DEVELOPMENT OF CERAMIC ITEMS INJECTION MOULDING TECHNOLOGY USING COMPUTER MODELING

Abstract

Research projects in foreign materials science were analyzed. Specific technological methods for forming ceramic items were examined. The installation diagram for the injection molding of thermoplastic items based on ceramic powder and metal-ceramic developed at the Bakul Institute for Superhard Materials of the National Academy of Sciences of Ukraine was presented. The heat transfer process during injection molding of a nozzle and the ball with an axial cylindrical hole, ring, and solid ball formed from ceramic materials based on powders of aluminum nitride, tungsten carbide, and silicon has been computer-modeled. Danger areas of local isothermal concentrations in molds have been identified. It has been established that the cooling time of thermoplastic mass in molds to reach the solidification temperature of the binder depends on the material type to be injected. The temperature change program for the furnace that provides uniform heating of a cast product at one stage of the distillation of the binder was calculated. A sample of the temperature change programs calculated during the distillation of the binder from the product in the form of a sphere of different sizes was presented. The process of mold filling with thermoplastic mass during injection molding of ceramic items in the form of a ball with a cylindrical hole, ring, solid ball, nozzle, and funnel based on powders of aluminum nitride, tungsten carbides, and silicon has been modeled with computer-assistance tools. Pressure distributions in mold cavities and filling time with thermoplastic mass were obtained. The optimal location of the injection hole in the molds, when the minimum length of the seam lines in the items at the end of the injection takes place, has been determined. The dependencies of the mold filling time and the seam lines length at different viscosities of the material on the dimensional product parameters have been defined. The experimental part of the injection molding technology of the aluminum nitride powder nozzle for argon arc welding was considered. The graphs of minimum injection temperature changes, at which the defect-free nozzle blanks formation occurs, with binder concentration change and the mass viscosity, have been obtained. The obtained calculated data determine the whole complex of the injection molding process’s technological features and can be used to produce various shapes of ceramic items.