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German companies develop unique, one-step gear hobbing system

German companies develop unique, one-step gear hobbing system

Hanover, Germany -- Two German companies, Fette GmbH and Liebherr Verzahntechnik GmbH, have combined technologies to produce a unique gear hobbing system that rough cuts, chamfers and finish cuts a gear on one machine with one tool.

The companies put together technologies originally developed for complex grinding operations that index and move the tool to several points on the work piece to get to the desired result.

Fette, a unit of the Leitz Metalworking Technology Group, designed the “Twist-Free Hob,” the tool used in the system. The tool produces a helical gear with a highly finished surface in a one-step, dry-hobbing process. The tool is the first carbide hob produced with a diamond coating, according to Alfred Wolff, product manager for hobbing works for Fette. Wolff’s company is based in Schwarzenbek, Germany.

Both the tool and the machine designed to run it, a Liebherr LC-120, were displayed at the EMO 2005 trade show in Hanover Sept. 14 through 21.

Liebherr developed software based on applications used for its grinding machines for the standard-platform LC-120, according to Oliver Winkel, an engineer for the company’s gear cutting applications. The software positions the tool to hob a work piece, then moves it to perform chamfering and moves it again so that the tool’s finishing cutting edges are in position to complete the work. Liebherr is based in Kempten, Germany.

Wolff said the companies are working together to develop initial commercial applications for the system, and are targeting the automotive industry as a primary market.

The tool was one of several new tools Fette introduced at the EMO trade show. Fette is a tooling specialist.

Additional information on the dry-hobbing system can be had from the companies’ Internet sites, or

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