An Overview of Die Cast Aluminum

Aluminum die casting is a time-tested, cost-effective manufacturing method. Ideal for fabricating massive quantities of intricate parts, it is a sustainable manufacturing solution for a wide range of industries, including agriculture, construction, heavy equipment, industrial storage, and manufacturing machinery.

In this post, we’ll answer the question, “What is aluminum die casting?” and explain the most important parts of the process.

Understanding Die Casting

Definition of Die Casting

First invented in 1838, die casting is the process of forcing molten metal into a steel mold to fabricate a part. Unlike gravity die casting, where the molten metal is poured directly into the mold, high-pressure die casting applies significant pressure to the liquid metal to force it into the die. This pressure usually ranges between 1,500 and 25,000 psi.

Typically, die casting works well for non-ferrous metals such as aluminum, zinc, or copper. It’s especially effective for producing parts with intricate geometries and generally produces a quality surface finish.

Benefits of Die Casting Aluminum

While other materials such as zinc and magnesium are also used, aluminum is the most common material for die casting due to its advantageous properties, such as:

• Lightweight: Die casting is often used to mass-produce lightweight, intricate parts,such as those used in agricultural machinery, construction equipment, and industrial machinery. Aluminum is incredibly lightweight, making it highly compatible with die casting.
• Corrosion resistance: Many parts made by die casting, such as components used in agricultural machinery, construction equipment, and manufacturing machinery, are subject to corrosive environments. Aluminum’s corrosion resistance helps it withstand extreme conditions.
• Thermal conductivity: Aluminum is an excellent heat conductor, making it ideal for heat transfer components like radiators and heat exchangers, both of which are made by die casting. 
• Cost-effectiveness: Aluminum is an inexpensive material, so it’s suitable for low-cost, mass-produced parts such as decorations or other components.

While other materials, such as zinc, possess desirable properties that also lend themselves well to die casting, aluminum’s lightweight resilience and versatility make it the metal of choice for many parts made by die casting.

Aluminum Die Casting Process

Step-by-Step Overview

The aluminum die-casting process is both simple and efficient. The exact steps may vary with the type of injection method, but a general overview of the die-casting process is: 

1. Pattern-making. Before manufacturing the actual part, the first step is to create a pattern or model. Models are often made from materials, such as metal, wax, plastic or wood, and can be made by 3D printing or computer numerical control (CNC) machining.
2. Molding. The next step is to design a die-casting mold. Typically made from steel via CNC machining, the mold will contain the molten metal until it hardens, so it must possess the necessary injection sites and have an exact negative of the model’s geometry. Die-casting molds are typically made into two halves so that the final product can be easily extracted, and most are reusable to allow for multiple pours. 
3. Melting and Injection. Once the mold is prepared, the aluminum ore is heated until it becomes completely molten and is inserted into the mold. Gravity die casting is done by pouring the molten metal into the mold, but injection die casting employs high-pressure injection to force it into each cavity. Aluminum melts at approximately 1220°F (660°C). 
4. Extraction. Once the molten metal has cooled, the two halves of the mold are separated to extract the finished part. 

After the part is extracted, some machining may be needed to produce an especially fine finish or to remove the seam that naturally occurs where the two mold halves meet. However, this type of manufacturing process usually requires minimal surface finishing, one of its chief advantages.

Comparison With Other Casting Methods

Die casting is an excellent way to mass-produce intricate, high-precision parts, but other metal casting methods include:

• Sand casting, where the molten metal is gravity-fed into a disposable mold made from wet sand
• Permanent mold casting, which also employs a permanent mold but uses gravity instead of pressure injection

While each process has advantages, manufacturers often prefer die casting because of its superior surface finish and suitability for high-volume production. The ability to inject the molten metal into hard-to-reach cavities also gives die-casted products a more uniform wall thickness for greater strength. 

The chief disadvantage is that the upfront cost of designing and building the mold can be more significant, but higher production rates and a longer mold lifetime can offset this. 

Aluminum Die Casting Materials

Common Alloys Used

Aluminum is a highly diverse metal with multiple alloys, each with its own material properties and unique applications. The most common aluminum alloys and their chemical compositions are: 

• A380, one of the most versatile alloys. 
• A360, which is similar to A380 but is infused with less copper and more silicon
• B390, which has excellent hardware and wear resistance
• A413, which is highly machinable and has good thermal and electrical conductivity

Properties and Applications of Each Alloy

The unique material properties of each alloy make them suitable for different applications. For example:

• A380, which is highly versatile and lightweight, is ideal for use in manufacturing machinery, industrial components, and consumer electronics.
• A360 has greater corrosion resistance and strength at high temperatures, making it ideal for marine or hydraulic components. 
• B390 is “hypereutectic” or supersaturated with silicon at levels of >13%. This gives it extra hardness and wear resistance, making it ideal for applications in the automotive sector (engine blocks, powertrain components, and heat exchangers).
• A413 possesses especially high machinability and strength and is commonly found in electrical and telecom components.

Consider your part’s application when choosing an aluminum alloy for your die-casted part.

Applications of Die Cast Aluminum

Because aluminum has so many alloys, many industries use it. The primary industries that rely on die-cast aluminum are:

• Agricultural Machinery (equipment components, structural parts)
• Electrical (electronic housings, transmission components)
• Industrial Machinery (machine parts, enclosures)
• Healthcare (medical devices, mobility aids)
• Construction (hand tools, safety devices) 

Aluminum is lightweight, conductive, and durable, making it the ideal material for any application requiring these properties at a cost-effective price.

Design Considerations for Die Cast Parts

Wall Thickness and Uniformity

Die casting allows you to inject the molten metal into the crevices that gravity-poured aluminum would be least likely to flow into. This creates uniform wall thickness across the entire product, reducing the likelihood of air pockets and subsequent cracks or casting defects. Aluminum die-casting components are more uniform than those built from other manufacturing processes.

Machining Allowances

Machining allowances supply extra material to die-casted parts to account for surface roughness, slight shape deviations, and the need for additional machining. This ensures that the final product meets any precise requirements after machining and removes any imperfections to achieve the desired final design.

Surface Finishing Options

The aluminum die casting of parts typically requires very little surface finishing, but when it does, there are several surface finishing options available, including:

• Anodizing is a process where a chemical layer is added to aluminum by immersing the part in an electrolyte solution and applying an electric current. This method not only enhances the material’s durability but also allows for the anodized aluminum to be dyed, offering both protection and aesthetic appeal.
• Powder coating, where a metal powder is sprayed onto the surface of the part and then set under heat.
• Chemical film deposition, where gasses are deposited onto the part via a chemical reaction.

With such a wide variety of finishing options, aluminum die-casting providers can offer the surface properties needed for nearly any application.

Environmental Impact and Sustainability in Aluminum Die Casting

Aluminum die casting is a very efficient, low-cost, and highly sustainable manufacturing method. Aluminum is completely recyclable, meaning manufacturers can reuse any scrap or wasted material in the next round of production. Also, recycling aluminum saves up to 95% of the energy required to produce new aluminum from bauxite ore. 

This makes aluminum an environmentally friendly solution for many everyday products.

Aluminum Die Casting Stands the Test of Time

Time-tested, aluminum die casting has proven to be one of the most effective manufacturing processes for creating intricate parts that would otherwise be impossible to produce. The Federal Group is proud to work with industry leaders across many sectors as they integrate our die-casted components into their assemblies, and our experts are eager to help your team as well. 

Contact us today to learn more about what our aluminum die casting company can do for you.