The online molten metal filter unit has a porous ceramic foam filter installed horizontally in the filter box. The filter box is provided with an inlet and an outlet for molten metal. When operating the device, metal is supplied through the inlet to completely cover the filter, and the outlet is closed, whereby the box is placed in a vacuum, so that the metal is forced downstream through the filter. Then, once the metal flow starts, a vacuum is drawn and the outlet is opened so that the metal can flow through the filter under the force of gravity. Therefore, the vacuum is only used to induce the metal to flow through the filter.
The online molten metal filter unit includes a metal casing or an internal heat-insulating internal cladding made of heat-resistant insulating and refractory materials. A removable lid is provided on the top of the container to keep the container sealed during the operation of the ceramic foam filter (CFF). The container has an inlet (the inlet chamber should be as small as possible), and an outlet chamber with a CFF filter installed on the outlet chamber.
The use of CFF filters requires additional costs. These costs are partly related to the filter itself, which usually must be replaced after each casting operation. There are also costs involved in heating the CFF filter and filter box.
For filters with small pore sizes (>50 PPI (pores per inch)), activating the entire filter during start-up and making it function optimally may also be problematic. The primer of the entire filter is usually related to the correct preheating, but can also be related to obtaining a sufficiently high pressure through the initial metal of the filter.
Before metal filtration operations, the preheating of the CFF filter and the filter container is very important. This can be done by a preheating system through the inlet or outlet opening, or some preheating can be done in the lid of the filter container.