|SIVEX non-ceramic filters for aluminium alloys|
SIVEX FC filters are non-ceramic foam filters used in aluminum casting. Although capable of removing inclusions from the metal stream, its primary purpose is to reduce turbulence and ensure quiet, smooth mold filling to minimize the risk of oxidation defects. Best results are achieved when positioned as close to the casting as possible.
SIVEX FC phosphate-free, non-ceramic, reticulated foam filters are ideal for filtering molten aluminum alloys in both sand and permanent molds. The graphite-based formulation provides significant advantages in performance and remelt characteristics compared with conventional alumina-based or silicon carbide-based ceramic foam filters.
SIVEX FC filters clean the metal stream by removing dross and non-metallic inclusions. Because of the filter’s high surface area, even particles much smaller than the size of its pores can be captured and retained in the depth of the filter. The foam structure also smoothes the metal exiting the filter, minimizing turbulence and avoiding air entrainment and oxide formation during mold filling.
The graphite composition is more easily wetted by molten aluminum than are typical filter ceramics, so the metal head height required to prime the filter in the early stages of pouring is reduced. Additionally, the low density and low thermal capacity of SIVEX FC filters reduce heat loss from the metal to the filter, preventing premature freezing and allowing feeding through the filter when used in direct pouring applications.
Because SIVEX FC filters do not contain abrasive ceramic components, the user has more freedom in application and placement - even very close to casting surfaces - since the filter can be removed by cutting or machining without tool damage. With their low density (approximately 60% that of comparable ceramic foam filters,) SIVEX FC filters float readily in remelt so they can be easily removed by skimming. Because of their phosphate-free binder, SIVEX FC filters eliminate any risk of phosphorus pick-up during remelt.
SIVEX FC filters are available in various porosities:
• coarse (10 ppi)
• medium (20 ppi)
• fine (30 ppi)
*ppi = average number of pores per linear inch.
KALFLO for aluminum units can be used for all aluminum alloys . They are particuarly suitable for permanent mold applications as well as hand-molded castings, and horizontal and vertical automatic moulding lines.
The benefits of foam filtration are seen throughout the foundry. Depending on the alloy and the application, many of the following benefits are achievable:
• lower levels of rejects produced;
• reduction in expensive machine scrap and customer returns;
• running systems and downsprues fill smoothly and remain full, reducing the risk of gas bubbles entering the mold cavity.
• 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;
• because SIVEX FC 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.