Commutator Undercutting

Commutator undercutting is performed to undercut the mica separating the copper segments so that the carbon brushes will wear evenly. Mica is hard and does not wear down evenly with the copper segments. Over the lifetime of a DC motor, the commutator will be undercut as part of a prevent maintenance program to eliminate arcing and extend the brush life.

The U.S. Navy has approved this process for all of its DC armatures.
Automated undercutting provides for a quicker and more accurate job. The floating head and power feed ensures the cutting wheel follows the mica and minimizes burrs. A de-burring attachment removes burrs and rounds the corners of the newly cut bar.


  • Minimizes Burrs
  • Faster and More Efficient
  • Helps Ensure Even Wear on Copper Bars