In modern manufacturing—from automotive transmission housings to consumer electronics casings—the processes of die casting determine part quality, production efficiency, and cost-effectiveness. These processes aren’t a one-size-fits-all solution; they range from basic high-pressure methods to advanced semi-solid technologies, each tailored to specific material needs (zinc, aluminum, magnesium) and application requirements (mass production, high precision). This article breaks down core process categories, technical principles, application scenarios, and selection strategies, helping you match the right die casting process to your production goals.
1. What Are the Basic Processes of Die Casting?
Basic die casting processes form the foundation of industrial production, focusing on high efficiency and cost-effectiveness. High-pressure die casting (HPDC) is the most widely used, with two sub-types based on metal melting points:
1.1 High-Pressure Die Casting (HPDC): The Industry Mainstream
HPDC injects molten metal into closed steel molds at high pressure (30-120MPa) and speed (0.5-120m/s), enabling rapid solidification (0.05-0.5 seconds) for mass-produced parts. It’s divided into two variants:
| Process Variant | Core Principle | Key Parameters | Suitable Metals | Advantages | Limitations | Typical Applications |
| Cold Chamber Die Casting | Molten metal is poured into an independent “cold chamber” (not in direct contact with the furnace) before injection; The chamber is cooled to prevent metal solidification during waiting | – Injection pressure: 50-120MPa- Mold temperature: 150-250°C- Cycle time: 30-120 seconds/part | High-melting-point metals: Aluminum (A380, A356), magnesium (AZ91D) | – Handles large/complex parts (up to 50kg)- Avoids mold overheating (extends mold life to 100,000+ cycles)- Suitable for high-strength parts | – Longer cycle time vs. hot chamber- Higher equipment cost | NEV battery brackets, automotive engine housings, aerospace structural parts |
| Hot Chamber Die Casting | The injection system (plunger, nozzle) is fully immersed in a molten metal furnace; Metal is sucked into the chamber directly for fast injection | – Injection pressure: 30-80MPa- Mold temperature: 100-180°C- Cycle time: 10-30 seconds/part | Low-melting-point metals: Zinc (Zamak5, ZA27), lead, tin | – Ultra-fast production (ideal for mass batches >100,000 parts)- Simple operation (low labor cost)- Low energy consumption (no need to reheat metal) | – Limited to small parts (<5kg)- Mold prone to corrosion (shorter life: 50,000-80,000 cycles) | Zinc alloy toys, electronic sensor housings, decorative trim (e.g., door handles) |
2. What Are the Improved Die Casting Processes?
Improved processes address flaws in basic HPDC (e.g., porosity, low precision) by optimizing mold design, gas control, or injection methods. They’re critical for high-quality parts like pressure-bearing components:
| Improved Process | Key Innovation | Technical Details | Problem Solved | Ideal Applications |
| Non-Porous Die Casting | Adds a vacuum system to remove air from the mold cavity before injection | – Vacuum degree: -0.095 to -0.098MPa- Gas removal rate: >95%- Works with cold/hot chamber systems | Reduces porosity by 80-90% (a major cause of leakage in basic HPDC); Eliminates internal voids | Zinc alloy hydraulic valve bodies, aluminum alloy fuel injector nozzles |
| Direct Injection Die Casting | Integrates the furnace with the injection chamber (no separate pouring step); Uses a plunger to push metal directly into the mold | – Metal utilization rate: >98% (vs. 85-90% for basic HPDC)- No sprue waste (cuts material cost by 10-15%) | Reduces material waste; Shortens cycle time by 15-20% | High-volume aluminum parts (e.g., consumer electronics midframes), zinc alloy hardware |
| Precision & Dense Die Casting | Invented by General Dynamics; Uses ultra-precise mold machining (cavity tolerance: ±0.01mm) + high-specific-pressure compensation (120-150MPa) | – Surface roughness: Ra ≤0.8μm (no post-polishing needed)- Dimensional accuracy: IT7-IT8 (better than basic HPDC’s IT8-IT10)- Part density: ≥99.5% | Improves surface quality and precision; Enables parts to meet strict assembly requirements | Aerospace aluminum components (e.g., cabin brackets), medical device casings (e.g., surgical tool handles) |
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