In the ceramic molding process, due to the simple structure, it is suitable for the dry press molding method, and the dry compression mold is also used. It is known from the production practice that the product stratification has a certain relationship with the smoothness and fit of the dry die, the molding pressure, the pressurization mode, the pressurization speed and the dampening time, the demolding mode, and the demolding speed, which must be reasonable. control.
Dry pressing has higher requirements on the quality of dry die. Firstly, the hardness of the die is required to meet certain requirements. Secondly, the finish of the die is very high. If the finish does not meet the requirements, the flow of the material will be affected during dry pressing, resulting in delamination. Appearance. At the same time, some compression molds are not well matched, and the gap is large, which will result in less powder around the mold, so that the four sides cannot be compacted when pressed, and the layer will be delaminated due to inconsistent pressure transmission. .
The forming pressure is a very important factor in the application of the dry stamping mold. The pressure is too small and too large to suppress the desired blank. If the pressure is too small, the density of the product after burning is small, the product shrinks greatly, and the compaction degree of the blank is not easy to be delaminated; and the pressure is too large, and the blank is also prone to cracking, delamination and difficulty in demolding.
In the process of manufacturing a product by dry pressing, the pressing method has two types of single-sided pressing and double-sided pressing. In contrast, the density of the single-sided pressed blank is much more uniform than that of single-sided pressing. . Therefore, the ceramic dry pressing should be double-sided pressurized.
In addition, it is necessary to control the pressurization speed and the dwell time of the dry press molding. The speed of the dry die falling should be slower. If the pressurization speed is too fast, the gas in the green body is not easily discharged, resulting in delamination of the green body. The surface is dense and the middle is loose, and there are bubbles and the like. If the holding time is too short, the gas in the blank is not easily discharged.
In addition to this, the demolding mode and the demolding speed of the dry stamper are also controlled. Generally, the tool is used to push the blank out of the cavity, and the demoulding speed is uniform and slow; the demoulding tool should be flat, otherwise the blank will be unevenly stressed and cause cracking.