Flow forming is one of several metal forming techniques that is a more advanced form of spin forming. It allows variation in wall thickness of its products, which are hollow and tubular or rotationally symmetric products. Flow forming helps manufacturers meet complex design specifications and allows for a wider range of dimensional flexibility.
Many metals, including stainless steel, titanium, copper, aluminum, nickel and brass are subjected to flow forming, which produces products for the aerospace, automotive, nuclear, chemical and petrochemical industries. Flow forming offers many benefits, including the reduced need for welding, shorter length of stock shapes and tighter design tolerances. Though this process is energy saving, the workpiece is subjected to a great amount of friction and deformation.
Flow forming is a cold working process, meaning the metals being formed are shaped at or around room temperature, which ensures that they retain their tensile strength and ductility. While flow forming is able to produce any shape that standard metal spinning can, it specializes in producing automotive wheels for several different kinds of vehicles.
There is a key difference between flow forming and standard metal spinning. Conventional metal spinning uses a thin blank and produces a finished part from the diameter of that blank, while flow forming produces the finished shape by working from the thickness of the starting blank, which creates a part thinner than the original starting blank. The blank, or preformed metal part, is a flat metal disc, which can be stamped with a hole or left whole, that is clamped down.
It is spun on a lathe while rollers apply pressure, forcing it to take the mandrel’s shape. The rollers extrude the cross sectional area of the blank’s wall thickness. The thickness of the finished part is determined by a gap that is maintained between the mandrel and the rollers. The flow forming process is used in conjunction with swaging, flattening, bending and machining. It produces a smooth, complex part without any chipping or unwanted deformation.