Fundamentals and development trends of aluminium die casting process

The Basic Concept of Aluminium Die Casting

1. Definition: The Process Principle of Aluminium Die Casting

Aluminium die casting is a process in which molten or aluminium alloy is rapidly injected into a metal mould cavity under high pressure. After cooling and solidification, it produces parts with precise dimensions, complex shapes, and excellent surface quality. The principle involves using high pressure to rapidly form molten metal, with the mould design ensuring the part’s strength, precision, and functionality.

2.The Basic Concepts of Aluminium Die Casting

Aluminium die casting is an efficient metal forming process in which molten aluminium or aluminium alloy is injected at high pressure and speed into a precision mould cavity. After cooling and solidification, it produces aluminium components of the desired shape and size. This process is widely used for manufacturing metal components with complex structures due to its high precision, low cost, and high production efficiency.

Main Features:

1. High Precision: Aluminium die casting can produce components with accurate dimensions and smooth surfaces, reducing the need for subsequent machining.
2. High Efficiency: As a one-step forming process, it is suitable for mass production, significantly enhancing manufacturing efficiency.
3. Versatility: It enables the production of components with complex shapes, thin walls, and intricate details.
4. Excellent Performance: Aluminium components are lightweight, strong, corrosion-resistant, and exhibit excellent thermal and electrical conductivity.

Process Fundamentals:

• Equipment: The core equipment includes die casting machines and metal moulds.
• Materials: Commonly used aluminium alloys, such as A380, ADC12, and A356, offer excellent flowability and mechanical properties.
• Process: The steps include melting, injection, forming, cooling, demoulding, and post-processing.

The Aluminium Die Casting Process Flow

1. Mould Design and Manufacturing

• The mould is designed according to the shape and performance requirements of the product, including the cavity, gating system, and venting system.
• Moulds are typically made from high-strength steel, which is heat-treated to enhance durability and precision.

2. Selection of Aluminium Alloy Raw Materials

• Choose the appropriate aluminium alloy materials (such as A380, ADC12, etc.) based on performance requirements.
• Conduct raw material inspections before use to ensure that the composition and quality meet the specified standards.

3. Aluminium Alloy Melting and Refining

• The aluminium alloy is heated in a furnace until it reaches a liquid state, typically at a temperature of 650°C to 750°C.
• A suitable amount of flux is added to remove impurities and gases from the molten metal, improving the material’s purity and flowability.

4. Die Casting Forming

• The molten aluminium alloy is injected into the mould cavity under high pressure and speed using a die casting machine.
• The mould’s cooling system rapidly cools the molten metal, causing it to solidify and take shape.
• The forming process is typically completed within a few seconds, making it highly efficient.

5. Mould Opening and Part Removal

• After die casting, the mould automatically separates, and the solidified casting is removed.
• Demoulding is carried out using either robotic arms or manually to avoid damaging the product’s surface.

6. Post-Processing Operations

• Deburring: Remove excess parts such as gate marks, flash, and overflows.
• Surface Treatment: Perform processes such as sandblasting, polishing, painting, or electroplating as required.
• Quality Inspection: Inspect the dimensions, surface quality, and internal defects to ensure the finished product meets the required standards.

7. Packaging and Shipping
The inspected and approved products are packaged according to requirements, labelled, and then shipped to the customer or sent for further processing.

The aluminium die casting process at Conco is carried out using automated machinery, ensuring high-efficiency production while maintaining quality and precision. Additionally, we offer post-processing services, which guarantees timely product completion and helps avoid unnecessary shipping costs, significantly saving both time and processing costs.

Advantages of Aluminium Die Casting

1. Strong Forming Capability

• Complex Structural Parts: Capable of forming complex-shaped components in a single step, without the need for multiple processes.
• High Precision: Aluminium die castings offer excellent dimensional accuracy and shape consistency, reducing the need for further machining.

2. High Production Efficiency

• Rapid Forming: The die casting process is typically completed within a few seconds, making it ideal for mass production.
• High Automation: Modern die casting equipment supports automated operations, significantly increasing production efficiency and reducing labour costs.

