Medical injection molding is transforming how life-saving devices are built. Guided by ISO 13485 standards, it ensures every component meets the strict quality and safety expectations of the healthcare industry.
From implantable components to wearables, nearly every modern medical device depends on precisely molded plastic or silicone parts that – at minimum – meet FDA and USP Class VI requirements.
At Extreme Molding, we specialize in silicone and thermoplastic injection molding for the medical industry, delivering traceable, FDA-compliant parts made in the USA under ISO 13485:2016 certification and clean, controlled manufacturing conditions.
What Is Medical Injection Molding, and Why It Matters
Medical injection molding is a specialized manufacturing process that creates plastic and silicone parts for healthcare applications under tightly controlled conditions.
It involves injecting liquified medical-grade materials into a precision mold to produce components with exceptional consistency, quality, and cleanliness.
Where typical molding prioritizes speed or cost, medical molding prioritizes:
- Biocompatibility - Only polymers and elastomers that have passed rigorous biocompatibility testing, such as USP Class VI or ISO 10993, are used. You can't just use any commercial plastic or silicone; it must be a certified material to ensure it won’t cause harm when in contact with the human body.
- Clean Environment - Production may happen in a certified cleanroom where air quality is continuously filtered to control dust, microbes, and other airborne particulates.
- Process Validation & Documentation: The manufacturing process is formally validated through a protocol known as IQ/OQ/PQ (Installation, Operational, and Performance Qualification). Steps are documented to create a traceable record, from the raw material lot to the final packaged part.
- Quality Management System: A medical molder must operate under a robust quality system, typically certified to ISO 13485:2016, the global standard for medical device quality management. This ensures disciplined processes for risk management, change control, complaint handling, and corrective actions.
It’s what makes the mass production of everything from disposable syringes to complex surgical tools and custom silicone injection molding components possible and safe.
Medical-Grade Thermoplastics vs. Silicone
Choosing the right material is the cornerstone of any successful medical device. The decision impacts functionality, sterilization compatibility, and most importantly patient safety.
Medical-Grade Thermoplastics
These polymers are melted and solidified, making them highly efficient for injection molding. Because medical devices require virgin materials and don’t permit regrind or recycled plastics, selecting the right polymer plays a key role in overall product performance:
- Polycarbonate (PC) - Known for its toughness, rigidity, and transparency. It’s a go-to for IV components, surgical instruments, and housings for diagnostic equipment.
- Polypropylene (PP) - Offers excellent chemical resistance and is cost-effective, making it ideal for disposable syringes, connectors, and containers. It holds up well to gamma and EtO sterilization.
- PEEK (Polyether Ether Ketone) - A high-performance polymer with exceptional strength and the ability to withstand repeated steam autoclave cycles. Its properties make it a popular metal replacement for spinal implants and orthopedic devices.
- ABS & PC/ABS Blends - Commonly used for external housings, casings, and non-patient-contact components due to their durability and impact resistance.
Liquid Silicone Rubber (LSR)
Silicone is a thermoset elastomer prized in the medical field for its unique combination of properties. Unlike thermoplastics, it cures into a solid in the mold via a chemical reaction.
- Superior Biocompatibility - Medical-grade, platinum-cured silicone is biologically inert, hypoallergenic, and doesn’t support microbial growth, making it perfect for implants, catheters, and skin-contact devices like wearable sensors.
- Extreme Temperature Resistance - LSR can handle a wide range of temperatures and is highly resistant to degradation from repeated steam autoclave cycles, a common requirement for reusable surgical instruments.
- Softness and Flexibility - Silicone offers a soft, pliable feel that’s ideal for patient comfort. It’s used for everything from respiratory masks and seals to wound care pads and soft-touch overmolded grips.
So, when should you use which?
Use thermoplastics for rigid, structural components where strength and durability are key.
Use LSR molding for medical devices when you need biocompatibility, flexibility, and high-heat sterilization resistance.
USP Class VI vs. ISO 10993: Decoding Biocompatibility
"Is this material biocompatible?" is a question every medical device designer asks. The answer lies in data from two key standards: USP Class VI and ISO 10993. They aren't interchangeable, and understanding the difference is crucial.
USP Class VI is a set of tests defined by the United States Pharmacopeia. It’s a good baseline screening test that involves injecting material extracts into subjects to test for systemic toxicity and intracutaneous irritation, as well as an implantation test to observe local tissue response. For decades, it was the de facto standard for "medical-grade."
