The chamfering and deburring of gears is often an undervalued process in gear production. However, it has a great influence on the usage characteristics of the work piece. Improvements in ratings for gear shifting in vehicles also depends on the process used for this operation. Below we explain the sophistication required in tools using plastic deformation for chamfering and rolling and cutting action for deburring.

Gears need to be chamfered and deburred with a controlled, high quality process for the following reasons:

  • To avoid breakage: Excessive carburizing along the tooth edges can often cause breakage when the gear is running
  • To avoid damaging gears and bearings: If burrs are not removed, they may chip off during the running cycle and cause damage to the other gears and bearings.
  • To avoid poor tool life in the finishing processes
  • Removal of very sharp burrs reduces the risk of tool handling injuries.
chamfering and deburring
Gear before chamfering and deburring
chamfering and deburring
Gear after chamfering and deburring
Gear-with-big-burr
Gear with big burr

There are four different types of gear chamfering: in only one (type A), or in both flanks with a constant size along the profile (type B), with (type C) or without (type D) chamfer in root diameter. Sometimes a further rolling operation is required (refer section on Rolling below).

Chamfering and deburring
Type of chamfer on gear
Chamfering and deburring
Tooth of Gear in various conditions

Chamfering with Plastic Deformation / Compression Tools

Advanced chamfering tools use compression (as against cutting) for creating chamfers on the edge. The pressure and the deformation of the material may modify the structure of the steel. The chamfering tool is like taper gear, with a width of roughly 10 – 15 mm, and normally is very well finished, with a surface like a mirror in order to prevent a quickly wear.

The key benefits of Chamfering with such tools are:

  1. Stronger gear tooth due to better material flow
  2. Accurate Chamfer Angles
Chamfering and deburring
A Pair of Chamfering Tools

The angles of the chamfers are definite by the tool drawing, but the size depend on the rolling time and the pressure of the tool against the gear. If the contact time between the tool and piece increase the chamfer becomes bigger.

The Pressure which defines the deformation force is generated with a pneumatic cylinder.

This method guarantees an “elastic force” that prevents some breakages.

Chamfering and deburring
Position of tools between two teeth of gear

Further the tools are self-centering, thus guaranteeing symmetrical chamfer on both sides of the work piece.

 

TO BE CONTINUED…. Rolling Operation