Centrifugal Casting

Centrifugal casting forms high-integrity, axisymmetric hollow parts by spinning a mold so molten metal solidifies from the outside in with very low porosity.

Overview

Centrifugal casting produces cylindrical and ring-shaped parts by rotating a mold at high speed while pouring molten metal. Centrifugal force drives the metal to the mold wall, forcing impurities toward the bore and creating a dense, fine-grained outer structure. The process excels at tubes, rings, bushings, liners, and other rotationally symmetric sections that need high strength and good pressure containment.

Use centrifugal casting when you need clean, low-porosity, near-net-shape rings or cylinders in steel, iron, or high-alloy materials at low-to-high production volumes. It reduces or eliminates cores, improves soundness over many other casting methods, and can yield good as-cast surfaces that need only machining stock on critical surfaces. Tradeoffs: geometry is limited to axisymmetric shapes, length and diameter ranges depend on machine capacity, and bores and sealing surfaces usually require finish machining to hit tight tolerances and surface finish requirements.

Common Materials

  • Stainless steel 304
  • Carbon steel 1020
  • Ductile iron
  • Bronze C932
  • Inconel 625
  • High-chromium white iron

Tolerances

±0.010" to ±0.030" on as-cast dimensions (tighter after machining)

Applications

  • Pressure pipe and tube sections
  • Bearing bushings and sleeves
  • Pump and valve bodies (ring-type)
  • Cylinder liners and engine sleeves
  • Steel mill and rolling mill rings
  • Brake drums and flywheel rings

When to Choose Centrifugal Casting

Choose centrifugal casting for axisymmetric hollow parts that need high structural integrity, low porosity, and good mechanical properties through the wall. It fits medium to high volumes or recurring production where tooling costs can be amortized. It is ideal when the part is essentially a tube, ring, or sleeve and you plan to machine critical bores and faces afterward.

vs Sand Casting

Pick centrifugal casting instead of sand casting when you need much lower porosity, better mechanical properties, and superior surface finish in cylindrical sections. It is also preferable when you want to avoid complex cores for bores and can live with axisymmetric geometry limits.

vs Die Casting

Choose centrifugal casting over die casting when you’re working with steels, irons, or high-temperature alloys that die casting cannot handle. It also makes more sense for thick-walled, structural tubes and rings where mechanical properties and soundness matter more than very high production rates or intricate external details.

vs Investment Casting

Use centrifugal casting instead of investment casting when the part is primarily a ring or tube and material soundness and low inclusion levels are more critical than fine external detail. It generally offers lower part cost and better economics for larger, heavy-section cylindrical parts where investment tooling and shells would be expensive and slow.

vs Permanent Mold Casting

Select centrifugal casting when you need higher cleanliness and directional solidification in cylindrical parts than permanent mold casting typically provides. It is especially useful for larger diameters and wall sections where gravity-fed permanent molds struggle with porosity and shrinkage control.

Design Considerations

  • Limit geometry to axisymmetric forms: tubes, rings, sleeves, and features that can be machined from these basics
  • Keep wall thickness as uniform as possible; avoid abrupt section changes that can trap shrinkage and distort during cooling
  • Specify required machining allowances on OD, ID, and faces so the foundry can size the casting and control stock
  • Call out critical material properties and inspection zones (e.g., ultrasonic in the working wall) instead of over-constraining every dimension as-cast
  • Provide realistic length and diameter ranges based on available centrifugal casting equipment; very short, stubby parts or extremely long slender tubes are harder to control
  • Clarify which surfaces are function-critical and which can remain as-cast to help optimize process choice and cost