Liebherr recently introduced a new series of generating and profile grinding machines for hard machining of external and internal gears on workpieces with diameters of up to 500 millimeters. The LGG series follows the successful Liebherr LCS 300-500 series. With an impressive range of added features, they offer more flexibility and grinding performance with a significantly reduced footprint.

The LGG 500 and its sister models the LGG 300, LGG 380 and the manual solution LGG 700 M are Liebherr’s new series to succeed the LCS 300-500 generating and profile grinding machines that have been popular all over the world. The machines are suitable for generating grinding, profile grinding and both processes combined. The new series also retains essential features such as maximum precision, robust machine design and high flexibility. Corundum and CBN tools are available, the latter from Liebherr’s own production. The high level of performance and versatility now also extends to hard machining of internal gears: changing from external to internal profile grinding is possible in less than 30 minutes. There are also newly developed grinding heads and even more machine options.

On the outside, the first thing that catches the eye is the machine's new, compact monolith design. With the footprint reduced by a third, the work area is just as big as the one of the previous model, ensuring maximum ease of use even with manual loading. With an axial travel range of up to 1,000 millimeters, the machine column allows the machining of long shafts, for example for commercial vehicles.

Three different directly driven grinding heads with optimized rigidity are available for the new series, and can be configured precisely as the customer requires. The grinding heads have a large effective speed range, which allows the use of large and small grinding worms at optimal cutting speed. Liebherr is a pioneer when it comes to machining collision gears with dressable and dressing-free grinding worms: the compact counter bearing ensures the highest grinding and polishing quality for critical components. Optionally, the grinding heads can be equipped or retrofitted with an auxiliary spindle or an internal grinding arm. 

The most powerful grinding head, the GH 320 CB, can easily handle generating grinding jobs up to module 14 mm. Grinding worms with a volume of up to 320 millimeters in diameter and 250 millimeters in length are used. Cutting speeds of up to 80 m/s achieve high grinding performance for dimensionally critical components at much shorter grinding times, especially for workpieces with long face widths.

The selection of direct drive tables is tailored to the specific component range with regard to the component weight (up to 100 kilograms), required machining speed and optimum pitch quality. The robustly built table allows speeds of up to 2,000 rpm for generating grinding and highly accurate positioning for profile grinding. 

The new LGG machine generation offers the best possible compatibility with the available clamping fixtures, so that the existing equipment can be used or inexpensively modified. The Liebherr OpenConnect concept allows GDE data to be imported and exported which, together with the gear check integrated in the machine, ensures short setup times for heavy components. 

“With the new generation of machines, the customer is not buying a specialist machine, but an all-rounder that embodies maximum flexibility combined with optimum grinding performance and quality,” explains Martin Schwarzmann, product manager for gear cutting machines at Liebherr. “A fully equipped grinding machine for external and internal gears with immense grinding performance as well as an automation system – that’s a very versatile combination and pretty unique in the market.” 

The machine offers flexibility for small and medium batch sizes. With its integrated ringloader automation system and configurable Liebherr storage systems, it creates a unique basis for highly efficient large-scale production, for example of complete planetary gears, including ring gears. The huge scope of possibilities allows companies, and in particular small businesses, to carry out a wider range of processing so that they can respond much more flexibly to future market requirements.