Medical injection molding fabricates plastic medical devices and components by melting plastic resin pellets and injecting the molten material into a mold to create specific shapes. The method allows control over size and shape, adhering to strict quality and regulatory standards.

It’s a common method to form plastic parts with tight tolerances, capable of producing U.S. Food and Drug Administration (FDA)-approved devices that are reliable and durable. It can be done in a cleanroom environment and components can be sterilized without compromising their integrity.

Medical injection molding sometimes uses thermoplastics—materials that can be melted, injected in a mold, then cooled into precise shapes. These can vary from simple to very complex, depending on the molded part’s design. It’s also common to combine metal and plastic components in a process called insert molding, typically used to manufacture needles, EKG hookup leads, and other complex devices.

Medical injection molding is also useful for prototyping as part of the FDA’s approval process. This mainstay of medical manufacturing is ideal for projects needing high volumes of durable, accurate, and sterilization-friendly parts.

In order to glean insights on the technologies, material advances, and market forces impacting medical molding, MPO spoke to a dozen experts in the field over the past few weeks:

Jarrod Aydelott, senior tooling engineer, APTYX
Eric Bowersox, director, Beaumont Advanced Processing
John Budreau, director of new business development, PTI Engineered Plastics
Tom Graham, COO, Elevaris Medical Devices
Brent Hahn, senior VP, Isometric Micro Molding
Scott Herbert, founder and president, Rapidwerks
Benedikt Hoell, business director, medical, Vaupell Medical
Vijay Kudchadkar, director of plastics and sales engineering, Isometric Micro Molding
Rey Obnamia, customer relations/strategic accounts, IRP Medical
Dave Pentland, CEO, Jefferson Rubber Works
Ron Ringleben, VP of business development, Currier Plastics
Ray Scherer, global engineering manager, APTYX

Sam Brusco: What latest advances in molding technologies/supporting technologies have you invested in, and what are they making possible for medical manufacturing?

Jarrod Aydelott: We’ve used CT scanning with great results and recently invested in an in-house CT scanning system. In the hands of experienced engineers, it’s a critical addition to our toolbox and gives us quick, real-time part views and data that weren’t possible before.

With a conventional coordinated measuring machine (CMM), you program a specific area of the part to look at, and you don’t get the full understanding of warp and deformation across the entire part. That’s where CT scanning comes in. It allows us to get a full picture of the interior and exterior of the part before we go into full-scale metrology, which can be very time-consuming.

Eric Bowersox: One of the most exciting technologies we’re currently implementing is AI-powered inspection cameras for defect detection at our molding presses. These cameras are equipped with advanced AI learning systems that analyze large quantities of parts, learning to distinguish between acceptable variations and actual defects. This lets the system identify anomalies in real-time, with a level of precision that exceeds what human inspectors can achieve.

Another newer technology that we utilize is ROCTOOL Induction Heating, especially for challenging applications like those in the microfluidics sector. We were approached with a product that was traditionally made through CNC machining of a plaque to create flow paths and through holes. This method struggled to keep pace with market demand and traditional injection molding couldn’t achieve the desired results. The process would often produce highly visible weld lines and sink marks that compromised the product’s functionality, particularly the fluid flow paths.

John Budreau: We continue to invest in automation with our MAR (mobile automation robot) systems as they offer many unique capabilities and flexibility with part handling, secondary processing, inspection, and other part finishing processes. Our MARs run within our general molding environment as well as our newly expanded ISO Class 8 Cleanroom. The unique flexibility of these systems allows our manufacturing teams to support medical device customers’ growing product requirements/needs.

We’ve invested in a 30-ton high speed injection Sodick molding machine, allowing for better control of machine shot size and injection speeds for very small, complex parts. We’ve also invested in mold-mounted servo-driven cores that provide finer control for delicate part geometries. Process engineering has invested in thermal imaging cameras for process development. Mold-flow technologies optimize mold design and processing before steel is even cut, and press assigned hot-runner systems allow for more repeatability and less downtime.

