Aluminum Casting

Aluminum is a very soft metal. In commercial uses, it is commonly added or mixed with other metals to improve ductility, malleability, rigidity. Aluminum-based alloys are light, stable, corrosion-resistant, and therefore widely used to manufacture aircraft parts, building materials, electrical conductors, chemical equipment, and more. These parts are mostly made by casting. In this article, we will talk about aluminum casting and we hope you can walk away with the basic casting knowledge after the reading.


Fig. Aluminum Casting Parts

Basic Casting Process Explained

In the metalworking industry, metal die casting is very old technology; it can be traced back to about 6,800 years ago. Metal die casting is a production process where liquid metal is poured into a mold and retrieved until it fully solidifies. The mold is a container (made of sand, clay, rubber, steel, aluminum, etc.) that has a hollow cavity with the desired geometry and details. This method is used to create castings with complex shapes that are difficult or costly to make using other methods.

The solidified part is called casting. In some processes, retrieving the castings involves breaking the mold apart. In the modern die/molding casting processes, the mold comes in a set of two paring pieces. Just divide the two pieces and the casting can be obtained and the mold can be retained and reused. Die casting materials are usually metals and plastic materials. Besides aluminum castings, the other common metal casting materials include iron, zinc, brass, and more.
 

Features

Aluminum castings fit the applications where resistance to pressure, corrosion, and temperature are required. They make good construction and structural support parts. In the aerospace and automotive industries, engine blocks, impellers, cylinder heads, valve housings are often aluminum castings. The low density also makes aluminum castings suitable for these applications because aluminum reduces the weight significantly (two to three times lighter than steel). In the next section, we will talk about how these parts are made.
 

Methods

In the case of an aluminum casting procedure, the castings can be achieved by relatively simple and inexpensive methods. Die casting, permanent mold casting, and sand casting are the methods that are most typically used to manufacture aluminum castings. Let us take a quick look at how these processes work.
 

Sand Casting

Sand Casting is deemed the most widely used casting method in manufacturing. It not only produces aluminum castings but almost all metal materials. It is called sand casting because the mold is essentially made of sand. Because sand is resistant to high temperatures, it can process materials with both low and high melt points. This method can produce engine blocks, cylinder heads, pump housings, and valves. To obtain the end product, the sand mold has to be broken. See the video below to learn more details.
 


What is Sand Casting, Skill Lync

Die Casting

Aluminum die casting uses steel dies/molds. Preheating and coating the molds are the first steps. Coating the dies/molds with the die casting release agent is a must because it lubricates and protects the dies during the process. After the dies are prepared, the molten aluminum is injected into them with extremely high pressure. These dies can better withstand the high-pressure injection than permanent molds do. This method provides the castings with excellent accuracy and precision. Aluminum casting products made with this method include electronic consumables, building materials, and engine housing.
 


Die Casting Process, RCM Industries, Inc.

Permanent Mold Casting

The term permanent mold indicates that the mold can be reused over and over again, hence permanent. The two paring pieces of the mold are designed for easy and precise opening and closing. It also uses steel molds to fabricate soft (non-ferrous) metals such as aluminum, copper, tin, zinc, and magnesium. The mold is also heated and coated so that the molten metal spreads evenly in the mold and it is easier to open and retrieve the casting. This method is ideal for processing low melt point materials. It provides stronger castings and good surface finishes. Aluminum castings made using this method include gear housings, pipe fittings, impellers, and wheels.
 


Permanent Mold Casting, ForceBeyond Inc.

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