Metal spinning or otherwise known as spinning, spin forming or metal turning is a process of metalworking by which a tube or disc of metal is being rotated at high speed and form into axially symmetric part. There are a couple of ways of how the spinning may be done such as CNC lathe or by hand. Metal spinning involves the removal of material as in traditional metal or wood turning. As for the molding or forming of sheet material, it’s done over existing shape.
In reality, metal spinning range from the expertise and experience of the artisan up to the most complicated and beneficial way to form round metal parts for commercial purposes. Artisans use this process to be able to produce architectural detail, decorative household goods as well as urns or even specialty lighting.
Commercial applications for metal spinning process is quite a lot and this includes rocket nose cones, cookware, gas cylinders, brass instrument bells, public waste receptacles and so forth. Virtually, any kind of ductile metal could be formed from stainless steel or aluminum to high temperature, high strength alloys. Both the depth and diameter of formed parts are only limited by the size of available equipment.
The process of spinning is quite simple; in drive section of lathe, a formed block will be mounted and then, pre-sized metal disk is clamped against the block using pressure pad, which is attached to tailstock. At high speeds, the block and the workpiece are being rotated together. Local force is applied in the workpiece in order to make flow to the block. Normally, the force applied is through the use of different levered tools. Simple workpieces are removed from the block but more complex shapes might require several blocks.
As for extremely complicated shapes, it can be spun on ice forms which melts after spinning. Because the final diameter of workpiece is less than the starting diameter, the workpiece ought to be thickened, buckled circumferentially and elongated radially.
For more involved process that is referred to as necking or reducing, it lets the spun workpiece to integrate reentrant geometries. If the surface form and finish aren’t that critical, then the workpiece is being spun on air and no mandrel has to be used. If the form or finish is hard however, it will demand eccentrically mounted mandrel.
There are metal spinning tools that are allowed on the bearings throughout the forming process. What these tools do is reduce heating and friction of the tool, improve surface finish while prolonging its life. Rotating tools may be coated as well with thin film of ceramic to be able to extend the life of the tool.