Optimal Gear Teeth & Radius for Low Friction & Weight

[Bern123]

Hi all, i have a doubt. How much teeth in relationship to his radius need to have a gear to be optimal? And, if i have 2 gears with same radius and same #of teeth, to have low friction and low negative effect from weight how much teeth they need to have and with which radius?

I know it's too generic question, it depends from material of the gear, lubrification type and shape of teeth. But is there a standard table used in industries with gear types and optimal applications?

 

[Baluncore]

There is no simple answer, but for spur gears you will need at least 20 teeth. The teeth should be as big as possible so they are strong. That sets a maximum number of teeth at about 30.
Spur gear teeth roll against each other, they do not slide, so there is low friction.

 

[SteamKing]

This article discusses the various types of gears and their primary uses:

http://en.wikipedia.org/wiki/Gear