Aluminium encyclopaedia

Semi-finished products

Semi-finished products, also called "semis", are wire, profiles, rod and bar, and tube made from aluminium that are used to manufacture end products. Generally speaking, semi-finished products or semis are products between raw material and finished product or end product. In order to become an end product, a semi-finished product has to undergo one or more finishing steps.

In the aluminium industry, the term "semi-finished product" also covers intermediate products that are made by forming (or working) unalloyed aluminium or an aluminium alloy obtained from primary or recycled aluminium. Such forming processes are also referred to as working (hot working, cold working) and the products are called "wrought products" (wrought is an old past participle of work).

Thus, one also uses the expression "wrought semi-finished products" (or "wrought semis"):

  • blanks for the manufacture of forgings
  • circles or slugs for impact extrusion
  • extruded products such as wire, profiles, tube, and rod and bar
  • rolled products like strip, sheet and plate
  • drawn products like wire, rod and bar, and tube.

Foil is also rolled but is not generally regarded as a semi-finished product (for example capacitor foil for use in electrical engineering). It is often already a finished product (for example household foil).