A magnet assembly, having a disk-shaped magnet, which is made predominantly of metal material and has a through-hole and, by the through-hole, can be placed onto a region of a shaft made of plastic by a press fit. In the region of the magnet placed onto the shaft, the shaft has a diameter that is smaller than the diameter of the through-hole. The shaft has a plurality of radially protruding projections in the region of the magnet placed onto the shaft. The projections are distributed evenly on the circumference of the shaft and, with respect to the longitudinal axis of the shaft, having a radius, the double of which is oversized relative to the diameter of the through-hole before the magnet is placed onto the projections of the shaft.