Precision Forging of Gear Wheels

The conventional process chain for the production of gear wheels demands many
manufacturing steps. Typically this process chain consists of cutting, heating, forging, and deburring. Subsequently, the teeth and the bores of the gears are shaped in a machining process such as milling, slotting, or broaching. Afterwards, a heat treatment by case hardening is applied and the gears are finally finished by grinding. This process chain is often disrupted by buffer storage and transports.

Precision forging can significantly reduce this process chain because deburring and machining steps become unnecessary. Additional advantages can be gained, if the heat of the precision forging process is used for an integrated heat treatment. Moreover, specific component characteristics can be reached by integrating the heat treatment in connection with an adapted process technology. Hot formed parts are directly hardened by using the forging heat. A new solution for a homogenous cooling consisting of a two-phase nozzle array will be introduced. The application of this technique allows the hardening of particular component regions according to typical strain profiles of this component.

Besides demands on material properties, an even allowance after the precision
forging process has to be maintained. The allowance after the forging process depends on varying alloys and the geometry of the part as well as the forging temperature and related heat loss. The tool must therefore be corrected and adapted accordingly. The new approach for the presented process chain with new tool concepts and an integrated heat treatment using the forging heat will solves many problems. Moreover, a dramatic change in the process management is necessary. But on the other hand it offers great potentials for cost reduction. Particularly, high-duty automotive components offer a wide application field for the precision forging technology. Advantages like shortened production cycles achieved by eliminating machining operations and saving of raw material contribute to the ongoing cost-saving trend in the automobile industry.