Medical silicone molding utilizes medical-grade silicone to create life-saving medical parts, including pacemaker seals and wearable insulin pumps. This speedy process completes most parts in a very short cycle time. This combination of speed and precision is necessary for the healthcare industry to produce many complicated, tiny parts that support the health of consumers.
With this guide, you will gain a straightforward understanding of this advanced manufacturing process. You will learn what medical silicone molding is, the key stages, and its basic benefits. We will discuss material selection and applications to help you implement this game-changing manufacturing process confidently.
What Is Medical Silicone Molding?
Medical silicone molding takes liquid medical grade silicone for molding and turns it into a solid. This is done inside specially designed clean rooms that are ISO 13485 certified. The final parts can range from implantable medical devices to disposable components, created through a highly controlled and precise process.
The four stages listed below comprise the Liquid Silicone Rubber (LSR) molding action. Let’s highlight the important stages.
1. Mold Clamping
Medical-grade steel molds shut tightly under significant pressure, and this offers an ultra-tight seal. This immense force is vital to prevent “flash,” which is excess material on the part edge. Maintaining a strong seal is especially important for higher-risk implantable manufacturing for medical devices, ensuring the integrity of the product and providing safety for you.
2. Injection
The next step is to inject Liquid Silicone Rubber (LSR) into the mold under high pressure through cold-runner valves. Cold runners expose the material to less heat. This matters because heat directly affects silicone’s properties, especially its viscosity during LSR injection molding. This precise injection ensures the liquid silicone fills every tiny detail, creating complex and highly accurate parts.
3. Platinum Cure
The core of the process is the rapid platinum-catalyzed cross-linking, or curing. This reaction occurs quickly at elevated temperatures. Utilizing a platinum catalyst ensures an extremely clean and fast cure that delivers minimal extractables in the finished part. This high purity is essential for safety and meeting strict medical component requirements.
4. Controlled Ejection
Finally, the finished parts are gently removed using vacuum-assisted robotic systems. This automated process is performed without talc or lubricants. The non-contact method of removing the component helps ensure the strict bioburden limits required in medical manufacturing, while maintaining the quality of the sterile environment and the component itself.
Advantages of Silicone Injection Molding for Medical Device Manufacturing
Silicone injection molding has several distinctive advantages that other processes often cannot provide, which include unmatched precision, high design flexibility, and very impressive cost savings when increased at scale.
Micro-Reproducibility
This process offers incredible consistency, with a Cpk that ensures superior process capability on extremely thin-wall components. Cpk is a measure of the process’s ability to consistently meet specifications. This level of precision is maintained across millions of production shots.
The ability to repeatedly produce parts with such tiny tolerances is a huge benefit for you. Every component meets strict quality standards. This matters most for implantable medical devices like pacemakers or spinal implants—here, consistency isn’t optional.
Multi-Shot Versatility
You can use multi-shot molding to over-mold sensitive electronics or critical drug-contact layers in the same cycle. This capability drastically reduces the need for secondary assembly steps and post-processing. This combination significantly cuts down on overall manufacturing time for medical devices.
This versatility simplifies the production of complex devices with multiple materials. It means a more integrated and often more robust final product for you. It’s an efficient way to make hybrid parts in one go, increasing functional density.
Complex Geometry Capability
Liquid Silicone Rubber (LSR) possesses exceptional fluidity – a significant property of silicone as a material. This allows the material to easily fill submillimeter micro-features, which are common in catheter tips with very fine, intricate features. Thermoplastics often struggle to reach these tiny, delicate spaces in medical silicone molding.
This superior flow means you aren’t limited in your design complexity or component size. You can create highly intricate and specialized parts that function perfectly for critical medical uses, enabling advanced device design.
Low Unit Cost at Scale
When using large multi-cavity molds, you can achieve a very low unit cost per part. For instance, small valve discs can be produced for minimal expense. The high level of automation in this process slashes labor costs significantly compared to slower compression medical silicone molding.
This efficiency makes high-volume production very cost-effective for you and your company. You receive high-quality parts at a scalable and affordable price point, which is great for mass-market manufacturing for medical devices.
Clean-Room Sustainability
The use of flashless cold-runner systems in this method is highly sustainable. These systems trim silicone waste substantially compared to traditional hot runners. Furthermore, the runners (the solidified channel waste) can often be fully reground and reused.
This commitment to less material waste aligns with modern environmental goals. It makes medical silicone molding a responsible and efficient choice. It ensures your manufacturing process is cleaner and more resource-efficient.
Silicone Molding for Components of Medical Devices: Material Selection
The right grade of silicone is just as important as the molding process. You need to consider regulatory standards, cure types, and specialty properties to match the material with your application.
FDA 21 CFR 177.2600 Silicones
These are ingredient-listed grades specifically approved by the FDA for extended tissue contact. Using these grades ensures your components comply with essential US regulatory standards for safety.
Choosing an FDA-listed silicone is the first critical step in material selection. It officially confirms the material’s safety and suitability for direct contact with the human body, giving you peace of mind.
USP Class VI & ISO 10993-1 Matrix
You must match your material selection to the intended use and body contact duration. This means selecting from surface-device, externally communicating, or permanent implant tiers. You will then choose the ISO 10993 tests you need, like -5 cytotoxicity or -10 irritation, depending on the indication of your device.
