These are exciting times for extruders, who are being pushed by the challenging designs and smaller features their medical device customers are requesting. So far, equipment manufacturers are making improvements (often incremental) to meet these growing needs, turning to technologies such as finite digital machine control, automated manufacturing processes, and expanded IoT capabilities. This is especially true for customized extruded tubing and complex profiles for various medical applications across a number of diverse sectors such as drug and fluid delivery systems, surgical instruments, diagnostic devices, and dental tools.

Additionally, advancements in minimally invasive surgeries and the growing demand for precision medicine have heightened the need for unique medical extrusions and engineered material qualities. And a critical part of being able to create complex profiles with tight tolerances and specific characteristics is finding the right materials.

“By altering the properties of unmodified base resins, extrusion can create customized tubing and profiles with unique properties, utilizing advanced polymeric resins and incorporating additives as required,” said Varun Venoor, senior extrusion engineer for Teleflex Medical OEM, a Jaffrey, N.H.-based medical device development and manufacturing partner.

Medical device manufacturers (MDMs) are always looking for ways to integrate technology, equipment, tools, and materials into fewer and faster steps. As a manufacturer of extrusion equipment, PLA GIKEN Company, an Osaka, Japan-based designer and manufacturer of precision extrusion equipment, sees a trend toward MDMs seeking “turn-key” extrusion solutions, sometimes for their own internal use. As medical devices become increasingly complex, and their components more diverse, “it becomes challenging for companies to continue to invest in ‘upstream’ technologies, such as extrusion,” said Yoshiharu Kikuzawa, president of PLA GIKEN Company. “One solution is outsourcing processes and/or components to contract manufacturers, but sometimes MDMs often want to keep their innovations to themselves. To do this, the challenge becomes constructing a custom extrusion line that suits their purposes. This is where a company like us, which supplies full-line equipment and support during process development, comes into play.”

Latest Trends

MDMs and their contract manufacturers (CMs) are challenged by more complex extrusion designs due to technology advancements and more functionality in new devices, which typically requires a shift from common commodity tubing to highly specialized materials, geometries, and features. “Shrink tubing, for example, in a variety of materials and options, is a strong bull market, with the need to combine tubing with other components of assembly in a safe and efficient manner,” said Lawrence Alpert, manager of medical extrusion technologies for Graham Engineering Company, a York, Pa.-based manufacturer of integrated extrusion systems for various industries, including medical devices.

These complex tubing designs and structures can include multiple, irregular lumen shapes, layers, stripes composed of varying materials, or sometimes combinations of these features. In terms of dimensions, extrusion technology is achieving increasingly smaller and narrower profiles—for example, sophisticated and accurate pressure controls can minimize tubing wall variations and allow for smaller sizes, such as outer diameter (OD) less than 0.01 inches, inner diameter (ID) about 0.0006 inches, and wall thickness less than 0.001 inches.

“After COVID-19 turned the medical extrusion market from a focus on procedural microtubing to commodity airway tubing, the market is now refocusing on high-precision microtubing, with the innovation necessary to keep pushing the boundaries of this market forward,” said Alpert.

Among medical applications, the atrial fibrillation ablation sector stands out as a hotbed of growth and innovation. “Notably, there is a shift in patient preferences away from daily oral anticoagulant medications toward more enduring solutions,” said Clement Mosnier, product manager for medical extrusion for Saint-Gobain, a Solon, Ohio-based medical components contract manufacturer. “The impending FDA approvals for pulsed-field ablation [PFA] technologies, and the active development of combination PFA/radiofrequency devices, are contributing to the increasing demand for extrusion services, particularly to produce ablation catheters and irrigation systems.”

There is a shift in medical extrusion toward biocompatible and bioresorbable polymeric materials. These unique compounds offer advantages such as reduced risk of adverse reactions, compatibility with physiological environments, and the ability to degrade naturally over time (for example, magnesium), eliminating the need for subsequent interventions. In addition, numerous research efforts from resin manufacturers have focused on the development and commercialization of biobased resins that offer comparable performance and function to traditional fluoropolymers. To enhance patient safety, there is also “a clear trend toward manufacturing products that had been made from PVC [polyvinyl chloride] and di (2-ethylhexyl) phthalate [DEHP] to being manufactured with non-PVC, or at least non-DEHP plasticizers,” said Sergio Medina, chief technology officer for PiSA-USA, a contract manufacturer for the pharmaceutical and medical device industries with commercial operations in the U.S. and primary manufacturing facilities in and around Guadalajara, Mexico.