Tom Graham: We believe in automation as a means to improve accuracy and efficiency and to reduce costs. For instance, with our insert over-molding, we are gradually moving away from manual loading to semi-automated and fully automated production lines.

Brent Hahn & Vijay Kudchadkar: We have dedicated resources to advancing molding technologies that enable the miniaturization essential in medical and drug delivery manufacturing.

Our injection molding machines offer precise plastication and injection control, ensuring accuracy, repeatability, and efficiency. Our machining equipment can produce tooling with sub-micron precision, a critical factor in achieving a high Cpk on tight tolerance parts and multi-cavity, high-volume production. We recently added another CT scanner, utilizing CT scanning and ultra-high resolution vision inspection systems to meticulously examine every surface of a component and assembly. Furthermore, our integration of 3D printing technology allows for quick and inexpensive innovative design reviews and our expansion of advanced micro automation assembly is pushing the boundaries of what’s possible in medical manufacturing.

Scott Herbert: We’ve invested in micro injection molding, a specialized form of injection molding used to produce extremely small, high-precision plastic parts typically weighing less than a gram and often with very fine details or complex geometries. The process handles tiny part sizes, often in the milligram range or just a few millimeters in size. Tolerances can be in the sub-micron range. It’s complemented by servo controls with precision ground ball screws.

The specialized equipment involved uses micro injection molding machines with extremely small injection units and highly precise mold tooling. Common thermoplastics like PEEK, LCP, or PMMA, and sometimes bioresorbable materials, are used in medical applications like micro-needles, implants, and hearing aid parts. For electronics, they’re used for connectors, sensors, and micro gears. In optics, they’re used in micro lenses and components for imaging.

Benedikt Hoell: We place a strong emphasis on a stable supply chain and maintaining high quality throughout our product portfolio; therefore, we’ve heavily invested in automation. This greatly reduces our dependence on labor, addressing issues related to labor shortages and enhancing efficiency. 

Additionally, specialized coatings to achieve tighter tolerances are being utilized, along with living polymers. Additive manufacturing is another key area of investment, particularly in end-of-arm tooling (EOAT), secondary machining fixtures, and inspection fixtures.

Rey Obnamia: We developed a fully automatic molding process—injection molded, LSR material with 3rd streaming for color, cold runner with very high cavitation, with end-of-arm tooling EOAT to transfer product from the mold to an in-line camera for visual/dimensional inspection system, decides to accept or reject product instantaneously then product separation. No secondary operations required other than a post-cure process due to product functional requirements. This product is only 3.5 milligrams per part.

We have invested on this setup, replicating the same fully automatic system three times: same injection machine/model/make, same LSR material pump/model/make, same cold runner mold design/fabricator, same cavitation, same EOAT, same automation/camera system. This provides us assurance of product quality and assurance of supply in hundreds of millions of parts per year.

Dave Pentland: We’ve invested in liquid silicone preparation and dosing equipment. This has resulted in reduced material waste, easier material changeover, and reduced labor in material change and cleanout. We’re also continuously investing in and developing cost-efficient mold concepts to produce trimless and flash free parts, as well as automatic molding concepts to minimize human dependence and labor costs.

Ron Ringleben: One of the foundational steps we’ve taken is achieving ISO 13485 certification and building out Class 8 cleanroom capabilities, which are critical for ensuring regulatory compliance and product safety in the medical space. 

On the technology side, we’ve put a strong focus on automation—not just in packaging, but also in assembly processes. Automation has allowed us to achieve highly consistent and repeatable processes and optimize costs. We’ve also recently added a new ISBM machine into our Class 8 cleanroom. This is a strategic move that expands our capabilities in precision molding for complex medical components. 

Finally, we believe quality isn’t just about equipment—it’s about the people behind it. Long lead times in development cycles make it critical to optimize and automate quality inspection processes early. We continuously upgrade our inspection technologies and train our teams to stay ahead of rising expectations.

