When looking for a new piece of cookware, be it a pan, a pot or a roaster, you often come across the material designations aluminium and cast aluminium and perhaps ask yourself: Is there a difference?
Yes and no. Basically, it is aluminium in both cases. The difference lies less in the material than much more in the way it is processed, i.e. how aluminium is turned into a pan, for example.
Cast aluminium, as the name suggests, is cast aluminium. To produce a pan, a pot or a roaster from cast aluminium, an aluminium alloy is melted by strong heating and then transferred to a casting mould.
The standard process is die casting, in which the aluminium is pressed into the mould under high pressure. With this process, even complex moulds can be cast safely.
For simpler moulds there is also the hand casting, in which gravity alone distributes the melt in the mould.
With cast aluminium, different wall thicknesses can easily be achieved in the cookware, e.g. a thick base that distributes and stores the heat well, a thin side wall that saves weight and does not absorb unnecessarily much heat, and finally a strong edge that gives the cookware stability.
Another advantage of cast aluminium is that it is largely free of material stresses. The cooking utensils are poured in liquid form and cooled. A reshaping is not necessary. Since aluminium expands relatively strongly during heating, it is advantageous if the material stresses in the cooking utensils are not compounded by forming.
The manufacturing process is usually more expensive and therefore also the end product.
Pans and pots which are not made of cast aluminium are not cast but pressed or forged. For this purpose, a piece is punched out of an aluminium plate and then pressed into shape or cold forged with a lot of force.
Pressing in particular is mainly used for rather inexpensive products, which usually have a wall thickness of only 2-3 mm.
Cookware made of forged aluminium has a modified, more stable material structure due to the forging process, in which much more force is applied to the aluminium than during pressing. A cookware made of forged aluminium is therefore generally more robust than one made of pressed aluminium. More complex structures can also be achieved during forging, e.g. a reinforced rim, which is actually typical for aluminium casting.
Pressed aluminium pots and pans are usually cheaper than cast aluminium pots and pans; the price difference for forged aluminium is smaller.
Cookware made of formed aluminium already carries residual stresses in the material when cold, because the actually flat aluminium plate was forced into a pan-shaped or pot-shaped form. In addition to these material stresses, there are also the thermal expansion stresses in use. Especially with thin material, we have observed that in extreme situations (e.g. overheating of the ladle), permanent deformations of the base tend to occur here.
Therefore, thin, pressed aluminium cookware is sometimes not approved for use on the widespread ceramic hobs.
Aluminium (whether cast, pressed or forged) has the great advantage that it is very easy to reuse. Due to the relatively low melting point (only 650-700° C) compared to other metals, less energy is also required. So if you ever discard a pan or pot made of aluminium / cast aluminium, please put it in the recycling bin. And perhaps your cookware will then have a future as a railway wagon or engine block or railing or blind or...........