This month I'd like to discuss climb versus conventional hobbing.

As you can see from the above picture, in conventional hobbing, the feed direction and the rotational directional are the same. When cutting in this mode you are, in effect, pushing the chips into the cut.

In climb cutting the feed direction and the rotational direction are opposite. This tends to push the chips out through the portion of the tooth that has already been cut. Typically, climb cutting will improve the surface finish of the gear, all other conditions being equal. You would think that this is a "no-brainer" and everything should be cut in the climb fashion, however this is not the case. There are instances where the feed direction cannot be reversed due to part configuration or tooling. There are cases where the only way you can climb cut puts the cutting forces towards the tailstock instead of the work spindle. This can cause just as many problems in the gear that offset any improvement in surface finish. Finally, if your coolant is very dirty or worn out, simply climb cutting will not likely improve the finish near as much as replacing or cleaning your coolant.

Repair Parts wishes you a happy holiday season! We look forward to to providing with more useful tips next year that will make your work a little easier.