Pyrotek has developed a new filtering product for foundries called Rigid Glasweve®. This patent-pending rigidized fibreglass sprue filter helps low-pressure casting aluminium foundries save money by internally remelting their own sprue returns—without sacrificing metal quality.
As pressure causes molten aluminium to rise in the stalk tube, it passes through a filter in the sprue bushing to fill and solidify in a mould. Along with the resulting cast aluminium part, there is also excess solidified metal that contains the sprue filter.
Until now, foundries typically haven’t been able to remelt and recycle aluminium sprue returns, also called “carrots,” internally. That’s because foundries conventionally use steel sprue filters, which would cause iron contamination in the melting furnace. Due to this, foundries have had to pay external companies to process their sprue returns, which can each weigh 150–250 grams (0.3–0.5 pounds). If a foundry produces 2–3 million aluminium sprue returns per year, the annual cost to have them externally processed is about EUR€200,000–300,000 (USD$236,000–$354,000).
Using Rigid Glasweve filters results in the filters floating at the top of the melting furnace bath because the fibreglass is less dense than the metal. Workers simply skim them off as part of normal furnace cleaning.
Rigid Glasweve filters combine a heat-resistant fibreglass fabric and a patented mixture. A unique manufacturing process is used to produce the filters, and they are robust enough that they maintain their shape throughout the low-pressure casting cycle. Pyrotek makes the filters in multiple shapes and dimensions, and designs can be customized. They don’t generate toxic fumes or gases when used or create porosity in cast parts, unlike competitor filters made of fibreglass with phenolic coatings. Rigid Glasweve filters are rigid enough that they don’t move during casting, compared with other fibreglass filters on the market that are easily displaced by molten aluminium flow.
Pyrotek adds small metal inserts to Rigid Glasweve filters in foundries where magnetic handling or X-ray detection or both are utilized, helping improve quality control.
Pyrotek is also offering Rigid Glasweve for the additional purpose of ceramic foam filter (CFF) replacement in permanent mould and sand casting.
In contrast to ceramic foam filters, Rigid Glasweve filters provide customers with a cost-effective solution that doesn’t reduce casting quality. Thus far, customers have seen benefits such as more consistent pouring times, easier recycling gating, and an improved mould fit to prevent metal bypass.
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Posted in New Product.