Your vehicle’s ability to stop relies heavily on the brake pads’ ability to grab the brake rotors properly. Because they’re made of metal, these rotors naturally wear down with use over time. Also, excessive heat caused by heavy braking can cause the rotors to warp.
To help restore the performance of the brake rotors, the technician will “turn” or resurface them if there’s still enough metal left to do so safely. The rotors are put on a lathe one at a time, and an extremely sharp bit cuts into the rotor to smooth the surface.