Development of a six-axis wire electrical discharge machine for the fabrication of micro end mills

Abstract

Micro/nano milling applications are needed due to the miniaturization tendency of components used in medical devices and aerospace equipments. Accordingly, micro end mills are needed. However, there are no special purpose machine tools designed for the fabrication of such tools made of ultra hard materials and with complicated three-dimensional geometries. In this paper, a six-axis wire electrical discharge machine (WEDM) designed for the fabrication of micro end mills is developed. Direct drive linear motors and rotary motors are used for linear and rotary axes respectively to realize direct drive instead of ball screws or gearboxes. A special cooling system for all motors makes the thermal effect minimum on the mechanical structures. After the introduction of the developed WEDM, its kinematics model is built. The error analysis for the key axis directly supporting the wire is introduced and the corresponding results are used to guide the mechanical design of the six-axis WEDM and to compensate for position errors during machining. Based on these techniques, high machining accuracy is achieved. Finally, the fabrications of a cutter with complicated geometry and a cutter made of ultra hard material are successfully demonstrated on the developed machine tool.