The manufacture of gearwheels for machine building applications usually involves machines especially designed for the purpose. Important techniques include gear hobbing, gear shaping, gear-generating planning, profile milling and profile broaching. Generally, specialized tools whose geometry is precisely adapted to the workpiece are required. Due to the stringent requirements placed on the hardness of the gearwheel surfaces, manufacturing is often carried out in three steps: soft machining, hardening and finishing. New developments in the field of hard machining now enable fast, single-stage manufacture with general-purpose 5-axis machining centers.

“In the production of gearwheels for industrial use, such as in mechanical engineering, speed and flexibility are often crucial factors,” said Dipl.-Ing. Jürgen Röders, managing director of Röders GmbH in Soltau.

While sectors such as the automotive industry prioritize large quantities, the batch sizes in mechanical engineering are significantly smaller. Sometimes less than ten items are required and occasionally only single pieces. However, the deadline pressure is frequently considerable. This is true when the machining steps and the elaborate advance production of tools with a specially adapted geometry prove to be a handicap. A plant technology which enables a medium-sized gearwheel to be produced in good quality from a hardened blank within roughly one working day is of particular interest for sub-contract job shops, who have specialized in the manufacture of industrial gearwheels in small quantities and short deadlines.

“For the production of gearwheels, one needs purpose-designed CAM software that covers the various types of tooth profile correction,” said Carsten Wendt, who supervises the development project. The technology partner here is the CAM software developer Euklid, a company that has developed a program designed precisely for these assignments in the form of Euklid GearCAM. This convenient software module supports the user in producing highly accurate gearwheels on standard milling machines. This solution is of particular interest for those companies which need one-off items or small batch sizes as a prototype, a special model or a replacement for failed parts in existing gears – either in parallel to or as a supplement to their normal production. 

The program also takes account of the usual tooth profile correction functions such as width and depth crowning as well as tip and root relief. Another benefit of producing on a 5-axis machining center is that no correction is required for what is known as the tooth flank bias, which may cause problems in some of the conventional manufacturing technologies as a consequence of limitations to the machine kinematics. In contrast, this problem does not occur in the first place when a 5-axis milling machine is used. 

“The precision of the machining center used plays a crucial role in gearwheel production,” said Sales Manager Dr.-Eng. Oliver Gossel. Since Röders developed its system for use in particularly demanding mold and die-making operations, the system inherently meets the most stringent requirements concerning precision and dynamics. Activities within this segment involve machining materials with degrees of hardness in excess of 60 HRC, while maintaining accuracies down to the single micrometer range. Learn more in the June issue of Gear Technology.