CFF filter has been widely used in actual production. They are very common on-line filtration systems used in the production of standard products (rolled slab or squeeze billet casting).
CFF ceramic foam filters are popular because of their small size, compact structure and easy use. In order to improve filtration accuracy, the pore size of the filter plate has been developed from 20-50ppi to 60ppi, 70ppi, and a composite filter plate appears, that is, the filter plate is divided into upper and lower layers, with a large pore size on the top and a small pore size on the bottom. Varieties and specifications are 30/50ppi, the composite filter plate has a good filtering effect and a large amount of metal.
CFF filtration equipment adopts the principle of deep filtration. The ceramic foam filter is a porous medium, and the molten aluminum flows in this medium according to the set route. In order to avoid the second pollution caused by the oxide layer, the movement in the gap is a layered trajectory. Particles are blocked by four methods: direct interception, inertial force, Brownian motion, and gravitational force. The impurities are gradually absorbed by the wall and gradually block the filter layer. The filtration efficiency increases with the increase of inclusion particle size and filter thickness, and decreases with the increase of pore size and metal flow rate.
In semi-continuous casting, the original casting process stipulates that the filter plate must be replaced every time the casting, that is, the filter plate is only used once. In other words, it is thrown away without seriously affecting the filtration efficiency. Therefore, the researchers conducted a study on the effect of metal flow rate on the filter efficiency. The test proves that the flow rate is set correctly, and the filter after continuous use is very efficient. When the speed is too fast, the efficiency continues to decline over time.
The focus of the development of on-line filtration technology outside the modern melt furnace should be whether the filtration effect can effectively remove the inclusions in the melt. Tubular filtration, deep bed filtration and CFF filtration are accepted by most aluminum foundries.
Regardless of tube filtration or deep bed filtration, the best configuration is to add CFF filtration equipment before filtration, so as to achieve the most perfect combination to obtain the most ideal filtration effect.