What is the correct way to harden gears ?

Question

how I can harden carbon steel gear after machining?

Answer 1

It depends on what kind of steel they are made of but generally you heat them until they are non-magnetic and quench them in the appropriate medium.  It could be water, oil or air cooling depending on the alloy.  Then you re-heat them to the right temperature for the correct hardness.  This also depends on the alloy.  If they are very low carbon they might need case hardening.  

Answer 2

Gears must tolerate high level of dynamic stress while facing a huge weariness. so the only acceptable hardness method for these parts , physically and financially is SURFACE HARDENING.

The best way to gain surface hardness for a gear is INDUCTION hardening . this is the only way nowadays used for carbon steel gears.

depending on the amount of carbon in the raw material, you can have up to HRC60 by this method.

Please be noticed that induction hardening can not be applied to Aluminum or cast iron gears.

Read more in : http://en.wikipedia.org/wiki/Induction_h...

Wish you luck