Improving the Casting Process in Ceramic Forms Using Additive Technologies in Manufacturing Model Kits

The free linear shrinkage of samples from PLA, HIPS, and ABS filaments, used for 3D printing by FDM technology in extrusion operating temperature ranges, has been studied. It is found that the PLA filament is characterized by shrinkage values in the range of 0.2-0.6% in operating extrusion temperatures of 200-220 degrees C. HIPS filaments (operating temperature range of 220-240 degrees C) and ABS filaments (operating temperature range of 240-270 degrees C) have shrinkage in the range of 0.3-0.8%. The values of linear shrinkage must be taken into account when designing mathematical models of the future cast product. The influence of print density d(p) (the degree of filling of the internal structure) on the value of the ash residue A during the burning of samples obtained from the studied filaments is studied. It is shown that, with an increase in d(p) (5-15-30%), the value of A also increases. The minimum values of A (0.19-0.48%) have a filament of the PLA. It is concluded that, for the 3D printing of castings models by the FDM technology for casting into refractory ceramic molds (RCM), the PLA filament is the most technologically advanced according to the set of indicators of free linear shrinkage and ash residue. Model blocks are 3D printed from PLA filament by FDM technology to produce Branch Pipes by casting into an RCM. The RCMs are formed according to the model blocks. In the process of burning out the model blocks from the RCM, it was found that part of the RCM cracked under linear heating. This was due to the excessive pressure of the expanding material of the model block during heating to its softening temperature, and the gas pressure formed during the subsequent burning of the model block. With an increase in the heating rate, the proportion of cracked RCMs increased. In order to prevent cracking, a stepwise mode of heating the RCM, combined with their calcination, has been developed. When removing the model blocks according to the stepwise mode, the RCM did not crack. Experimental Branch Pipe castings were obtained from bronze of the BrA9ZH3L brand. The quality of the castings met the requirements of the design documentation.