To produce sheets and strips, copper rolling slabs are pre-heated to about 800 to 950 °C and hot-rolled to a thickness of 10 to 20 mm. These pre-rolled sheets are then usually milled and finish-rolled to the required thicknesses in a cold state – possibly with the inclusion of intermediate annealing and pickling. Because of their good cold formability, copper sheets and strips can be easily processed further by deep drawing, spinning, forcing, etc. Copper tubes are usually made from cast billets which are extruded or hot rolled into a tube. The tube blanks are brought to the final cross-section in stages by cold forming on pilger rolling mills or drawing benches. The most economical way is to finish drawing copper tubes in long lengths as coils on barrel drawing machines. To produce rods from copper, preheated extrusion billets are first pressed into strands on an extrusion press. During the subsequent cold forming to the desired final cross-section, the extruded strand is drawn through a die on drawing benches.
Wires are either rolled as wire rod immediately after casting in the casting heat or wire ingots are heated to 800 to 900 °C and rolled out on calibre mills into wire rod of 8 or 12 mm Ø, then pickled and, for higher demands, also peeled. The wire rod is then drawn to the required size on multiple drawing machines. Copper can be formed during wire drawing with a reduction in cross-section of more than 99 % without intermediate annealing.
In the production of drop forgings, bar sections are usually inserted into a hollow mould (die) enclosing the material on all sides after heating to the forming temperature and formed under the powerful pressure of a press. In contrast, open-die forgings are semi-finished products that are formed by impact or pressure and are mainly produced with simple tool parts that do not enclose the material on all sides (e.g. flat webs, saddles).
Copper casting materials
Copper casting materials include all materials suitable for the production of moulded parts by casting. The finished castings solidify close to their final dimensions during the shaping process and are generally not subsequently formed, but only fettled and in certain cases machined. They can be produced using the sand, chill, centrifugal, continuous or die casting processes.
Wrought copper materials
Wrought copper materials include all copper materials that are processed into semi-finished products (rods, profiles, tubes, wires, sheets, plates, strips or shaped parts) by solid forming such as extrusion, casting-rolling, rolling, drawing or forging. The compositions of wrought copper materials are also specified in the respective product standards. These standards also contain mechanical properties, dimensions, tolerances and surface properties in the area of requirements. Furthermore, in addition to information on definitions, designations and ordering details, information on sampling, test procedures, declaration of conformity and test certificate as well as on marking, packaging and labelling can be found there.
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There are more than 400 copper alloys, each with very special properties, and the number is growing all the time.More