At present, most aluminum foundries use plate filter equipment, which mainly filters through ceramic foam filters.
The following issues should be paid attention to when designing and using ceramic foam molten aluminum filters:
(1) According to product requirements, select a filter material with appropriate pore size. Generally, 50PPI ceramic foam filters are used for extruded products that require high internal purity, and 30PPI filters can be used for other general products. Properly improving the filtration accuracy will reduce the tendency of the ingot to produce coarse crystals and feather crystals.
(2) From the perspective of improving the filtering effect and service life of the filter, the effective filtering area of the filter should be increased as much as possible, that is, a large-size filter should be used.
(3) When installing the ceramic foam filter plate in the filter box, it should be tight and seamless to prevent molten aluminum from leaking.
(4) Before use, the filter should be fully preheated, and the preheating temperature should not be lower than 720℃. In the interval between casting times and melting times, attention should also be paid to heat preservation.
(5) In order to meet the requirements of fine filtration and to improve the service life of the filter, it is best to use glass cloth to coarse filter the melt before the ceramic filter.
6) Reasonably arrange production, and try to avoid frequent changes of alloys that hinder the effective use of filters.
(7) When filtering, it is strictly forbidden to sprinkle flux powder in the filter and the static furnace launder. During the casting process, the static pressure head of the melt should rise steadily to prevent fluctuations in the liquid level and vibration and shock to the mold. Before the casting is finished, the scum on the metal surface of the filter should be removed to avoid clogging of the filter plate.
(8) Prevent secondary pollution of the filtered melt.