Studies on hole-flanging process using multistage incremental forming

Hole-flanging is a manufacturing process used to produce flanges around holes in sheet metal parts. Traditional hole-flanging processes, which use dies and punches, are not cost competitive to make prototype parts or batches of small quantities. Since incremental forming does not require dedicated dies, it has shown promise to reduce cost and cycle time to manufacture such parts. In the present study, incremental forming with three forming strategies was investigated to produce prototype parts with hole-flanges. Results indicate that the forming strategy by increasing the part diameter in small steps during the forming process reaches the final optimum part geometry to improve the formability while it can produce a relatively higher neck height, maximum forming limit ratio (LFRmax), and uniform wall thickness. Also this strategy can be fine tuned to control the thinning band such that fracture can be avoided.