What are the Types of Aluminium Casting?

Choosing the wrong aluminum casting process may lead to increased manufacturing costs and quality issues, etc. This article will provide you with a detailed introduction to the common types of aluminum casting, analyze their advantages and applications, and help you select the most suitable casting solution.

Sand Casting

What is Sand Casting?

Sand casting is a metal casting process that uses a sand mixture. Molten metal is poured into the cavities by gravity. After the molten metal cools and solidifies, the sand is broken away to reveal the finished component.

Advantages of Sand Casting

Create Different Sizes and Structures: Because it is not limited by the size and shape of the parts, you can use this process to manufacture large components or parts with complex structures.

Low Tooling Costs: The raw materials are mainly composed of casting sand, clay, or resin, which are inexpensive and readily available, helping you reduce production costs.

Environmentally Friendly: Natural raw materials do not produce harmful gases, and the old sand can be recycled, which has an environmental benefit. It can increase your raw material utilization rate and reduce production costs.

Disadvantages of Sand Casting

Rough Surface: Due to the granular structure of the sand mixture, the surface of the cast parts will be relatively rough. This requires secondary processing, which will increase your additional processing costs.

Low Accuracy: When pouring, the sand mixture is not yet dry, and the accuracy of the cast parts will deviate after casting, which is not conducive to your production of parts with high precision.

Destroy the Mold  Every Time: After each casting is completed, the sand mixture on the surface needs to be removed, which is time-consuming and labor-intensive.

Applications of Sand Casting

Because of its low tooling costs, it is suitable for single-piece or low-volume production, especially for the production of large-sized and heavy items.

For example, heavy equipment in the mechanical engineering industry, engines and chassis components in the automotive industry, or various industrial pumps.

Die Casting

What is Die Casting?

Die casting is a metal casting process that injects molten metal into the mold under high pressure at high speed. Once the parts have cooled and solidified, the detachable part can be removed, and you will obtain the required part.The main types include traditional die casting, low-pressure die casting and high-pressure vacuum die casting.

Advantages of Die Casting

Create Intricate Shapes with High Accuracy: The surface of the parts after high-pressure die-casting is highly precise and smooth, and minimal secondary processing is required. It can help you produce parts with complex structures and high precision.

Fastest Production Rates: High-pressure technology can instantly complete the casting of parts, with high production efficiency, and the molds can be reused. You can obtain parts of the same quality in a short period of time.

Minimal Material Waste: Using high-pressure technology to cast molten metal into the molds that are closest to the final product design can help you reduce waste of raw materials. Even a small amount of waste can be recycled and reused.

Disadvantages of Die Casting

High Cost of Raw Materials: Because the mold can withstand thousands of production cycles, the tooling costs will be relatively high.

High Cost of Tooling Modification: The molds are made of extremely hard steel and are produced through special processes. If modifications are needed for the molds after production, it will incur high costs.

Poor Product Gas Tightness: During traditional high pressure die casting, there will be a small amount of gas inside the mold, forming porosity. This is not suitable for manufacturing parts that require high gas tightness, unless you spend money on upgrading the technology, using vacuum casting technology or low-pressure die casting technology.

Applications of Die Casting

If the parts you need to produce are in medium to large quantities and have high precision requirements while having low requirements for porosity, then you can definitely consider the aluminium die casting.

Currently, this method is widely used in the non-structural aerospace industry or automotive industry that need to withstand high temperatures, such as engine components and the casing of electronic devices.

Permanent Mold Casting (Gravity Die Casting)

What is Permanent Mold Casting?

Permanent mold casting has the advantages of slightly lower cost compared to die casting and better product performance than sand casting. After the molten metal solidifies through the cooling system, the part you want can be obtained.

Advantages of Permanent Mold Casting

Durable Used Mold: High-temperature-resistant metal molds can be reused, enabling you to produce a large number of parts in batches and saving mold-making time.

High Accuracy and Quality: The parts made by metal molds have a smoother surface and higher precision, helping you reduce the cost of secondary processing.

Disadvantages of Permanent Mold Casting

High Tooling Cost: The production cost of metal molds is relatively high. They are more suitable for medium- to large-scale production. If your budget is tight, please consider this carefully.

Melting Point Limitation: Since the molds are made of steel and iron, you must be aware that the melting point of the cast object must be lower than that of the mold.

Applications of Permanent Mold Casting

Permanent mold casting is more suitable for industries that require large-scale production, long-term use, or the ability to withstand extreme environments,  and where there are extremely high demands for the durability of the parts.

For example, engine cylinder blocks in the automotive industry, components in the shipbuilding industry, firearms equipment in the military, and household appliances commonly use this casting method.

Investment Casting (Lost Wax Casting)

What is Investment Casting?

Investment casting is a type of metal casting that uses a wax mold or a 3D-printed material as the master mold and ceramic slurry as the raw material. At high temperatures, the master mold melts and leaves behind a cavity, while the surface-coated ceramic slurry hardens and traps the molten metal solution, which then solidifies, resulting in the desired part.

Advantages of Investment Casting

Highly Detailed: The wax mold or 3D-printed master mold is of a precision similar to the metal part you need, which can help you reduce the usage of raw materials and produce complex parts.

Great Surface Finish: The surface covered with ceramic slurry becomes very smooth after baking, so the cast parts will also have a smooth surface, reducing the need for secondary processing.

Enhance Production Efficiency: The investment casting process can weld multiple wax molds onto the same runner, which can improve casting efficiency.

