Casting
Sand Casting vs Investment Casting
Sand casting is cheap and scalable for large, rougher parts; investment casting delivers fine detail and smooth surfaces at higher cost. Tolerance and finish versus part size and tooling economy.
| Sand Casting | Investment Casting | |
|---|---|---|
| Mold | Bonded sand, single use | Ceramic shell around wax, single use |
| Tolerance | 1 to 3 mm | 0.1 to 0.5 mm |
| Surface finish | Rough, 250 to 900 microinch | Smooth, 63 to 125 microinch |
| Part size | Ounces to many tons | Grams to ~50 kg |
| Tooling cost | Low | Moderate to high, wax tooling |
| Per-part cost | Low | Higher |
| Complexity | Moderate | High, thin walls and fine detail |
Choose Sand Casting when
- Large or heavy parts where finish is secondary
- Lower volumes or cost-sensitive castings
- Simple to moderate geometry
Choose Investment Casting when
- Fine detail, thin walls, and smooth as-cast surfaces
- Tight tolerances that reduce machining
- Complex net-shape parts in steel or superalloys
The verdict
Sand cast for large, cost-driven parts where a rough surface is fine, and invest in investment casting when detail, thin walls, and finish justify the higher tooling and per-part cost by cutting downstream machining.
Cost comparison
Sand tooling starts around 2,000 to 10,000 USD against 8,000 to 50,000 USD for wax tooling and shell processing, and per-part cost follows the same order. The equation flips when investment casting's near-net surfaces delete machining: a part that needs five machined faces after sand casting may cost less overall as an investment casting despite a higher casting price.
Common questions
Why is investment casting more expensive than sand casting?
Investment casting builds a ceramic shell around an expendable wax pattern for each part, which adds material and labor. Sand molds are cheaper, so sand casting costs less per part but gives a rougher surface.