Posted by BillS on August 03, 2017 at 13:31:51:
In Reply to: Questions about gear material and Heat Treatment posted by Mike Kelly on August 03, 2017 at 13:20:40:
Back in the day we used C1117L for machinability and carburized 18 NDP gears.
Made a lot of 20NDP and 18NDP gears this way, and Our Heat Treat Guy had what he called "Shallow case" which I think was .010-.020 deep.
We also made a superior gear by using 8620L and used same HT, but maybe to higher Rc hardness? This produced a stronger tooth for certain applications.
8620L was a bit pricey by comparison to C1117L...but is a higher alloy and is not too bad for machineability - just watch your hob wear!
These are both leaded materials and cold rolled and meant for smaller gear OD's.
What ever you do, don't choose C11L14 - it will not stand up to HT and you can look sternly at the teeth and they pop off!