Quick Answer
Centrifugal casting vs static casting — centrifugal casting spins the mold at high speed while pouring metal, using centrifugal force to distribute molten metal against the mold wall. This produces parts with superior density, minimal porosity, and fine grain structure, ideal for rings, tubes, cylinders, and sleeves. Static casting (sand, investment, die) fills the mold by gravity without rotation. For hollow cylindrical parts, centrifugal casting wins on material quality and yield.
What Is Centrifugal Casting?
In centrifugal casting, the mold rotates around its axis (typically 300–3,000 RPM) while molten metal is poured in. Centrifugal force pushes the metal outward against the mold wall, producing:
- Pure metal outer layer: Lightweight impurities and slag are forced to the inner surface (where they are machined away)
- Dense, fine-grained structure: Centrifugal force compacts the metal during solidification
- Minimal porosity: No gas entrapment; excellent for pressure applications
- Near-net shape cylinders: Less machining required than static cast-and-bored parts
Types of Centrifugal Casting
True Centrifugal Casting
The mold spins horizontally or vertically around its own axis. Metal forms against the mold wall, creating a cylindrical part with inner diameter set by the amount of metal poured:
- Pipe, tubes, rings: Most common application
- Typical sizes: 10 mm to 3,000 mm diameter
- Length: Up to 6 meters (horizontal) or limited by vertical space
- Metals: Gray iron, ductile iron, carbon steel, stainless steel, copper alloys
Semicentrifugal Casting
Mold rotates around a central axis but parts are not truly cylindrical. Used for symmetrical parts like wheels, pulleys, and flanges:
- Better density than static sand casting
- Used for non-cylindrical symmetrical shapes
Centrifuge Casting (Vertical Axis)
Small molds spin on a vertical axis for investment castings. Used for small precision parts (jewelry, dental, small industrial):
- Investment casting + centrifugal force
- Thin walls, complex shapes, excellent surface
- Small parts only (under 10 kg typically)
Centrifugal Casting vs Static Sand/Investment Casting
| Factor | Centrifugal Casting | Static Sand Casting | Static Investment Casting |
|---|---|---|---|
| Best for shape | Cylindrical rings, tubes, sleeves | Complex 3D parts | Complex precision parts |
| Material density | Excellent (no gas/slag entrapment) | Good (some porosity) | Good |
| Porosity | Very low (impurities forced inward) | Moderate | Low–Moderate |
| Grain structure | Fine, directional (radial) | Coarse (equiaxed) | Fine |
| Yield (material efficiency) | 85–95% (near-net shape) | 55–75% | 80–95% |
| Pressure-tightness | Excellent (no porosity) | Good (but risk of shrinkage) | Good |
| Surface (ID) | Relatively rough (centrifugal force marks) | Rough (sand mold) | Smooth (ceramic shell) |
| Typical metals | Iron, steel, stainless, copper | Any metal | Any metal |
| Minimum wall | 5–10 mm | 3–5 mm | 1.5–2 mm |
Why Centrifugal Casting Wins for Cylindrical Parts
Material Quality Advantage
Centrifugal force creates cleaner, denser metal:
- Slag and inclusions: Forced to the inner diameter (machined away)
- Gas pores: Pushed to inner surface; outer 90% of wall is pore-free
- Dendrite structure: Fine, directional dendrites perpendicular to the wall
- Mechanical properties: 10–20% higher tensile strength and toughness than static cast equivalents
Yield Advantage
Centrifugal casting is highly material-efficient:
- No gating system: Metal goes directly into the mold cavity
- Near-net shape: Minimal machining required
- Yield: 85–95% vs 55–75% for static sand casting
- Material savings: Especially significant for expensive alloys (stainless steel, copper alloys)
Cost Advantage for Cylindrical Parts
For rings, tubes, and sleeves:
| Method | Process | Machining Required | Typical Yield |
|---|---|---|---|
| Centrifugal casting | Cast to near-net shape | ID/OD finish machine only | 85–95% |
| Static sand + bore | Cast oversized, machine ID | ID bore + OD machine | 50–65% |
| Forged + machine | Forge, then machine all surfaces | Machine all surfaces | 30–50% |
Bottom line: For a 100 kg stainless steel sleeve, centrifugal casting saves 30–45 kg of material vs sand casting and 50–65 kg vs forging.
Applications for Centrifugal Casting
Pipe and Tube
- Oil country tubular goods (OCTG)
- Process piping (chemical, petrochemical)
- Boiler tubes
- Hydraulic cylinders
Rings and Sleeves
- Engine cylinder liners (automotive, marine)
- Journal sleeves
- Wear rings
- Pump and compressor sleeves
Wheels and Discs
- Flywheels
- Pulleys and sheaves
- Flanges and rings
Metals Cast Centrifugally
| Metal | Common Grades | Applications |
|---|---|---|
| Gray Iron | Class 30, 40, 50 | Pipes, cylinders, sleeves |
| Ductile Iron | 65-45-12, 80-55-06 | High-strength sleeves, rings |
| Carbon Steel | 1020, 1040, 4140 | Mechanical tubing, rings |
| Stainless Steel | 304, 316, 310, 410 | Chemical, food, medical pipe |
| Copper Alloys | C83600, C95400 | Bearings, sleeves |
Before finalizing the sourcing decision, many OEM buyers also compare Sand Casting, Casting Tolerances, Material Selection, and Casting Price Factors to clarify process fit, cost trade-offs, tolerance expectations, and supplier risk.
If you need application-specific guidance, drawing review, or a quotation, you can Contact YCUMETAL.
Buyer Checklist
- Is the part cylindrical or axis-symmetric?
- Is pressure-tightness required? (Centrifugal is excellent for pressure applications)
- Does the part need high material purity/density?
- What is the material and how expensive is it?
- What is the required surface finish on ID and OD?
- What tolerance is required?
- Has centrifugal casting been compared to sand casting on total cost (including material yield)?
FAQ
Can centrifugal casting produce non-cylindrical parts?
Semi-centrifugal casting can produce symmetrical parts (wheels, pulleys, flanges). For truly complex 3D shapes, static sand or investment casting is required.
What is the inner surface quality of centrifugal castings?
The inner surface (where impurities concentrate) is relatively rough and must be machined. Outer surface quality depends on mold material — steel die gives Ra 3.2–12.5 µm, which is usually acceptable without machining.
What is the size range for centrifugal casting?
From about 10 mm diameter (small bronze bearings) to over 3,000 mm diameter (large pipe). Length is typically limited to 6 meters for horizontal centrifugal casting, but longer lengths are possible with specialized equipment.