Medical tubing | machinery feature
While new materials are an important factor in the latest medical tubing, advanced machinery is also a vital component in creating the right product. Lou Reade reports
Machinery helps deliver advances in medical tubing
Medical tubing relies heavily on materials advances. However, it is also critical that these materials are processed correctly – especially when making micro- bore tubing. Davis-Standard recently sold a PLLA tubing line to a
medical start-up in Tianjin, China. The line, installed last year, is making products ranging from 1.7 to 2.0mm OD with a tolerance of +/-20 microns. As the market for polymeric and antineoplastic
devices for internal drug delivery continues to grow, so does manufacturing of micro-bore tubing made from PLLA (Poly-L-Lactide), says the company. “PLLA is a bio-absorbable resin ideal for applica- tions that require a polymer to reside in the body for a controlled length of time before safely degrading and being absorbed internally,” said Glenn Beasley, senior sales engineer for Davis-Standard. “Very few companies process this material due to the high resin cost and diffi culty in achieving a quality end result.” The line can process tubing from PLA and PLLA as
well as a variety of other thermoplastic resins at rates up to 50 meters per minute. Davis-Standard supplied the entire line, including a fl ood cooling tank. Beasley noted this type of cooling has usually been problematic for PLLA. However, recent developments in formula- tions permit water cooling for a limited residence time without compromising the tube surface. “To ensure immediate success, the customer relied on us to address their requirement of tight OD/ID
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tolerances and a smooth, gel-free tube surface when processing PLLA,” said Beasley. “The high cost of this material requires a fast start-up and no room for error during processing to keep costs reasonable.” Medical tubing remains a strong market for Davis-
Standard in China. The company has a subsidiary in Suzhou with a lab line that can demonstrate PLLA technology, among other processes. Depending on application, Davis-Standard’s turnkey medical tubing systems can support extruder outputs up to 700 pounds per hour (315kg/hr) and line speeds up to 800 feet per minute (240m/min). The material range includes PLA, Peek, FPVC, polyurethane, nylon, Pebax and FEP. Extruder options are available depending on process and application and engineered for a fast delivery and competitive pricing. Advantages include line control with data acquisition, precision vacuum sizing, closed loop ID/OD control, ultrasonic gauging, puller/cutter systems and more. The Suzhou lab features direct-drive 19mm and 24mm single screw extruders, each with a polymer melt pump, three-layer spiral fl ow tubing die, PLC line control with data acquisition, vacuum sizing tank for both rigid and fl exible products, closed loop ID/OD control via an ultrasonic gauging system, a servo controlled combination puller/cutting system, and a transport conveyer with single-zone air eject. The lab also includes a single layer tubing line designed specifi cally for the production of FPVC tubing for
Machinery and materials
advances are
both vital in the development of medical tubing
September 2016 | PIPE & PROFILE EXTRUSION 13
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