Sefar America Inc. offers SEFAR Micro Tube, an ultrasonically seamed tube with an ID ranging from 2-10 mm (0.08-0.4 in). The seam is an overlap construction and reportedly provides a true circular cross-section. According to Scott DeWitt, manager of market and product development, there was previously no way to make circular cross-section filtration tubes as small as this product without protruding seams. "This is an exciting breakthrough, particularly for insert injection molders who struggle to make small diameter in-line filters. This technology will reduce material handling and offers several advantages over previous technology."
The primary benefit is said to be the ultrasonically welded seam, which forms the tube. It is inherently stronger than other types of seams, giving designers the option of eliminating longitudinal ribs normally used to encapsulate the weak seams, according to Mr. DeWitt. Eliminating the molded ribs reportedly provides more flow area through the filter, so reduced component sizes are possible.
The micro tubes can be made from a variety of the company's filter fabrics. Applications include medical IV filters, blood filters, in-line air filters, and more.