Forming Slot Liner Insulation Materials Into Electrical Machines: Manufacturing Considerations and Effects on Performance

Novel and complex stator slot geometries demand precise forming of slot liner insulation materials to ensure a reliable interface with the ground-wall insulation, thereby optimizing electrical machine performance. This paper presents a new approach to forming liner materials within the stator slot using a custom-designed, additively manufactured insertion tool. The study evaluates the impact of this approach on the electrical and mechanical properties of five distinct slot liners. Experimental validation comprises of breakdown voltage, coefficient of friction and ultimate tensile strength at room and elevated temperatures (up to 220° C), revealing minimal degradation in both insulation and mechanical properties, with only minimal failure near the creased regions. Coefficient of friction tests also demonstrate variations in interaction forces between different slot liners, stator core pack and the bespoke insertion tooling. The findings confirm the suitability and effectiveness of this forming approach for lowvolume or prototype level electrical machine manufacturing.