What does hobbing mean?
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Hobbing
Hobbing is a machining process for gear cutting, cutting splines, and cutting sprockets on a hobbing machine, which is 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. It is the most widely used gear cutting process for creating spur and helical gears and more gears are cut by hobbing than any other process as it is relatively quick and inexpensive. A type of skiving that is analogous to the hobbing of external gears can be applied to the cutting of internal gears, which are skived with a rotary cutter (rather than shaped or broached).
Gear Hobbing – Parts, Working, Diagram, Advantages, Disadvantages
(a) Gear hobbing is a fast and continuous process so it is realized as an economical process as compared to other gear generation processes.
Advantages of gear hobbing process are described below :
(b) Lower production cycle time, i.e. faster production rate.
(c) The process has a larger variability’s in the following of sense as compared to other gear machining processes.
(i) Capable to make a wide variety of gears like spur gear, helical gears, worms, splines, sprockets, etc.
(ii) The process of required indexing (named so) is quite simplified and capable to make any number of teeth with consistent accuracy of the module.
(iii) A special type of gear named herringbone gear cam be generated by gear hobbing exclusively.
(iv) A wide variety of batch sizes (small to large volume) can be accommodated by this process.
(d) Several gear blanks, mounted on the same arbor, can be processed simultaneously.
(e) Hob is a multipoint cutting tool having multi cutting teeth or edges at a time few number of cutting edges work so lots of time is available to dissipate the generated heat. There is no overheating and cutting tool.
Difference Between Gear Milling and Gear Hobbing | What is Gear Milling | CNCLATHING
How to differentiate gear hobbing and gear milling?
1. The way gear teeth are produced
In gear milling, a single tooth spacing or gap between gear teeth will be created by a rotating multi-edge cutter at a time, the cross-section of generated teeth is similar to that of the cutter. In gear hobbing, the gear teeth are progressively produced by a series of cuts with a hob. So the hob cuts several gaps simultaneously.
2. Cutter
Gear milling uses a rotating form cutter, when each tooth space is cut, the cutter will return to the starting point and gear blanks are indexed for next cutting process; gear hobbing uses a helical hob cutter, the hob and the workpiece are both rotating constantly when the hob is fed across the face width of the blank.
3. The number of teeth cut in one time
Each cutter in gear milling is designed to cut a range of tooth numbers, while in gear hobbing, both the hob and gear blank rotate continuously as in two gears meshing until all teeth are cut.
4. Price of tool
Generally, the gear milling cutting tool is cheaper than that of hobbing, but the productivity of gear hobbing may be higher.
5. Application
Gear hobbing is more often used for high production runs, and gear milling is a low production process.
6. Others
– Gear milling requires deburring
– Gear milling is often used when other generating processes are unavailable.
