Extrusion Overcoating & Overjacketing
In overjacketing or overcoating, a core mandrel with one or more components (the substrate) is fed through an extruder to add a layer of thermoplastic polymer over the substrate. An example of a common substrate is an etched PTFE liner with a reinforcing stainless steel braid, onto which a Pebax® or polyurethane extrusion can be applied (for example). The extrusion overcoating fully encapsulates the braid and adheres to the innermost layer of the substrate (the PTFE liner). A wide variety of polymers can be used for overcoating, and substrates may be coated with like material.
There are numerous benefits of extrusion overcoating. In the above example, the overjacketed wire braid gives the tubing greater kink resistance and a higher pressure rating, making it ideal for catheter shaft applications. Overcoating can also be used to apply a thin polymer layer over metallic guide wires. Extrusion overcoating can be used to provide insulation for electrodes, to provide damage protection for sensitive technology (such as sensors or optical fibers), and more.
Overjacketing by DUKE Extrusion
DUKE Extrusion can add extrusion overcoating to single lumen tubing with multiple embedded axial fibers or wires. We can provide overjacketed tubing as small as 0.005" of an inch or as large as 1/2” in diameter; substrate wires and cables can be coated with a thermoplastic layer as thin as 0.001".
We can overjacket laser cut hypotube for balloon catheter applications, where the balloon is bonded to the tubing’s composite structure. This process can be used to create catheter products of variable stiffness.
DUKE works with numerous materials in extrusion overcoating, including polyurethane, Pebax®, nylon, and PET. We will work with you to determine the ideal overjacketing material for your unique application.