Aluminum foam compared

Which two comparisons does a decision need?

They answer different questions and should be asked in this order. The material comparison settles whether aluminum foam can take the place of sheet metal: as a solid material it is considerably softer than steel or aluminum and becomes a replacement only as a sandwich, because the cover layers then carry the bending load. Once that is settled, the design comparison follows: AAS with aluminum cover layers is the lighter choice, SAS with steel cover layers the stiffer one, and only SAS allows foamed-in or welded-in fastening points. Both comparisons have their own pages, with the tables that go with them.

What else is aluminum foam from Havel metal foam compared with?

With other metal foams, and the difference lies in the production process. Havel metal foam foams by powder metallurgy, which produces a closed-cell foam; the processes of the melt route, that is, gas infiltration and blowing agents, produce open-cell foams. The material values follow from the process, and so does what can be built with it at all: sandwiches without adhesives, 3D shaped elements, foamed tubes and profiles, integrated cooling and heating tubes, weldability and zinc foam. The figures for this are in the material comparison of aluminum foam against aluminum and steel; here, what counts is the reason behind them.

Havel metal foam compares itself with process families, not with individual suppliers. Havel metal foam's material values are those of its product data sheets.

How does aluminum foam compare with other lightweight materials?

Against the materials otherwise considered for lightweight construction, the deciding factor is usually not stiffness but what ultimately happens to the component. Aluminum foam is purely metallic, with no adhesives or plastics, and is therefore non-combustible and 100 % recyclable; carbon and glass fiber reinforced plastics are hardly recyclable and bring a fire load of their own. A honeycomb structure is regular and open; aluminum foam is closed-cell and stochastic in structure. And in practice Havel metal foam also displaces materials that are not metals at all: concrete as damping ballast and mineral wool for sound.

What do these comparisons not tell you?

The price. These comparisons contain no cost comparison with steel sheet or aluminum, not even a qualitative one. Two further limits belong here, because they affect every substitution: a sandwich needs overall height, since its stiffness comes from its depth, and where the height is fixed, replacing a sheet with a sandwich is first of all a question of geometry. And corrosion protection is needed, just as with steel; the natural oxide layer makes the metal resistant but does not replace the protection. The information here consists of technical comparisons, not an economic assessment.