What is metal spinning?
Metal spinning is a rotary forming process for the production of hollow, rotationally symmetrical parts in sheet metal. The starting blank is usually a flat disc but may also be a tube or a pressed pre-form. In a series of sweeps and employing a forming roller, the metal is progressively shaped onto a mandrel conforming to the internal form of the finished part whilst the workpiece is rotated.
What metals can be spun?
All ductile metals can be spun and tougher materials can often be spun by the application of heat.
What is shear forming?
Shear forming is a variant on spinning applied to the manufacture of conical or ogival shapes. Unlike multi-pass spinning, the wall thickness of the workpiece is deliberately reduced in a single pass of the work roller, the reduction being a direct function of the change in angle.
What is flow forming?
Derived from spinning, flow forming is a precise rotary method for reducing the wall thickness of cylindrical parts, with or without a closed base. A short, thick walled pre-form is used which grows in length during the forming process as a function of the reduction in thickness. Thicker collars can be left at the ends as well as external steps or tapers. Even high-strength alloys in the heat-treated condition can be cold flow formed.
What are the practical applications for these techniques?
There are a thousand and one applications for spinning ranging from the everyday, such as pots and pans, to the exotic, such as parts for satellites. Spinnings are widely found in the lighting, heating and ventilating, bulk storage and transport, food, medical, giftware and automotive industries.
Why spin rather than press?
In general, spinning offers flexibility with low tooling costs and is widely used for low- to medium-volume production. Depending on the application, spinning can offer major benefits which makes it first choice, even for high-volume production. Production machines can be configured with a range of attachments to produce a finished part in one hit eliminating secondary operations. Each case needs to be examined on its own merits.
Can I buy a spinning machine and use it for shear forming and flow forming as well?
Shear forming can be carried out on a general-purpose spinning machine employing a single forming roller. Precision cones, as used for example in missile applications, require the higher accuracy of special-purpose two rollers machines with two opposed forming slides. Higher powers are needed for flow forming where three forming rollers are employed simultaneously on special-purpose machines. All machines are built in a range of sizes, increasing in terms of both centre height, distance between centres, slide strokes and power ratings etc. The machines are configured with tool changers, auxiliary toolposts and attachments to suit the application.
Where can I find out more?
We can point you towards a wealth of published information on the subject and can advise, without obligation, on specific applications.