Posted by BillS on August 29, 2005 at 19:50:25:
In Reply to: Re: heat treatment posted by gangi on August 10, 2005 at 11:06:20:
My experience agrees with MKK. For furnace hardening I could also add that, when we masked off the bores, there was no dimensional change. We often masked bores by stacking the gears on threaded rods with washers to keep the furnace atmosphere out.
Also, if the bore was large relative to the OD (like a ring gear) the bore would usually increase in diameter.
Also with a keyway slot, the bore seemed to distort, but overall would reduce in diameter for a bore relatively small compared to OD.
I would also agree that honing was the best fix, since it reduced the bore's distortion, removed keyway bur, and restored proper size. We made special go-nogo gages to check bores during honing.