ISO 10993, on the other hand, is the current global standard recognized by the FDA and other regulatory bodies. It’s a comprehensive, risk-based framework that outlines a series of over 20 standards to evaluate a device's interaction with the body. The required tests depend on the nature and duration of body contact. The FDA expects a biological risk assessment and supporting data based on the ISO 10993 framework.
For more information, see the FDA's guidance on Use of International Standard ISO 10993-1.
Common Applications of Medical Injection Molding
Here are some of the most common applications of medical injection molding:
- Implantable Devices - PEEK spinal cages, orthopedic anchors, platinum-cured silicone seals.
- Surgical Tools - Overmolded grips, forceps, clamps, catheter hubs.
- Diagnostic & Labware - Pipette tips, Petri dishes, PCR plates, optically clear components.
- Disposable Consumables - Syringes, IV connectors, test vials — high-volume, tight-tolerance production.
- Wearables & Skin-Contact Devices - Silicone patches, sensor enclosures, CPAP masks, hearing aids.
Cost Drivers and Finding the Right Molding Partner
While quality and compliance are essential, cost is always a factor. Knowing what pushes cost up helps you make smarter decisions:
- Tooling - The mold is often the biggest upfront investment. A simple, single-cavity aluminum prototype mold might cost a few thousand dollars, while a complex, multi-cavity hardened steel production mold can run into the tens to hundreds of thousands.
- Material - Medical-grade materials carry a premium. Implant-grade materials can be over 100 times more expensive than commodity material options.
- Part Complexity - Features like undercuts, varying wall thicknesses, and extremely tight tolerances can increase mold complexity and may alter cycle times, resulting in higher costs.
- Quality & Validation - Testing and documentation add cost but ensure compliance. The labor and resources required for IQ/OQ/PQ, documentation, and maintaining an ISO 13485:2016 quality management system are factored into the cost. This is the price of compliance and peace of mind.
- Cleanroom Operations - The stricter the environment, the higher the overhead — but also the lower the contamination risk. Manufacturing in a certified cleanroom adds overhead for gowning, air handling, and environmental monitoring.
Checklist for Selecting a Supplier
Choosing a partner is about more than just a quote. It's about finding a team that can mitigate risk and act as an extension of your own.
- ISO 13485:2016 Certification - Is their quality management system certified for medical devices?
- Cleanroom Capabilities - Do they have a certified and validated cleanroom appropriate for your device's risk class?
- Technical Expertise - Do they have experience with your chosen material? Do they use scientific molding principles and have a robust validation process?
- In-House Tooling & Engineering - Can they support you from DFM (Design for Manufacturability) through tool building and maintenance?
- Traceability and Documentation - Are their systems set up to provide complete Device History Records (DHRs) and material certifications?
- Location & Communication - Partnering with a U.S. based manufacturer can help de-risk your supply chain. Choosing a Made-in-USA company (like Extreme Molding) ensures easier audits, clearer communication, and stronger IP protection.
Frequently Asked Questions (FAQs)
What’s the difference between medical-grade and food-grade silicone?
While both must be non-toxic, medical-grade silicone undergoes far more rigorous biocompatibility testing (per ISO 10993) to prove it's safe for short- or long-term contact with the human body, including internal tissues and fluids.
Food-grade silicone is typically tested under standards like FDA 21 CFR 177.2600, which focuses on safety for contact with food. Class VI-approved silicones, however, can be used in devices implanted for 30 days or less, in accordance with medical regulatory guidelines.
What is a Device History Record (DHR)?
A DHR is a compilation of all records for a specific production lot of a medical device component. It contains everything from the raw material lot numbers and machine processing parameters to inspection results and operator logs. It provides end-to-end traceability, which is a requirement of the FDA.
How long does the IQ/OQ/PQ validation process take?
It varies from several weeks to a few months, depending on device complexity, customer requirements, and testing scope.
Which materials survive autoclaving?
PEEK, PPSU, Ultem, and silicone are top choices for reusable parts.
Bring Your Medical Device to Life
Medical injection molding is a field where precision, quality, and expertise are not just goals - they are requirements. From selecting a biocompatible USP Class VI silicone to validating your process in an ISO-certified cleanroom, every step is critical to ensuring patient safety and achieving regulatory approval. It can be challenging to find a medical injection molding company, if you don’t know what to look for.
At Extreme Molding, we pride ourselves in providing a wide range of injection molding services to meet our customers’ specific needs.. We also offer value-added services such as packaging and fulfillment. As a Made in the USA manufacturer, we have helped companies with reshoring production. To learn more about us and how we can help you, contact us.