What Are the Main Feeding Methods of Die Casting and Their Applications?

The feeding method of die casting is the “starting line” of the entire production process—it directly determines production efficiency, product quality, and the scope of applicable materials. Choosing the wrong feeding method can lead to 30% higher defect rates (Por exemplo, porosity from unstable metal supply) ou 50% lower production efficiency (Por exemplo, manual feeding delays). But with multiple mainstream options available—from manual charging to intelligent automated systems—how do you distinguish their strengths? Which fits your production scale and part requirements? This article answers these questions with detailed classifications, technical data, and a practical selection guide.

1. Classification by Automation Degree: From Manual to Intelligent

Automation level is the most intuitive way to categorize die casting feeding methods, as it directly impacts labor costs and production stability.

UM. Manual Charging

• Princípio Fundamental: Workers use tools like shovels or crucibles to manually add molten metal into the injection chamber of the die casting machine. No automated equipment is involved.
• Principais características:
• Eficiência: Low—only 10–15 parts per hour can be produced, as feeding speed depends on human operation.
• Estabilidade: Poor—temperature fluctuations of molten metal can reach ±15°C (Por exemplo, aluminum liquid drops from 680°C to 665°C during manual transfer), and feeding quantity varies by ±10% (easy to cause undercasting or flash).
• Custo: Baixo custo inicial (no need for automated equipment), but high long-term labor costs (1–2 workers per machine).
• Cenários de aplicação típicos: Small-batch trial production (Por exemplo, laboratory testing of new magnesium alloys), special alloy casting (Por exemplo, high-purity copper alloys with small demand), or low-budget small workshops.

B. Automated Ladling System

• Princípio Fundamental: Combines a robotic arm com um quantitative furnace—the robotic arm automatically scoops a fixed amount of molten metal from the furnace and pours it into the injection chamber, achieving regular and quantitative feeding.
• Key Upgrades Over Manual Charging:
• Eficiência: 3–5 times higher than manual—can achieve 30–50 parts per hour, and the robotic arm’s cycle time is stable at ±0.5 seconds.
• Estabilidade: Significantly improved—molten metal temperature loss is controlled within ±3°C (thanks to short transfer distance), and feeding quantity accuracy reaches ±2% (avoids material waste or defect risks).
• Intelligent Linkage: Can be integrated into the factory’s central control system—automatically adjusts feeding frequency according to the die casting machine’s cycle time (Por exemplo, speeds up feeding when the machine runs at high efficiency).
• Cenários de aplicação típicos: Medium-volume production lines (Por exemplo, monthly output of 50,000–200,000 aluminum alloy auto parts like sensor brackets), or production lines with multiple die casting machines (one central furnace supplies 2–3 machines).

2. Classification by Equipment Structure: Cold Chamber vs. Câmara quente

The location of the molten metal furnace relative to the injection system is a core difference in die casting equipment, which defines two unique feeding methods.

UM. Cold Chamber Die Casting Feeding

• Equipment Structure Feature: The furnace is independent of the die casting machine—molten metal is stored in an insulated furnace and transferred to the machine’s injection chamber only when needed.
• Standard Workflow:

1. The independent furnace maintains molten metal temperature (Por exemplo, 670°C for aluminum alloy) with insulation layers and auxiliary heating.
2. A manipulator (or automated ladle) scoops a fixed amount of molten metal from the furnace.
3. The manipulator pours the molten metal into the horizontal injection chamber of the die casting machine.
4. The punch pushes the molten metal into the mold cavity at high pressure (50–150MPa) para formar.

• Principais vantagens:
• Versatilidade material: Suitable for high-melting-point alloys (alumínio, magnésio, cobre) that would damage hot chamber components. Por exemplo, aluminum alloy’s melting point (660° c) is far higher than the heat resistance limit of hot chamber punches.
• Large Part Compatibility: Can handle large casting weights (up to 50kg or more), as the independent furnace and horizontal injection chamber can accommodate more molten metal.
• Critical Design Detail: O gooseneck conveying system (used in some cold chamber machines) is designed to resist metal splashing—its curved structure guides molten metal smoothly into the injection chamber, reducing air entrainment.
• Cenários de aplicação típicos: Production of large structural parts (Por exemplo, automobile engine blocks, Capas de transmissão, new energy vehicle battery pack frames) that require high-melting-point alloys and large sizes.

B. Hot Chamber Die Casting Feeding

• Equipment Structure Feature: The injection cylinder (including the punch) é directly immersed in the molten metal furnace—no separate transfer step is needed.
• Princípio de trabalho central:
• The furnace is integrated with the die casting machine—molten metal (Por exemplo, zinc alloy at 380–420°C) surrounds the injection cylinder.
• When the punch retracts, molten metal is automatically sucked into the injection cylinder through the inlet.
• When the punch advances, it directly pushes the molten metal in the cylinder into the mold cavity at high speed.
• Principais vantagens:
• Velocidade: The theoretical cycle time is 30% faster than cold chamber die casting—can achieve 60–100 parts per hour, as it eliminates the time-consuming metal transfer step.
• Simplicidade: Fewer components (no independent furnace or transfer manipulator) reduce equipment failure rates and maintenance costs.
• Material Restriction: Only applicable to low-melting-point alloys (zinco, estanho, liderar) with melting points below 450°C. High-melting-point alloys would melt the steel injection punch and cylinder, leading to equipment damage.
• Cenários de aplicação típicos: Mass production of small, thin-walled precision parts (Por exemplo, zinc alloy mobile phone metal frames, micro gears for 3C products, thin-walled sensor housings with weights less than 10kg).

