Erosion coefficient in electric contact processing of metals

In the production of rocket and space technology, difficult-to-machine steels and alloys are used by traditional methods. Therefore, electrical methods for processing parts are used that use a variety of thermal effects of an electric current directly in the process of removing a layer of material. In the technology of dimensional electrical processing, the role of electroerosive methods is increasing, which are increasingly used in all branches of mechanical engineering as the most effective, and often, and as the only possible ways of processing parts made of modern high-strength and viscous structural materials. One of the most promising methods of electrical processing of metal blanks is electrocontact. Performance is applied to evaluate the effectiveness of this method. The carried out literary analysis showed that the product of the current strength and the coefficient taking into account the processing mode and the material of the electrodes is used to assess the productivity. Later, this coefficient was called the coefficient of electrical erosion. For metals used in switching equipment, the value of the coefficient is given. However, it cannot be used to calculate the performance of electrical contact processing due to the significant difference in erosion processes occurring in the interelectrode gap. According to the literature data, the erosion coefficient was calculated during electrical contact processing, the results are presented in the table. In several works it is indicated that the erosion coefficient depends on the polarity of the inclusion of the rotating disk electrodes and the workpiece being processed. The data presented are contradictory; therefore, studies were carried out on the influence of the inclusion polarity on the erosion coefficient. With the same grade of the processed material and the rotating disc, the polarity of the inclusion does not matter. It was revealed that for steel grade St.3 the erosion coefficient depends on the voltage on the electrodes and, when approaching the arcing voltage, increases sharply, regardless of the polarity of the inclusion. For stainless steel, a sharp increase in the erosion coefficient is observed only at the straight polarity of the inclusion.