Coextrusion is the process of combining 2 or more extrusions to produce tubing with layers of 2 or more materials. Coextruded multilayer tubing can combine materials with different but complementary properties—including durometer, color, opacity, radiopacity, or tensile strength—to provide custom catheter solutions. The most common application is medical extruded tubing with radiopaque stripes visible under X-ray. This is accomplished by encapsulating stripes containing a filler visible under X-ray within the wall of the tubing. Typical fillers include these compounds, which can be used in various concentrations to enhance radiopacity:
Tapered tubing has a transition in outer and inner diameter in a section of the extruded tube. More complex than typical extrusion operations, tapered tubing production requires sophisticated control on the tube pulling/cutting station combined with other process equipment to achieve precise tapered tubing dimensions.
Bump tubing is similar to tapered tubing but has a bump (area of increased outer diameter) along the length of the tube.
The dimensions that can be achieved using this technology depend on the material used. Advantages of this type of specialized extruded tubing include eliminating labor-intensive assembly steps such as welding and stretching.