STELEX PrO filters smooth metal flow in the mold when used in a conventional gating system. They also remove non-metallic inclusions such as furnace and ladle slag, furnace and ladle refractory materials, molding sand, products of deoxidation, and products of reoxidation. Filtration reduces internal re-work costs in welding and cleaning, reduces the rate of casting returns, improves machinability, improves machine tool life, and increases casting yield. Proper filter use provides improved quality, productivity, and profitability.STELEX PrO filters are high capacity ceramic foam filters specfically developed for high performance priming in steel casting applications. The recommended maximum application temperature is 3056 °F.
They provide optimal priming characteristics for carbon, low-alloy, manganese and high chrome iron-steels. Because STELEX PrO filters effectively prime at lower temperatures than traditional zirconia based filters, many new applications for filtration practice are being developed.
The effectiveness of STELEX PrO foundry filters is due to their foam structure. Some 90% of the volume consists of open, reticulated, interconnected pores. This produces many changes in direction and velocity, leading to intensive contact with the filter surface which allows small non-metallic particles to be retained within the foam structure.
Due to the open pore structure and large surface area, STELEX PrO filters are highly effective in the removal of slag, sand, refractories and deoxidation products suspended in the metal stream.
STELEX PrO foam filters enable smooth, non-turbulent mold filling, thereby reducing the risk of reoxidation defects and molding sand erosion problems.
Filtration effectiveness is largely dependent on the correct application and positioning of the filter. Foseco Product Application Engineers are able to provide technical application support for the calculation and design of gating systems. For correct filter positioning, Foseco’s standard filter print designs are recommended.
STELEX PrO filters are available in a variety of sizes in 10 ppi porosity (ppi = average number of pores per linear inch.).
The Al2O3+C based refractory system in STELEX PrO filters give a number of significant advantages over traditional zirconia ceramic products:
• increased filtration capacity;
• better flow-rate characteristics;
• flexible location in the pouring system;
• filter floats more easily in KALPUR direct pour units reducing risk of chill;
• no disadvantages when re-melting.
STELEX PrO filters are routinely tested to ensure compliance with specifications for physical dimensions, weight, cold compression strength and porosity.
The benefits of foam filtration are seen throughout the foundry. Depending on the alloy and the application, many of the following benefits are achievable:
Scrap Control
• improved ability to diagnose scrap problems due to a clearer separation of metal and mold factors;
• 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
• simplified gating systems since the filter itself will reduce velocity and smooth the flow of liquid metal
• simplified pattern plate designs can allow a foundry to reduce mold sizes or increase castings per mold;
• more molds per melted ton;
• lower levels of cash tied up in work-in-progress.
Casting Quality Improvements
• 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 and increased work schedule flexibility and foundry competitiveness.