A gear cut to the right dimensions will still wear out or break quickly if it is made of the wrong material. Material is chosen according to the transmitted load, the running speed, shock loading, the working environment and the material of the mating gear.
Structural steels
General structural steels such as S355 (St52) are an economical choice for low to medium loads at low speed. Used without heat treatment, their wear resistance is limited.
Through-hardening steels
C45 and 4140 (42CrMo4) gain high strength through hardening and tempering. They are common in medium and high load gears, shafts and pinions; the tooth flanks can be induction hardened on top of that.
Case-hardening steels
16MnCr5, 20MnCr5 and 8620 are carburised and hardened, giving a very hard, wear-resistant tooth surface over a tough core. They suit high and shock loads: gearboxes, reducers and construction machinery.
Stainless steels
AISI 304 and 316 resist corrosion and are preferred in food, chemical and marine applications. They cannot be hardened by heat treatment, so their load capacity is limited. Where hardness is needed, martensitic grades such as AISI 420 are considered.
Bronze and brass
Bronze is used above all for worm wheels: paired with a steel worm it gives low friction and protects the worm. Brass suits small, lightly loaded precision mechanisms where corrosion is a risk.
Castings
Large, slow-running gears can be made from cast iron (GG25) or cast steel. Cast iron damps vibration well but is sensitive to shock loads.
Engineering plastics
POM (acetal) and PA (polyamide) gears are light and quiet and can run without lubrication. They suit low to medium loads where quiet running matters. Under high temperature and high load they deform.
A short comparison
| Material | Load | Wear resistance | Typical use |
|---|---|---|---|
| Structural steel | Low–medium | Low | Simple mechanisms |
| Through-hardening steel | Medium–high | Medium–high | Shafts, pinions, reducers |
| Case-hardening steel | High, shock | Very high | Gearboxes, machinery |
| Stainless steel | Low–medium | Medium | Food, chemical |
| Bronze | Medium | High (sliding contact) | Worm wheels |
| POM / PA | Low | Medium | Quiet, oil-free mechanisms |
If you cannot decide
Tick "I don't know / please advise" as the material in the quote form. Describing the machine and the working conditions is enough for our engineers to recommend the right material.