In the era of lightweight, energy-saving, and high-efficiency production—from new energy vehicles (NEVs) to consumer electronics—light metal die casting has become an irreplaceable manufacturing technology. It injects molten light metals (aluminum, magnesium, zinc alloys) into precision molds at high pressure and speed, forming complex, high-performance components that balance weight reduction, structural strength, and cost efficiency. This article breaks down its core principles, material characteristics, process types, application scenarios, and solutions to industry challenges, helping you fully grasp its value and practical application.
1. What Are the Core Principles and Features of Light Metal Die Casting?
To understand its advantages, we first clarify the technical logic and unique traits that distinguish it from traditional casting processes.
1.1 Core Working Principle
Light metal die casting relies on a “high-pressure filling + rapid solidification” mechanism:
- Melting: Light metals (e.g., aluminum alloy) are melted in a crucible to form a molten state (temperature: 650-720°C for aluminum, 380-450°C for zinc).
- High-Pressure Injection: The molten metal is pushed into a closed steel mold cavity at pressures of 30-120MPa and speeds of 0.5-120m/s—ensuring it fills even thin-walled (0.5-3mm) or complex structures.
- Rapid Solidification: The mold’s cooling system (water or oil circulation) accelerates solidification (0.05-0.5 seconds), locking in the part’s shape and dimensional accuracy.
- Demolding: The mold opens, and an ejection system pushes out the finished part—ready for post-processing (e.g., deburring, surface treatment).
1.2 Three Key Features
| Feature | Technical Advantage | Practical Impact |
| High Efficiency | Standardized molds enable rapid cycle production (10-60 seconds per part for zinc alloys; 30-120 seconds for aluminum alloys) | Mass production of small/medium parts (e.g., 10,000+ NEV battery brackets per day) |
| Precision Forming | Dimensional tolerance: IT8-IT10; Surface roughness: Ra 1.6-6.3μm | Reduces post-processing by 50-70% (e.g., aluminum alloy electronic housings need no extra grinding) |
| Material Adaptability | Optimizes process parameters for light metals’ properties (e.g., aluminum’s corrosion resistance, magnesium’s lightweight) | Maximizes material advantages—e.g., magnesium alloy parts are 33% lighter than aluminum while maintaining strength |
2. Which Light Metals Are Commonly Used, and What Are Their Traits?
Material selection directly determines part performance and application scope. Aluminum, magnesium, and zinc alloys are the three mainstream options, each with distinct strengths:
2.1 Comparison of Common Light Metals for Die Casting
| Metal/Alloy | Key Characteristics | Density (g/cm³) | Mechanical Properties | Typical Application Areas |
| Aluminum Alloy (A380, A356) | – Excellent corrosion resistance (resists oxidation in humid environments)- Good thermal conductivity (205 W/(m·K), 2x better than steel)- Cost-effective (1/3 the price of magnesium alloy) | 2.7 | – Tensile strength: 200-350MPa- Elongation: 3-12% | – NEV: Battery shells, motor housings- Electronics: 5G base station antenna brackets- Aerospace: Cabin structural parts |
| Magnesium Alloy (AZ91D, AM60B) | – Ultra-lightweight (lightest structural metal for die casting)- High specific strength/stiffness (strength-to-weight ratio better than aluminum)- Strong electromagnetic shielding (protects electronic components from interference) | 1.8 | – Tensile strength: 170-280MPa- Elongation: 2-10% | – Automotive: Dashboards, wheel hubs- Electronics: Laptop shells, smartphone frames- Medical: Lightweight device casings |
| Zinc Alloy (ZA27, Zamak5) | – Low melting point (easy to process, saves energy)- Excellent fluidity (fills tiny mold details <0.1mm)- Long mold life (100,000+ cycles, 2x longer than aluminum alloy molds) | 6.4 | – Tensile strength: 280-400MPa- Hardness: HB 80-120 | – Small precision parts: Toy gears, stationery accessories- Decorative components: Door handles, zipper sliders- Electronics: Sensor housings |
3. What Are the Main Process Types of Light Metal Die Casting?
Process selection depends on metal melting points, part complexity, and quality requirements. Traditional processes meet basic needs, while improved technologies solve defects like porosity:
3.1 Traditional Die Casting Processes
| Process Type | Core Mechanism | Suitable Metals | Advantages | Limitations |
| Cold Chamber Die Casting | Molten metal is poured into an independent cold chamber before injection | High-melting-point metals (aluminum, magnesium) | – Handles large/complex parts (e.g., NEV battery trays)- Avoids mold overheating | – Longer cycle time (30-120 seconds/part)- Higher equipment cost |
| Hot Chamber Die Casting | The injection system is immersed in a molten metal pool (integrated design) | Low-melting-point metals (zinc, lead) | – Ultra-fast cycle time (10-30 seconds/part)- Simple operation, low energy consumption | – Limited to small parts (<5kg)- Mold prone to corrosion (short life for zinc alloys) |
3.2 Improved & Innovative Processes
These technologies address traditional defects (e.g., porosity) and expand application scope:
| Innovative Process | Key Improvement | Suitable Scenarios | Performance Gain |
| Vacuum Die Casting | Extracts air from the mold cavity (vacuum degree: -0.095 to -0.098MPa) before injection | High-quality parts (e.g., automotive engine cylinder heads) | Reduces porosity by 80-90%; Improves tensile strength by 15-20% |
| Oxygenated Die Casting | Injects oxygen into the cavity to form oxide particles (diffused distribution) | Parts requiring heat treatment (e.g., aluminum alloy suspension arms) | Eliminates internal pores; Enables T6 heat treatment (strength +25%) |
| Semi-Solid Die Casting | Controls solid phase rate (40-60%) of molten metal; Uses laminar flow filling | Thin-walled, high-precision parts (e.g., smartphone midframes) | Reduces shrinkage by 70%; Improves structural uniformity |
| Squeeze Casting | Applies external pressure (100-200MPa) during solidification | Thick-walled structural parts (e.g., aerospace brackets) | Increases density to ≥99.5%; Boosts impact resistance by 30-40% |
