This paper shows the results of studying the technology of manufacturing cortical electrode-instruments (EI) with the use of indirect methods of the Rapid Prototyping technology. Functional EI prototypes were made by layered synthesis of the photopolymer material with the use of the stereolithography technology (SLA - Stereo Lithography Apparatus). The article is focused on two methods of indirect EI manufacturing. One of the EI prototypes was used for making a molded wax model for hot investment casting, followed by applying copper coating. The second prototype was used for applying copper plating to a prepared current-conductive layer. As a result of EDMing a steel workpiece, both EIs reached the desired depth, which is 1 mm. The copper plating applied to the EI preserves its integrity. Through the use of the casting technology, there is a possibility to cut the economic costs by 35%. Using a prototype with preliminarily applied conductive coating makes it possible to make geometrically-complex EIs.

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The aim of the work is to obtain an empirical model for calculating the value of the spark gap in the electrical discharge machining of 38X2H2MA steel. Due to the fact that the discharge machining is a non-contact method, when the tool electrode is inserted into the workpiece between the end faces and the side surfaces of the tool electrode and the cavity formed, respectively, the end and side clearances are formed. The main factors affecting the size of the gaps are processing modes and material of the electrodes. The actual task is to predict the size of the spark gap when processing chromium-containing steels, depending on the modes of copy-piercing erosion processing. To obtain the empirical model, the method of factor cladding of the experiment with subsequent regression analysis was used in the work. The criterion for optimality of a plan in orthogonal central compositional planning is the orthogonality of the columns of the planning matrix. For the experiment, the following factors are selected: I -current strength (A), T on -pulse time (µs), T au -pulse fill factor (%). According to the carried out experiment and the subsequent regression analysis, a model is obtained for calculating the size of the lateral gap. On the basis of the obtained data, it becomes possible to predict the correction value when processing steel 38X2H2MA. The analysis of the model showed that the size of the gap is affected not only by the factors themselves, but also by their totality. A geometric representation of the law of variation of the lateral clearance value is presented depending on the erosion control modes. The received data allow to make adjustments of the electrode-tool dimensions in order to provide the given parameters of processing accuracy.

The study of the mechanical properties of photopolymer material SI500. For the manufacture of experimental samples used the method of rapid prototyping stereolithography. The effect of process parameters on tensile and compression strength was studied. It was found that the mechanical strength of the samples is influenced by the layer thickness, exposure time, and additional processing in an ultraviolet chamber. The values of maximum tensile stresses, which are achieved when the layer is exposed for 30 seconds and additional processing, are determined. Changing the layer thickness does not significantly affect the values of maximum tensile stresses. The maximum is in the range from 53.4 MPa to 55.4 MPa. Values of maximum mechanical strength during compression of the samples is achieved with a flash of 10 seconds. The maximum compressive stresses range from 229 MPa to 230 MPa. Changing the layer thickness does not significantly affect the compressive strength.

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