TEL : +81 48 254 1744

"Easy" Gear Selection Screen

- Choose a gear by pitch, # of teeth, or bore size.
- 2D/3D Drawings Available
- PDF Catalog Available
- Strength Calculation Available

Go to Gear Selection Screen


Materials for Gears and Heat Treatment

Related Links : 齿轮的材料及热处理 - 中文版

1-8 Materials for Gears and Heat Treatment

The materials herein described are generally used in Japan.

Case-hardening steel

The carbon content of case-hardening steel is low, usually about 0.15 to 0.20% . Case-hardening steel also contains Ni, Cr, Mo, Mn, etc. It is suitable for carburizing and quenching.
case hardened steel

Aluminium bronze casting

Description : Aluminium bronze casting Type 2
Applications : Gear, bearing, bushing, valve seat, impeller, propeller for ships, etc. (Suitable for those which require strength and rust, erosion and/or wear resistance.)
Aluminium bronze casting

Bronze casting

Description : Bronze continuous casting Type 6
Applications : Valve cock, machine parts etc. (Suitable for those which require pressure resistance, machinability and suitability to casting.)
bronze casting

Carbon steels for machine structural use

The most commonly used material. KHK mainly uses S45C. Suitable for high-frequency induction hardening.
carbon steel

Chromium molybdenum steel

Chromium molybdenum steel is thermal-refined and then hardened by high-frequency induction hardening.
chromium molybdenum steel


Quenching is a process to surface-harden tooth areas to increase their strength.
Cited here are two processes among others – (a) carburizing and quenching, and (b) high frequency induction hardening.

Carburizing and Quenching – The suitable material is SCM415 etc.

Carburizing – Quenching – Cleaning – Tempering – Shot blast – Testing/Inspecting

By heating low carbon steel in carbon gas atmosphere to high temperature and holding, carbon molecules are diffused into the surface making the material similar to S45C.
This, in turn, allows the surface to be hardened by quenching.
– Surface hardness……55 – 60HRC
– Depth of surface hardening……Approx. 1.0mm
(Use thicker depth as the load increases)

Features :
Carburizing and Quenching produces a hard, wear-resistant surface with progressively softer core which retain ductility.

carburizing and quenching furnace hardened layers
Left : Carburizing & quenching furnace
Right : Hardened layers

High-Frequency Induction Hardening – The suitable material – S45C, SCM440 etc.

One shot entire perimeter hardening One shot single tooth hardening Continuous hardening
Left : One-shot entire perimeter hardening
Center : One-shot single tooth hardening
Right : Continuous hardening

Thermal refining – Hardening – Tempering

Features :
When heated with the induction coil, the steel is hardened. But the hardened area is limited to the surrounding area of the coil.
In order to reduce the chance of cracking, it is desirable to have material with low sulphur (S) and phosphorus (P) content and carbon content of less than 0.55%.
Various types of induction coils are used depending on the shape of the gear. Some experience is required to do this work as cracking and/or deformation are apt to happen.

Hardening apparatus Tempering furnace
Left : Hardening apparatus
Right : Tempering furnace

Related links :
Gear Materials and Heat Treatments
Spur Gears
Gear Materials
Heat treatment of gears

Go to Top