Ceramic Foam Filters

A ceramic foam filter is a block of ceramic with an open, sponge-like structure. Molten metal flows through its small connected holes, and oxides, slag and other dirt get caught inside. Clean metal goes on into the mould. The result is castings with fewer holes, inclusions and rejects.

Main features

• Catches small particles. The twisting path through the foam traps both large pieces and fine oxide films.
• Calmer metal flow. The filter slows and smooths the stream, so less new oxide forms in the mould.
• Strong at pouring temperature. The filter keeps its shape when hot metal hits it.
• Ready-made sizes. Square, rectangular and round filters in standard sizes, and other sizes on request.

Types by metal

Filter material	Used for
Alumina	Aluminium and aluminium alloys
Silicon carbide	Grey and ductile iron, copper alloys
Zirconia	Steel and other very hot metals

Pore size (PPI)

Filters are graded by PPI (pores per inch, the number of holes along one inch of the filter). A lower number, such as 10 PPI, means bigger holes and faster flow. A higher number, such as 30 PPI, means smaller holes and finer cleaning, but slower flow. The right choice depends on the metal, the size of the casting and how clean it must be.

Where they are used

• Aluminium casting: car parts, wheels, sheet and foil
• Iron foundries: grey and ductile iron castings
• Steel and copper-alloy foundries

Tips for use

1. Keep filters dry and store them in their box until use.
2. Seat the filter firmly in the gating system so no metal can flow around it.
3. Choose a filter area large enough for the amount of metal you pour.

Read more in our article on ceramic foam filters in casting.

How to order

Tell us the metal, the pouring temperature, the filter size and shape you need, and the PPI if you know it. Contact us for a price.