What is Metal Spinning?

Metal Spinning

Metal Spinning, Also known as metal turning, metal spinning is a type of metalworking process that involves the use of a rotating machine — typically a CNC lathe — to deform metal over a pre-shaped mold. Unlike with other metal turning processes, however, it doesn’t strip away or otherwise remove any of the metal material. Rather, metal spinning changes the shape of metal to reflect that of the mold on which it was spun.

Metal Spinning Advantages

Metal spinning has significant advantages over other forms of metalworking such as stamping, forging, or casting.

· Lower tooling costs than other forms of metal shaping
· Equally perfect for prototyping or high quantity production
· Multiple forming steps may be accomplished at the same time
· Single piece (seamless) parts may be stronger or withstand higher pressure

Process

The spinning process is fairly simple. A formed block is mounted in the drive section of a lathe. A pre-sized metal disk is then clamped against the block by a pressure pad, which is attached to the tailstock. The block and workpiece are then rotated together at high speeds. A localized force is then applied to the workpiece to cause it to flow over the block. The force is usually applied via various levered tools. Simple workpieces are just removed from the block, but more complex shapes may require a multi-piece block. Extremely complex shapes can be spun over ice forms, which then melt away after spinning. Because the final diameter of the workpiece is always less than the starting diameter, the workpiece must thicken, elongate radially, or buckle circumferentially.

A more involved process, known as reducing or necking, allows a spun workpiece to include reentrant geometries. If surface finish and form are not critical, then the workpiece is "spun on air"; no mandrel is used. If the finish or form are critical then an eccentrically mounted mandrel is used.

"Hot spinning" involves spinning a piece of metal on a lathe while high heat from a torch is applied to the workpiece. Once heated, the metal is then shaped as the tool on the lathe presses against the heated surface forcing it to distort as it spins. Parts can then be shaped or necked down to a smaller diameter with little force exerted, providing a seamless shoulder.

Spinning Tools

The basic hand metal spinning tool is called a spoon, though many other tools (be they commercially produced, ad hoc, or improvised) can be used to effect varied results. Spinning tools can be made of hardened steel for use with aluminum, or from solid brass for spinning stainless steel or mild steel.

Some metal spinning tools are allowed to spin on bearings during the forming process. This reduces friction and heating of the tool, extending tool life and improving surface finish. Rotating tools may also be coated with a thin film of ceramic to prolong tool life. Rotating tools are commonly used during CNC metal spinning operations.

Commercially, rollers mounted on the end of levers are generally used to form the material down to the mandrel in both hand spinning and CNC metal spinning. Rollers vary in diameter and thickness depending the intended use. The wider the roller the smoother the surface of the spinning; the thinner rollers can be used to form smaller radii.

Cutting of the metal is done by hand held cutters, often foot long hollow bars with tool steel shaped/sharpened files attached. In CNC applications, carbide or tool steel cut-off tools are used.

The mandrel does not incur excessive forces, as found in other metalworking processes, so it can be made from wood, plastic, or ice. For hard materials or high volume use, the mandrel is usually made of metal.

Metal Spinning Application

We are proud to serve a wide variety of industries and markets. Parts produced by Spindustries are used in commercial, industrial, residential and institutional applications around the world. Industries and products that utilize our parts and services:

Are There Disadvantages to Metal Spinning?

The only real disadvantage to metal spinning is the potential for damaging the metal piece. If the metal piece cracks during the process, for example, there’s no way to repair it. The piece must be scrapped and replaced with a new one to achieve the desired outcome.