Ring Rolling

Ring rolling forms seamless, near-net-shape rings with oriented grain flow, ideal for strong, fatigue-resistant circular parts in medium to high volumes.

Overview

Ring rolling (ring forging) produces seamless rings by expanding a pierced preform between driven rolls, creating near-net-shape circular parts with excellent grain flow and strength. It excels at medium to large diameter rings with relatively uniform cross-sections, where machining from billet or plate would waste material and compromise mechanical properties.

Use ring rolling when you need strong, fatigue-resistant rings such as bearing races, flanges, and gear blanks, often in alloy steels, stainless, nickel alloys, or titanium. It supports a wide range of diameters and wall thicknesses, with consistent cross-section and good concentricity. Expect to leave machining stock on OD, ID, and faces to hit final tolerances and surface finishes.

Tradeoffs: geometry is limited to ring-like shapes with modest profile complexity, and tooling (rolls, mandrels) has upfront cost, so the process favors repeat production and larger parts. Expect secondary machining and heat treatment for tight tolerances, precision bores, and finished surfaces.

Common Materials

  • Carbon steel 1045
  • Alloy steel 4140
  • Stainless steel 304
  • Stainless steel 316
  • Inconel 718
  • Titanium Ti-6Al-4V

Tolerances

±0.010" to ±0.030" on diameters after rolling; tighter features and surfaces require finish machining

Applications

  • Bearing races and slewing ring blanks
  • Pipe flanges and connectors
  • Gear and sprocket blanks
  • Turbine and compressor case rings
  • Aerospace structural rings
  • Wind turbine hub and tower interface rings

When to Choose Ring Rolling

Choose ring rolling for circular parts where you want a seamless ring, strong grain flow around the circumference, and better material yield than machining from solid. It suits medium to large diameters, relatively uniform cross-sections, and medium to high production volumes. It is most effective when you plan for subsequent machining to bring critical features and surfaces into final tolerance.

vs Open Die Forging

Pick ring rolling instead of open die forging when the part is clearly a ring with a relatively consistent cross-section and you need better dimensional control and concentricity. Ring rolling reduces machining stock and material waste versus hand- or press-forged rings from open dies, especially on repeat parts.

vs Closed Die Forging

Choose ring rolling over closed die forging when the geometry is essentially a ring and you want to avoid costly impression dies for large diameters. Ring rolling handles size changes more flexibly and economically, while still delivering controlled grain flow and good repeatability for families of ring sizes.

vs Cold Forging

Use ring rolling instead of cold forging when part size, section thickness, or material strength pushes beyond what cold forming presses and tooling can handle. Hot ring rolling is better for large, high-strength alloy rings where you need robust grain flow and aren’t chasing cold-work surface finishes straight off the press.

vs Upset Forging

Select ring rolling instead of upset forging when the primary shape is a ring, not a headed shaft or flange on a bar. Ring rolling forms the full circumference efficiently with controlled OD/ID, while upset forging would require more material, more steps, and additional machining to reach a seamless ring geometry.

Design Considerations

  • Keep ring cross-section as uniform as possible around the circumference to reduce rolling loads, tooling cost, and dimensional variation.
  • Specify machining stock on OD, ID, and faces (often 0.040"–0.120" depending on size) so the forger can hit your finished tolerances after machining.
  • Avoid intricate grooves, steps, or flanges in the as-rolled section; design a simple ring blank and plan to machine complex features.
  • Call out required material grade, target ring OD/ID/height, and final weight range in RFQs so forgers can select existing tooling and quote accurately.
  • Define allowable tolerances on OD, ID, and height separately and indicate which surfaces will be fully machined versus as-forged.
  • When possible, design ring sizes that match or are close to common roll sets to minimize custom tooling and lead time.