OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 6 4 4 5 samples of tool-electrodes for CPEDM of a blind profi le groove in special-purpose products were produced using investment casting method; a sketch of the TE is presented in Fig. 1. The tool-electrodes were designed taking into account the inter-electrode gap (IEG) calculated according to the methodology presented in [17, 18]. CAD-model with sprue-feeding system was designed in SOLIDWORKS computer-aided design system. Processing of the CAD-model for the production of investment pattern by stereolithography (SLA) method was carried out using the Materialles Magics software package. The design of supports (Fig. 2) is necessary for free removal from the working place of construction. To minimize cost of SLA production, the internal fi lling of the TE was performed with a cellular structure of a Wigner – Seitz face-centered cubic lattice (Fig. 2). This type of lattice holds equiaxial loading well, which allows obtaining a master model with acceptable shape deviations after post-polymerization of the material in air [19–21]. Fig. 1. Sketch of the tool electrode Fig. 2. Supports for TE Growing of TE was carried out on a mask-type Envisiontec Perfactory XEDE unit. The mode parameters are presented in Table 1. The patterns were manufactured using a photopolymer material based on acrylates (Si500), which belongs to the class of cross-linked polymers. The characteristics of the material under normal conditions are presented in Table 2. The CAD model of the TE prototype with a sprue-feeding system (SFS) is shown in Fig. 3. The ProCast software package was used to calculate the SFS. When designing the SFS, it is necessary to take into account the following: 1) identical conditions for each section of the casting during casting; 2) for thick-walled sections, the presence of an additional depot of liquid metal in order to eliminate defects (shrinkage cavities, weakness and porosity in the metal); Ta b l e 1 Parameters of the build mode of the investment pattern by SLA method Parameter Value Layer thickness, μm 50 Supports height, mm 3 Thickness of supports, μm 280 Time of illumination of model section and supports, ms 8,500
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