Used Gear Hobbing Machines
Gear Cutting Machines : Hobbing Made Easier
From the time the hobbing process was patented in 1835 until now, hobbing has made it possible to produce gears efficiently and precisely in complex configurations. A gear cutting machine cuts teeth and other regular patterns onto shafts and flat parts by machining away excess material in a subtractive process. Common gear cutting processes include hobbing, milling, broaching, grinding and are different from forming processes like forging, extruding and 3D printing which may be able to make similar parts, but with different mechanical properties. Gears may be cut from any hard material, though when it comes to machining, metals are by far the preferred medium. Typically, the gear is cut from a solid block or cylinder, though for very demanding applications, parts may be near-formed and machined as a secondary operation.
Basics of Gear Hobbing
Hobbing uses a tool called a hob to cut the teeth into a blank work piece. The cutter and gear blank in a gear hobbing machine are rotated at the same time to transfer the profile of the hob onto the gear blank. This method of cutting gears is often used for medium to high production volumes. The angle between the cutter and the gear blank and proportional ratio of their turns determine the number and type of teeth on the finished product. The shape of the hob determines how many cutting edges work simultaneously, which provides the potential for shorter cycle times and faster production. CNC hobbing supports high precision, tight tolerances and fine surface finishes. Some companies also use CNC gear inspection systems to check the accuracy of all tooth cutting operations.
Wet Vs. Dry Gear Hobbing
Most gear cutting machines use coolant to carry away the chips and maintain thermal stability of the workpiece and cutting tools, however, as coolant costs rise and the technology to use coolants increases the complexity and expense of hobbing machines, dry gear cutting machines have entered the market. A dry cutting CNC gear machine uses better carbide tooling, specialty coatings and ceramic tools to make parts with faster cutting speeds and improved technology.
Types of Gears Made by Hobbing
The finished gears made by hobbing include cycloid gears, helical gears, involute gears, ratchets, splines, sprockets, spur gears, chain gears, straight-sided splines and worm gears.
Top Gear Hobbing Machine Brands
Below are five of the top gear hobbing machine manufacturers. These companies provide not only gear cutting machines, but cutting tools, replacement parts, work holding tools, field service, application development, training programs, engineering support and machine rebuild services.
- Mitsubishi Heavy Industries
- Gleason Corporation
- Aeromech Technologies
In summary, gear hobbing is both an art and a science. Hobbing requires expertise and a commitment to contineous learning. Equipment manufacturers are making equipment capable of producing gears and similar parts faster, more precise and complex than ever imagined before.