Draft:Flowforming

• Comment: Thank you for the last round of editing, it is heading in the right direction.
  But it's not just the superficial wording that is a problem here, it's how the sources are not being worked into the text. So for example the first and second sources both detail that there are multiples processes here, such as staggered roll and inline processing. The second source mentions spin forming, which is in the draft, but the source gives a lot more information about using both techniques together, which doesn't come across in the article here. So this is still superficial LLM overview, rather than a human getting to grips with the available information.
  A more minor issue is that you have put citations into the section header Advantages and Limitations. You can't do that under MOS, but you can just add a line of text above the bullets stating "There are advantages..." and then adding the references into the text. So a very easy one to fix
  So some more reworking is needed here, and by all means use the Teahouse to get advice on pitch and context. There is a useful article in here, so please keep working this. ChrysGalley (talk) 15:15, 14 December 2025 (UTC)

• Comment: No inline citations, which are required for articles. Please see referencing for beginners. More formatting which meets the manual of style (appropriate headers, etc.) will be needed. Haj (talk) 23:15, 20 August 2025 (UTC)

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Flow forming (also flow-forming and sometimes tube spinning) is an incremental rotary metal forming process used to produce axisymmetric hollow parts with reduced wall thickness. In the process, a hollow blank is rotated on a mandrel while one or more rollers apply localized pressure; material is displaced primarily in the axial direction and the part length increases as the wall is thinned. Studies of wheel manufacture describe wheel flow forming in similar terms—as an incremental process that lengthens material in the axial direction while thinning it radially.

Background and development

Flow forming is typically discussed alongside related rotary forming processes such as metal spinning and shear forming, and published definitions and classifications vary between sources. In their review, Wong et al. note that powered and automated spinning machines enabled the development and broader use of shear forming and flow forming techniques, and describe combined spinning/flow-forming routes being used to make parts nearer to net shape. A later review article describes growing industrial interest in flow forming driven by demand in industries including aerospace, automotive, and defense.

Process

In flow forming, the starting blank (often a sleeve or cup) is fitted onto a rotating mandrel and deformed by rollers that move along the part while applying radial pressure. Wong et al. describe multiple manufacturing routes for producing the starting blank, including spinning, deep drawing, and forging followed by machining to improve dimensional accuracy before flow forming.

During deformation, the metal flow beneath the roller has both axial and circumferential components; the balance between these components is one factor associated with whether sound parts are produced or whether defects (such as bulging ahead of the roller) occur under some conditions. Because deformation is localized, modern machines commonly use more than one roller. Wong et al. describe common multi-roller configurations (including three-roller arrangements spaced around the circumference) used to balance loads and improve dimensional control, and note that rollers may be offset (staggered) in the axial and radial directions to improve dimensional accuracy and surface finish.

Process integration with related methods

In practice, flow forming is often part of a multi-step route rather than a standalone operation. Wong et al. describe combined spinning and flow forming being used increasingly, with spinning and other operations used to establish an initial hollow shape and subsequent flow forming passes used to achieve target wall thickness and properties.

Variants

Flow forming may be classified by the direction of material flow relative to the roller feed direction. Wong et al. illustrate commonly described forward and backward (reverse) flow forming arrangements in which the blank is formed on a mandrel while material is displaced axially during roller travel.

Applications

Flow forming is used to manufacture cylindrical and other axisymmetric hollow components, including parts with stepped sections. The process is also used in wheel manufacture; Hwang et al. study aluminum wheel flow forming and discuss it as a weight-reduction approach but note that achieving high geometric precision can be challenging, motivating parameter studies of roll geometry, feed rate, and compression amounts.

Advantages and limitations

Published discussions describe a mix of benefits and constraints. Wong et al. describe reported benefits including increased hardness associated with cold work, good surface finish, and comparatively simple tool designs for certain parts; they also present flow forming as an alternative when component size or complexity is beyond the capacity of some conventional press-based methods. In the wheel-manufacturing context, Hwang et al. cite weight reduction as a motivation, while noting challenges in achieving high geometric accuracy.

Advantages

• Potential for increased hardness due to cold work, and good surface finish in suitable applications.
• Material and weight reduction by thinning the wall while maintaining an axisymmetric hollow form.
• Use in multi-step routes (for example, producing a preform by spinning or drawing, then flow forming to final dimensions).

Limitations

• Primarily applicable to axisymmetric hollow parts formed over a mandrel.
• Dimensional accuracy depends on machine configuration and process parameters; difficulties achieving high precision are discussed in wheel flow forming studies.

Distinction from metal spinning

Wong et al. distinguish flow forming from conventional spinning by emphasizing that flow forming intentionally produces significant variation in wall thickness and displaces material axially along the mandrel, whereas spinning is often described as forming a blank over a mandrel without the same degree of thickness reduction.

See also

• Metal spinning
• Shear forming