Laminated fabrication of micro-stepped gear mold based on femtosecond laser cutting of stainless steel foil

This paper proposes that a micro-stepped structure is fabricated based on the characteristics of femtosecond laser (high-precision and cold machining) and the laminated manufacturing principle in rapid prototyping. This process is composed of two parts: the single-layer graphics cutting and the layer laminating. The cutting experiment results show that when the femtosecond laser power is 230 mW and the cutting speed is 50 μm/s, the cutting effect of the 20 μm thick 0Cr18Ni9 stainless steel foil is guaranteed and the over-ablation of the lower layer steel foil caused by excessive power is avoided. During the experiment, the principles and error of focus adjustment are analyzed and a compensation plan is proposed. When the laminated procedure is finished, the overall intensive spot welding is performed on the area surrounding the mold cavity to reinforce the mold cavity and reduce the gap between layers. For a six-layer micro-mold, the nugget thermal field simulations and the metallographic analyses showed that when the welding time is 10 ms, the pressure is 20 N and the voltage reaches 0.22 V, the overall welding effect is satisfactory. Eventually, three kinds of micro-stepped gear molds are prepared and a micro-mold is bulged and replicated by Cu foils.