What is the Difference Between Cast Aluminium and Extruded Aluminium

The main difference between cast aluminium and extruded aluminium is their manufacturing process. Extrusion of aluminium involves forcing the aluminium billets through a die, whereas manufacture of cast aluminium involves pouring molten aluminium into a mould and solidifying.

Aluminium, the 13^th element in the periodic table, is a silvery metal commonly found in a solid state. Aluminium is the third most common element on Earth. It also makes up about 80% of the Earth’s core mass. Aluminium is a quite reactive metal, and it binds with other elements to form compounds; hence pure aluminium is rare in nature. It commonly occurs in nature with sulphates like aluminium sulphates. Moreover, industrial applications of this metal include the production of automobile parts, kitchen utensils, building construction parts, factory machine parts, etc. Aluminium is extracted from aluminium ores, processed, and shaped into the desired profile shape by two methods called extrusion and casting.

Key Areas Covered

1. What is Cast Aluminium
      – Definition, Properties, Manufacture
2. What is Extruded Aluminium
      – Definition, Properties, Manufacture
3. Difference Between Cast Aluminium and Extruded Aluminium
      – Comparison of Key Differences

Key Terms

Aluminium, Cast Aluminium, Extruded Aluminium

What is Cast Aluminium

Cast aluminium is a type of aluminum we manufacture by pouring molten aluminium into a mold and allowing it to solidify. There are different casting methods, including sand casting, plaster casting, die casting, permanent mould casting, and investment casting. All the casting methods involve pouring molten aluminium into molds and allowing them to solidify. The solidification happens by cooling the pored aluminium.

There might be imperfections in the molds, which require a secondary process, fetting. Manufacturers remove imperfections by sanding, grinding, or cutting the aluminium. This is a relatively slow process in comparison to extrusion. Cast aluminium is mostly useful in the automobile industry. Manufacturers also use them to produce kitchen utensils, decorative parts, and components of small appliances. The initial cost of casting is high. Cast aluminium is less strong than extruded aluminium. However, casting aluminium has no shape constraints. It can make large, finished products. Cast aluminum also requires a high cost.

What is Extruded Aluminium

Extruded aluminium is a type of aluminum we manufacture by forcing aluminium billets through a die, resulting in the shape of the desired cross-section. Aluminium extrusion die used in this process has an opening in the desired shape of the profile. Extruded aluminium comes in a variety of shapes with a consistent cross-section. Moreover, the size of the extruded aluminium depends on the size of the aluminium billet and the capacity of the cylinder.

The surface of the extruded aluminium is very smooth. The initial cost for the extrusion process is lower, while the entire process is economical. Furthermore, custom designs of this aluminium take about eight weeks to finish. Extruded aluminium is stronger than cast aluminium. Moreover, new profiles of extruded aluminium are easy to make. Furthermore, industrial applications of extruded aluminium include the production of door and window frames, manifolds, and heat sinks.

Difference Between Cast Aluminium and Extruded Aluminium

Definition

Cast aluminium is a type of aluminum we manufacture by pouring molten aluminium into a mold and allowing it to solidify, whereas extruded aluminium is a type of aluminum we manufacture by forcing aluminium billets through a die.

Strength

Cast aluminium is less strong, whereas extruded aluminium is very strong.

Size

Moreover, cast aluminium can make larger finished products than extruded aluminium. While cast aluminium can come in different sizes, extruded aluminium has size constraints in production.

Surface Nature

Cast aluminium’s surface is rough and has imperfections, whereas extruded aluminium’s surface is very smooth.

Cost of Manufacture

The manufacture of cast aluminium is an expensive process, but the manufacture of extruded aluminum is a less expensive process.

Porosity

Cast aluminium has considerable porosity when compared to extruded aluminium, which has no porosity.

Conclusion

Aluminium is a common metal and has many industrial and commercial uses. Moreover, according to the method of production, aluminium is of two types: cast aluminium and extruded aluminium. In other words, the main difference between cast aluminium and extruded aluminium is their manufacturing process. Extrusion of aluminium involves forcing the aluminium billets through a die, whereas cast aluminium involves pouring molten aluminium into a mould and solidifying.

Reference:

1. “Everything You Need to Know About Cast Aluminum.” CFS.
2. “What is Aluminum Extrusion? The Process in 10 Steps.” GABRIAN.

Image Courtesy:

1. “Mopar Big-Block Cast Aluminum Polished Valve Covers” By Fiat Chrysler Automobiles (CC BY-NC-ND 2.0) via Flickr
2. “Slotted Aluminum Extrusion – 20mm x 40mm – 610mm long” By Adafruit Industries (CC BY-NC-SA 2.0) via Flickr