Ray Scherer: We’ve invested in specialized equipment and techniques for molding highly engineered, high-temperature resins like PEEK and ULTEM. Our equipment is engineered to achieve and withstand the high temperatures required to process these materials, with ceramic band heaters and specialized temperature control units. We also use a unique thermal control technique with our injection molds that significantly reduces thermal loss caused by convection, resulting in very stable processing temperatures. This combination of equipment and techniques gives us the capability to mold high-performance materials with a range of characteristics that traditional materials like metals and ceramics can’t match, like light weight, corrosion resistance, and cost-effectiveness.

Brusco: What medical device material advances are impacting or challenging molding processes, and how?

Bowersox: Use of biopolymers—these materials are often touted as direct replacements for traditional plastics but don’t always behave the same way during the manufacturing process, especially when it comes to processability. Biopolymers tend to be more sensitive to variations in processing temperatures required for injection molding, which can make them trickier to work with.

We need to approach their integration with great care and precision. Developing a validated process window for these materials is critical to ensure consistent quality and performance. It requires a deeper understanding of how the material reacts at different stages of production, as well as rigorous testing and optimization. While use of biopolymers aligns with our sustainability goals, it’s important to adapt our processes carefully to ensure we’re achieving the best possible results.

Graham: In a global trading market, the historic trend of naming specific polymer resin brands in component specification has always provided a challenge to contract manufacturers. We continuously strive to find solutions that provide equivalent products with economic benefit. Many of the material advances apply to implantable or subcutaneous surgical interaction component requirements. Molding parameters for some of these high-performance materials can vary significantly from standard polymer types, and our engineers continuously work very closely with the material developers to optimize this process.

Hahn & Kudchadkar: For medical applications, especially miniaturized applications, original equipment manufacturers (OEMs) are increasingly opting for resins with higher molecular weights to create stronger, thin-walled parts. This choice results in more viscous materials, presenting challenges in processing and filling long aspect ratio components without flash or short shots. Our advancement in high aspect ratio molding has resulted in a 400:1 scalable solution. As medical devices continue to get smaller, there’s a growing need for components to be reinforced for added strength. In various two-shot applications, use of two distinct materials is becoming more prevalent. Additionally, bioresorbable materials are being integrated into an expanding array of applications, highlighting their growing importance in the field.

Herbert: High-performance thermoplastics are increasingly used for implants and surgical tools due to their biocompatibility, sterilization resistance, and mechanical strength. One challenge of using these is high processing temperature. Materials like PEEK require temperatures over 350°C, which demands specialized molds, tooling, and process control. Excessive shear during molding can degrade properties and cooling takes longer, increasing production time.

Bioresorbable polymers (e.g., PLA, PGA, PLGA) are used for temporary implants, sutures, and drug delivery systems. These materials degrade at relatively low temperatures and have narrow processing windows. They must be kept extremely dry before and during processing, and scrap is often unusable due to degradation.

Silicone elastomers (LSR and HCR silicones) are preferred for wearables, soft implants, and catheters due to flexibility and biocompatibility. Liquid silicone rubber (LSR) needs very tight tolerances and often requires cold-runner systems. Silicone’s low viscosity increases the risk of flash—precision gating and venting is essential. Cure time can be long, especially for high-consistency rubber (HCR) unless platinum-catalyzed.

Antimicrobial and drug-eluting materials help reduce infection risks and improve patient outcomes (e.g., in catheters or orthopedic implants). Antimicrobial agents may interfere with polymer flow or degrade during molding. Ensuring even distribution without segregation during melt flow is tricky. Drug release profiles may be affected by molding temperature or pressure.

Composite materials (e.g., fiber-reinforced thermoplastics) are used in structural components that need high stiffness and strength without adding weight. Flow paths during injection molding can lead to inconsistent mechanical properties. Reinforcing fibers (like carbon or glass) are abrasive and reduce mold life. Shrinkage and warpage are more complex to predict and manage compared to standard thermoplastics.

Additive-compatible or 3D-printable polymers are designed for hybrid manufacturing (molding + additive), offering complex geometries with embedded features. For these, material compatibility and surface preparation become critical. Also, differential shrinkage between printed and molded portions can cause warping.

