Aluminum Gravity Die Casting
Unlike pressure die casting, aluminum gravity die casting utilizes gravity to fill the mould with liquid aluminum alloy. CFS Foundry can provide aluminum gravity die casting services to meet any drawing’s specification.
- Support Small to Medium Production Runs
- Better Dimensional Accuracy And Surface Finish Than Sand Casting
- Mainly cast in A356-T6 aluminum alloy.
What is Aluminum Gravity Die Casting?
Aluminum gravity die casting, also called permanent mold casting, is one of the traditional aluminum casting processes to create custom aluminum parts with complicated parts. Different from high-pressure die casting, this process produces cast aluminum parts by pouring liquid metal into the mold under gravity rather than high pressure. The production efficiency is slightly lower than high-pressure die casting, so it is more suitable for manufacturing small to medium runs. However, parts made from aluminum gravity die casting have excellent mechanical properties and smooth surface finishes.
The Auminum Gravity Die Casting Process at CFS Foundry
The Aluminum Gravity Die Casting Process utilizes a reusable steel mold and involves several steps. It is a popular casting process to produce precise aluminum parts with high quality at CFS Foundry. Below is a step by step process introduction on how aluminum gravity die casting process works.
Like all the casting types, aluminum gravity die casting also requires a pair of metal molds to finish its casting process. The mold is mainly designed and precision machined following the design of the part whose cavity is the same as the desired cast shape. The mold cost is always charged but is affordable.
After the preparation of the mold, it’s time to start the casting process. Firstly, the aluminum ingots are ordered from a material factory, and the material compositions should be tested for approval. Next, heat them in a furnace for melting. Once the solid aluminum ingots melt to liquid status, it pours into the mold by a ladle until it fills the mold completely.
Then, the molten aluminum cools and solidifies at room temperature for a while. The solidification speed varies based on the size and complexity of the part. In this step, it is not difficult to under why gravity die casting process can create aluminum parts with more complex shapes, while there is a greater size limitation by other casting processes.
Once the aluminum is solidified, the mold is opened, and the part is taken out. To release the part from the mold easily, the mold is equipped with ejector pins, and there is an ejector pin mark on the surface of the casting part.
After casting, the part may require finishing operations such as trimming, heat treatment, surface finishing, or machining to achieve the desired dimensional accuracy and surface finish. Heat treatment, typically T6, can further enhance the mechanical properties of the cast aluminum part.
Aluminum Gravity Die Casting Alloy: A356-T6
A356 is a type of aluminum alloy especially for gravity die casting. A356 cast aluminum alloy has good casting and machining performance, suitable for use in aircraft, pump housings, impellers, high-velocity blowers, and other structural castings that require high strength. This light alloy is often used to manufacture intricate and complex aluminum castings, which provide lightweight, pressure tightness and great mechanical properties. Sometimes, A356 is used as an alternative for 6061 aluminum.
Chemical Compositions
| A356 Aluminum Alloy | Elements | ||||||||
| Cu | Mg | Mn | Si | Fe | Zn | Ti | Others | Al | |
| ≤0.2% | 0.25%-0.45% | ≤0.10% | 6.5%-7.5% | ≤0.2% | ≤0.1% | ≤0.2% | ≤0.15% | balance | |
Mechanical Properties
- Elongation at Break: 3%-6%
- Fatigue Strength: 50-90 MPa
- Shear Modulus: 26 GPa
- Ultimate Tensile Strength: 160-270 MPa
- Yield Tensile Strength: 83-200 MPa
- Melting Onset: 570℃
- Density: 2.6 g/cm³
After gravity die casting, T6 heat treatment is suggested to improve the mechanical properties of A356 aluminum castings. The hardness, tensile strength, and ductility of A356 castings could be improved by 106%, 106%, and 214% respectively.
Aluminum Gravity Die Casting Gallery
Benefits of Aluminum Gravity Die Casting
- The tolerances and surface finish are good.
- The gravity die casting method is a competitive casting method when the production quantity is relatively small or when heat treatment is needed to improve the mechanical properties.
- This casting method gives better tolerances and surface finish than sand casting. But the tooling costs are a bit higher than by sand casting.
- Using sand cores in gravity die casting makes it possible to manufacture items with complicated inner shapes in a cost effective way in small and medium quantities.
