The Manufacturing Principle
Gear manufacturing is primarily divided into two methodologies: Forming and Generating. Understanding the distinction is crucial for optimizing both precision and tooling investment.
FORMING METHOD
Tooth profile is shaped by a cutter that matches the tooth gap. Lower flexibility, higher profile dependence.
GENERATING METHOD
The tooth profile is created as a result of the relative motion between the cutter and the workpiece. Higher accuracy and versatility.
| Machining Method | Type | Accuracy (ISO) | Relative Cost |
|---|---|---|---|
| Gear Grinding | Generating | Grade 3-5 | Highest |
| Gear Shaving | Generating | Grade 6-7 | Medium-High |
| Gear Hobbing | Generating | Grade 7-8 | Low-Medium |
| Gear Shaping | Generating | Grade 7-8 | Medium |
| Gear Planing | Generating | Grade 8-9 | Medium |
| Gear Broaching | Forming | Grade 7-8 | High (Tooling) |
| Gear Milling | Forming | Below Grade 9 | Lowest (Unit) |
Process Features & Applications
FINISHING POST-HARDENING
Gear Grinding
Highest accuracy and surface quality. Essential for high-speed, noise-sensitive applications.
TYPICAL APP:
Automotive EV Transmissions, Aerospace
UNIVERSAL EFFICIENCY
Gear Hobbing
The most common method for roughing and semi-finishing external gears.
TYPICAL APP:
General Industrial Reducers, Worm Wheels
INTERNAL GEOMETRY
Gear Shaping
Suitable for machining internal gears, compound gears, and rack forms.
TYPICAL APP:
Planetary Gear Carriers, Splines, Internal Gears
SURFACE POLISHING
Gear Honing
Focuses on improving Ra (roughness), deburring, and noise reduction post-hardening.
TYPICAL APP:
Precision Finishing for Hardened Gears
Technical FAQ
Does accuracy grade depend only on the machine?
No. As noted in Wenlio standards, accuracy depends on the synergy of the standard (ISO/AGMA), material state, heat treatment distortion, machine capability, fixturing precision, and the inspection method used.
When should I choose Gear Shaving over Gear Grinding?
Choose Shaving for high-efficiency finishing of unhardened gears where Grade 6-7 is sufficient. Grinding is necessary for hardened parts or when Grade 5 or better is required.
Why is Gear Broaching considered “High Cost”?
While the production rate is extremely high, the broaching tools are custom-made and very expensive. It is only cost-effective for large-batch production of internal ring gears or splines.