Hoell: The continued development of bioresorbable polymers allows creating of devices that safely dissolve in the body over time, reducing the need for surgical removal. However, their unique properties pose challenges throughout manufacturing to safely and cost-effectively turn these materials into high-quality products. A thorough approach and robust understanding of requirements to products, as well as the processing environment, is a key advantage of making such devices successful. 

Along these lines, increased use of high-performance thermoplastics offers enhanced biocompatibility and durability, which is crucial for long-term implants. Similarly, these materials often require precise molding techniques to achieve the necessary complex shapes and tight tolerances. 

In parallel with an industry trend to include as much functionality as technologically possible into devices or manufacturing processes, material developers and medical device designers will continue to push the boundary, creating new challenges for manufacturers and necessitating continuous innovation to adapt to evolving demands.

Obnamia: The majority of medical devices utilize silicones, primarily LSR liquid silicone rubber, for injection molding and, in some cases, HCR high-consistency silicone rubber otherwise called “silicone gum” that we usually use for injection molding but can also be achieved by other molding processes like transfer and compression molding.

There are cases where special material properties aren’t available from various standard LSRs for unique performance and functionality requirements. Now, a new technology exists called “customized LSRs” which are available when customization of specific material properties can be achieved for LSR such as: modified viscosity for better processing, improved cure rate profile and better cross link density, improved physicals such as tensile strength, ultimate elongation, modulus, and more importantly compression set, special additives and modifiers, as warranted through 3rd/4th streaming.

There are special cases where the appropriate material to choose isn’t silicone. We offer a variety of other customized rubber materials for medical purposes such as fluorosilicone, EPDM, nitrile, polyisoprene, and Buna-N.

Pentland: As material performance increases, so do customer requirements. The challenge is staying up to date and ahead of competition to acquire the best performing and most sustainable silicone materials.

Ringleben: The materials landscape is evolving rapidly in the medical space, pushing us to innovate right alongside it. One key trend we see is the push toward complex geometries, especially in the medical field. These require us to be more precise and adaptable in our molding techniques. 

There are also exciting advances in material formulations that allow for new processing methods—for example, materials that are more heat resistant or chemically stable, which open up options for different molding or secondary processes.

Scherer: We specialize in molding highly engineered, high-temperature materials like PEEK, ULTEM, and Radel. Customers increasingly ask if we can mold these high-performance materials, so we’ve made a significant investment in specialized molding equipment to meet their needs.

We also see advances with filled materials. With the move from reusable to single-use devices and increasing miniaturization, the advantages of filled resins are driving metal-to-plastic conversions. Glass fibers add the strength and rigidity required to convert components such as gears from metal to plastic. We can achieve cost reduction while maintaining or improving overall performance.

With those advantages come challenges, like shape control. We’ve invested in Moldflow simulation software and the training to fully leverage its capabilities to predict outcomes, particularly for filled resins. Fillers with high aspect ratios, like glass and carbon fibers, tend to produce uneven shrink rates across different areas of the same component. As the fibers orient themselves along the direction of polymer flow, the shrink rate is reduced along the flow axis but increased along the crossflow axis. This variation in shrinkage can lead to shape distortions, often resulting in significant warp. We’ve found simulation software is a critical first step to identify gate locations that optimize fiber alignment and shape control.

Brusco: How do you ensure molding remains competitive with other manufacturing technologies? (CNC hybrid machining, additive manufacturing, etc.)

Aydelott: When it comes to high-volume production, injection molding is hands-down the most cost-effective manufacturing method and it continues to improve with advancements in automation. However, the downside is the time and cost required to create a mold, which isn’t as attractive for lower-volume needs.

That’s the gap that our Q-Drive Mold System was designed to fill—it can be very competitive for lower-volume needs. We create a custom tool insert that fits into a master Q-Drive mold base. The customer owns only the custom tool insert, which saves time and cost. It’s ideal for injection molding of small plastic parts, including complex applications like gears. With up to 250,000 cycles, the Q-Drive system has the flexibility to handle prototypes, bridge tooling, and production-level parts, as well as clinical and regulatory needs.

