I have been following developments on gear making in general-purpose CNC machines with great interest. The advent of affordable gear grinding seems to have spurred an interest in at least roughing out gear teeth in ways never before possible. The ability to rapidly remove metal with accuracy and repeatability has never been better, so I expect this trend to continue.
The first “alternate” machining of gear teeth that I witnessed was back in the late 1970s. Business was booming and, as coating had not yet become commonplace, hobs were in short supply. A clever engineer at P&H figured out a way to use saw blades on an arbor in a single-index milling machine to cut pie-shaped chunks of metal away, and thus reduce wear and tear on his precious cutting tools.
Twenty years later, we were forced to experiment with wire EDM cutting of teeth because no one could produce a high contact ratio hob to meet our schedule. The results exceeded our expectations and eventually some teeth were even finish cut with EDM.
Supposedly, a crowd-funded water jet machine will soon be available cheap enough for a home hobbyist to afford. Water jet-cut gears in your garage won’t be far behind. A client even made a rotating ¼ scale model of a new product a few years ago with 3-D printing; it was a bit “toothy” but a finer mesh or a bit of sanding could have cured that.
Will these new methods change our industry? Can they fully replace hobbers and shapers and bevel cutters? It is way too early to tell. What it will certainly do is change the way we think about gear design. No longer will engineers feel constrained by “standard” tooth forms or pitches.
As always, you can count on Gear Technology to report on these developments in both the editorial and advertising sides of the magazine. It is yet another reason to attend this year’s Gear Expo and Fall Technical Meeting. Check out the magazine and website for details.