Rigid Glasweve® Filters for Low-Pressure Casting


Automotive wheel, suspension, steering, and engine component casters around the world have typically had to send aluminium sprue returns, also called “carrots,” out to other companies to be recycled. That’s because these low-pressure casters traditionally use steel sprue filters, which if remelted in-house would cause iron contamination in melting furnaces. Foundries producing 2–3 million aluminium sprue returns annually could pay EUR€200,000–300,000 (USD$232,000–348,000) during that time to have them processed.

With Pyrotek’s Rigid Glasweve® filters, a patented rigidized fibreglass sprue filter, low-pressure casting aluminium foundries are avoiding that expense. Using these special filters, foundries now remelt their own sprue returns—without sacrificing metal quality. Rigid Glasweve filters float to the top of the melting furnace bath because the fibreglass is less dense than the molten metal. As part of routine furnace cleaning workers simply skim them off the surface.

Pyrotek Offerings

Pyrotek makes the filters in custom shapes and dimensions, ensuring they will fit into position and won’t require any changes by the casters themselves. Just like the wire mesh or tin plate filters that casters have been using, Rigid Glasweve maintains its structural integrity throughout the low-pressure casting cycle.

They also remove oxides and inclusions, and successfully convert metal flow from turbulent to laminar. The multiple weave style options of Rigid Glasweve match specifications and metal flow characteristics of wire mesh or tin plate filters.

To help improve product quality control, Rigid Glasweve filters can be manufactured with small metal inserts for filter magnetic handling or X-ray detection or both. Alternatively, they can be vacuum-placed into the sprue at the casting machine.

  • Foundry cost savings by remelting sprue returns
  • Custom filter designs to fit existing moulds
  • Magnetic handling or vacuum handling
  • X-ray detectable
  • No off-gassing


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