gear hardness RA 1

[bmech21]

I am reviewing some prints for helical and spiral bevel gears that my company purchases. Under "Heat Treat" the prints state "Harden Teeth to 80-83 RA" The only Ra I am familiar with is Roughness Average. Does anyone know what RA is under heat treatment?

Thanks

 

[israelkk]

RA is a hardness under 60 Kg test load where RB is under 100 kg test load RC is under 150 kg test load.

For example 80-83RA is equivalent to ~58-63RC. I assume these are carburized or nitrided gears. Look at

http://www.bostoncenterless.com/hardness.htm

 

[bmech21]

Yes, they are carburized gears. Looks like I should review my hardness tests. Thanks!

 

[unclesyd]

If the print calls for Ra don't measure using Rc and convert as you stand the chance of punching through the case on the gear.
In your case the hardness readings will convert but the procedures will not.
It is always good practice if possible to use a method for the hardness as specified on the print and not convert.