3. Advanced Special Feeding Methods: For High-Quality Requirements

For parts with strict quality requirements (Por exemplo, baixa porosidade, alta resistência), two advanced feeding methods have been developed based on traditional technologies.

UM. Vacuum Die Casting Feeding

• Core Innovation: Combines “quantitative feeding” with “vacuum environment”—before feeding, the mold cavity is evacuated to a negative pressure state (<10KPA), and molten metal is injected into the vacuum cavity simultaneously.
• Quality Breakthroughs:
• Porosity Reduction: The vacuum environment eliminates 90% of air in the cavity—porosity of finished parts is reduced to <0.5%, compared to 1–3% for ordinary die casting.
• Melhoria de desempenho: Reduced porosity makes the material structure denser—elongation of aluminum alloy parts increases to 8–12% (ordinary die casting only reaches 1–3%), and tensile strength is improved by 15–20%.
• Feeding Control Requirement: The feeding speed must be precisely matched with the vacuum pumping speed—if feeding is too fast, air may be drawn into the cavity; if too slow, molten metal may solidify prematurely.
• Cenários de aplicação típicos: Production of critical parts that withstand dynamic loads (Por exemplo, new energy vehicle shock absorber tower brackets, aircraft landing gear small components) —these parts must pass strict fatigue tests (Por exemplo, ASTM B39 standard for aluminum alloys).

B. Semi-Solid Die Casting Feeding

• Inovação de Materiais: Feeds a semi-solid metal slurry (a mixture of solid primary crystals and liquid eutectic, with a solid phase ratio of 50–60%) instead of fully molten metal.
• Feeding Process Characteristics:
• The semi-solid slurry is prepared in a special mixing furnace (via mechanical stirring or electromagnetic stirring) to form spherical solid particles suspended in the liquid phase.
• The slurry is fed into the mold cavity at a lower injection speed (1–3m/s) than fully molten metal—its “toothpaste-like” viscosity avoids turbulence and air entrainment.
• Key Performance Advantage: Solves the problem of traditional die casting parts being prone to cracking during heat treatment—semi-solid parts have uniform microstructures, and their tensile strength is close to that of forged parts (Por exemplo, aluminum alloy parts reach 350–400MPa, comparable to forged 6061 alumínio).
• Cenários de aplicação típicos: Production of safety-critical components (Por exemplo, motorcycle hubs, high-speed rail brake discs, hydraulic valve bodies) that require both high strength and heat treatment stability.

4. Comprehensive Selection Guide: How to Choose the Right Feeding Method

To avoid wrong choices, use the following decision framework based on 5 key indicators. The table below also compares the core parameters of each feeding method for quick reference:

Practical Selection Suggestions:

1. Produção em massa + complex large parts: Priorize cold chamber die casting with automated ladling—balances material versatility and production efficiency (Por exemplo, auto engine blocks).
2. Micro precision parts + Voltação rápida: Escolher hot chamber die casting feeding—its fast cycle time meets high-volume demands for small parts (Por exemplo, 3C product components).
3. Critical parts with dynamic load requirements: Opte por vacuum die casting or semi-solid die casting feeding—their low porosity and high strength ensure part reliability (Por exemplo, EV shock absorber brackets).
4. Multi-variety small-batch production: Usar cold chamber die casting with modular quick mold change system (applying SMED concept)—the independent furnace allows flexible switching of alloys, suitable for producing multiple part types.

5. Yigu Technology’s Perspective on Die Casting Feeding Methods

Na tecnologia Yigu, we believe the right feeding method is the “foundation of stable die casting production.” For our automotive clients, we adopt cold chamber die casting with automated ladling—the central control system links 3 die casting machines to one furnace, reducing feeding errors by 90% and improving production capacity by 40%. For 3C product clients needing zinc alloy parts, nosso hot chamber feeding lines achieve a cycle time of 20 segundos por parte, meeting monthly output of 300,000 mobile phone frame orders.

For high-end clients (Por exemplo, new energy vehicle manufacturers), we deploy vacuum die casting feeding units—parts’ porosity is controlled below 0.3%, passing 1 million-cycle fatigue tests. We’re also developing intelligent feeding systems that use AI to predict molten metal demand—adjusting feeding quantity in real time based on part weight and machine efficiency. Our goal is to help clients match feeding methods to their actual needs, avoiding over-investment in advanced technologies or efficiency losses from outdated methods.

Perguntas frequentes

1. Can hot chamber die casting feeding be used for aluminum alloy parts?

No—aluminum alloy’s melting point (660° c) exceeds the heat resistance limit of hot chamber injection punches (usually ≤450°C). Using aluminum alloy would melt the punch and cylinder, causing equipment damage. Aluminum alloy parts must use cold chamber die casting feeding methods.

2. What is the main cost difference between automated ladling and manual charging?

Automated ladling has higher upfront investment (sobre \(50,000- )100,000 for a robotic arm + quantitative furnace), but saves \(20,000- )30,000 in annual labor costs per machine (replacing 1–2 workers). For production lines with a lifespan of 5 anos, automated ladling is more cost-effective than manual charging.

3. Is vacuum die casting feeding suitable for small-batch production?

Generally not recommended—vacuum die casting equipment has high initial investment (about 2–3 times that of ordinary cold chamber machines), e produção em pequenos lotes (Por exemplo, <10,000 peças/ano) cannot spread the equipment cost. For small-batch high-quality parts, we suggest using ordinary die casting with post-processing (Por exemplo, impregnation) to reduce porosity, which is more economical.