If you know anything about gear manufacturing, you’re probably somewhat familiar with hobbing. But if you’re new to the game, it may sound like a strange term.
Hobbing is an important machining process that allows manufacturers like Federal Gear to cut precision gears from raw materials. It’s one of the most widely used techniques for cutting gears. So how exactly does it work?
History and Applications
Gears themselves are simple machines that date back to the 27th Century BCE. For many centuries, gears were used in basic applications like water wheels and clocks, but it wasn’t until the 1600s, with the discovery and utilization of the involute curve, that gear functionality was able to expand. In the 1800s, gear manufacturers started using form cutters and rotating cutters to shape gears more precisely.
The first gear hobbing process was patented in 1835; hobbing machines use hobs, which are specialized spiral-shaped cutting tools to generate gear teeth. Throughout the 1800s, manufacturers worked on making semi-automated processes with these hobs, with the first hobbing machine capable of cutting both spur and helical gears emerging in 1897.
It wasn’t until the late-20th century that hobbing became fully automated, capable of producing thousands of gears in an hour; in 1975, the Pfauter Company introduced the first NC hobbing machine, followed by the full 6 axis machine in 1982. Hobbing machines can now be used to produce cycloid gears, helical gears, splines, sprockets, worm gears, and of course, spur gears.
The Basics
A hobbing machine has two skew spindles, one of which contains the blank, and the other of which contains the actual hob. The type of gear being produced dictates the angles at which these are held to one another. The machine is then set -up to rotate the two shafts at the proper ratio for whatever gear is being produced, while the hob gradually cuts each individual tooth to the proper depth. In many cases, multiple gear blanks can be stacked and cut simultaneously.
Equipment
There are different types of hobbing machines, or hobbers, for different applications, but the most important variable is size. Gears come in many different sizes, and not all hobbers can accommodate them. The hobs themselves come in two varieties; single-threaded hobs and multi-threaded hobs. Multi-threaded hobs can increase total production, but at the cost of some accuracy, so they can’t be used in precision applications.
Hobbing is one of the most important breakthroughs we’ve had in the gear manufacturing world, and it continues to be an efficient process for manufacturing gears today. If you’re interested in having gears hobbed for your application, contact us at Federal Gear today!