Punching and packing in the process of production of magnetic cores for electrical machines result in the most significant deterioration of their magnetic properties. Specific total losses increase and magnetic polarization curve steepness decreases. This article presents a method that lets measure magnetic properties of cores following different methods of core packing. The effect has been shown of some technological operations in the production process of magnetic cores for electrical machines on their magnetic properties. (C) 2003 Kluwer Academic Publishers.