Aluminium Casting vs Die Casting — Differences, Cost and Method Selection

“We need an aluminium component cast — which method should we choose?” This is one of the most common questions buyers and design engineers ask us, and the short answer is: it depends. Aluminium casting is a collective term for at least four different methods that produce entirely different results in terms of tolerances, surface finish, mechanical properties, tooling cost and unit cost.

Choosing the wrong method can make your component three times more expensive than necessary — or make it impossible to manufacture at the required quality level.

The four main aluminium casting methods

1. Sand casting

The most versatile method. A sand mould is formed around a pattern, filled with molten aluminium, and destroyed after solidification. Suitable for prototypes, small series and large components.

Tolerances: CT9–CT11 (ISO 8062)
Surface finish: Ra 6.3–25 µm
Tooling cost: Low (EUR 500–5,000)
Economical volumes: 1–5,000 per year

2. Gravity die casting (permanent mould)

Molten metal is poured into a reusable steel mould under gravity. Better tolerances and surface finish than sand casting, with lower tooling cost than HPDC.

Tolerances: CT7–CT9
Surface finish: Ra 3.2–12.5 µm
Tooling cost: Medium (EUR 5,000–20,000)
Economical volumes: 500–50,000 per year

3. High-pressure die casting (HPDC)

Molten metal is injected under high pressure into a steel die. The dominant method for high-volume aluminium components.

Tolerances: CT6–CT7
Surface finish: Ra 1.6–6.3 µm
Tooling cost: High (EUR 15,000–80,000)
Economical volumes: 5,000+ per year

4. Investment casting (lost-wax)

A wax pattern is coated with a ceramic shell, which becomes the mould after the wax is melted out. Ideal for complex geometries with tight tolerances.

Tolerances: CT5–CT7
Surface finish: Ra 3.2–6.3 µm
Tooling cost: Low–medium (EUR 1,000–10,000)
Economical volumes: 100–10,000 per year

Decision matrix

Criterion	Sand	Gravity	HPDC	Investment
Volume <500/yr	Best	Good	Too expensive	Good
Volume 500–5,000/yr	Good	Best	Marginal	Good
Volume >5,000/yr	Expensive	Good	Best	Expensive
Complex geometry	Good	Limited	Good	Best
Tight tolerances	Limited	Good	Best	Best
Thin walls (<2mm)	Difficult	Possible	Best	Good

How Traficator can help

We evaluate your component and recommend the optimal casting method based on geometry, volume, tolerance requirements and budget. Our network includes foundries specialising in each of these methods.

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