Commonly used die casting aluminum alloys form the backbone of modern manufacturing, combining lightweight properties, good castability, and versatile performance to meet diverse industrial needs. From automotive engine parts to electronic device shells, these alloys enable the mass production of complex, high-precision components via high-pressure die casting. This article breaks down the key types of commonly used die casting aluminum, their characteristics, process advantages, application scenarios, and selection criteria—helping you pick the right alloy for your specific manufacturing needs.
1. Key Types of Commonly Used Die Casting Aluminum Alloys
The most widely adopted die casting aluminum alloys fall into two main categories: aluminum-silicon-copper (Al-Si-Cu) series (represented by ADC12) and industrial pure aluminum (represented by AL99.70 and AL99.70A). Below is a 总分结构 with detailed comparisons:
1.1 ADC12 (Al-Si-Cu Series): The Workhorse Alloy
ADC12 is the most commonly used die casting aluminum alloy, accounting for over 60% of global die casting applications. Its balanced properties make it ideal for high-volume production.
| Attribute | Details | Industrial Significance |
| Composition | Base: Aluminum (≥85%); Key alloying elements: Silicon (9.5–12%), Copper (1.5–3.5%); Trace elements: Manganese (≤0.5%), Magnesium (≤0.3%) (some variants add these to boost strength). | Silicon improves fluidity (critical for filling thin-walled cavities); copper enhances tensile strength—striking a balance between castability and mechanical performance. |
| Core Characteristics | – High Fluidity: Easily fills complex mold cavities (even for parts with 0.5–1 mm thin walls).- Good Dimensional Accuracy: Achieves ISO 8062 CT6–CT7 tolerance (±0.1–0.2 mm for small parts).- Moderate Mechanical Properties: Tensile strength (220–280 MPa), hardness (80–100 HB); elongation is lower than pure aluminum (3–5% vs. 10–15%). | Meets the needs of most non-load-bearing and light-load components, where castability and cost-effectiveness matter more than ultra-high strength. |
| Typical Applications | Automotive: Engine mounts, transmission housings, door handle brackets.Electronics: Smartphone charger shells, router housings, LED heat sink bases.Home Appliances: Air conditioner compressor covers, washing machine control panels. | Its versatility makes it the “go-to” alloy for manufacturers seeking a balance of performance and affordability. |
1.2 AL99.70 & AL99.70A (Industrial Pure Aluminum): High-Purity Options
These alloys are part of the 1XXX series (industrial pure aluminum) and are used for applications requiring high purity and specific physical properties. The table below contrasts their key differences:
| Feature | AL99.70 | AL99.70A | Key Impact on Applications |
| Purity & Composition | Aluminum content ≥99.70%; Silicon content ≤0.10%; Other impurities (iron, copper) ≤0.30%. | Aluminum content ≥99.70%; Silicon content ≤0.08% (stricter than AL99.70); Total impurities ≤0.25%. | AL99.70A’s lower silicon and impurity levels reduce surface defects, making it better for decorative parts or components sensitive to impurity-induced corrosion. |
| Identification Marking | Color code: A red vertical line on the ingot or packaging. | Color code: A red horizontal line on the ingot or packaging. | Simple visual distinction helps prevent mix-ups during material handling—critical for high-precision production lines. |
| Core Properties | – High electrical conductivity (60–65% IACS).- Good corrosion resistance (natural oxide layer forms quickly).- Low strength (tensile strength 90–120 MPa) but high ductility (elongation 12–15%). | Same as AL99.70, with slightly better electrical conductivity (63–68% IACS) and corrosion resistance (due to fewer impurities). | Suitable for parts where purity, conductivity, or corrosion resistance is prioritized over strength. |
| Typical Applications | AL99.70: Low-voltage electrical connectors, decorative trim for furniture.AL99.70A: High-precision electronic components (e.g., sensor housings), medical device casings (non-implantable), architectural decorative panels. | AL99.70A is preferred for medical and electronic applications, where even trace impurities can affect performance or biocompatibility. |
2. Process Advantages of Commonly Used Die Casting Aluminum
The popularity of these die casting aluminum alloys is not just due to their material properties—their compatibility with high-pressure die casting processes amplifies their value. Below is a linear breakdown of key process advantages, supported by data:
2.1 High-Pressure High-Speed Forming: Enabling Complexity
- Process Parameters: Uses 2,000–15,000 kPa pressure and 0.5–5 m/s filling speed to inject molten aluminum into molds.
- Outcome: Produces parts with intricate features (e.g., internal channels, micro-holes) that are hard to achieve with sand casting or CNC machining. For example, an ADC12 automotive sensor housing with 3 internal holes (φ1 mm each) can be cast in one step—no post-drilling needed.
- Efficiency: A single die casting machine can complete 1,000–3,000 cycles per day for ADC12 parts, far outpacing traditional manufacturing (e.g., 100–200 parts/day for sand casting).
2.2 Enhanced Precision & Surface Finish
- Dimensional Accuracy: As mentioned earlier, ADC12 achieves CT6–CT7 tolerance, while AL99.70/AL99.70A (with stricter process control) can reach CT5–CT6 (±0.05–0.1 mm). This reduces post-machining by 70–80% compared to sand casting.
- Surface Quality: The high-pressure process delivers a surface finish of Ra 1.6–6.3 μm for ADC12, and Ra 0.8–3.2 μm for AL99.70A (with optimized mold polishing). For many applications (e.g., electronic device shells), this eliminates the need for additional grinding or polishing.
