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 normally consists of the removal of material like in traditional metal or wood turning. However, forming or molding of sheet material is over an existing shape.
Actually, metal spinning is ranging from the artisan’s specialty to the most sophisticated way of forming round metal parts primarily for commercial applications. As a matter of fact, artisans are utilizing this process as a way to generate architectural detail, decorative household goods as well as urns and specialty lighting too.
The commercial applications for metal spinning process are quite a lot which includes cookware, rocket nose cones, gas cylinders, public waste receptacles, brass instrument bells and so on. Basically almost any type of ductile metal can be formed form aluminum or stainless steel to high strength and high temperature 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. The block and workpiece are rotated together at fast speeds. To make it flow to block, a local force is applied to workpiece. Usually, the force is being applied through different levered tools. Simple workpieces are being removed from block however, several blocks may be required for more complex and sophisticated shapes.
As for extremely complicated shapes, it can be spun on ice forms which melts after spinning. Since the final diameter of workpiece is less than its starting diameter, the workpiece has to be elongated radially, thickened or buckled circumferentially.
For the more involved procedures, it’s referred to necking or reducing, it allows the spun workpiece to incorporate reentrant geometries. If for example that the surface form and the finish is not that hard, the workpiece is spun on air and no mandrel ought to be used. If for example that the form or finish is critical, then it will require eccentrically mounted mandrel.
There are also the metal spinning tools allowed on bearings throughout forming process. What these tools do is reduce heating and friction of the tool, improve surface finish while prolonging its life. To be able to extend the life of the tool, the rotating tools are coated using thin film of ceramic.