Catheter extrusion is the process of forming the thin, precise polymer tube that becomes the body of a catheter. It sounds simple — a hollow tube — but a catheter shaft has to slide through the body, hold tight tolerances, sometimes carry several channels, and bend without kinking. That combination makes it one of the most demanding jobs in all of extrusion. This guide covers the main catheter tubing types, how they are made, and what separates a good catheter tube from a rejected one.
The main types of catheter tubing
Most catheter tubing falls into a few construction families, often combined in a single device:
- Single-lumen tubing — one channel; the simplest catheter body.
- Multi-lumen tubing — two or more channels in one wall, for infusing separate fluids, guidewires or inflation.
- Tapered and bump tubing — the diameter changes along the length so the shaft is stiff at the hub and soft at the tip.
- Reinforced tubing — a braid or coil embedded in the wall for torque and kink resistance.
A high-performance catheter frequently uses several of these at once: a reinforced, multi-lumen shaft that tapers to a soft distal tip.
Material comes first
Before geometry, the polymer sets the envelope — flexibility, biocompatibility, bond behaviour and how the tube feels in use. TPU, nylon, PEBA and silicone each suit different catheter roles, and the polymer you choose determines much of what the finished device can do. Hygroscopic materials like TPU and nylon must be dried carefully before extrusion, or the tube comes out with bubbles and inconsistent walls.
How catheter tubing is extruded
The tube is formed on a precision line: dried resin is melted in the extruder, pumped through a die and over a mandrel that forms the lumen, then drawn into a vacuum sizing trough where it is cooled and held to dimension. A laser micrometer reads the diameter continuously and the line adjusts haul-off speed and vacuum in real time to hold tolerance. The whole chain is what a purpose-built medical tubing extrusion line is engineered to deliver — melt stability and take-off precision tight enough to hold microns across a full run.
Why concentricity matters
For catheter tubing, the wall must be even all the way around the lumen. An off-centre lumen means a thin wall on one side (a weak point) and wasted material on the other. Tooling such as a well-centred medical tubing crosshead is what keeps the lumen concentric as the tube runs.
Tapers, bumps and multi-lumen: the hard geometries
The features that make catheters useful are also the hardest to produce. Tapers are created on the fly by ramping haul-off speed and extruder output together so the diameter transitions smoothly. Bumps step the diameter up at precise intervals for bond zones. Multi-lumen tubing relies on fixed pins in the die to form each channel, with the fragile internal walls (septa) kept straight by careful draw-down. All of these are dynamic geometries created as the tube runs, so they lean heavily on closed-loop measurement and a stable melt.
Custom catheter extrusion
Because every device is different, most catheter tubing is a custom job: a specific material, lumen layout, taper profile and tolerance set built to a drawing. Getting it right depends on matching the line, tooling and downstream to that specification rather than forcing a standard setup to fit. If you are specifying catheter tubing or a line to produce it, our team can help match the extruder, crosshead and sizing to your product.
Frequently asked questions
What is catheter extrusion?
Catheter extrusion is the manufacturing process that forms a catheter’s polymer tube by melting a medical-grade resin and drawing it through a die into a precise hollow profile — single or multi-lumen, often tapered or reinforced — held to micron-level tolerances.
What materials are used for catheter tubing?
The most common are thermoplastic polyurethane (TPU), nylon, PEBA (Pebax) and silicone, each chosen for a balance of flexibility, strength, biocompatibility and how the tube behaves at body temperature.
What is a multi-lumen catheter tube?
A multi-lumen tube carries two or more separate channels inside a single outer wall, letting a clinician infuse incompatible fluids, pass a guidewire, or inflate a balloon through one catheter.
Related: compare the polymers in our guide to choosing a medical tubing material, and see our medical tubing extrusion line and medical tubing crossheads.
