PRODUCT SHOWCASE: CBN Ranks High For Internal Gears


For about two years, Liebherr has been using single-, double-, and triple-ribbed CBN profile grinding discs with great success.

"Our users are very satisfied with the results," said Janus Siegfried, head of tool production and technology in the Ettlingen plant.

Together with diamond, CBN (Cubic Boron Nitride) is one of the super-hard grinding materials. Both materials are superior to the conventional grinding materials corundum and silicon carbide in terms of hardness. There is no need for the time-consuming dressing when grinding with electro-plated CBN profile grinding discs; the discs also have a longer tool life. High-process stability meets a high rate of metal removal — a combination users appreciate.

"There is also the fact that we provide individual grain sizes for various applications, Siegried said. "Our customers can select the appropriate grinding material for each application."

Liebherr-Verzahntechnik offers various discs that can be used with the new grinding head generations IG, OPAL 4.0, and 4.1 for internal grinding. CBN also has another advantage over corundum for internal grinding:

"These tools can be manufactured with very small diameters. Corundum tools reach their geometric process limit much quicker," said Siegfried. With double- or triple-ribbed grinding discs, the two-step roughing and finishing can be completed in only one process as the individual ribs have different grain sizes. As a result, the grinding time can be significantly reduced, but the high surface quality required can still be achieved.

The first users of this technology came from the aerospace industry, thus having high quality requirements.

"We also see huge opportunities for this technology in the automotive sector and for some industrial gear unit applications", Siegried said. "The market calls for the use of low-noise planetary gear trains particularly in combination with electric motors."

High-quality internal gearing is also decisive for these planetary gear trains. Liebherr sees a promising market here, which can benefit from the contribution of Liebherr's internal grinding technology.