3. Excellent Material Properties

• Lightweight and High Strength: Aluminium alloys have a low density while offering high strength and rigidity, making them suitable for lightweight products.
• Excellent Thermal and Electrical Conductivity: Aluminium alloys perform exceptionally well in heat dissipation and electrical conductivity, making them ideal for applications such as heat sinks and electrical components.
• Strong Corrosion Resistance: The natural oxide layer on the surface provides protection against corrosion, extending the lifespan of the components.

4. High Cost-Effectiveness

• Reduced Machining Steps: Die castings have smooth surfaces and shapes close to final dimensions, reducing the need for subsequent machining.
• Material Savings: Precise mould design and die casting processes minimise waste, ensuring high material utilisation.

5. Good Surface Quality
Die castings have a dense, smooth surface that can be used directly for decoration or further processing (such as painting, electroplating, anodising, etc.).

6. Wide Adaptability

• Suitable for production at various scales, from small batch prototyping to large-scale manufacturing.
• Covers multiple industries, including automotive, aerospace, electronics, home appliances, and more.

7. Environmental Friendliness

• High Recyclability: Aluminium is a recyclable metal, supporting sustainability.
• Low Energy Consumption: Aluminium alloys have a relatively low melting point, reducing energy consumption.

Common Issues in Aluminium Die Casting and Their Solutions

The following are common issues that may occur during the aluminium die-casting process at Conco:

1. Porosity Issues
Manifestation: Small holes in the internal or surface of the casting, which reduce strength, affect appearance, and compromise airtightness.

Causes:

• Poor venting in the mould, causing gas to be trapped in the molten metal.
• Excessive pouring speed leads to the formation of air entrainment due to turbulence.

Solutions:

• Optimise the mould venting system by adding vent grooves or vent plugs.
• Control the pouring speed to avoid turbulent flow.
• Use flux during melting to remove gases from the molten metal.

2. Shrinkage Cavities and Porosity
Manifestation: Localised volume shrinkage in the casting, leading to cavities or porous areas, which reduce mechanical properties.

Causes:

• Metal shrinkage during solidification, with insufficient feeding to compensate for shrinkage.
• Poorly designed gating system, leading to uneven cooling.

Solutions:

• Optimise the gating system design by properly arranging the gates and internal runners.
• Use risers or feeding systems to improve the compensation for shrinkage.
• Adjust the cooling rate to ensure an even solidification process.

2. Shrinkage Cavities and Porosity
Manifestation: Localised volume shrinkage in the casting, leading to cavities or porous areas, which reduce mechanical properties.

Causes:

• Metal shrinkage during solidification, with insufficient feeding to compensate for shrinkage.
• Poorly designed gating system, leading to uneven cooling.

Solutions:

• Optimise the gating system design by properly arranging the gates and internal runners.
• Use riser systems to improve the compensation for shrinkage.
• Adjust the cooling rate to ensure an even solidification process.

3. Cracking Issues
Manifestation: Cracks appearing on the surface or internally within the casting, which affect mechanical strength.

Causes:

• Poor mould design, leading to excessive thermal stress.
• Cooling rate either too fast or too slow, causing stress concentration.

Solutions:

• Improve mould design by avoiding sharp corners and areas prone to stress concentration.
• Adjust cooling parameters and adopt a segmented cooling process.
• Select aluminium alloy materials with better toughness.

4. Flash and Burrs
Manifestation: Excess metal sheets or burrs along the edges of the casting, affecting both appearance and further processing.

Causes:

• Inadequate mould closure or insufficient clamping force.
• Excessive pressure from the molten metal.

Solutions:

• Inspect the mould clamping system to ensure tight closure.
• Adjust the injection pressure and speed to prevent excessive metal pressure.

5. Surface Defects
Manifestation: Pits, wrinkles, or oxide layers appearing on the surface of the casting.

Causes:

• Low temperature of the molten metal, resulting in poor flowability.
• Improper mould temperature control, leading to uneven cooling.

Solutions:

• Increase the temperature of the molten metal to improve flowability.
• Optimise the mould temperature control system to maintain a uniform and stable mould temperature.
• Ensure a continuous and stable pouring process to minimise the formation of oxide layers.

6. Inclusion Issues
Manifestation: Non-metallic particles or oxides are present in the casting, affecting mechanical properties.

Causes:

• Improper control during the melting process, resulting in inclusions not being removed.
• Poor gating system design, preventing the separation of inclusions from the molten metal.

