When producing large castings, special attention is paid to the setting of the filter. What to consider when using ceramic filters?
①Select the appropriate type of filter.
②The filtration capacity of the filter should be considered.
In general filter, for gray iron, the capacity of the filter per 1cm² to filter molten iron is 4~6Kg.
For ductile iron, the ability to filter molten iron per 1cm² is 2 to 4Kg.
For insurance, the lower limit is usually taken.
③ The effective filtering area of the filter should be considered.
The blocking section cannot be set at the filter part. There are also data showing that the filter is suitable to be set in the open casting system. The filter should be avoided in the closed casting system as much as possible.
The porosity of filters produced by different manufacturers is also quite different. When designing the gating system (especially the size and quantity of the filters), it is necessary to ensure that the sum of the effective filtering areas of all the filters in the gating system is >(2~5) times the blocking cross-sectional area.
④The placement of the filter
Place the filter as close as possible to the cavity casting for the best filtering effect.
Try to avoid the molten metal directly impacting the filter, and the pouring height should preferably be ≤300mm when directly impacting the filter.
⑤ The filter should not have any abnormal conditions such as cracks and moisture before use.
Another main function of the filter is to change the flow state of the molten metal, so that the turbulent molten metal in the gating system passes through the filter to form an advection state. Filters can be “icing on the cake”, but don’t imagine that just relying on the filter can filter all slag inclusions.