In the casting process, the installation position of the ceramic foam filter directly affects the purification effect of the molten metal and the quality of the casting. The layout of different positions needs to be comprehensively considered in combination with the principles of fluid dynamics, the characteristics of the production scene and the performance of the filter material. The following are key installation strategies and technical points:
Application of the pouring cup area
The pouring cup is the first gate for the molten metal to enter the cavity. Installing a filter here can achieve primary filtration. This method is suitable for manual wet sand molding, iron mold sand coating process and some vertical molding lines (such as DISA molding lines).
- Technical advantages: The slag can be retained on the surface of the pouring cup by buoyancy, reducing the risk of impurities entering the cavity; it is convenient to observe the impact resistance of the filter in real time, and it is convenient to quickly handle abnormal situations.
- Operation points: It is necessary to use a robot for automatic positioning or manual precise placement to ensure that the filter forms a stable contact surface with the inner wall of the pouring cup; before pouring, high-pressure gas is required to remove residual slag to avoid secondary pollution.
- Risk Control: The instantaneous impact force generated by the free fall of molten metal is large. It is recommended to use a ceramic filter with a honeycomb gradient pore structure to disperse the stress.
Configuration of the bottom of the sprue
The integrated filter at the bottom of the sprue is suitable for complex casting systems with multi-mold co-casting, especially in mass production scenarios such as automotive parts.
- System Advantages: The diversion design can balance the flow of molten metal in each cavity and reduce the damage of the filter caused by local overload; it is suitable for the layout of the central sprue with multi-branch cross runners.
- Technical Difficulties: Too high static pressure head can easily cause the filter to be blocked prematurely, and the critical pressure difference parameters need to be calculated through numerical simulation; it is recommended to configure an emergency overflow channel as process redundancy.
Ideal layout of the cross runner
The cross runner is the most recommended installation location for foam ceramic filters, especially for precision casting of small, medium and large castings.
Filter mechanism: When installed vertically, the turbulent flow of the molten metal is transformed into laminar flow through the pore structure, reducing secondary oxidation and gas encapsulation; at the same time, the slag floats to the slag bag, significantly improving the filtration efficiency.
Engineering practice:
The filter is installed vertically, and its thicker filter sheet can withstand continuous scouring of the molten metal.
Avoid horizontal installation to reduce the interference of turbulence at the bottom of the sprue on the filtration effect.
Material selection:
Silicon carbide material is resistant to high temperature impact (1500℃) and is suitable for cast iron and copper alloys.
Zirconia material has higher heat resistance (1760℃) and is suitable for cast steel and high-temperature alloy casting.
Alumina material is suitable for aluminum alloy purification.
Conclusion
The pouring cup configuration is suitable for small-batch flexible production, but the casting filter needs to be replaced frequently; the sprue integration is suitable for large-scale production, but the pressure difference risk needs to be controlled; the vertical installation of the runner is the best solution, which can take into account both filtration efficiency and process reliability.