More MDMs are asking their extruding partners for tighter tolerances, more complex configurations, and greater consistency. “These demands are pushing processing limits but, at the same time, inspiring innovation,” said Jason Cummings, vice president of sales and customer service, fluid management, for Spectrum Plastics Group, a DuPont Business headquartered in Wilmington, Del., that provides medical components and devices contract manufacturing services. “Our engineers are highly skilled in solving challenging projects, enabling next-generation medical devices a speedier time to market release.”

Medical extrusion continues to evolve in exciting ways, driven by technological advancements and the growing demand for innovative healthcare solutions, including miniaturization, advanced materials, multi-layer and coextrusion technologies, and the quest for non-fluoropolymer resin alternatives. “Thin-walled extrusions with tighter tolerances are in high demand, with larger IDs employed in structural heart applications, such as catheter builds, while smaller ID tubing finds use in neurovascular interventions,” said Mihir Goradia, engineering manager for Teleflex Medical OEM in Annacotty, Ireland.

Multi-layer extrusion and coextrusion techniques continue to gain momentum in medical applications. These processes enable combining dissimilar materials with varying properties, such as flexibility, strength, and barrier properties, within a single extruded component. “This versatility promotes the creation of tailored products that meet specific medical requirements,” said Goradia. “By incorporating multiple layers and materials, manufacturers can develop medical devices with enhanced performance, improved drug delivery capabilities, and superior infection control measures.”

What OEMs Want

MDMs count on advanced extrusion equipment to achieve consistent, optimal results by delivering precise control over crucial process parameters. Expectations include accurate measurement and control of OD, ID, and wall dimensions using seamless and easy validation processes, including sophisticated data gathering and analysis. MDMs also want to use versatile polymer resins that allow for diverse product designs and specifications, without significant reconfigurations. Ultimately, the end result is a well-designed “turnkey” extrusion solution that strikes a balance between performance, reliability, and affordability.

Beyond the basics of high quality, consistency, and competitive pricing, OEMs are asking for rapid product development and the ability to ramp up production quickly. “Simply put—speed to market,” said Cummings.
This means process optimization is crucial, as it enables continuous enhancement of extrusion techniques by fine-tuning parameters such as melt temperature, die design, and screw speed. “This not only ensures consistency but also emphasizes the need for ensuring quality at source by continuously monitoring critical-to-quality specifications,” said Goradia. “Moreover, incorporating updated control systems for automation, real-time process monitoring, and data logging enhances precision and traceability and minimizes human error.”

Mosnier added that de-risking supply chains is another top priority for MDMs, including domestic/localized manufacturing. Less risk means operations are more efficient and easier to predict, and problems are easier to fix, thereby saving time and money and getting products to market faster. “De-risking is a common theme among both supply chain and product development groups,” he said. “Engineers seek some assurance that our products will meet their performance and regulatory requirements before they begin feasibility testing. Our ability to provide product support data, whether that be in the form of bending radius, chemical resistance, or ISO 10993 testing, is paramount.”

Technology Advancements

With precise control over die design and advanced cooling methods, extruders can produce profiles with extremely tight tolerances and intricate geometries. This enables the creation of micro-extrusions or thin-walled structures that were previously very difficult to achieve. Such advancements open up new design possibilities in various segments within the medical device industry.

A recent innovation for PLA GIKEN is the “Mixing Head,” an extrusion mold for designing catheter shafts that enhances catheter performance and production efficiency. A catheter shaft consists of tube segments that have different degrees of hardness (from the soft distal end to the hard proximal end) that are welded together, using a heat shrink tube and heating chamber. “The Mixing Head offers an alternative way of achieving gradual stiffness change in the catheter shaft by extruding resins directly on the core,” said Kikuzawa. “We have already applied this technique to endoscope insert tubes and similar products.”

