Residual Stress Characterization of Electroformed Ni-Base Alloy for μ-Gear Mold

The micro gear molds for powder injection molding were fabricated by electroforming process of Ni-Fe alloys. The residual stress at interface between electrodeposit and substrate was important for micro electroforming. Addition of 6 g/L saccharin lowered residual stress from 466.3 MPa up to 32.8 MPa and increase of Fe content resulted in increase of residual stress. Electrodeposition by pulse current decreased residual stress in deposit although Fe content was increased. These results reveal clearly that decrease of residual stress due to pulse current is larger than increase of residual stress due to higher Fe content. The micro electroformed gear molds with 550 μm and 2,525 μm in outer diameter and 400 μm in height were fabricated by micro electroforming and 316L feedstock was injection-molded into micro molds. As a result, it is suggested strongly that micro electroforming is very useful process to manufacture micro mold with high dimensional accuracy for micro PIM.