Disadvantages of Investment Casting

High Tooling Cost: The initial wax mold-making process involves numerous steps and requires a significant amount of mold-making and time investment. Therefore, it is best for you to produce a large quantity of parts in order to achieve higher cost-effectiveness.

Take Longer Production Time: The ceramic slurry  applied to the surface needs several days to dry naturally before being sent for baking to remove the mold. This will prolong the production cycle. If your delivery deadline is short, you should carefully choose.

Size Constraint: Because the surface coating is ceramic slurry or plaster, it is not suitable for casting very large or heavy parts as it may crack during the firing process.

Applications of Investment Casting

If your concern is more about the equipment precision, you can consider investment casting. It can help you cast parts with high precision and that requires less secondary processing afterwards.

It is particularly suitable for industries that need to use high-performance materials and have lightweight requirements. For example, engine parts in the automotive industry, surgical instruments in the medical industry, and precision parts in the semiconductor industry.

Centrifugal Casting

What is Centrifugal Casting?

Centrifugal casting is a process that utilizes centrifugal technology to make molten metal closely adhere to the inner wall of a rotating mold. After the molten liquid solidifies, the metal is removed.

Advantages of Centrifugal Casting

Refined Grain Structure: Under the action of centrifugal force, impurities with lower density in the molten metal can be separated out during the casting process. You will obtain a casting with good density and fine grain structure.

Low Material Costs: As long as the required rotational speed for the inner diameter size of the casting is calculated in advance, a nearly net-shaped casting can be obtained, reducing the waste of raw materials and the need for secondary processing.

Disadvantages of Centrifugal Casting

Strict Specification Limitations: The length-to-diameter ratio of the casting must meet certain requirements. Otherwise, the machine will lack sufficient centrifugal force, which will prevent the molten metal from adhering to the inner wall of the mold, resulting in burrs on the surface of the casting and increasing production costs.

Mold Limitation: Centrifugal casting is suitable for cylindrical and symmetrical casting. However, if the internal shape of the casting is complex, it may result in uneven distribution of molten metal during rotation, failing to achieve the desired quality you want.

Applications of Centrifugal Casting

If the majority of the parts you need to produce are cylindrical in shape, centrifugal casting is the best choice for you, as it can bring you better economic benefits and results.

Currently, it is used in various industries such as pipelines; engine housings in the automotive industry; engine valve seats in the aerospace industry, etc.

Squeeze Casting (Liquid Metal Forging)

What is Squeeze Casting?

Squeeze casting combines the technical advantages of die casting and forging. It uses the pressure generated by the hydraulic machine to press the two parts of the mold until the molten material solidifies and you obtain the desired aluminum castings.

Advantages of Squeeze Casting

High Mechanical Performance: Squeeze casting combines the advantages of die casting and forging, allowing you to obtain castings with better performance in terms of strength and toughness.

Save Production Costs: During the squeeze casting process, the molten metal fills the mold without wasting your raw materials. You can obtain castings with near-net shapes and smooth surfaces, and no secondary detailing processing is required, helping you save costs for subsequent processing.

Disadvantages of Squeeze Casting

High Setup Costs: A complete set of extrusion and die-casting equipment is very expensive. Unless you are in a high-tech industry or need a large quantity of parts that can balance the production cost through production volume, it is not recommended that you use this technology.

Design must be Precise: The cost of die-casting mold making is very high. Therefore, you must clearly define the indicator values of the parts to be produced. Otherwise, if any problems with the mold design are discovered later, it will consume your time and cost.

Applications of Squeeze Casting

Squeeze casting is suitable for industries that require extremely high performance and precision in the casting of parts, such as brackets in the aerospace industry; components in the automotive industry; and hydraulic valves in the electrical machinery industry, etc.

FAQ

Which Type is More Suitable for Mass Production?

Die Casting is more suitable for larger-scale production because although the investment cost is high, it can generate higher cost-effectiveness when producing in large quantities, balancing the factor of high investment cost. Moreover, Die Casting utilizes high-pressure technology, and the casting speed is the fastest among all types.

Which Type is More Suitable for the Production of Complex Parts?

Investment Casting is more suitable for complex and highly precise parts because the molds made of wax and 3D printing completely replicate the shape and structure of the parts, enabling the casting of metal parts that are more finely detailed than other types.

What is the Most Cost-Effective Aluminum Casting Process?

It depends on your production scale. For small-scale production, sand casting is more cost-effective as it has a lower production cost. For medium-scale production, permanent mold casting is more suitable as it offers a cost balance while providing better product precision. However, for large-scale production, die casting is recommended. Although the equipment cost is high, it has high production efficiency, low labor costs, and the product precision is also the highest, resulting in the lowest unit cost.

Can Aluminum Castings Be Heat Treated for Better Performance?

Sure. Through heat treatment, the microstructure of the internal elements of the aluminum casting can be altered, allowing the reinforcing elements to be more evenly distributed throughout the aluminum, thereby significantly enhancing the strength of the aluminum casting.

After casting, selected surfaces and mounting features may require aluminum CNC machining to achieve the final dimensions and fit required by the assembly.

What Aluminium Alloys are Commonly Used for Casting?

At present, the internationally recognized common types of aluminum alloys are mainly divided into the following series:

Final Thoughts

Selecting the correct type of aluminum casting depends on your production volume, the purpose of castings, and your budget. As an aluminum casting supplier in China, contact us if you are unsure which casting type suits you. Inoxcast can make the most suitable casting solution for you.