Belvorming

Belvorming, or bell forming, is a term used in Dutch technical contexts to describe the shaping of a component to a bell-like profile. The word combines bel (bell) and vorming (forming). It denotes an intentional flare of a surface or hollow body, from a narrower neck to a wider opening, producing a convex, outward-curving form.

The process can be achieved by multiple forming techniques, including forging, stamping, hydroforming, extrusion, and additive manufacturing, typically using a die, mandrel, or mold that defines the flare. Achieving a smooth transition and uniform wall thickness is central to a successful belvorming operation, and post-processing such as smoothing or annealing is often employed.

Applications are found across industries. In musical instrument manufacture, the term is used to describe the shaping of the bell end of brass instruments. In fluid handling and exhaust systems, flared or bell-shaped components help manage flow and reduce separation. In architecture and consumer products, bell-shaped profiles are used for decorative and functional purposes.

Designers consider material behavior, thickness distribution, surface finish, corrosion resistance, and manufacturing feasibility when planning belvorming. The approach can be combined with other forming techniques and computer-aided design to optimize the flare.

See also: flaring, bell mouth, metal forming, extrusion, hydroforming.