What is Metal Spinning?
Metal spinning is a forming process in which a disc of metal is revolved at controlled speeds on a specialized machine similar to a lathe. At the head end of the machine, instead of a chuck to clamp the workpiece, a spinning mandrel made of hard maple or metal is mounted to the machine. The mandrel’s form corresponds to the internal contour of the part to be produced. The round blank is clamped between the spinning mandrel and tailstock spindle; then the blank and mandrel are rotated together. During rotation, a roller or other spinning tool makes multiple passes over the blank, forcing it against the mandrel and causing the metal to flow mechanically, taking the shape of the internal form. The roller or spinning tool may be forced through its motion by hand or auxiliary power, such as a hydraulic cylinder. The size of the part and the thickness and alloy of the blank will determine the force required to cause the metal to “flow” effectively over the mandrel.
Summary of Spinning Process
The mechanical working of the metal during the spinning process refines and strengthens its grain structure, as well as eliminating hidden and surface discontinuities to improve metal integrity. The process is particularly adaptable to concentric circular shapes and segments and can present considerable savings in materials and machining when compared to cast or forged parts. Spinning also makes it possible to produce components with thinner wall thicknesses directly, without machining them down to size. Simple tooling requirements, involving primarily a contoured spinning mandrel, reduce lead times and keep tooling costs relatively low, particularly for prototype and limited production quantities.