Flowforming

Flowforming is a metal forming process that produces hollow axisymmetric parts by rotating a tubular blank over a forming mandrel while rollers apply controlled radial and circumferential deformation. The material is displaced along the length as the tube is fed axially, causing plastic flow from the preform onto the mandrel. The outer diameter and profile are built up by the rollers, while the inner diameter is constrained by the mandrel, enabling near-net-shape parts with tailored wall thickness.

Equipment and process parameters vary, but flowforming typically uses a set of rollers mounted on a forming head around a mandrel. The tube is supported and lubricated to control friction as it is rotated and gradually fed to achieve the desired length and diameter. Some variants apply internal pressure to aid material flow. The process is often performed at ambient temperatures for certain alloys, with high-temperature variants applicable to others.

Materials commonly flow-formed include aluminum, various steels, magnesium, and titanium alloys. The technique is valued for producing lightweight, high-strength components and is widely used in aerospace, automotive, and energy sectors.

Applications include flow-formed wheels, long shafts, tubes, hydraulic cylinders, and other hollow structural parts where near-net-shape geometry and improved mechanical properties are advantageous. Advantages consist of improved strength and stiffness due to work hardening and refined microstructure, near-net-shape capabilities, and potential weight savings. Limitations include the need for specialized equipment and tooling, higher capital costs, and suitability primarily for axisymmetric shapes with certain wall-thickness and length constraints.