Metal Spinning for 60 Years

The Process - Flow Forming

Flow forming, though sometimes thought of as a metal spinning process, is really a separate technology that requires a dedicated flow-forming machine. It involves forming rotationally symmetrical hollow parts. A blank or preform is clamped between the mandrel and tailstock and rotated. Metal is formed by localized radial pressure from (usually) three rollers applied simultaneously. The metal is made to flow and, in a single roller pass, assume the contour of the mandrel on the inside. Common applications include the thinning out of tubes and one-piece wheels.

Flow forming is an excellent method for forming nickel-cobalt-based super alloys, stainless steels, aluminium, brass, tantalum, columbium, titanium, and other heat-resistant steels. Flow forming produces parts that are cylindrical, conical, or contoured with precise control of desired wall thicknesses.

The key difference between flow forming and metal spinning is that spinning does reduce wall thickness of the starting blank; therefore spinning does not hold precise control of contours. Flow forming is based on a calculated reduction of the thickness of a starting blank or preform. The reduction is closely controlled, which results in precise wall thicknesses and accurate profiles of the final part. Flow forming is a cold forming process, which ensures the final part's controlled characteristics are to design with no distortion. The products manufactured with flow forming are more restricted—mainly to pipes and tubes with highly precise geometries, including their inside diameters and thicknesses.

Flow forming also strengthens the material, which presents some economic advantages. The process starts with thick, short preforms to obtain long, thinner-walled and precise final parts. Metal spinning uses only one, sometimes two, rollers, and only the roller tips control the work piece shape and thickness.

In flow forming, three or more rollers apply constant pressure against the material and mandrel throughout each stroke. Using parameters from the CNC, the machine controls the pressure and the work piece thickness at the forming rollers’ point of contact, all along the stroke. The result: Flow forming can produce a part with a highly accurate, uniform material thickness.

Advantages of Metal Spinning

• Relatively low tooling cost and capital investment
• Rapid prototyping
• Smooth transition from prototype to production
• Fast turnarounds
• Economical short or long runs
• Design flexibility - tooling may be modified to meet simple design changes without being modified
• Materials that may be difficult or impractical to press can be ‘spun’
• Base materials can be changed without retooling
• Close tolerances can be produced
• Improved tensile strength
• Less material waste than other methods
• Fewer steps required for spinning that press forming

Products Produced Through Metal Spinning