Surface Finishing Options
| Surface Finish | Images | Process | Advantages |
| Shot Blasted Finish |  |
High-speed steel shots are propelled at the surface to remove imperfections and improve surface quality. |
|
| Powder Coated Finish |  |
A dry powder is applied electrostatically to the surface, which is then cured under heat to form a hard, durable coating. |
|
| Anodized Finish |  |
An electrochemical process that converts the metal surface into a decorative, durable, and corrosion-resistant oxide layer. |
|
| As Machined Finish |  |
Computer numerical control (CNC) machines remove material from the die-cast part to achieve the desired shape and finish. |
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Applications of Aluminum Gravity Die Casting
- Automotive Industry: Aluminum gravity die casting is widely used in the automotive industry to create high performance automotive components. The lightweight feature of cast aluminum can effectively reduce vehicle weight and improve fuel efficiency. Moreover, gravity die casting allows for complex geometries with tight tolerances, which can help to reduce post machining cost and save cost. Typical automotive parts made from aluminum gravity die casting are engine components, cylinder heads, suspension parts, intake manifolds, and other critical components.
- Marine Applications: The lightweight feature and good corrosion resistance of aluminum make it a great choice for creating aluminum marine hardware. Aluminum gravity die casting can create intricate and precise components for marine industry like propeller blades, pump housings, and engine blocks. The process’s high strength ability can further enchance good safety and performance.
- Lighting Industry: CFS’ aluminum gravity casting process can produce durable lighting components with unique properties, such as lightweight, aesthetically pleasing surface, and excellent corrosion resistance. For lighting applications like street light housings, heat sinks, and other lighting componets, aluminum gravity casting offers a durable and weather-resistant solution.
- Agriculture Industry: The agricultural industry relies on aluminum gravity die casting for producing components for modean faming equipments. The excellent dimensional accuracy and high strength-to-weight ratio makes gravity casting ideal for agriculture application. Components made from CFS Foundry by this process include: gearbox housings, exhaust manifold, gear housings, pump bodies and more.
- Other Applications: It is not limited to produce aluminum gravity die cast components for above four industies, this process can also make cast aluminum parts for other industrial applications, such as medical devices, furniture hardwares, sports equipment, electronic components and other. CFS’ custom solution can help you to produce high quality gravity die cast aluminum parts for various applications.
Why CFS Foundry for Aluminum Gravity Die Casting Services?
CFS Foundry has been involved in aluminum gravity die casting since 1998. During these years, we have continuously introduced advanced gravity die casting machines to improve production efficiency. For large quantity orders, such machines greatly shorten the production cycle and offer our customers a much lower price. However, for some small orders, we also reserve our handwork gravity casting process in a cost effective manner.
Currently, our aluminum gravity die cast products are supplied to a wide range of industries, such as automobile industry, oil field industry, agriculture implements, furniture parts, housing appliances, etc. Typical products produced this way are, e.g. air intake components for diesel engines, valves for flow systems, tanks for air conditioning systems, etc. Those gravity die casting parts are mostly exported to American and European countries. We can provide custom aluminum gravity die casting with different aluminum alloys and value added services such as heat treatments, surface treatments (including electroplating, powder coating, painting), assembly, etc.
Aluminum Gravity Die Casting vs. Aluminum Sand Casting
| Aspect | Aluminum Gravity Die Casting | Aluminum Sand Casting |
| Process | Molten aluminum is poured into a metallic mold, relying on gravity for filling. | Molten aluminum is poured into a sand mold, created using a pattern. |
| Precision | High precision; good dimensional accuracy and repeatability. | Moderate precision; can accommodate larger tolerances. |
| Surface Finish | Smooth and fine surface finish. | Rougher surface finish, often requires additional finishing processes. |
| Tooling Costs | Higher due to metallic molds, which are more expensive to produce. | Lower, as sand molds are generally less expensive to make. |
| Production Speed | Faster, suitable for medium to high volume production. | Slower, more suitable for low to medium volume production. |
| Complexity of Parts | Suitable for complex geometries but may have limitations for very intricate parts. | More flexible with complex shapes and internal geometries. |
| Material Waste | Minimal waste, efficient use of material. | Can result in more material waste and requires proper sand management. |
| Mechanical Properties | Consistent mechanical properties due to controlled process. | Can have varied mechanical properties depending on sand quality and process. |
| Economic Considerations | More cost-effective for larger production runs due to mold reusability. | Often more cost-effective for smaller batches and prototypes. |
| Environmental Impact | Less waste and efficient energy consumption, but requires proper handling of molds. | The use of sand can lead to waste management concerns and potential emissions. |
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