Liebherr LSF 1200

Gear shaping uses a reciprocating cutting motion — the cutter strokes down, cuts, then retracts and returns, generating the tooth profile in sequential strokes. At large gear diameters and many teeth, the number of strokes required and the return time make shaping slow. Gear skiving is a continuous rotary process: the cutter and workpiece rotate simultaneously with no reversal, generating teeth in a single continuous pass. This eliminates the non-cutting return stroke time, producing 3-8x faster cycle times depending on gear size.

Standard CNC gear skiving is a soft-cutting process performed before heat treatment. Hard skiving (skiving after hardening) is possible with appropriate cutter materials and is an active area of development, but is generally limited to smaller modules and lighter cuts. For the large modules handled by the LSF 1200, heat treatment is typically performed after skiving, followed by gear grinding for final accuracy. Liebherr's applications team can advise on hard skiving feasibility for specific gear and material combinations.

Gear skiving on the LSF 1200 achieves DIN 6-8 quality in production conditions, comparable to gear hobbing and better than gear shaping in many cases due to the continuous cutting motion. The pre-heat-treatment accuracy determines the grinding stock required for finish grinding, so higher skiving accuracy directly reduces grinding cost. With closed-loop probing correction, the LSF 1200 maintains consistent skiving quality across long production runs.

Gear skiving on the LSF 1200 is applicable to the standard gear steels: case-hardening grades (20MnCr5, 16MnCr5, 18CrNiMo7-6) and through-hardening grades in the soft-cut (pre-heat treatment) state. Stainless steel and other materials are skivable with appropriate cutter selection. Liebherr's applications team provides material-specific cutting parameter recommendations and cutter recommendations for the LSF 1200.

For large ring gears (600-1,200 mm diameter, module 8-12), the LSF 1200's skiving process is typically 3-5x faster in cycle time than a gear shaper of equivalent capacity. The capital cost of the LSF 1200 is higher than a comparable gear shaper, but the cycle time advantage delivers a compelling payback period in high-volume ring gear production. For low-volume or prototype ring gear production, a gear shaper may be more economical given its lower initial cost and simpler process setup.