2.3 Improved Material Performance Post-Processing
- Strength & Hardness: While as-cast ADC12 has moderate strength, heat treatment (e.g., T6) can boost its tensile strength by 15–20% (to 250–320 MPa). AL99.70/AL99.70A can be cold-worked (e.g., rolling) to increase hardness by 30–40% (from 25 HB to 35–38 HB).
- Corrosion Resistance: Both ADC12 and AL99.70/AL99.70A benefit from surface treatments:
- Anodizing: Creates a 10–20 μm oxide layer, improving corrosion resistance (ADC12 withstands 48-hour salt spray testing; AL99.70A lasts 72+ hours).
- Coating: Electroplating (nickel, chrome) or powder coating enhances aesthetics and durability for decorative parts.
3. Core Application Areas: Industry-by-Industry Breakdown
Commonly used die casting aluminum alloys serve diverse sectors, each leveraging their unique strengths. The table below summarizes key applications and alloy choices:
| Industry | Key Components | Preferred Alloy | Rationale |
| Automotive | Engine mounts, transmission housings, body structural parts, EV battery brackets. | ADC12 (primary); AL99.70A (decorative trim). | ADC12’s castability and cost-effectiveness meet high-volume automotive needs; AL99.70A’s corrosion resistance suits exterior trim. |
| Electronic Appliances | Device frames (smartphones, tablets), heat sinks, connectors, charger shells. | ADC12 (most components); AL99.70A (high-precision sensors). | ADC12’s thin-wall capability fits miniaturized electronics; AL99.70A’s purity avoids signal interference in sensors. |
| Machinery & Engineering | Hydraulic valve bodies, pump housings, precision gearbox covers. | ADC12 (primary); AL99.70 (low-pressure valves). | ADC12’s dimensional accuracy ensures tight fits for hydraulic parts; AL99.70’s corrosion resistance suits fluid-handling applications. |
| Emerging Fields (NEVs) | Integrated battery housings, motor casings, charging port components. | ADC12 (structural parts); AL99.70A (high-conductivity connectors). | ADC12’s strength supports battery weight; AL99.70A’s conductivity enhances charging efficiency. |
4. How to Select the Right Commonly Used Die Casting Aluminum Alloy
Choosing between ADC12, AL99.70, and AL99.70A requires evaluating four key factors. Use this step-by-step guide:
4.1 Define Core Requirements
- Mechanical Needs: If the part is load-bearing (e.g., automotive engine bracket), ADC12’s higher strength is better. For non-load-bearing parts (e.g., decorative trim), AL99.70/AL99.70A suffices.
- Purity & Corrosion Resistance: For medical devices or coastal applications, AL99.70A’s low impurities and superior corrosion resistance are critical. For indoor electronics, ADC12 (with anodizing) is cost-effective.
- Electrical/ Thermal Conductivity: For heat sinks or electrical connectors, AL99.70/AL99.70A’s higher conductivity (60–68% IACS) outperforms ADC12 (40–45% IACS).
4.2 Consider Process Compatibility
- Part Complexity: ADC12’s high fluidity is ideal for complex, thin-walled parts. AL99.70/AL99.70A has lower fluidity—avoid using them for parts with <1 mm walls or intricate cavities.
- Production Volume: For high-volume runs (>10,000 parts), ADC12’s lower cost and faster casting speed reduce per-unit expenses. For small batches (<1,000 parts), AL99.70/AL99.70A’s higher material cost is less impactful.
4.3 Evaluate Total Cost
- Material Cost: ADC12 is 15–20% cheaper than AL99.70, and AL99.70A is 5–10% more expensive than AL99.70 (due to stricter purification).
- Post-Processing Cost: AL99.70A requires less surface treatment (e.g., no extra polishing for decorative parts), which may offset its higher material cost. ADC12 may need additional machining for high-precision features.
Yigu Technology’s Perspective
At Yigu Technology, we see commonly used die casting aluminum alloys as the foundation of efficient manufacturing. For automotive clients, we recommend ADC12 for engine components—optimizing its casting parameters (8,000 kPa pressure, 2 m/s filling speed) to reduce defects by 30%. For electronic clients needing high-purity parts, we use AL99.70A with custom anodizing (15 μm layer) to meet 72-hour salt spray standards. We also help clients balance cost and performance: for example, using ADC12 for smartphone middle frames (cost-effective) and AL99.70A for internal connectors (high conductivity). Ultimately, the right alloy isn’t just about properties—it’s about aligning with your product’s function, volume, and budget.
FAQ
- Can ADC12 be used for load-bearing automotive parts?
Yes, but with limitations. ADC12 works for light-load parts (e.g., engine mounts, transmission covers) with tensile strength requirements <280 MPa. For heavy-load parts (e.g., suspension brackets), we recommend upgrading to A380 (a stronger Al-Si-Cu alloy) or combining ADC12 with reinforcing ribs in the mold design.
- What’s the main reason to choose AL99.70A over AL99.70?
AL99.70A’s stricter impurity controls (lower silicon, total impurities ≤0.25%) make it better for applications where corrosion resistance or surface quality is critical. For example, medical device casings or architectural trim—AL99.70A’s cleaner composition reduces the risk of surface pitting or impurity-induced failure.
- Do commonly used die casting aluminum alloys require post-treatment?
Most do, but the type depends on the alloy and application. ADC12 often needs anodizing (for corrosion resistance) or CNC trimming (for precision). AL99.70/AL99.70A may only need light polishing (for decorative parts) or no treatment at all (for internal electrical components, where conductivity is prioritized over aesthetics).