A die is the tool shape that the aluminium is pushed through to create the profile. Dies are made of tool steel (normally sis 2242). The die aperature, which corresponds to the desired cross section of the profile, is produced by spark erosion.
There are two main classes of profile – solid and hollow
Solid profiles are produced using a flat, disc-shaped die.

Hollow profiles are produced using a two-part die. In hollow dies, the mandrel (the part that shapes the cavity in the profile), is supported on a bridge. During extrusion, the metal separates around the bridge. The other part of the die shapes the outer contour of the profile. Large and medium-sized profiles are pressed through a die with only one aperture. Smaller profiles can be advantageously pressed through multi-apertured dies – there may be as many as 16 apertures. Die lifetime depends on the shape and desired surface quality of the profile.

Die Casting

Casting is a manufacturing process by which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process. Casting materials are usually metals or various cold setting materials that cure after mixing two or more components together; examples are epoxy, concrete, plaster and clay. Casting is most often used for making complex shapes that would be otherwise difficult or uneconomical to make by other methods.

Die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mould cavity. The mold cavity is created using two hardened tool steel dies which have been machined into shape and work similarly to an injection mold during the process. Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter and tin based alloys. Depending on the type of metal being cast, a hot- or cold-chamber machine is used.