Production processes like cutting, performed on electrical steel laminations, influence their magnetic properties locally. Since the magnetic design of electrical machines does not take this effect into account accurately, the design may be suboptimal. Therefore, the need exists to develop a numerical procedure which is capable of optimizing electrical devices, taking into account the local material degradation and featuring high accuracy and acceptable calculation time. We developed a space mapping procedure meeting these requirements and we quantified the influence of the material degradation on the design of a switched reluctance motor (SRM). The results of the optimization show that the local material degradation has a significant influence on the dimensions of stator and rotor yoke