Spinning and Flow Forming
For the sake of simplicity we will define spinning as the process whereby a circular blank is centred and held against a form block in a rigidly built lather. The part is rapidly rotated and pressure is applied to the metal surface by means of a spinning tool. This induces material flow, which is accompanied by limited thinning of the material and cups, cones, etc. are produced. The process can be both manual or automatic.
Flow forming is a similar process but in this case extensive thinning of the material (over 50%) is achieved. Due to the loads required this process is either fully or semi automatic. Manual spinning due to its low tooling costs is extensively used to produce small quantities of any given part. Flow forming on the other hand due to its higher tooling and equipment costs is used for a larger number of a smaller range of items. Figure 4 and 5 details arrangement and tooling for manual spinning.
Flow forming generally requires bigger, more robust and sophisticated purpose built lathes and tooling. These processes can be used to produce items from as small as Domestic mixing bowls to dished ends several metres in diameter. The simple tooling used in spinning can be used for a range of materials including stainless steel. In flow forming the chucks are usually manufactured from cast iron or steel. Other tools are used not only to flow, but to flange, bevel, trim, etc. and the materials used will depend on the function of the tool.
The most common lubricants used in spinning are adherent bar soaps and waxes. These must be used to reduce friction, galling and tool drag. In flow forming, it is important that the lubricant has a coolant action and that specialised proprietary brands are used.
All austenitic grades can be formed by both processes, but the lower work hardening types 304, 304L and 304DDQ can be spun to greater reduction, before intermediate annealing becomes necessary. The ferritic grades are more readily flow formed than manually spun.
Generally, parts produced by the processes have rough surface with characteristic spiral or helical grooves. Unless being used for non aesthetic applications, the parts require extensive finishing operations t make them smooth and bright.
Cold Forming - Blanking and Piercing | Press Breaking and Roll Forming | Spinning and Flow Forming | Coining and Embossing | Press Forming | Deep Drawing
Cutting - Sawing | Hand Hacksawing | Shearing | Abrasive Cutting | Thermal Cutting
Hot Rolling - Hot Rolling Process | Hot Rolling Application | Types of Hot Rolling Mill | Hot Rolled Steel Tube | History
Cold Rolling - Physical metallurgy | Degree of cold work | Cold Rolling Stainless Steel | Manufacturing Process
Foil rolling | Rolling Mill | Steel Mill | Production methods | Recycling of Steel | Modern Steelmaking | Contemporary Steel
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