Posted by Mike Tate on October 04, 2002 at 08:56:56:
I would like for anyone on the board that will to address a problem I am having with a gear. It is a 42T 2 module,20 deg. P.A. 15 deg. helix angle, 25MM face. I have been having a problem with teeth chipping. Also, you can look at the gear face and there is a definite pattern of contact across about 1/3 of the face, on one side, the rest of the face shows no wear or even contact. This suggests an alignment problem of some type, but the customer is not fully convinced of this. The teeth are chipping only on the side where the contact is.
We started out making this gear from C11L17 CRS heat treated to 52-54RC. The problem showed up then. Due to the inavailability of C11L17, we switched to C1144 CRS, also heat treated to 52-54 RC. Problem still there. Next, we stayed with C1144 but dropped the heat treating to 42-44RC. Problem still there, matter of fact the wear seemed to increase. The next step was to switch to 86L20 heat treated to 58-60 RC.(The factory gears are heat treated to this spec by the way). This seemed to be an improvement in that it is a longer period of time before the chipping takes place, but the problem is still there. There seems to be some starting and stopping with this particular gear.
I thought of switching to 4140 material, but my heat treater says that since it hardens all the way through, it may be too brittle.
The customer has asked us to try to come up with something else that may help.
Metallurgy is not my area of expertise, so if anyone has any suggestions, I would appreciate your help.
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