If you are looking at manufacturing options for products or items needed for industrial or commercial projects that involve a decision between extruded aluminum and cast aluminum, we cover these two forming methods here. So, what is the difference between extruded aluminum and cast aluminum? Before laying out the differences, it is important to understand what each process involves. At Howard Precision Metals, we are your trusted source for custom extruded aluminum products that are required in numerous industry applications.
What is Die Casting?
The die casting process that creates aluminum products involves the melting of aluminum ingots, filling a die with the molten metal using a piston or power cylinder, and allowing the solidification of the aluminum as it cools in the die mold’s shape. The process is actually more involved than this, including steps such as adding alloying elements and deburring. However, the overall process is still straightforward.
Die castings is much different than the process for making cast aluminum plate as it produces near net shapes that may be completed in a wide array of sizes and can create intricate geometries for various applications – an engine block is one example. Once you create a tool steel die mold, you can cast the product many times over before the mold becomes non-useful due to deterioration. Various factors determine how many times you can reuse a mold, including the permissible tolerances for the final product, the part’s shape, and the processing conditions.
What is Extruding?
Custom extruded aluminum products are manufactured by forcing an aluminum billet at very high temperature through a die to achieve the intended cross-sectional form. Then, the extruded piece may be cut to the required length and undergo additional modifications, such as adding bolt holes or connection for joining various parts together.
Comparing the Two Processes
Die casting of aluminum or any metal is a different process that extrusion. In the die casting process, molten metal is injected with force into mold, referred to as a die. These dies may consist of complex shapes such as those with irregular cross-sections.
Custom extruded aluminum has advantages over aluminum shapes made from die casting. With some materials such as aluminum alloys containing zinc and magnesium, the extruded components have a rigidity similar to die cast parts, but often a higher ductility. Also, the costs for tooling with extrusion are often lower than for die casting.
On the other hand, die casting has some advantages over aluminum. Parts made through die casting are less elastic and have greater stiffness values than parts made through extrusion. Also, components made through die casting are often completely finished with surface textures and require little finish machining to complete the part.
One of the major benefits of die casting it is not restricted to creating components that have a uniform cross section. With extruded parts, additional cross-sectional changes or slots, holes and other design features require other machining services that carry an additional expense. During die casting, all the intended features of the piece can be incorporated into the mold in a one-step manufacturing process. However, a benefit that extrusions bring is strength. Typically, the process of elongating the grain and heat treating after extruding adds strength to the alloy. Die cast parts have the potential of porosity as well, which extrusions do not. There are pros and cons to each process, so it is best to consider all the benefits of each.
Choosing the Process Best for Your Project
Here is a short summary of the advantages and disadvantages of the die casting and extrusion processes:
Extrusion
- Size of the billet limits the size of the shape
- Wide range of shapes possible, but must have consistent cross-section (2 dimensional)
- Produce a very smooth surface finish
- Work hardening during forming increases the strength of the end product
- A flexible process with minimal effort needed to make changes
- Generally, less expensive than die casting which also makes it more ideal for short production runs
- Extrusion dies cost less than molds for die casting, and new extrusion profiles can be easily made
Die Casting
- Can produce larger finished pieces than through the extrusion process
- Produces more intricate shapes than through extrusion (3 dimensional)
- Produces a rough surface finish and can show imperfections, such as seams
- Products manufactured through die casting are generally not as strong as extruded products. Also, porosity is possible if air gets trapped in the mold
- Changes to a die mold can be costly and time consuming, taking several weeks for new mold preparation in some cases
- Often more expensive than extrusion and often used in high production requirements to offset the higher upfront costs
- Die molds are more time-consuming and costly than extrusion dies and usually require replacement more often
Whether you choose custom extruded aluminum production or cast aluminum plate production (or other shape production) will depend on the specific requirements of your project. Each processing method carries different manufacturing costs and results in different mechanical properties for the pieces produced.
If you need aluminum extrusions in the form of plate or other shapes, we are the premier aluminum extrusion supplier you can trust. For information about how we can help you with your custom extruded aluminum needs, give us a call today at 800.444.0311 or leave us a request for quote through our online form.
