Kinaguiden is a precision aluminium die casting company based in Stockholm, Sweden, specialising in custom mould design, HPDC, re-engineering, and global logistics.
Selecting the right aluminium alloy is one of the most important decisions in any die casting project. The alloy affects everything — mechanical strength, corrosion resistance, surface quality, machinability, and ultimately, the cost and performance of your finished part. Yet many buyers leave this choice entirely to their supplier without understanding the trade-offs involved.
This guide walks through the most common high-pressure die casting (HPDC) alloys and helps you match the right material to your application.
Why Alloy Choice Matters
All aluminium die casting alloys are silicon-aluminium systems, but the exact composition — the balance of silicon, copper, magnesium, zinc and other elements — dramatically affects how the metal behaves during casting and in service. A wrong alloy choice can lead to porosity defects, poor corrosion resistance in outdoor applications, difficult machining, or a part that simply doesn't meet its mechanical specification.
The Most Common Die Casting Alloys Compared
| Alloy | Strength | Corrosion Resistance | Machinability | Castability | Best For |
|---|---|---|---|---|---|
| ADC12 / A383 | Good | Moderate | Good | Excellent | Automotive, general engineering |
| A380 | High | Moderate | Good | Very good | Motor housings, brackets |
| A360 | Moderate | Excellent | Moderate | Good | Marine, outdoor, EV parts |
| AlSi9Cu3 | High | Moderate | Excellent | Very good | Hydraulic, transmission parts |
| AlSi12 | Moderate | Good | Moderate | Excellent | Thin-wall, complex geometry |
ADC12 / A383 — The Workhorse Alloy
ADC12 (the Japanese designation) and A383 (the American equivalent) are the most widely used die casting alloys in the world. Their high silicon content gives them excellent fluidity, meaning the molten metal fills complex moulds easily — which is why they are the default choice for most general-purpose applications.
They offer a good balance of strength, castability, and cost. If you don't have a specific requirement that rules them out, ADC12/A383 is almost always the right starting point. The main limitation is moderate corrosion resistance — they are not ideal for parts permanently exposed to moisture or salt air without surface treatment.
A380 — When You Need Strength
A380 is the strongest of the common HPDC alloys. It offers higher tensile strength and good thermal conductivity, making it popular for motor housings, heat-generating components, and structural brackets. Like ADC12, it has moderate corrosion resistance and should be anodized or coated for outdoor use.
A360 — The Corrosion-Resistant Option
A360 has lower copper content than A380 and ADC12, which significantly improves its corrosion resistance. It is the right choice for parts that will be exposed to weather, marine environments, or aggressive cleaning chemicals — such as EV battery housings, solar mounting components, or outdoor lighting.
The trade-off is slightly lower strength and a narrower processing window during casting, which requires more careful mould design.
AlSi9Cu3 — For Machined Parts
AlSi9Cu3 (also known as EN AC-46000) is particularly well-suited to parts that require significant CNC machining after casting. Its composition gives excellent chip formation and tool life, making it the preferred alloy for hydraulic valve bodies, transmission components, and precision mechanical parts where tight machined tolerances are needed.
AlSi12 — For Thin Walls and Complex Geometry
AlSi12 has the highest silicon content of the common HPDC alloys, giving it outstanding fluidity. This makes it the best choice for parts with very thin walls, long flow lengths, or highly complex internal geometry where other alloys might not fully fill the mould. Heat exchangers, decorative covers, and intricate housings are typical applications.
Key Questions to Ask When Choosing an Alloy
- Will the part be exposed to outdoor conditions, moisture, or chemicals?
- Does the part require significant CNC machining after casting?
- Are there high mechanical load or impact requirements?
- Does the part have very thin walls or complex internal channels?
- What surface finish is required — anodizing, powder coating, or as-cast?
Kinaguiden's advice: Share your application requirements with us and we'll recommend the optimal alloy. In most cases, ADC12 or A380 is the right choice — but for corrosive environments, outdoor use, or high-precision machined parts, the right alloy selection can save significant cost and quality issues downstream.