Abstract: A method of making a pole and coil assembly for a dynamo-electric machine (e.g., interpole for locomotive traction motors) comprising providing the coil wires with a polyphenylene sulfide coating, filling the pole-coil interspace with solid, foamable polyphenylene sulfide ground insulation and heating the assembly such as to foam the ground insulation in place and cause it to constrictively engage and bond to the pole as well as fuse to the PPS coating on the coil. The pole surface may be roughened and/or coated with PPS for improved pole retention and/or may be nickel plated for improved corrosion resistance.