Why is it such an important process?
During motion gear teeth are designed make point contact at the pitch-line. Under load, both rolling contact and deformation take place at this point. Over time the tooth wears, pits, becomes noisy and ultimately needs replacement.
Hardening of gear teeth before they are put into service, by whatever method, increases the life of the gear many times, extending the replacement cycle and saving valuable downtime.
It remains a critically important step in the design and manufacture of gears because it extends the service life significantly and reduces the life-cycle cost.
Gear types and sizes
We harden all types of gears:
- double helical
- spiral bevel
- pinion shafts
- internal and external splines
We can harden a large range of sizes, typically from 1 module (25DP) up to 30 module(0.85DP) and up to 800mm face width.
The most common materials we harden are 1045, 4140, 4340, EN25, EN26 and SG iron.
Case hardening steels such as EN36 and 8620 are not suitable for flame or induction hardening.
It is easier, quicker and cheaper to spin harden small pitch gears, particularly in quantity.
To do this the gears should be supplied with a pilot bore (the bore may move because of the heat input) and there should be no holes in the heat affected zone that may cause cracking through the tooth root.