Tekni-Plex Medical Specialty Extrusions

Tekni-Plex Medical, formerly Dunn Industries, manufactures small-diameter medical tubes with diameters as narrow as 0.008 inches, and inside diameters as narrow as 0.004 inches. For larger medical device and equipment applications, we can manufacture precision medical tubing with diameters as large as 0.480 inches. We are capable of achieving tolerances as low as +/- 0.0005 inches.

In addition, our team of medical extrusion engineers can manufacture a wide range of non-cylindrical profile options for applications that require novel or customized production. These extruded tubes can be spooled or cut to precise length requirements to suit virtually any minimally invasive medical device.

Single and Multi-Lumens

Lumens provide working channels within minimally invasive devices through which fluids or other devices pass. These can be medical tubing solutions with extremely narrow lumens used in neurovascular devices, or relatively large passageways for laparoscopy devices. Tekni-Plex Medical is capable of producing single lumen tubes with diameters as small as 0.008 inches and as large as 0.480 inches.

Multiple lumens are commonly used in interventional devices to allow for multiple fluid channels, accommodate multiple small-diameter medical devices, or both. These lumens come in a wide variety of shapes, from circular channels for guide wires to ‘D’ configurations used in peripherally inserted central catheters (PICC lines). Tekni-Plex Medical has produced small catheters with more than 17 lumens.

With decades of experience manufacturing extruded small-diameter medical tubing, we have established an extensive library of mandrels and dies. These have proven to be invaluable for creating rapid prototypes to accelerate time-to-market for medical device brand customers.

Coextrusion

In the production of small-diameter medical tubing, simultaneous extrusion of multiple materials with unique property profiles can improve functionality and reduce secondary manufacturing operations. Minimally invasive catheters often require discrete physical properties on the inner and outer surfaces. For example, passage of guide wires and other instruments through the lumens requires low-friction polymers on the inner surface of a tube, while atraumatic requirements often require soft, flexible polymers on the outer catheter surface. Coextrusion of different materials for the inner and outer layers allows us to achieve both outcomes.

Minimally invasive device tubes frequently require radiopaque fillers added to the polymer to provide visibility under X-ray or fluoroscopy. However, these compounds can be substantially more costly than unmodified polymers. Coextrusion of longitudinal radiopaque stripes with unmodified polymers can be an economic alternative.

Tekni-Plex Medical offers a wide array of coextrusion combinations for small-diameter medical tubes that include multiple materials, colors, layers, stripes and more.

Tapered Tubing (Bump)

Precision controlled pullers and die head technologies allow for varied extrusion cross-sections along the length of a medical tube. This tapering effect can provide greater access to multiple lumens at the larger, proximal end of the medical device. This is commonly referred to as bump tubing.

Variation in diameter can also enhance the structural performance and feel of the tube. Larger diameters at the proximal end provide clinicians with greater rigidity and control, while smaller diameters at the distal end provide more flexibility for navigation.

Tekni-Plex Medical offers tapered small-diameter medical tubing for single lumen, multi-lumen and coextruded extrusions.

Longitudinal Wires and Jacketing

Wires or fibers can be incorporated along all of part of the walls of small-diameter medical tubes. These inclusions provide benefits such as tensile strength, flexural control or electrical transmission. Jacketing often refers to a wire placed in the center of the extrusion, surrounded by polymer.

Tekni-Plex Medical offers a wide range of options for incorporating longitudinal wire and fibers with custom extrusions for small-diameter medical device components.

Microextrusion

The term “microextrusion” refers to medical tubing solutions with extremely small diameters. Catheters less than 0.33 mm (1 French size) * (3 French size = 1mm) are used to reach the narrowest of blood vessels. Neurovascular procedures also frequently require catheters of this size.

Tekni-Plex Medical has the ability to extrude medical tubing with outside diameters as small as 0.008 inches; less than 1 French size. We can achieve tolerances as low as +/- 0.0005 inches.

*The metric measurement for catheter diameter (mm) can be determined by dividing the French size (Fr) by 3 (i.e., D (mm) = Fr/3). For example, a 3 Fr micro catheter has a diameter of 1 mm. Increasing French sizes correspond to larger diameters).

French GaugeDiameter (mm)Diameter (inches)
10.330.013
1.50.50.02
20.670.026
310.039
41.350.053
51.670.066
620.079

Catheter Mandrel Technology

Tekni-Plex Medical’s catheter mandrels, also known as catheter cores, are precision extruded, solid acetal rods supplied on continuous spools for ease of use during catheter processing operations. Our mandrels are used throughout this process to maintain critical inside wall dimensions during initial extrusion of the inner polymer layer, application of the reinforcing fiber layer, and extrusion or ”jacketing” of the outer layer. Our mandrel diameter tolerances – as low as +/- 0.0005 inches – set us apart from in-house options or competing vendors.

Available in diameters from 0.020 to 0.25 inches, our medical mandrels create reinforced tubing solutions for diagnostic catheters, guide catheters, high pressure contrast injection tubing, and other minimally invasive, small-diameter medical devices. Adding such reinforcement to tube walls improves torque transmission, kink resistance, column strength and internal pressure resistance.

Reinforcements are constructed from metal or polymer fibers, and applied in braided or coiled constructions depending on the application requirements. Application of the reinforcement is typically performed over a thin-wall polymer tube. An outer polymer layer is extruded or hand assembled and reflowed over the reinforcement layer to form the multilayer construction.

Medical catheter manufacturers around the world use Tekni-Plex Medical’s catheter mandrels to retain critical lumen tolerances during extrusion, braiding, coiling and jacketing processes. Low friction material properties and ultra-smooth surfaces allow these cores to be easily removed after catheter shaft assembly.

Catheter Core diameter range (inches)Standard tolerances (+/- inches)
0.0250 – 0.10690.0005
0.1070 – 0.12190.001
0.1220 – 0.15090.002
0.1510 – 0.22490.003
0.2250 – 0.30000.004

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