Additive manufacturing (AM) is transforming how medical components and products with highly complex and high-resolution features are manufactured—but not in the extrusion industry. However, Spectrum Plastics Group has developed proprietary AM technologies and processes to create virtually limitless 3D-printed components from medical-grade thermoplastic materials. “We use the exact same resins in our AM process that would be used in the production extrusion process,” said Cummings. “This allows us to move from concept prototyping into full-scale production quickly. We can 3D-print single- and multi-lumen tubing configurations in multiple materials with turnaround times of hours to days. This allows our customers to move through the development phase more quickly and launch into production seamlessly.”

On Line Controls, a Shrewsbury, Mass.-based manufacturing company that builds “MicroAir” ultra-low air pressure regulators and controllers for plastic tubing extrusion, operates within a strong niche market. MicroAir provides high precision control of tubing outside diameter by regulating air pressure to a set point during the manufacture and extrusion of all types of profile extrusion for plastic medical, catheter, and automotive tubing.

Sizeable diameter variations can be caused by the slightest pressure change during the extrusion of thin-walled products. To avoid this, the MicroAir uses differential air pressure to shape the interior of the tube by maintaining outward pressure on the sizing tooling. The outward pressure ensures the finished product has a proper ID and OD. Some extrusion materials, such as fluoropolymers in medical tubing, require special attention for air handling and evacuation systems.

“High-precision machining has allowed us to achieve higher precision and accuracy in our MicroAir units, allowing them to reach lower pressures,” said Kay DeWolfe, president of On Line Controls. “We have had frequent orders for units with ranges of 0.0 to 2.0 inches of water, as we can now regulate down to 0.2 of water [0.00072 psi] with high precision.”

She also noted the growing preference for higher functionality (more lumens) in tubing. Thirty or more lumens can be packed into a tube, “which then requires more air controllers to control each lumen in the tube,” said DeWolfe.

Advancements in quality inspection techniques have enhanced the reliability and efficiency of extrusion processes. Non-destructive testing methods such as inline vision systems, ultrasonic testing, and optical inspection systems allow for continuous quality monitoring during production. These technologies ensure the detection of defects, wall thickness variations, or surface imperfections, enabling manufacturers to address issues promptly and maintain high-quality standards.

“As tubing products continue to get smaller, inspection systems must be able to measure smaller items with greater accuracy, said Martin Forrester, R&D technical manager for GlobalMed/MDI, a Tempe, Ariz.-based global provider of specialized engineering and manufacturing services to the medtech industry. “The ability to share production data allows for more refined processing and higher levels of quality.”

The Internet of Things

The Internet of Things (IoT) and Industry 4.0 technologies, when integrated into extrusion systems, can capture and analyze data from production lines, providing a higher level of understanding of overall equipment performance. By incorporating IoT technology, extruders can use sensors to collect real-time data, such as temperature, pressure, and speed, throughout the extrusion process. This data is then analyzed and processed to identify anomalies, enabling operators to make data-driven decisions, improve process control, and enhance product quality.

For example, the interrelation between plastic extrusion process parameters and product quality is critical to ensure quality. “Factors such as melt temperature, cooling rate, die design, line speed, and material composition significantly influence the final product’s characteristics, such as dimensional accuracy, surface finish, mechanical properties, and uniformity,” said Goradia. “Understanding and managing these process parameters is crucial for achieving consistent and high-quality extruded products.”

Software tools can integrate various IoT technologies into a single platform to further enhance efficiencies and capabilities. For example, Graham Engineering’s Navigator XC300 control technology utilizes an industrial PC to enable intuitive, integrated process control. Navigator XC300 is available in a variety of models, including configurations for standalone extruders, multi-extruder operations, and extrusion systems with downstream components such as pullers, water baths, or winders. It can also be customized to meet specific customer operational requirements.

“Navigator XC300 is naturally compatible for IoT applications, as it is nearly limitless in storage and retention, fully integrated with all upstream and downstream devices as well as measurement devices,” said Alpert. “It is based on a Windows platform, allowing for ultimate flexibility to integrate with processors’ total quality management systems. The Navigator also allows users to remote monitor or control from virtually anywhere with common devices such as iPhones, tablets, and PCs.”

IoT also has a role in the integration of hybrid equipment. A common hybrid application is coextrusion, where multiple materials are extruded simultaneously through separate channels, enabling the creation of composite or multi-layered profiles. Tri-extrusion is another hybrid approach involving the simultaneous extrusion of three materials to form multi-component profiles, ideal for applications such as medical tubing with varying properties like softness or transparency.

