Forging and rolling

A brief process description

Open-die forging is a non-cutting forming technology that takes place under pressure between two dies. At ZOLLERN, this type of forging is achieved with a forging press (hydraulic pressure) or a pneumatic hammer (air pressure) The process alters the cross-section of the workpiece and compacts the microstructure of the material. First, the beam blanks cast in a casting shop are heated in a gas-fired furnace to forging temperature. Then they are shaped in a specially defined temperature window to produce rings, sleeves, discs, round rods and flat rods made of pure copper, copper-chromium, copper-aluminium, copper-nickel, copper-tin or copper-zinc alloys. The forgings can have piece weights of up to 3,500 kg, with diameters of up to 1,000 mm and lengths of up to 10,000 mm. Depending on the properties required of the finished workpieces, the material can also be shaped in semi-hot or cold forging, or refined with subsequent heat treatment.

At ZOLLERN, we use not only this kind of forging technology, but also ring rolling and closed-die forging. Ring-rolling is a process developed from forging. A billet blank is pierced on a forging press and rolled out in a ring rolling mill. ZOLLERN has the capacity to roll seamless rings with diameters of up to 1,800 mm and piece weights of 250 kg.

Unlike open-die forging, in closed-die forging the product is shaped in a closed tool or die. A die-maker mills, erodes or grinds the contour of the finished forging into this die. Individual as well as serial parts can be cost-effectively produced with the open-die and ring-rolling processes, but the high tool costs involved in closed-die forging make this process only economically viable for serial production. After undergoing the necessary forging processes and/or heat treatment, the workpieces are either tested in various ways at ZOLLERN, mechanically pre-machined or finish-machined, or supplied to customers as forging blanks.