A Comprehensive Review of Electrical Steel Cutting Techniques for Electric Machine Cores: Insights from PMa-SynRel Motor Case Studies

Cutting processes significantly influence the magnetic properties of electrical steel laminations, affecting torque, iron loss, and overall efficiency in electric motors. Techniques such as punching, laser cutting, abrasive waterjet cutting (AWJ), and wire electrical discharge machining (WEDM) each cause varying degrees of plastic deformation, residual stress, and thermal damage, which affect local permeability and core loss. This paper examines these effects using strip-level measurements, analysis of geometry-related degradation, process comparisons, and finite-element models for steels M400-50A, M270-35A, and NO20-1350N. Two PMa-SynRel motor case studies, rated at 3.75 kW and 225 kW, evaluate how laser-cut, punched, and WEDM-cut laminations affect torque, iron loss, and efficiency. Results indicate that laser cutting causes the greatest degradation, especially in thin or narrow magnetic regions, where heat-affected zones nearly double iron loss and reduce torque by over 6% in M270-35A. Punching causes moderate deterioration due to plastic deformation and residual stress, while WEDM causes the least damage, preserving more of the original magnetic properties. The study emphasizes that accurate prediction of machine performance requires incorporating geometry-dependent degradation and cutting-process effects into electromagnetic models. These findings offer practical guidance on selecting cutting techniques, lamination thicknesses, and joining methods to optimize high-efficiency PMa-SynRel machines with thin laminations, narrow teeth, and high-power density.