“The extruders in tri-layer systems, in an integrated and human-machine interface [HMI]-controlled environment, can be moved from one line to another to allow for one, two, or three extruders, without concern for which extruder’s HMI is the controlling or controlled system,” said Alpert.

GlobalMed/MDI has developed its own in-house hybrid lines for producing specialty tubing. One example is for tubing used for surgical smoke evacuation. “We designed a novel process to achieve differentiated tubing inline without secondary processes,” said Forrester. “The inline process is automated for quality and reliability, including the proper amount of stretch, which results in extruded tubing that is more elastic at the device end, providing a better user experience for the surgeon without increasing cost.”

Another GlobalMed/MDI advancement is an innovative extrusion process utilizing a hybrid line, which enables the production of a tapered helically wound profile extruded tubing for respiratory delivery applications. The tubing can have a 10-millimeter diameter at one end and can then taper up to say 15 millimeter or larger at the other end. “This allows for a robust machine connection at one end and a lightweight patient interface at the opposing end of the tube,” said Forrester.

Looking Toward the Future

Regulatory considerations will always be at the forefront of design and medical device manufacturing. Regulatory agencies continue to push for lower levels of particulates, endotoxins, and bioburden. Compliance with these regulatory standards is imperative to ensure the quality and safety of medical devices produced using extrusion processes. CMs must have stringent process controls in place for monitoring and testing to address regulatory requirements and other customer concerns, including document control processes that show the thorough testing and validation that ensures regulatory compliance. These sophisticated data collection systems are critical for proving validated product parameters that will satisfy FDA and other regulatory requirements.

Extruders and extrusion equipment manufacturers will continue to innovate to meet increasingly challenging customer requests, particularly in the field of catheter shafts. A top MDM demand is usually thinner and smaller for catheter walls and diameters (for example, sub-0.002-inch wall ultra-low durometer polyurethane [single lumen] extrusions for neurovascular applications). Co-extrusion is also in high demand, with MDMs having greater interest in combining materials that have different melt temperatures, viscosities, and molecular makeups—which can be highly challenging. In some cases, dual durometer extrusion can eliminate secondary joining operations.

“Screw and system designs allow for a very low output process with varying pellet geometries, allowing for the continued miniaturization of catheter tubing,” said Alpert. “Also, the design of interesting and challenging multi-lumen tubing is making advancements in surgical procedures that were once considered science fiction to be reality, saving and improving lives every day.”

As focused as designers and engineers are on getting as small as possible, another area of growth is large-diameter catheter projects. Teleflex Medical OEM, for example, has developed extrusion systems that produce bigger-sized polytetrafluoroethylene (PTFE) liners. Historically limited to 20-22F sizes, Teleflex Medical OEM can now manufacture liners up to 26F.

The medical extrusion industry is currently driven by strong collaborative efforts between MDMs, equipment manufacturers, and resin suppliers. “More MDMs are moving from purchasing discrete components and integrating locally to working with qualified and experienced machinery manufacturers to engineer, build, and prove a complete system for guaranteed startup success,” said Alpert.

“Not only do we provide an excellent machine build, we also guarantee the machine is capable of producing the products to the tolerances the customer requires,” added Kikuzawa. “This does not mean, however, that the finished products can immediately be used as components in medical devices. The functionalities of tubes are dependent on many factors—such as designs and materials, not just the extrusion process. We are not medical device experts, but professionals of extrusion—during design for manufacturing, we work closely with our customers to let them know what they can or cannot achieve with our equipment and build them the best solution to meet their needs.”

Such collaborations (including R&D) have contributed to a deep understanding of the extrusion process and its capabilities—allowing them to explore and push the boundaries of extrusion technology, often in partnership. “This collective knowledge-sharing and expertise has enabled the industry to overcome previous limitations and continuously innovate,” said Goradia. “As medical extrusion continues to forge ahead, fueled by collaboration and shared knowledge, OEMs can stay at the forefront of technological advancements and fully leverage the potential of extrusion for their diverse needs.” 

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Mark Crawford is a full-time freelance business and marketing/communications writer based in Corrales, N.M. His clients range from startups to global manufacturing leaders. He has written for MPO and ODT magazines for more than 15 years and is the author of five books.