Liebherr LGH 280

The Liebherr LGH 280 is a CNC gear honing machine engineered for the precision hard-fine finishing of hardened cylindrical gears up to 280 mm (11.02 in) in diameter. Manufactured by Liebherr-Verzahntechnik GmbH in Kempten, Germany, the LGH 280 uses the generating gear honing (also called gear finishing or gear honing) process to simultaneously improve tooth profile accuracy, surface texture, and noise behavior of hardened gears that have already been hobbed, shaved (if applicable), and case-hardened or through-hardened. Gear honing on the LGH 280 is particularly valuable for automotive transmission gears, where noise-vibration-harshness (NVH) performance requirements demand both geometric precision (DIN 4–6) and exceptionally smooth tooth surface finish (Ra 0.2–0.4 µm) after hardening.

The gear honing process on the LGH 280 operates by meshing the hardened gear workpiece with an abrasive-impregnated honing ring (an internal gear-shaped tool) and driving both in a crossed-axis generating motion. The abrasive action of the honing ring simultaneously refines the tooth profile, corrects minor geometry deviations introduced during hardening, and creates a fine, directional surface texture on the tooth flanks. This surface texture is favorable for lubrication film retention and reduces sliding friction in the gear mesh, directly improving transmission efficiency and reducing acoustic emission. Unlike gear grinding, gear honing is a gentle abrasive process that does not generate significant heat in the workpiece, eliminating the risk of grinding burn and residual tensile stresses that can reduce gear fatigue life.

The LGH 280 features Liebherr's double-flank honing principle, where both tooth flanks are processed simultaneously in a bi-directional honing cycle. This approach maintains the honing ring in continuous contact with the gear, maximizing material removal rate per unit time compared to single-flank alternatives. The machine's workpiece spindle is driven by a direct-drive torque motor for precise speed control and phase synchronization with the honing ring spindle, which is essential for maintaining the crossed-axis motion geometry. Honing ring dressing is performed on the machine with a dedicated diamond dressing device, allowing the honing ring profile to be corrected or retopographed to introduce specific gear tooth modifications.

In automotive transmission production lines, the LGH 280 is typically positioned downstream from a hardening cell and upstream from gear inspection, forming the final manufacturing step before assembly. Automated loading via gantry or robotic cell is standard in high-volume automotive applications, with the LGH 280 control managing production counters, honing ring wear compensation, and statistical process control data output. Liebherr integrates the LGH 280 with its Gear Technology Center quality management system, enabling real-time monitoring of honing process parameters across multiple machines in a production line.

The LGH 280 competes with the Gleason Genesis 200 HSD gear honing machine and the Kapp Niles KNH series. New LGH 280 machines are priced between $450,000 and $650,000 depending on automation level and dressing configuration. In automotive transmission manufacturing, the LGH 280 is valued as a productivity alternative to gear grinding for gears where DIN 4–6 quality and smooth surface finish after honing meet application requirements, offering shorter cycle times and lower per-part tooling costs than profile or generating grinding.