Electric Motors

The repair of electrical generating equipment presents many areas in which the SIFCO Process of Selective Plating can be used with great success. The primary application areas are the bearing housing (end bell) and the rotor journal.

End bells, which house the bearings that support both ends of the motor shaft, experience fretting corrosion during operation. The SIFCO Process is used to plate these bores to size with copper, tin, or nickel. Machining the bores, prior to plating, is only necessary to reestablish concentricity.

Plating a worn bearing housing can take less than thirty minutes and is a cost effective alternative to machining the bore oversized and pressing in a pre-machined sleeve, or flame spraying and machining to the print dimension.

DC motors and generator slip rings can develop copper oxide films which reduce electrical conductivity and cause arcing and pitting especially during locked motor start-up. Excessive damage occurs in highly corrosive environments, such as in the bleaching areas of pulp and paper plants. Plating 2.5m (0.0001 in.) of rhodium and then 1.3m (0.00005 in.) of gold onto the refinished commentator extends brush life and maintenance intervals.