SEDEX filters prevent the ingress of slag, metal treatment residues or sand grains into the mold cavity. The inherently large surface area is well suited to intensive filtration and even finely distributed slag particles are retained both on the filter surface and in the filter structure. The high filtration effectiveness combined with a reduction in turbulence often allows gating systems to be greatly simplified. SEDEX filters can be positioned vertically, horizontally, or diagonally in a suitably designed runner system.

Filtration effectiveness is largely dependent on the correct application and positioning of the filter. Foseco Application Engineers are able to provide technical application support for the calculation and design of gating systems.

The filter can be positioned vertically, horizontally or in a horizontally inclined position depending on the specific application. For correct filter positioning, Foseco’s standard filter print designs are recommended.

SEDEX filters are available in a variety of sizes and 4 porosities:

• coarse (10 ppi)
• medium (20 ppi)
• fine (30 ppi)
(*ppi = average number of pores per linear inch.)

The benefits of foam filtration are seen throughout the foundry. Depending on the alloy and the application, many of the following benefits are achievable:

Reject Control
• lower levels of rejects produced;
• reduction in expensive machine scrap;
• running systems and downsprues fill smoothly and remain full, reducing the risk of gas bubbles entering the mold cavity.

Productivity Improvements
• higher tonnage shipped to tons melted ratio (yield) due to the elimination of long running systems;
• simplified gating systems since the filter itself will reduce velocity and smooth the flow of liquid metal;
• simplified pattern designs can allow a foundry to reduce mold sizes or increase castings per mold;
• more molds per melted ton;
• because SEDEX filters prime more easily, pouring temperatures may be lowered;
• lower levels of cash tied up in work-in-progress.

Casting Quality Improvements
• greater consistency in casting cleanliness;
• reduction in the variability of metal flow of hand-poured castings leading to increased casting consistency;
• improved mechanical properties due to greater metallurgical consistency;
• increased fluidity of the metal improves casting finish, appearance and surface details.

After Cast Operations
• improved machinability and reduced tool wear;
• machining allowances can be reduced with confidence due to a lower level of inclusions;
• reduction in inspection and expensive time-consuming non-destructive testing operations;
• faster cycle times, provided by fewer and faster after-cast operations like finishing and inspecting, can lead to increased work schedule flexibility and foundry competitiveness.