Due to their unique shape and performance requirements, the optimization and quality control of the injection molding process of special-shaped ceramic structural parts is particularly critical.
First of all, the selection and processing of raw materials are the basis. It is necessary to select ceramic powder with appropriate particle size distribution, high purity and good fluidity, and evenly mix it with an appropriate amount of binder. The type and proportion of the binder directly affects the rheological properties of the feed. For example, paraffin-based binders can provide better fluidity, but the degreasing process is more complicated. Full ball milling of raw materials can ensure uniform dispersion of each component and improve feeding consistency.
In the injection molding process, the optimization of injection parameters is crucial. Injection pressure, temperature and speed are interrelated and have a significant impact on molding quality. Too high a pressure may cause mold wear and blank defects, while too low a pressure cannot fill complex special-shaped cavities with feed material. The best parameter combination is generally determined through experiments. For example, for small special-shaped ceramic parts, the injection pressure can be controlled at 80-120MPa and the temperature at 150-180℃. At the same time, the injection speed should be moderate to avoid spraying or entrapment due to too fast speed.
Mold design is a key link in injection molding of special-shaped ceramic structural parts. The runner system of the mold should be optimized according to the shape characteristics of the special-shaped parts to ensure that the feed material is evenly filled in the cavity. For example, for special-shaped parts with thin-walled and thick-walled structures, it is necessary to use gradual flow channels to balance the feeding flow rate and prevent material shortage at thin-walled areas or air trapping at thick-walled areas. In addition, the exhaust design of the mold cannot be ignored. Properly setting the exhaust groove or using the parting surface to exhaust can effectively reduce bubbles and pores in the blank.
The degreasing process has a decisive influence on the quality of the final product. During the degreasing process, the binder needs to be removed slowly and evenly to prevent cracking or deformation of the green body. Common degreasing methods include thermal degreasing, solvent degreasing, etc. The appropriate degreasing process can be selected according to the complexity of the binder system and special-shaped parts. For example, for special-shaped ceramic structural parts with complex shapes, a combination of solvent degreasing and thermal degreasing can be used. The solvent is first used to remove part of the binder to reduce the stress during thermal degreasing.
Optimization of the sintering process is also indispensable. Sintering temperature, time and atmosphere need to be precisely controlled to obtain high-density, high-performance special-shaped ceramic structural parts. If the sintering temperature is too high, it may cause grain growth and performance degradation, while if the sintering temperature is too low, sufficient densification cannot be achieved. Generally, the sintering temperature range is determined according to the type of ceramic material. For example, alumina ceramics can be sintered at 1600-1800°C. At the same time, the heating rate and holding time must be controlled to ensure a uniform and stable sintering process.
Quality inspection and control run throughout the entire injection molding process. By testing the feeding performance, green body appearance and size, density and mechanical properties of the sintered product, problems can be discovered in a timely manner and process parameters can be adjusted. For example, X-ray flaw detection is used to detect internal defects of the green body, and the Archimedean drainage method is used to measure the density of sintered products.
By optimizing raw materials, injection parameters, mold design, degreasing and sintering processes, and strengthening quality inspection and control, the production efficiency and product quality of injection molding of special-shaped ceramic structural parts can be effectively improved to meet its needs in various fields. application requirements.