4. What Are the Key Application Scenarios and Industry Trends?
Light metal die casting is widely used in industries driven by lightweight and precision demands. Below are its core application fields and future development directions:
4.1 Core Application Fields
| Industry | Application Examples | Driving Demand |
| Automotive (NEVs) | – Aluminum alloy: Battery shells, motor housings, shock absorber towers- Magnesium alloy: Interior door panels, seat frames | Lightweight (every 100kg weight reduction increases range by ~100km); Structural strength (resists collision impacts) |
| Consumer Electronics | – Magnesium alloy: Laptop shells, tablet backplanes- Aluminum alloy: Smart TV frames, wireless charger housings | Thinness/lightness (e.g., laptop weight <1kg); Surface quality (Ra ≤3.2μm for aesthetics) |
| Aerospace | – High-performance aluminum alloy: Engine components, cabin partitions | Weight reduction (lowers fuel consumption); High-temperature stability (works at 150-200°C) |
| Green Manufacturing | – Recycled aluminum/magnesium alloys: Furniture hardware, garden tools | Environmental protection (recycled aluminum uses 5% of the energy of primary aluminum); Circular economy |
4.2 Future Trends (2024-2030)
- Intelligent Production: AI-based process monitoring (real-time adjustment of injection pressure/speed) reduces defect rates to <1%; Digital twins simulate mold life (extends service life by 20-30%).
- Material Innovation: Development of “heat-resistant magnesium alloys” (works at 200-250°C) to replace aluminum in high-temperature automotive parts (e.g., engine housings).
- Large Integrated Casting: NEV body-in-white (BIW) integration—one die-cast part replaces 50+ stamped parts (reduces assembly time by 60%; cuts body weight by 15%).
5. What Are the Industry Challenges and Practical Solutions?
Despite its advantages, light metal die casting faces technical and operational hurdles. Below are targeted solutions:
| Challenge | Root Cause | Solution | Expected Outcome |
| Magnesium Alloy Oxidation/Burning | Magnesium has low ignition point (550°C); Reacts with oxygen easily | – Use SF₆ + CO₂ mixed inert gas protection during melting- Add 0.5-1% calcium to magnesium alloy (improves oxidation resistance) | Burning risk reduced to <0.1%; Alloy yield increased by 10-15% |
| High Silicon Aluminum Alloy Mold Adhesion | Silicon in the alloy (e.g., 7.5-9.5% in A380) adheres to mold surfaces during solidification | – Coat mold cavity with TiN (titanium nitride) coating- Optimize mold temperature (maintain 180-220°C for aluminum alloys) | Adhesion defect rate reduced from 5% to <0.5% |
| Low Production Efficiency for Complex Parts | Traditional cold chamber processes have long cycle times | – Adopt robotic automatic pouring systems (reduces loading time by 40%)- Use multi-cavity molds (e.g., 4-cavity for zinc alloy sensor housings) | Production capacity increased by 50-80% |
| High Equipment Investment | Large die-casting machines (e.g., 9000T for NEV BIW) cost $10M+ | – Small/medium enterprises: Lease equipment (reduces upfront cost by 80%)- Industry collaboration: Share mold development costs (cuts R&D expenses by 30-40%) | Lowers entry barrier; Promotes technology popularization |
6. Yigu Technology’s Perspective on Light Metal Die Casting
At Yigu Technology, we view light metal die casting as the “core enabler of lightweight manufacturing”—especially for NEVs and consumer electronics. Our practice shows that 65% of clients achieve 20-30% weight reduction by switching from steel to aluminum/magnesium die-cast parts.
We recommend a “material-process matching” approach: For NEV battery shells, we use vacuum die casting + A356 aluminum alloy (ensures air tightness; reduces porosity to <0.3%); For laptop shells, we adopt semi-solid die casting + AZ91D magnesium alloy (achieves 1.2mm thin walls; cuts weight by 25%). We also integrate IoT sensors to monitor mold temperature in real time, reducing defect rates to <0.8%. Looking ahead, combining this technology with recycled materials will be key to balancing performance and sustainability.
7. FAQ: Common Questions About Light Metal Die Casting
Q1: Can light metal die-cast parts undergo heat treatment to improve strength?
Yes, but it depends on the process: Vacuum or oxygenated die casting eliminates pores, making parts suitable for heat treatment (e.g., T6 solution aging for aluminum alloys—tensile strength +25%). Traditional die-cast parts with high porosity cannot be heat-treated (heat causes pore expansion and cracking).
Q2: Which is more cost-effective for NEV parts—aluminum alloy or magnesium alloy die casting?
Aluminum alloy is more cost-effective for most cases: It has 1/3 the material cost of magnesium alloy and uses mature cold chamber processes (lower equipment maintenance). Magnesium alloy is better for high-end NEVs where weight reduction is critical (e.g., premium electric sedans)—the extra cost is offset by extended driving range.
Q3: What is the maximum part size achievable with light metal die casting?
Currently, the practical limit is parts weighing 50-80kg and measuring 2-3m (e.g., NEV BIW rear floors). For larger parts (e.g., 3m+ truck frames), multi-part die casting + welding is used. With 12,000T+ large die-casting machines, the limit will extend to 100kg+ parts by 2025.