Gear Hobbing Cutter: Resembles a cylindrical worm with multiple helical cutting teeth (called "flutes") along its length. The teeth are angled to match the helix angle of the target gear, and the cutter often has a central hole for mounting on a hobbing machine’s spindle.

Gear Milling Cutter: Typically has a disk-like or end-mill-like shape. Disk-type milling cutters have cutting teeth on their circumference (and sometimes sides), while end-mill types have teeth on the end and outer surface. Unlike hobbing cutters, milling cutters are often single-tooth or multi-tooth but do not follow a continuous helical pattern.

Gear Hobbing Cutter: Operates on a continuous generating principle (also called "hobbing"). The cutter rotates around its own axis (primary motion) while the workpiece rotates simultaneously (secondary motion), mimicking the meshing of two gears. As the cutter feeds axially along the workpiece, its teeth gradually "generate" the involute tooth profile of the gear. This is a continuous, uninterrupted process.

Gear Milling Cutter: Uses an intermittent forming principle (also called "milling"). The cutter rotates to cut material, but the workpiece only moves after each tooth slot is machined. For example, to machine a gear with 20 teeth, the cutter first cuts one slot, then the workpiece indexes (rotates by a fixed angle, e.g., 18° for 20 teeth) to position the next slot for cutting. This process repeats until all teeth are formed, resulting in intermittent cutting cycles.

Gear Hobbing Cutter: Far more efficient for mass production. The continuous cutting process eliminates downtime from workpiece indexing, allowing faster machining of gears—even for high-volume orders. For example, a hobbing machine can produce dozens of small spur gears per hour, depending on size.

Gear Milling Cutter: Less efficient, especially for large-batch production. The intermittent indexing step adds significant time between cuts, making it slower than hobbing. It is more suitable for small-batch manufacturing (e.g., prototyping) or repairing individual gears, where speed is less critical than flexibility.

Gear Hobbing Cutter: Delivers higher precision and smoother surface finish. The continuous generating process ensures uniform tooth profiles across all gear teeth, with minimal variation in dimensions (e.g., tooth thickness, helix angle). This makes hobbing ideal for gears requiring tight tolerances (e.g., automotive transmission gears, where precision affects performance and noise levels).

Gear Milling Cutter: Offers lower precision and slightly rougher surface finish. The intermittent cutting can cause minor inconsistencies in tooth profiles (due to indexing errors or tool wear), and the tool’s forming principle may not replicate the involute profile as accurately as hobbing. Post-machining processes (e.g., grinding) are often needed to improve precision if required.

Gear Hobbing Cutter: Less versatile. A single hobbing cutter is typically designed for a specific gear parameter (e.g., module, number of teeth, helix angle). Changing the gear design requires replacing the cutter, which increases tooling costs for small-batch or custom production.

Gear Milling Cutter: More versatile. A single milling cutter can machine gears with different numbers of teeth (as long as the module matches) by adjusting the workpiece indexing angle. This reduces tooling costs for small-batch or custom jobs, as fewer cutters are needed. However, specialized milling cutters (e.g., for bevel gears) may still be required for unique profiles.

Gear Hobbing Cutter: Best for cylindrical gears, such as spur gears, helical gears, and worm gears. It is not suitable for non-cylindrical gears (e.g., bevel gears, rack gears) due to its rotational design.

Gear Milling Cutter: Can machine a wider range of gear types, including spur gears, helical gears, bevel gears, and even gear racks. Its flexibility makes it a go-to tool for non-standard or complex gear profiles that hobbing cutters cannot handle.