Process for producing a magnet base for printing head of a wire dot

Abstract

A magnet base, having a flux density equal to that of an Fe-50%Co alloy and an input current response equal to that of an Fe--Si alloy, is used as a component of the magnetic circuit employed for a printing head of a wire dot printer, the magnetic circuit further having by-pass and armature components. The material of the magnetic base is an Fe-50% Co alloy and the base has an end face which is perpendicular to the magnetic circuit of the printing head. A layer, of a material selected from the class consisting of metals and metal alloys which function to increase the specific resistance of a magnet bases of an Fe-50% Co alloy, is formed on the end face of the magnet base and reduces eddy current loss therein, particularly at high frequency energization of the magnetic circuit, further serving to increase the input current response. The magnet base is formed by kneading soft magnetic powder, comprising the Fe-50% Co alloy, and a binder to form a kneaded mixture which is injection molded into the desired shape of the magnet base, heated for removing the binder and producing a degreased structure, and which then is sintered. The sintered base then is annealed and the layer formed on the end surface by vacuum deposition; alternatively, the layer may be vacuum deposited on the end surface of the sintered magnetic base and the composite structure then annealed.