What Is the Difference Between Cast Aluminum & Die Cast Aluminum?

Aluminum is a widely used metal because it is very suitable for a variety of manufacturing methods, two of which are extrusion and casting. You may find yourself asking, "what's the difference between aluminum extrusion and casting?" Extrusion is the process of forcing aluminum billet through the mold to produce the required cross-section. Casting is the process of pouring molten aluminum into the mold and then solidifying it. Each method of manufacturing aluminum parts has its advantages and disadvantages, but by creating near net shape and reducing processing time, both methods save more money than machining parts from solid. Whether you think you need aluminum extrusions or are considering aluminum castings, you can count on the team at Ningo Goal Sure Machining Co., Ltd to point you in the right direction.

What is die casting?

Die casting aluminum products are made by melting aluminum ingots, injecting molten metal into the mold with a power cylinder or piston, and then allowing the aluminum to solidify into the mold shape when cooled. Although the process is somewhat complex in practice - including steps such as adding alloying elements and deburring - the general principle is relatively simple.

What is extrusion?

Extruded aluminum products are manufactured by forcing the heated aluminum billet through the die to produce the required cross section. The extrusion can then be cut to the appropriate length and further processed - such as machining bolt holes or assembling different parts together to obtain the final product.

Aluminum extrusions are very suitable for high production. Due to the work hardening in the forming process, they can quickly produce reliable and high-strength aluminum products.

Die castings can be made in various sizes and can adapt to complex geometry, such as automobile engine cylinder blocks. After creating a tool steel mold, you can cast the product multiple times, and then the mold will deteriorate and need to be replaced.

The number of times you can reuse the mold depends on the shape of the part, the allowable tolerances of the final product, and processing conditions

Advantages and disadvantages of cast aluminum and extruded aluminum

Compared with the extrusion process, the casting process usually has a higher introduction cost. However, it may be more economical in high-yield operation or parts requiring excellent dimensional accuracy. This is especially true when the shape is complex, such as a shape with uneven thickness. Although castings may produce smaller tolerances, the extruded shape will be stronger. In addition, castings may contain some pores, while extrusions do not. In addition, the surface finish of the casting may require machining, but assuming that the resulting dimensional tolerances meet the needs of the part, the surface of the aluminum extrusion can be used for the finished part. Castings are limited to low melting point metals, such as aluminum, magnesium, and copper. The initial mold cost is high and the mold life may be short. Due to the lower start-up cost, extrusion is a better choice for a shorter production cycle. 

Unlike extrusions, castings are not limited by size. Because the extrusion can only be as large as the blank that the extruder can accommodate, the size range is limited. This is not the case for the mold of the casting. In fact, castings are very often used to produce large parts, such as a marine propeller or engine parts. For these products, extrusion cannot be selected due to size constraints. Whether casting or extrusion is considered, it is important to consider all variables for each variable. Limited size range. This is not the case for the mold of the casting. In fact, castings are very often used to produce large parts, such as a marine propeller or engine parts. For these products, extrusion cannot be selected due to size constraints. Whether casting or extrusion is considered, it is important to consider all variables for each variable. Limited size range. This is not the case for the mold of the casting. In fact, castings are very often used to produce large parts, such as a marine propeller or engine parts. For these products, extrusion cannot be selected due to size constraints. Whether casting or extrusion is considered, it is important to consider all variables for each variable.

Which Process is Better for Your Project?

Both die casting and aluminum extrusion have excellent advantages and a few disadvantages that make them better suited for certain applications. To help you decide which process is best for you, take a look at the side-by-side comparison below:

● Die Casting

Makes more complex shapes than extrusions.

Can make larger finished products than extrusions.

Generally not as strong as extruded products. There is also the potential for porosity if air gets trapped in the mold.

Have a rough surface finish and can show seams or other imperfections.

Die molds are costly and time-consuming to make. They also generally do not last as long as extrusion dies.

Process changes are time consuming and costly, taking several weeks to prepare a new die mold.

Typically a more expensive process, die casting is generally used in higher production runs to offset the initial costs.

● Extrusion

Can make a wide variety of shapes but must have a consistent cross-section.

Size is limited by the size of the aluminum billet.

The work hardening that occurs during forming strengthens the end product.

Typically have a very smooth surface finish.

Extrusion dies are less costly than die casting molds, and new profiles can be manufactured with relative ease.

A highly adaptable process with relatively little effort or notice needed to make changes.

Generally a less expensive process. The lower setup cost also makes it more suited to short production runs.

Die casting and extrusion are excellent methods for making aluminum products.

The upfront cost of die castings is usually higher, but depending on the parts being manufactured, you can save post casting processing and assembly costs. Extrusion may be limited in shape possibilities and may require additional post molding processing and assembly. However, they are usually stronger and cheaper to produce.

The choice you make ultimately depends on the specific situation of your project because you can expect each processing method to have different mechanical properties and manufacturing costs.