Foundry Filter Products

Molten Metal Filter Products | Foundry Filters

Niche FPP developed the first high-temperature, silica-mesh filter cloth for the foundry and metal casting industry. Since then, our goal has been continual technical improvement on molten metal filtration.

With investment casting, a well-designed filter cup offers significant advantages over a standard round (“hockey-puck”) geometry ceramic foam or cellular filter used in the pour cone. Flexsil & CerraFlex Filter Cups have a greater surface area on bottom and sides that allows slag and inclusions to be captured without slowing throughput or compensating by selecting a filter with larger pores.

Unlike other products, Molten Metal Filter Products Flexsil and CerraFlex filter cups may be gently removed by an operator from an investment casting pour cone after the molten alloy has been poured. A hot top agent can then be added to the pour cone to maintain the heat of the residual metal so it can flow into the investment tree without impediment.

For foundry sand casting applications (green sand, no bake, etc.), Flexsil and CerraFlex filter products are widely used for filtration and de-gating. Unlike ceramic foam, silicon Mesh can be placed at the riser contact to create a cleavage plane, allowing risers to be easily knocked off. This improves employee safety and lowers operational cost by avoiding the need for bandsaws, hydraulic wedges, and torches.

Flat cut filter sheets can be tailored to the dimensions of the gating, typically at the ingate of the end casting. Riser Breaker or riser knock-off applications will match the riser contact area with an appropriately sized Flexsil or CerraFlex Molten Metal filter sheet to ensure an adequate riser “feed” rate that also provides for a clean and uniform riser “knock-off” later on.

The average cost savings for a sand foundry in de-gating and riser knock off operations can be as high as 50%.


An alternative to cellular ceramic and reticulated ceramic foam filters, Flexsil mesh is made from silica fibers whose coating forms a film of Fayalite (Fe2SiO4) that entraps micron-sized inclusions. Keep Reading


A refractory-coated version of Flexsil, called Cerra-Flex, offers greatly increased thermal properties and rigidity for special investment casting applications using exotic alloys. Keep Reading