Solutions:

• Add flux during melting and allow the metal to stand to remove slag.
• Improve the gating system design by incorporating filters or diversion systems to separate inclusions.

7. Dimensional Deviation
Manifestation: The casting dimensions do not meet the design specifications, affecting assembly or functionality.

Causes:

• Deformation of the mould during machining or use.
• Overheating of the molten metal or improper mould temperature control.

Solutions:

• Regularly inspect and maintain the mould to prevent wear or deformation.
• Precisely control the temperature of the molten metal and the mould to ensure dimensional stability.

At Conco, addressing the above issues typically involves optimising mould design and adjusting process parameters to minimise unnecessary problems. Once these adjustments are made, we proceed with further processing and enhance quality inspection to ensure the products are defects-free. This approach effectively resolves common issues in the aluminium die-casting process, improving the quality and performance of the castings.

Main Application Areas of Aluminium Die Casting

Main Application Areas of Aluminium Die Casting
Aluminium die casting, with its excellent material properties and efficient forming characteristics, is widely used across various industries. It plays a particularly important role in sectors where lightweight and high precision are critical requirements.

1. Automotive Industry

• Application Areas:
  • Engine components (such as cylinder blocks, cylinder heads, pistons).
  • Transmission parts, such as gearbox housings and clutch housings.
  • Body structural components (such as door frames, bumper brackets).
• Advantages:
  • Enables lightweight automotive components, reducing fuel consumption.
  • Enhances the durability and mechanical performance of parts.

2. Consumer Electronics Sector

• Application Areas:
  • Casings for mobile phones, tablets.
  • Electronic components such as heat sinks and connectors.
• Advantages:
  • Die castings offer excellent surface quality, making them ideal for products that combine both decorative and functional elements.
  • Good thermal conductivity, meeting the heat dissipation requirements of electronic products.

3. Home Appliances Industry

• Application Areas:
  • Functional components such as rice cooker inner pots, oven brackets.
  • Core parts like motor housings and heat sinks.
• Advantages:
  • Meets the demand for lightweight and compact home appliances.
  • The material’s strong corrosion resistance makes it suitable for use in household environments.

4. Industrial Machinery Sector

• Application Areas:
  • Pump bodies, valves, gearbox housings.
  • Enclosures and structural components for industrial equipment.
• Advantages:
  • Increases the strength and durability of mechanical components.
  • Enables the efficient forming of complex parts, reducing production costs.

5. Lighting and Construction Industry

• Application Areas:
  • LED heat sinks, lighting enclosures.
  • Door and window hardware fittings, decorative components.
• Advantages:
  • Attractive surface quality, ideal for decorative requirements.
  • High durability and strength, meeting the long-term usage needs of the construction sector.

6. Medical Equipment Sector

• Application Areas:
  • Precision enclosures and structural components, such as surgical light brackets, medical instrument housings.
• Advantages:
  • High precision and strength, meeting the stringent requirements of medical equipment.
  • Surfaces are easy to clean and resistant to corrosion, complying with medical environment standards.

In the above application areas, Conco has extensive processing experience in the lighting and construction industry, heat sinks, automotive battery boxes, and the medical equipment sector.

Summary

Aluminium die casting, with its efficiency, precision, and lightweight advantages, has become an indispensable process in modern manufacturing. By selecting appropriate aluminium alloy materials, optimising the process flow, and addressing common defect issues, aluminium die-casting technology can meet the demands of various industries for complex, high-performance components.

At the same time, with the growing awareness of environmental protection and the development of the global green economy, the potential of aluminium die casting in sustainable manufacturing is becoming increasingly significant. By promoting the use of recycled aluminium materials and integrating intelligent and automated technologies, aluminium die casting can not only enhance economic benefits but also contribute to achieving carbon neutrality and resource recycling goals, laying a solid foundation for green manufacturing.

In the future, aluminium die casting will continue to play a vital role in key sectors such as automotive, aerospace, and consumer electronics. Driven by the development of new materials and innovations in digital processes, it will open up even more application scenarios.

Aluminium die casting plays a significant role at Conco as well. Through years of accumulated experience, the level of customer recognition has been steadily increasing. In recent years, the completion of numerous projects and high customer satisfaction have given us strong affirmation. We believe that in the future, we will continue to solve aluminium processing challenges for our customers with even better service.