These tests are comprehensive and demonstrate that the material will not induce any adverse biological response in the patient. They are an essential part of the due diligence required for any medical device component you develop for market release.
Platinum vs. Peroxide Cure
Silicone that is cured using platinum has the premium performance, resulting in extremely low amounts of extractables. This high level of purity is desirable for sensitive applications such as internal device systems for drug delivery. In contrast, peroxide-cured silicone offers significant cost savings and is often perfectly suitable for simple, non-implant seals.
Your application determines the best cure system for the job and your budget. While platinum offers superior cleanliness, peroxide is a great, cost-effective option for less critical seals and external components.
High-Tear / High-Transparency Grades
Specialized grades of silicone are available to meet demanding physical requirements. For example, high-tear strength is necessary for parts like self-sealing perforable septa that undergo repeated puncture. If your device includes optical sensors, you can find grades that offer exceptional light transmission in medical silicone injection molding.
These specialized grades allow for a much wider range of product capabilities and functions. You can find a silicone formulation that perfectly matches your component’s exact functional and physical requirements.
REACH & RoHS 2 Compliance
For seamless and straightforward global market clearance, your materials need EU compliance like REACH and RoHS 2. A qualified supplier provides the Certificate of Conformance for each medical silicone batch and handles the registration paperwork.
Compliance is not just about avoiding regulatory issues; it’s about accessing international markets seamlessly. Ensuring your materials meet these global standards is vital for a successful global product launch for you.
Applications of Medical Silicone Injection Molding
Silicone’s unique properties make it indispensable across the medical sector. The list of applications spans from tiny, life-long implants to comfortable, everyday wearable devices.
Implantable Medical Devices
This process is used for critical long-term components placed inside the body. Examples include pacemaker lead boots, cochlear gaskets, and long-term neural ports. These parts require ISO 10993 permanent implant platinum-cured LSR for the highest safety standard.
These are the life-support or function-critical components where absolute material integrity is necessary. The precision and purity of the molding process are paramount for your patients’ long-term health and well-being.
Surgical & Diagnostic Instruments
Silicone molding is perfect for complex parts used in surgical tools. You’ll find it in components like comfortable steerable catheter handles and flexible laparoscope sealing membranes. It’s also used for incredibly thin 0.2 mm bladders for trocar pneumoperitoneum devices.
The combination of flexibility and durability of the silicone is great for reusable surgical instruments. It allows for reliable function, superior ergonomics, and safe, repeated sterilization cycles.
Drug-Contact & Combination Products
Molding silicone is essential for devices that contact pharmaceuticals during use. It produces high-precision components, such as metered-dose inhaler valves and oxygenator pumps for insulin reservoirs. Biologic-filled syringe stoppers also use this method, often requiring USP Class VI container testing for safety.
The inert nature of the silicone ensures it won’t chemically react with or contaminate the medication. This is a critical factor for the intended efficacy and safety of all drug-delivery systems you design.
Disposable Wearables
Silicone is excellent for products that must contact the skin for extended periods. This includes comfortable continuous glucose monitor patches and soft sleep-apnea mask cushions. You can even find skin-friendly, self-adhesive gels with a low 20-Shore A hardness for comfort.
These wearable applications benefit from silicone’s inherent flexibility and hypoallergenic characteristics, providing comfort with a wearable device while avoiding skin irritations during prolonged device wear-time.
Sterile Packaging & Seals
Silicone molding creates robust seals that are essential for maintaining sterility. Examples are needle-free injection port discs and secure luer-lock sealing boots. These parts are often gamma-stable, ensuring they don’t discolor during terminal sterilization in medical device manufacturing.
These seals are your first line of defense against potential contamination in the field. Their material integrity is essential to keep the final medical product sterile and safe for the end user.
Conclusion
Medical silicone injection molding is a powerful technique. It allows for micron-level precision, a chemically inert material to the body, and increased speed via automation. This blend makes it the absolute backbone of modern medical device manufacturing, allowing for safe and complex designs.
At Fecision, we offer end-to-end medical silicone molding solutions, specializing in high-precision mold tooling and production-grade manufacturing. Our services cover the full product life-cycle, from rapid prototype tooling (as fast as 5-15 days) for concept validation to hardened steel molds for high-volume, millions-of-cycles mass production in certified cleanrooms.
Key Advantages of Fecision’s Services
- Fast Time-to-Market: Quick tooling times (5-15 days) and integrated design-to-production workflows can reduce your time-to-market by 30% or more.
- Micron Precision: Advanced CNC machining, EDM, and precision grinding for mold components ensures ±0.01 mm precision on components is standard practice.
- High-Volume Reliability: Hardened-steel, multi-cavity tools provide low-cost, high-performance mold solutions designed for millions of cycles.
- Medical Quality Assurance: We have ISO 13485 (Medical Devices) and ISO 9001 certifications for strict quality procedures to limit the risk of liability and safeguard quality plans.
- 24/7 Production: Automated, lean manufacturing cells are capable of producing up to 10 million units a year with repeatable part-to-part consistency.
- Comprehensive Support: You will benefit from mold flow analysis, CMM/SPC quality procedures, assembly, and ongoing technical support.
Are you ready to move forward with your medical device project, using high-tolerance silicone components? Contact Fecision today for your consultation and quote specific to your manufacturing needs.
