알루미늄 소재의 전자연마 공정에서 가공 특성 평가 및 최적화에 관한 연구

Abstract

The final status of workpiece surface decides product quality, manufacturing cost and improvement of functionality. Thus, numerous traditional finishing methods such as super-finishing, honing, grinding are widely employed for fine surface. However, these conventional techniques with rigid tools have limitation of complex shape of surface and productive efficiency. Since demands for better surface characteristics for free-form shape with less time and cost, it is necessary to develop advanced finishing ones which are required to achieve better surface integrity. Among the novel processes, magnetic finishing processes in the presence of the magnetic field have been especially attracted in the last decades. This is because it could acquire high geometric precision by adjusting magnetic force acting on free-form surface with the flexible tool. Although these processes have a number of benefits, it has also limitation of time consuming and process efficiency for non-ferrous materials due to lack of magnetic permeability. Some of research has attempted to increase magnetic intensity by applying permanent magnets for non-ferrous materials but distribution of magnetic flux density directly related to magnetic force is not symmetrical unlike ferrous materials. Consequently, this phenomenon leads to getting non-uniform surface and removing edge of the workpiece excessively. In order to overcome drawbacks of magnetic abrasive finishing, this study suggests a electro-magnetic finishing(EMF) process which combined magnetic energy derived form rotating disc with permanent magnets and kinetic energy acting on magnetic pins as polishing medium in the alternating magnetic field. To optimize magnitude and distribution of magnetic flux density in EMF process, finite element analysis is carried out by using Ansys workbench. In addition, experiments is carried out applying a Taguchi’s L9(34) orthogonal method based on computational simulation to verify effects of EMF process on improving surface roughness and burr removal rate. According to the results, grey relational analysis(GRA) is conducted to find out an optimal condition satisfying both requirements simultaneously. Moreover, it is proved that suggested EMF method in this study is valuable for manufacturing industries based on experimental results applied to the holder of solenoid valve.