Micro-skiving - (r)evolution of a Known Production Process
Production of internally toothed gear wheels is possible in many different ways. Different techniques such as gashing, broaching, wire EDM or shaving make it possible to achieve these profiles. However, skiving seems to be the optimal solution for reducing production time of this type of gears when large production batches are required.
This internal gear cutting technique has been known for several years and widely used in the industry for modules over 0.50 (DP>50).
However, cutting an internal gear with a module below 0.50 (DP>50) is not an easy task. The profile becomes very small and requires an optimized cutting tool, which can only be manufactured on special grinding machines that can cope with micron (µm) accuracy.
Micro-skiving has been developed allowing users to have access to the skiving technique for machining inner micro-teeth. The basic principle is similar to standard modules, with higher requirements in terms of shape, burr and surface finish. Modules as low as 0.15 have already been produced and the technical limits to go even lower are regularly crossed.
These developments expand the possibilities for fast and high-volume production of parts with internal micro-teeth. The production of micro-subassemblies, medical micropumps or micro-reducers can now be considered without the current manufacturing challenges of cycle time and quality level.
That being said, micro-skiving internal gear cutting requires suitable, high accuracy machines with fine adjustment options. In addition, a perfect synchronization between the spindles of the part and the tool is necessary. Once all these parameters mastered, machining times and therefore productivity are matchless.
Authors: Pierre Falbriard, and Hervé Baour
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