Laminated fabrication of micro-stepped gear mold based on WEDM and thermal diffusion welding

Abstract

This paper presents a method of micro-double-staged laminated object manufacturing (micro-DLOM) for fabricating three-dimensional (3D) micro-molds and verifies its feasibility of fabricating of micro-stepped gear molds. First, under the action of 10 μs pulse width, 40 μs pulse interval, 0.28 A wire-cutting current, and 60 V discharge voltage, a 100-μm-thick Cu foil is cut by wire electrical discharge machining (WEDM) to obtain a multilayer two-dimensional (2D) microstructure. Under the technological parameters of 850 °C thermal diffusion temperature, 10 h thermal diffusion time, and 1.0 N/mm2 pressure, the multilayer Cu 2D microstructure is then connected by vacuum-pressure thermal diffusion welding to fit the gear molds with two- and three-stage steps. Finally, on the basis of ultrasonic powder molding, two- and three-stage step plastic gears are respectively obtained. Compared with the ultraviolet lithography (UV-LIGA) process, the new process can fabricate complicated 3D microstructure with free-form surfaces; compared with the femtosecond laser-layering flat-scanning ablation process, the new process cuts only 2D microstructure of each layer with high processing efficiency; and compared with the micro-electrical discharge machining (EDM) process, the new process omits the step of microelectrode fabrication. Moreover, because there is no loss in the course of the microelectrode process, micro-molds in which the depth-to-width ratio is beyond limitation can be fabricated.