PURPOSE:To improve wear resistivity and both characteristics of torque and performance by executing Laser carburizing hardening work on the friction face between an armature and external and/or internal face of a magnetic pole. CONSTITUTION:A substance which has effects of preventing Laser reflection and enhancing carburization is applied on one of or both the opposed friction faces of an armature 4 and external/internal magnetic pole 6a and 6b, forming a black coat thereon. Laser carburizing hardening work by Laser radiation is executed to form layers 12a, 12b, 13a and 13b hardened by surface carburizing and quenching method. The Laser hardening work may exclude the treatment of the water or oil quenching which is necessary for normal thermal treatment because of self cooling of a work piece by heat conduction.
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