Cast iron
Cast iron material is traditionally used in the manufacture of Street Furniture. In this type of iron the graphite forms random flakes giving good casting qualities, whilst allowing complex geometrical shapes to be formed. This iron exhibits excellent corrosion resistance, when compared with steel, with the minimum of maintenance. Cast Iron is fully recyclable, as most grades of this material are manufactured from scrap, with various additions of alloying material to stabilise and maintain its mechanical properties. In fact this material can be recycled ad-infinitum.
Ductile iron
As its title implies this form of cast iron is very ductile, it has mechanical properties similar to that of steel. These properties help it flow better in its molten state, giving greater casting qualities. This allows ductile iron to be used in the manufacture of complex structural components. The graphite structure in this type of iron comes in the form of very small spheres (known as spheroidal graphite or SG), this is what gives it ductility. Ductile iron is fully recyclable, and also gives excellent corrosion characteristics when compared with steel.
Aluminium alloy
Aluminium alloy castings are used for lightness and small complex castings such as finial tops, crests and signage. The type of sand used for moulding is finer than that used for producing iron castings, giving a greater level of definition. Seat end castings and litter bins are also manufactured from this material where weight is of importance. Normally two types of alloy are used, types LM4 and LM6. Both of these grades give good corrosion resistance, even in a marine environment, but require the correct coating treatment.
Copper alloy
Brass & bronze copper based materials are sometimes used in the manufacture of Street Furniture. These, in the main would be used for signage and crests. Both types can be polished to give very decorative finishes although they would need a form of protective lacquer applied prior to installation. The only drawback to using this type of material is cost. This being roughly two to three times more expensive than grey iron, weight for weight.
