Optimization of Qualitative Indicators of the Machined Surface in Symmetrical Machining of TS by WEDM Technology

Current approaches in the process of evaluating the quality of the machined surface during wire electrical discharge machining (WEDM) generally do not include the assessment of micro- and macro-geometric indicators of both parts of the cut. In practice, however, there are specific cases when it is necessary to use both halves of the cut. In such cases, it is necessary to choose a special approach not only in the machining process but also when evaluating the quality indicators of the machined surface. Therefore, experimental measurements were aimed at the identification of these micro- and macro-geometrical indicators in symmetrical WEDM. Within them, qualitative indicators of flat and curved surfaces were assessed. The identification of individual characteristics was carried out using Suftes, Roundtest Mitutoyo, and a 3D coordinate measuring device. The design of the experiment followed the full DoE factorial design method, and the obtained results were processed using the Taguchi method. Based on the obtained results, the response of macro and micro-geometric parameters was characterized by means of multiple regression models (MRM) in symmetrically machined surfaces of tool steel EN X37CrMoV5-1 (Bohdan Bolzano, Kladno, ČR) by WEDM technology. They revealed the mutual dependence of the output qualitative indicators of the eroded area on the input variables’ main technological parameters (MTP). Subsequent multi-parameter optimization resulted in a suitable level of setting of the MTP input variable parameters I, ton, U, and toff (9 A, 32 μs, 15 μs, and 70 V), through which the greatest agreement of macro and micro-geometric output indicators of symmetrically machined surfaces can be achieved. By applying the optimized levels of MTP settings for symmetrical WEDM of tool steel EN X37CrMoV5-1, their agreement was achieved at the level of 95%.