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FiltersFiberOx® PBA Ceramic Foam Filters
Phosphate bonded alumina reticulated foam filters, also known as “PBA” filters. PBA filters are refractory, open cell, porous structures composed of high purity alumina. Their reticulated shape provides a deep bed filtration action that thoroughly removes large quantities of impurities without plugging. The economical phosphate bond system is able to withstand significant metallostatic pressure while maintaining efficient filtration. FiberOx PBA filters are typically used in pouring boxes for the primary and secondary smelting of aluminum, as well as for aluminum furnace filters. FiberOx® PBA filters provide the following benefits:
A fine-grain reticulated matrix characterizes FiberOx PBA filters. Uniformly sized spherical pores connect with each other through windows in their walls of about half the pore diameter. The tortuous flow of this structure attracts and captures molten slag and other impurities, resulting in superior filtering efficiency compared to other filter styles on the market. FiberOx PBA filters heat rapidly with little cooling effect on pouring temperature because of their low thermal mass. They have high thermal shock resistance and are easily wetted by molten aluminum. Their superior strength eliminates the need for a metal screen backup. Cleaner metal, improved fluidity, and enhanced metallurgical properties all result in increased profits for the smelter and the foundry. Less costly alloys may be used to produce given tensile and elongation requirements. FiberOx PBA filters are available in standard pore sizes of 10 ppi (pores per inch), 20 ppi, 30 ppi, and 40 ppi. Finer pore size are also available. Standard square shapes are available with either a straight edge or a tapered edge. FiberOx PBA filters can be ordered with gasket materials applied to the edge: Malcolm G. Stevens, Inc can produce custom shapes in different pore sizes for your particular application. In many cases, prototype pieces can be quickly fabricated and the design and performance approved before committing to expensive tooling costs.
Flexsil® and Cerra-Flex® refractory cloth filters serve dual roles in their ability to effectively filter molten metal and to provide a proficient and cost-effective method for de-risering and runner segmentation. The increase in casting quality comes from filtering out the slag and dross that forms in molten metal during the casting process, increasing end-casting machinability while simultaneously reducing the casting line scrap rate. Flexsil Silica cloth traps impurities using a method uniquely different than that of competing ceramic filters. When molten ferrous metals contact the cloth surface, special coating additives decompose to instantly form a continuous film of Fayalite (Fe2SiO4). This Fayalite coating becomes soft and viscous at high temperatures to entrap even micron sized inclusions as they pass through the filter. For Magnesium treated ductile iron, the Fayalite coating absorbs Magnesium reaction products (inclusions) contained in the molten metal, and forms lower melting solid solutions on the surface of the Silica fibers. This helps to trap inclusions on the filter surface, especially the Magnesium dross, sulfides and silicates that are formed by the MgFeSi nodularizing treatment. Conventional ceramic filters are unable to capture molten metal impurities in this manner.
Mica strainers are an inexpensive way to control pours and catch impurities in nonferrous metal sand castings. Standard sizes of 2" x 2" with 22, 93 or 148 hole pattern. Other sizes available upon request. |
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FiberOx® reticulated ceramic foam filters are supplied by Malcolm G. Stevens, Inc.
Flexsil® and Cerra-Flex® Filters
Mica Filters