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A brass vase spun by hand. Mounted to the lathe spindle is the mandrel for the body of the vase a shell sits on the "T" rest. The foreground shows the mandrel for the base. Behind the finished vase are the spinning tools used to shape the metal.
Metal spinning, also known asspin formingorspinning, is a metalworking process by which a disc or tube of metal is rotated at high speed and formed into an axially symmetric part.[1]Spinning can be performed by hand or by a CNC lathe.
Metal spinning ranges from an artisan's specialty to the most advantageous way to form round metal parts for commercial applications. Artisans use the process to produce architectural detail, specialty lighting, decorative household goods and urns. Commercial applications include rocket nose cones, cookware, gas cylinders, brass instrument bells, and public waste receptacles. Virtually any ductile metal may be formed, from aluminum or stainless steel, to high-strength, high-temperature alloys. The diameter and depth of formed parts are limited only by the size of the equipment available.
Advantages & disadvantagesSeveral operations can be performed in one set-up. Work pieces may have re-entrant profiles and the profile in relation to the center line virtually unrestricted.[1]
Forming parameters and part geometry can be altered quickly, at less cost than traditional metal forming techniques. Tooling and production costs are also comparatively low. Spin forming is easily automated and an effective production method for prototypes as well as high production runs.
Other methods of forming round metal parts include hydroforming, stamping and forging or casting. Hydroforming and stamping generally have a higher fixed cost, but a lower variable cost than metal spinning. Forging or casting have a comparable fixed cost, but generally a higher variable cost. As machinery for commercial applications has improved, parts are being spun with thicker materials in excess of 1" thick steel. Conventional spinning also wastes a considerably smaller amount of material than other methods.[2]
Objects can be built using one piece of material to produce parts without seams. Without seams, a part can withstand higher internal or external pressure exerted on it. For example: scuba tanks, co2 cartridges, and oxyacetylene tanks.
One disadvantage of metal spinning is if a crack forms or the object has a dent, it either must be thrown away, or a lot of work involved in fixing it; neither are cost effective.