Gear Cutting

Gears are today cut by either a hob or by a shaper cutter. There are a number of ways in which a gear can be cut prime among it is the hobbing. Hobbing is a sort of generating process, where the metal is gradually removed for a gear teeth to evolve out. In this process there is simultaneous rotation of a hobbing cutter and gear blank for transferring the hob's profile on to the gear blank.

Gear Cutting Tools
There are many types of gear cutter available today. Some of them is highlighted here:

• Gear Hobs
  There are many types of Gear hobs that are effectively used as gear cutting tools. The important among them are:
  
  

  Involute Gear Hob: They can generate gears with maximum precision. They are used when there would be no tooth finishing operation afterwards and there is need for better precision before tooth shaving operations.
  Involute Spline: They have an unique stud tooth depth to cut all types of standard or nonstandard involute Splines.
  Sprocket Hobs: They are used for cutting roller chain sprockets for a range spanning from 1/4th inch-3 inch pitch. Can be produced in single or multi start.
  Worm Wheel Hobs: They are designed for plunge cutting. The Worm wheel hobs are unique in a way, they match the wormshaft with sharpening allowance. They can be of shank or shell type.
  Serration Hob: They are designed for cutting the serrations as per job. They give high accuracy.

• Gear Shaper Cutter
  A Gear shaper cutter is essentially a gear that has a teeth, which is relieved for providing appropriate cutting edges and clearances. The stroking, along with related rotation of the Gear shaper cutter and the workpiece translates into a molding-generation process. Shaper cutter are one of the best process to produce gears. This technology is a very suitable replacement for hobbing which is sometimes not possible due to problems of accessibility.
  
  

There are following types of Gear Shaper cutter available:

Disc Type Shaper Cutter: Disc type cutters are effective for cutting any type of gear. Internal, external, spur, helical etc. They are also effective for cutting sprockets, splines, serrations or other types of involute forms. Popular cutters have bore diameters between 10mm-120mm or ½" to 4".
Shank Type Cutters: They are essentially designed to cut internal gears, both spur and helical. Can also be designed for externals. These are full form generated cutters whatsoever be the pitch circle diameter (PCD). A bit of problem in the shank type cutters is the strength factor.
Disk Type Helical Shaper Cutter: This cutter is applied to cut helical gears. The helix angle of the gear determines the number of teeth that the cutter would have.
Deep Counterbore Type Shaper Cutter: This type of cutter is commonly applied to cut shoulder gears.
Coniflex Cutter: Straight Bevel Gears are easily cut with Coniflex gear cutter. Coniflex gear cutters produce gear teeth with an accurate tooth contact. So the gears made this way operate in a smooth fashion.
Pinion Type Cutter: Pinion type cutters are typically shaped like spur gears. The Pinion type cutters are adept in cutting teeth of the internal gears.
Spiral Bevel Cutter: As is seen from the image Spiral Bevel cutters are shaped like crowns and they are used to generate Spiral Bevel gears.

Internal Gear Shaper Cutter
Internal Gear Shaper Cutter is used for the manufacturing of external gears in cases where a normal external disc cutter is not a viable option. The internal gear shaper cutter is fully equipped to generate excellent tool life and high rates of productivity in comparison to the small shank.

• Gear Milling Cutters
  Gear Milling cutters are the type of cutting tools used typically in milling machines or for that matter in a machining centre. They are a popular way to produce gears. Milling Gear Cutters are available in a variety of designs. Standard designs include convex and concave radius, Complex design can be like impeller rotor form cutter. Standard gear milling cutters can produce spur, helical, bevel, miter, rack gear teeth and special gear forms. Basic parameters to look out for in Milling Gear cutter are the following: Range, accuracy, material and surface treatment.
  
  

Following are the different types of Gear Milling Cutter

Side and Face Milling Cutters: They can be supplied either in staggered or in straight tooth form. They can be used for operations involving light or heavy deep slot. The Side Milling Cutters are good choice for steel.
Convex Cutters: Convex cutters operate on a very high speed for cutting gear teeth.
Concave Cutters: They are also high speed operators to be used on all types of material.
Single and Double Angle Cutter: Single cutters are used for bevelling, they can be produced in single right and left angle. Double angle cutters are used for serrations, grooves and other angular surfaces.
Involute Gear Cutter: Involute Gear Cutters can cut a vast number of teeth in gears. Like 0.5 module to 50 even module. Also there is a wide choice of diametral pitch.

• Rack Cutters

Rack type cutters are used for both spur and helical gears. Helical rack type cutters are used when a spur cutter is not the right choice to generate the shape of a helical gear.