What is the function of riser tube?
In aluminium casting, especially in low-pressure and differential pressure casting, the riser tube (feed tube or riser pipe) is a crucial component that connects molten aluminium to the mold.
Core role
The molten aluminum in the holding furnace should be smoothly and directionally conveyed from the bottom to the mold cavity to avoid turbulence or oxidation inclusions.
In low-pressure casting, pressure is applied by compressed gas (such as nitrogen) to force the molten aluminum to rise along the riser and fill the mold.
The riser is usually made of refractory materials (such as ceramics and graphite), which can reduce the heat loss of molten aluminum during transportation and prevent premature solidification.
By adjusting the inner diameter and height of the riser pipe and in combination with the air pressure parameters, the flow rate and pressure of the molten aluminum entering the mold can be precisely controlled to avoid air entringing or sand flushing defects.
4.Prevent impurities from flowing back
The bottom end of the riser tube is immersed in the molten aluminum, and the upper end is connected to the mold. Its structural design can prevent the gas or oxide in the mold from flowing back into the furnace.
Typical Application Scenarios
The riser tube is the core component. Under the action of air pressure (0.01-0.05 MPa), the molten aluminum fills the mold from bottom to top through the riser tube, which is suitable for the production of dense parts such as wheel hubs and cylinder heads.
Advantages: Smooth filling, high metal utilization rate (no riser waste).
Recommended use: silicon nitride bonded silicon carbide riser tube.
The mold and the furnace are simultaneously pressurized, and the riser conveys the molten aluminum under the pressure difference, further reducing porosity and enhancing the mechanical properties of the castings.
Recommended use: aluminum titanate riser tubes and silicon nitride riser tubes.
