CASTING FLOW DYNAMICS IN THE INJECTION MOULDING SYSTEM OF CERAMIC MATERIALS

The aim of this work is to qualitative assess the hydro-dynamic mechanisms which regulate the flow of the ceramic mass inside the cylinder during the pressing phase of the injection moulding system, through the comparison of different hinging methods. Three different hinging methods were compared: straight bar; straight bar with variable section; shaped "spiral" bar. Each sample was made of wax, surrounded with refractory coating material, preheated and then positioned in the pressing furnace. Two ceramic roughs of different colours were sectioned and reassembled to obtain a unique ceramic rough made of two different colours. The castings were then recovered, photographed and analyzed. The macroscopic evaluation of all the pieces revealed the absence of bubbles or missing parts. In all the samples, it was possible to recognize clearly the colour difference between the two masses used for pressing: the presence of curvatures or section's variations in the casting channels did not jeopardize the complete filling of the mould by the material, the formation of bubbles or missing parts. Only the T bar specimen showed perturbation in the ceramic flow. The results show that there are no qualitative differences in the various hinging methods for the injection moulding of ceramic materials.