Rigid Glasweve® Filters for Permanent Mould, Sand-Casting Improvement

foundryinsight badge


Foundries are finding they can save an average of 20 percent per filter when switching from a ceramic foam option to Pyrotek's innovative new filter design used in permanent mould and sand-casting processes.

Importantly, they don't sacrifice casting quality when they make the switch. In fact, casting quality can improve.

Aluminium foundries around the world have long trusted Pyrotek to develop innovative ways to improve their melting and casting processes and overall operational efficiency. For foundries that perform permanent mould casting and sand-casting processes today, the latest innovation from Pyrotek is the new patented Rigid Glasweve® (RGW) filtering technology.

RGWSPM1"While ceramic foam filters (CFF) have been a traditional filtration solution for sand and permanent mold casters, there are many difficulties associated with the product," says Jay Fritzke, Foundry Technical Manager for Pyrotek. "Problems like ceramic inclusions in the melt, CFF sticking to degassing rotors, furnace side walls, and floors, and reduced metal value for recycling can all be avoided with Rigid Glasweve."

RGW—for permanent mould casting and sand-casting processes—eliminates the difficulties foundries find with remelting gating, scrap from too much flow variation, the costs of separating filter pockets from gating, and metal bypass from poorly fitting filters. All are significant challenges presented by CFF. Pyrotek's RGW was engineered to address these challenges, along with others.

Remelting Gating – Problem Free

RGWSPM10Remelting gating efficiently within an existing recycle stream can save casting operations tens of thousands of dollars, and possibly more. Additionally, while several steps are required to remelt CFF gating, gating with RGW, by contrast, can simply be charged into the furnace without contaminating the metal.

RGW filters are less dense than molten aluminium, so they float to the top of the melt during remelting and don’t stick to the furnace walls or degassing rotors. They can be easily skimmed off the top of the melt with the dross.

"Our goal is to maximize our customers’ metal quality and improve their process," says Fritzke. "RGW filters simplify the remelting process."

Eliminate Snow, Reduce Scrap

RGW doesn’t contain any ceramic components, which can break off of a filter and cause ceramic inclusions, also known as "snow," to enter the casting. In RGWSPM11machined castings, Pyrotek has found ceramic snow from filters has resulted in foundries needing to scrap up to 0.7 percent of their castings.

Less Mis-Run and Cold-Shut Scrap

RGW eliminates the flow-rate variability that CFF can generate that leads to the production of mis-run and cold-shut casting scrap.


"Pouring time standard deviation can be reduced by up to 75 percent," says Fritzke. "This is giving our customers a much more consistent, reliable flow rate."

Along with greater pouring consistency, RGW can match current pouring flow rates foundries use with CFF. 

Better Filter Fit - Less Metal Bypass

RGWSPM7Metal bypass from a poor fitting filter can be the cause of many process issues, including lower casting quality, increased scrap rates, inconsistent mould filling times, and mould erosion. RGW is a non-abrasive technology manufactured to tight dimensional tolerances that gives foundries a better fitting filter for every cast.

"Customers can see longer life from their moulds, decreases in oxide inclusions, and improved casting quality," says Fritzke.

Other process benefits foundries are seeing by replacing CFF with RGW include:

  • Additional warehousing capacity (Required storage space is reduced by up to 75 percent compared with CFF)
  • Reduced furnace temperatures (reduced metal thermal loss from RGW filters)
  • Increased amounts of usable recycled metal from remelting 

"We set out to develop for our customers a filter technology that would perfectly fit our customers' existing mould equipment, matched their desired flow characteristics, and had automated placement capability," says Andrew Carlson, Pyrotek Product Manager. "It's great to see aluminium foundries around the world benefitting from this innovation and see their confidence grow over time in Rigid Glasweve once they make the switch from ceramic foam filters."

Posted in Article, Feature, New Product, Product Spotlight.

Tags: Aluminium, Filtration, Foundry.