Source: American Kuhne.
AK FluroFEP micro tube with six x-ray stripes.
American Kuhne has developed a 16 mm micro extruder designed to process fluoropolymers for miniature medical device applications such as fine wire jacketing for neuromodulation, microdialysis tubing and neonatal intravenous (IV) catheter tubing. These applications typically require an extruder that can process high performance fluoropolymers (ETFE, PFA and FEP) at very low volumes down to 3.4 grams/min (0.45 lb/hr).
Unlike most medical grade thermoplastics such as polyurethane, nylon and Pebax, it is difficult to process fluoropolymers on extruders smaller than 16 mm because the special corrosion resistant screw materials that are used such as Inconel and Hastelloy have low torsional strength and are prone to break at diameters below 16 mm. The smallest extruders for these applications have traditionally been 3/4-inch (19 mm) machines. The benefit of a 16 mm extruder for micro extrusion applications is an approximate 45% reduction in the minimum output rate and a short residence time in the barrel, which helps to minimise thermal degradation especially compared to traditional size extruders 3/4 inch (19 mm) and 1 inch (25 mm) running at very low screw speeds.