Below is a list of Solenoid Coils manufacturers from Polo, Illinois. Solenoid coils, also referred to as solenoids, are three-dimensional loops, or coils, of wire that have been wrapped around a metallic core, and function to provide a magnetic field when an electric current is passed through the coil. Thus, through becoming an electromagnet, meaning that its magnetic field is produced by an electrical current flow, the solenoid coil serves to convert electrical energy into linear motion.