Difference Between Aluminum Casting and Aluminum Extrusion

Aluminum is an extremely versatile metal which is able to used to creat parts by casting, forging, machining or extrusion. Aluminum casting and aluminum extrusion are the two similar, but not the same manufacturing methods that most of people may confuse. And, you may ask “What is the difference between aluminum casting and aluminum extrusion?” CFS Foundry is the experienced aluminum casting foundry in China, so we well know the differences between these two processes, now let’s discuss them in detail.

What is Aluminum Casting?

Aluminum can be cast using different casting methods. Typical aluminum casting methods include: gravity die casting, pressure die casting, sand casting, investment casting, etc. Each casting method has its own features, and we could select the right aluminum casting method according to the design of the part. Despite the different names and methods, all casting has one thing in common: Aluminum alloy has to be melted and poured into a mold and waits for solidification after cooling.

Aluminum casting is a custom process that can creat parts in a wide range of shapes and dimensions. Complex parts like automotive engine blocks, exhaust manifolds ,etc are all produced by aluminum casting technique. This process is a repetitive work that can cast the product thousands of or even more times, so large volume production is supported. Common aluminum casting alloys are: A356 , A380, etc.

What is Aluminum Extrusion?

Aluminum extrusion is the process by forcing a heated aluminum billet through a die to produce the desired cross-section. Different from aluminum casting, the extruded aluminum part could be cut to a proper length and subjected to further machining or fitting to a final product. Normally, for a new designed part, the custom extrusion process will take as long as two months. Extruded aluminum shapes are also produced with an excellent surface finish and are typically stronger in comparison. Some products produced by the extrusion process are heat sinks, window and door frames, manifolds, and lighting track equipment. The possibilites are endless. A disadvantage of extrusion when compared to casting is the size constraint. Aluminum extrusions are limited by the size of both the billet and the capacity of the cylinder on the extrusion press. Castings have no such limit and are often used to produce very large items. Even with the size limitations of extrusions, there are still a myriad of applications of which this method of manufacture is the preferred choice.

Aluminum Casting vs. Aluminum Extrusion

Aluminum Casting Aluminum Extrusion Makes more complex shapes than extrusions. Can make a wide variety of shapes but must have a consistent cross-section. Can make larger finished products than extrusions. Size is limited by the size of the aluminum billet. Generally not as strong as extruded products. There is also the potential for porosity if air gets trapped in the mold. The work hardening that occurs during forming strengthens the end product. Have a rough surface finish and can show seams or other imperfections. Typically have a very smooth surface finish. Die molds are costly and time-consuming to make. They also generally do not last as long as extrusion dies. Extrusion dies are less costly than die casting molds, and new profiles can be manufactured with relative ease. Process changes are time consuming and costly, taking several weeks to prepare a new die mold. A highly adaptable process with relatively little effort or notice needed to make changes. Typically a more expensive process, aluminum casting is generally used in higher production runs to offset the initial costs. Generally a less expensive process. The lower setup cost also makes it more suited to short production runs.

If you still doubt when to use aluminum casting or aluminum extrusion, pls freely contact us!