A hob is a cutting tool used to cut teeth into a piece of metal. The hob is attached to a special type of milling machine. The teeth or splines are progressively cut into the workpiece by a series of cuts made by a cutting tool called a hob. Compared to other gear forming processes it is relatively inexpensive but still quite accurate, thus it is used for a broad range of parts and quantities. This process has been the top choice in manufacturing many types of gears.
The important concept to know about gear hobbing is that it’s a generating process. It means that the final shape of the resulting gear tooth is not the conjugate form of the cutting tool. Instead, it’s the result of the combined works of the cutting tool and the material being machined.
The first gear manufacturing was done and popularized back in 1835 where machines use hobs to generate gear teeth. Then throughout the succeeding years, semi-automated manufacturing processes were done using hobs. It was in the late 20th century when gear manufacturing has been fully automated and hobbing machines can now be used to make all sorts of gears. These include spur gears, helical gears, cycloid gears, splines, worm gears, and so on.
When it comes the hobbing machine itself, it contains two skew spindles. One spindle holds the actual hob while the other one holds the work piece. Depending on the type of gear to be produced, the machine is set-up according to the angles required to create the said gear. The hob cuts through each tooth of the gear to the right depth. In most cases, the gear hobbing machine can cut simultaneously through multiple blanks.
Hobbers or hobbing machines come in different types with the two common varieties: single-threaded and multi-threaded hobs. While multi-threaded hobs are great for increased production, they are not ideal for high precision applications. Since gears are made in many different sizes, so the most important variable in using hobbers is its size. Overall, gear manufacturing continues to be a cost-effective and efficient process of manufacturing gears. So, if you have gears need hobbing, just get in touch with us at True Gear & Spline today!