g-series-high-speed-hard-cutting-hobs

The G-Series is engineered to process steels up to HRC 62 (e.g., case-hardened 20CrMnTi or 8620H) . Unlike standard carbide hobs that wear rapidly above HRC 48, the G-Series utilizes a specific Fine-Grain High-Toughness Substrate combined with a zero rake geometry or negative rake geometry to withstand high compressive loads without catastrophic breakage.

For gears requiring DIN 6 to DIN 7 quality and surface roughness of Ra ≥ 0.4µm, the answer is YES. Hard hobbing with the G-Series removes heat-treatment distortion significantly faster than grinding—reducing cycle time by 50-70%. However, for extreme precision (DIN 4-5) or profiles requiring Ra < 0.3µm, grinding remains the standard.

We strictly recommend Oil Cooling (Wet Cutting) for the G-Series. While our K-Series is for dry cutting, the G-Series utilizes a zero rake angle or negative rake angle to “push” hard material. High-quality cutting oil is essential here to: Lubricate the cutting edge to reduce friction heat. Flush away the abrasive hard chips immediately to prevent re-cutting. Achieve a superior “grinding-like” surface finish (Ra) that dry cutting cannot easily match on hard steel.

Chipping usually occurs because standard hobs have a positive rake angle (sharp but brittle). The G-Series features a Zero Rake Angle or Negative Rake Angle (0° to -15°) and a reinforced K-Land (Edge Honing). Instead of “shearing” the metal aggressively, this geometry directs the cutting force into the solid body of the tool, massively improving edge stability during interrupted cuts.

Hard hobbing generates cutting forces 2.5x higher than soft hobbing. You cannot run G-Series on older manual machines with backlash. We recommend rigid CNC Hobbing Machines (Direct Drive spindles preferred) with a rigid tailstock. The use of oil cooling also requires the machine to have an adequate filtration system to keep the cutting fluid clean from fine hard chips.

We use Oerlikon Balzers BALINIT® ALTENSA (or equivalent AlCrN-based coatings) . Even with oil cooling, the temperature at the cutting tip is extreme. This coating offers high hot hardness and excellent oxidation resistance, ensuring the substrate remains protected even under the heavy load of hard machining.

To save you shipping time and customs costs, we do not recommend sending hobs back to us. Instead, Nobeve provides a full “Refurbishment Technical Data Package” with every G-Series order. This includes the exact DXF profile, Edge Preparation (Honing) parameters, and Coating specs. You can simply provide this data to your local tool service center (e.g., a local Balzers or coating center) to restore the hob to Nobeve factory standards.

For external gears, Hard Hobbing with the G-Series is significantly more cost-effective. A solid carbide hob costs a fraction of a complex Skiving cutter and is easier to maintain. Power Skiving is superior for internal gears. But for standard external shafts/gears, G-Series Hard Hobbing offers the lowest Cost Per Part (CPP) and leverages your existing hobbing machines without needing expensive Skiving options.