flowformed

Flowformed, commonly written as "flow-forming" or "flow formed," refers to a metal forming process in which a preformed cylindrical piece is rotated on a mandrel while tooling applies radial and axial deformation. The metal flows plastically under controlled roller contacts, elongating the workpiece and forming a hollow cross-section with a near-net or net shape. The method emphasizes directional grain flow and can produce seamless or long-hubbed tubes with increased length and reduced wall thickness.

The process typically begins with a cylindrical preform mounted on a mandrel. Roller tooling advances along the surface while the part spins, compressing and stretching the material to achieve the desired geometry. Lubrication and precise control of rotation speed, feed, and axial displacement are essential to manage material flow, wall thickness, and residual stresses. Flowformed parts often exhibit refined grain structure aligned with the final geometry, contributing to improved strength-to-weight ratios.

Materials used for flowforming include aluminum, stainless steel, other steels, titanium, magnesium alloys, and copper alloys. The technique is valued for producing lightweight, high-strength tubes and shells suitable for aerospace, automotive, oil and gas, and sporting goods applications. Common advantages are near-net-shape capability, reduced machining, good surface finish, and enhanced mechanical properties through work hardening and grain alignment. Limitations include the need for cylindrical or near-cylindrical hollow sections, substantial tooling costs, process complexity, and potential thickness and dimensional control challenges for certain cross-sections. Flowformed parts are typically described as flowformed tubes or flowformed components.