid floated gyroscope can be improved with the surface quality of micro-holes improved. In this paper a new method for enhancement surface quality of Be-Cu alloys using multi-diameter electrode and different dielectrics is proposed. This method consists of two processing stages which are carried out in sequence on the same machine tool with the same electrode but different dielectric medium. In the first stage, the micro-hole was drilling by micro-EDM using the front of the multi-diameter electrode and deionized water as dielectric; in the second stage, with kerosene as dielectric, the large diameter part of multi-diameter electrode was used to improve the surface quality of the micro-hole. The characters of the surface obtained by micro-EDM were measured with confocal laser scanning microscope and scanning electron microscope. The results show that the surface quality is improved by using the multi-diameter electrode and deionized water and kerosene as dielectrics without changing the drilling time. It proves that this new method is possible and useful in the field of micro-hole drilling for Be-Cu alloys.