Viscous pressure forming (VPF): state-of-the-art and future trends

Viscous pressure forming (VPF) is a recently developed flexible sheet forming process. Different from conventional sheet metal forming technology, VPF uses a kind of semi-solid, flowable and viscous material as the pressure-carrying medium. In VPF, the viscous medium is applied on one side or both sides of sheet blank to improve its formability. VPF offers a new approach to the forming of high strength, difficult-to-form materials and complex-shaped parts. In this paper, the state-of-the-art of VPF in formability analysis of sheet metals, pressure control, numerical simulation, applications and forming devices is presented. VPF has shown potential application to superalloy and aluminum alloy. Several complex shaped parts formed by VPF meet the requirements of shape and dimensional accuracy and the thickness distributions are more uniform. Finally, critical issues for the future development of VPF are presented.