Gear production on a 5-axis machining centre

The 5-axis milling technology allows precision roughing and superfinish machining of gear teeth and other complex 3D contours on a Hermle machining centre, either a C 40 U or C 50 U fitted with a Heidenhain iTNC 530 or Siemens 840D control. The extensive set-up time required for multiple machines used in conventional gear production is avoided, allowing economic production which is ideal for producing small batches of gears and even one-offs in the size range 500 to 1,200 mm diameter. Using HPG's special software, a gear can be completely machined using standard milling cutters on a Hermle. The software performs the mathematical calculation for the exact tooth shape, which is developed as a point cloud and translated into an NC program for milling the gear. After the roughing cycle, the component is sent for hardening, after which it is returned to the machining centre for finish milling. It is then measured in situ, the data is compared with the CAD model and, if necessary, a few ultra-fine finishing passes are completed to bring the gear into its designated quality class (1 to 12). High resolution mathematical calculation as described is the best route for high quality gears, say classes 2 or 3, whereas quality classes 5 to 7 are best obtained by producing the gear machining cycle conventionally from the CAD model. HPG is said to be the only company that performs mathematical tooth shape modelling to achieve much higher resolution than is possible based on CAD data alone. Geo Kingsbury Machine Tools is Hermle's sole agent in the UK.