Q. I own a specialty electrical equipment manufacturing business, and one of our products is a torque motor. We are considering changing our core lamination material from vanadium permendure to silicon iron steel. Because of this change, we will now have to protect the silicon iron core from corrosion. What is the best protective coating material to apply to the outside diameter of the motors to prevent atmospheric corrosion? Because of the nature of our process, the coating would have to be done after final assembly of the motor. We prefer a spray application using an air-dry material and have the facilities to do so. Is polyurethane the only way to go, or is there something better for our motors? T.B.
A. I assume you don’t want to expose the assembled motors to normal paint-baking temperatures. Certainly, polyurethane enamels would provide corrosion resistance to the outside surface of your torque motor stators. You should also consider fast-drying alkyds and epoxy enamels. The polyurethanes and epoxies could be either one-part or two-part, depending on the coating’s ability to withstand the motor’s operating temperature. Using a two-part epoxy would offer the ability to withstand the highest operating temperature. In any case, it is important to remember that the stator surface must be free from dirt and oily soils before painting.