Study On The Numerical Simulation Of The Compaction Pressing Of Ceramic Powder

Because of such good qualities as high strength and toughness, heat-resistance, abrasion-resistance and radioactivity- resistance, ceramic products are widely used in the fields of metallurgy, mechanical engineering, national defence and aviation. Die pressing process and cold isostatic pressing process are the important methods of making ceramic parts. Die pressing method is mainly used to produce thin ceramic components. However, the structure of the compact produced by die pressing process is obviously inhomogeneous as the applied pressure is restricted in the axial orientation. Many Large and complicated components can be made by cold isostatic pressing process, and the density of the compact is more uniform than the one obtained by die pressing. Finite element simulation of the pressing process is the effective method to optimize the rubber mould design process, improve the product quality, heighten the efficiency and reduce the number of increasing trial and error cycles used in current industrial practice.This paper studied the die pressing process and wet isostatic pressing process of ceramic powders with finite element simulation method, and the large finite element software named Msc.Marc/Mentat 2003 was employed. At first, the distribution of relative density and equivalent stress as well as the changes of geometry size in die pressing were simulated respectively. What is more, the powder grain's flow rule and the friction between the powder and the die wall were taken into consideration. Then, The distribution of relative density and the changes of both axial size and radial size of the ZrO2 ceramic plunger in the wet isostatic pressing process were analyzed precisely. This paper also did some research on the optimization of rubber mold design in CIP.The causes of the low density regions in the compact were analyzed in this paper. The influence of friction between the powder and the die wall on the density of compact was also discussed. The shrinkage rate of the green compact obtained from the simulation result was 120%, while the experimental result was 119%. The wet isostatic pressing process of a ZrO2 ceramic plunger was simulated with finite element method (FEM). The FEM results were in well agreement with the experimental results in the aspects of relative density and shape of green compact.The errors of the sizes of green compact between the both were less than 1%. Furthermore, the optimization of rubber mold design in wet isostatic pressing was studied. A more uniform density of green compact was obtained when the outward orthogonal surface of---- rubber plug was changed to spherical one. The simulation results indicate that if the thickness of rubber bag is more than 2.5mm, it has little influence on the shape of the green compact, on the opposition, a large distortion is caused.