Dexmet Corporation, the manufacturer of precision expanded metals, foils and polymers, has added a high performance polymer to its PolyGrid® portfolio.
According to Dexmet, this was driven by the need to provide solutions for increasingly harsh environments in filtration for the industrial market. Dexmet chose APTIV® film made with VICTREX® PEEK polymer to add to its portfolio where an expansion procedure using specifically designed proprietary equipment and processes is used to produce diamond configured, open area mesh products.
Critical applications requiring high temperature stability to filter caustic gases or fluids, such as in the semiconductor, chemical processing, and petroleum/gas industries, have traditionally used polymers such as polytetrafluoroethylene (PTFE), perfluoroalkoxy copolymer (PFA), and ethylene chlorotrifluoroethylene copolymer (ECTFE).
"All of these materials provide excellent temperature and chemical resistance but none match the mechanical strength provided by the expanded APTIV films," explained Ken Burtt, vice-president of Sales and Marketing at Dexmet. "With the continual increase in demands on filter performance, VICTREX PEEK-based PolyGrid is the solution to meet the critical performance challenges."
"When Dexmet approached us they were familiar with PEEK but our ability to offer them this performance capability in a thin film format was revolutionary," said Tim Herr, Global Films Business Leader, Victrex Polymer Solutions. "Combining our material with their processing capability represents a significant advantage for Dexmet's customers and enables them to tailor a solution to their end use application requirements."
Dexmet utilises a precision expansion process which combines a 'slit and stretch' function to produce the high performance mesh product. "It's a process that's been around for over 100 years," said Burtt. "What makes it unique to Dexmet is our ability to produce an expanded product on very thin materials with very small openings at wide widths. There are no other expanders in the world that can expand thin materials, especially polymer films under 0.127mm (0.005in) with opening sizes down to 25 microns." The process has infinite variability which enables Dexmet to tailor a product to exact performance requirements, whether it is opening (pore) size, open area, weight per area, or overall thickness.
While variability is the major advantage of the expansion process, another is the yield per pound or linear foot of raw material. Because it's an expansion process, it will always yield more finished product than the initial raw material amount. "Unlike a perforation process that produces an open area product by punching holes in the material and producing scrap, the expansion process does not 'punch out' material to produce the hole so yield increases while minimising waste," continued Burtt. "The expansion process becomes a more economical solution when using precious raw materials such as silver, nickel, titanium or even the APTIV PEEK films."
Another advantage especially important in a filter design is that the material is one homogenous unit. "The strands do not move relative to the other strands so opening sizes do not change," said Burtt. "And, the material has a three dimensional geometry, which allows for multiple flow directions, improving cross flow while reducing pressure drop."
