Die Approach Makes Sub-Micron Fibers.

New die technology from NonWoven Technologies Inc. in Oyster Bay, N.Y., claims to be a breakthrough in the ability to make fibers thinner than the eye can see. Called a Disposable Extrusion Apparatus (U.S. Patent #5,679,379, issued in 1997), it combines plates to create square and rectangular orifices as small as 0.0005 in., allowing many more openings per inch than are possible by drilling conventional 0.015-in. holes in tool steel, says patent holder Anthony Fabbricante. The process (U.S. Patent #6114016, Sept. 2000) recently made submicron fibers through holes as small as 0.0025 in., believed to be the smallest known. The stainless-steel plates can withstand high pressures (up to 5000 psi) and tolerate corrosive polymers. The firm began converting spinnerets to the new die in 1998 for R&D and expects to commercialize it for a filter product within the next few months.