Bowersox: We live by the principle of never stopping learning. Our founder, John Beaumont, often says he never wants to be called an “expert” because experts believe they’ve learned everything. This mindset drives everything we do, especially in the field of injection molding. By constantly challenging ourselves and staying open to new ideas, we ensure we’re always evolving and pushing the boundaries of what’s possible in manufacturing.

This approach allows us to stay competitive in a rapidly changing industry. We’re never afraid to try new technologies, evaluate different methods, and adapt our processes. It’s this commitment to continuous improvement and learning that sets us apart and enables us to meet the changing demands of the market.

Budreau: Ensuring the mold designs, mold builds, and production molding processes are optimized lead to an efficient/effective long-term solution. Injection molding in a medium-to-high-volume product demand remains the optimum solution.  

We help customers make that decision by offering options as it relates to overall capital investment. This allows them to choose the most competitive path to market. The overall project requirements will ultimately drive the choice of manufacturing technology.

Graham: We’ve invested in several alternative technologies, including CNC hybrid machining and additive processes. They can be and are utilized when they provide a better solution, but their main advantage is speed and investment in early product lifecycles. We have found injection molding remains the most competitive and versatile solution for higher-volume product applications, but we’ll keep reviewing and watching.

Hahn & Kudchadkar: For low-volume prototypes, we offer both 3D printing and injection molding options. The method of manufacturing depends on the part geometry, functional requirements, and annual volumes.

Injection molding remains the lowest cost precision manufacturing technology for complex plastic parts. If the component has a trapped-steel condition, 3D printing is the only viable option; however, 3D printing tends to have variances between parts, limiting its scalable production opportunities, especially in challenging, thin-wall geometry. Injection molding provides far greater advantages in scalability in nearly unlimited resins compared to other manufacturing technologies.

Hoell: For injection molding to remain competitive, it’s essential these emerging technologies aren’t viewed as a replacement but rather complementary to injection molding processes. By integrating new technologies into the lifecycle of injection molded products—from design all the way through end-of-life management—specialized manufacturers can achieve long-term success and secure a technological advantage for their products and customers. 

Additive manufacturing processes are already integral and will continue to gain significance to optimize prototyping, mold design, and build timelines, resulting in reduced time-to-market for new products.

Obnamia: The primary drivers to be competitive in molding are proper material selection for the product application, and an exacting mold design/in-line inspection system that can produce and inspect product that meet part specifications such as dimensions, visual characteristics, and Flash requirements in such a way that product is ready to package, then ship straight from the molding machine/injection press.

No secondary processing is required, except for a post-cure process usually warranted when the product has a specific functional performance requirement such as under static/dynamic compression/tension in sealing/valving applications. 

The only time other manufacturing technologies help us reduce the development timeline is during prototyping, such as 3D printing/additive manufacturing of product or the Protomold.

We also have a standard cold deck injection mold base, where we can facilitate to fabricate cavity inserts only that can be mounted on this standard cold runner mold base and go to molding right away. This method reduces tool fabrication, since all we must make are cavity inserts and not the entire mold. It saves a lot of time.

Pentland: We implement standardization across the board, including materials, molds, and processes. With constantly increasing material and labor costs, we minimize material waste and post operations by building within the mold.

Ringleben: We believe success in this space comes down to being more than just a molder—we aim to be a value-added partner. That means helping customers solve problems creatively and cost-effectively. 

One way we stay competitive is by offering flexibility based on project needs. If a customer only needs a few initial samples, we might recommend using a lower classification mold or even 3D print an insert to reduce lead times and cost. It’s about choosing the right tool for the job, efficiently and intelligently. 

We also understand technologies like CNC and additive manufacturing have their place, but our focus is on high-volume, high-consistency production—that’s where molding really shines. By continually investing in automation, process optimization, and smart quality systems, we’re ensuring molding stays both competitive and future-ready.