Injection Moulding

In modern medical device design, functionality, ergonomics, and patient safety are more interconnected than ever. One technology enabling this integration is medical overmolding—a specialized form of multi-material injection molding used to combine soft and hard materials into a single, high-performance component. Whether for enhanced grip, integrated sealing, or aesthetic clarity, medical overmolding offers a reliable and validated route to durable, biocompatible solutions.

What Is Medical Overmolding?

Overmolding is the process of molding one material—typically a thermoplastic elastomer (TPE) or silicone—over another substrate, usually a rigid thermoplastic like polycarbonate (PC), polypropylene (PP), or ABS. In the medical field, overmolding is applied to create:

• Soft-touch grips on surgical or drug delivery devices
• Seals and gaskets integrated into housings or enclosures
• Color-coded or tactile identifiers for usability and compliance
• Vibration dampening or insulation features for diagnostic tools
• Transparent windows or optical components bonded to structural bodies

The process may be completed in a single machine (2K or multi-shot molding), or in separate steps, depending on design and volume.

Applications of Medical Overmolding

Overmolding is widely used across various sectors of medical technology:

Materials Used in Medical Overmolding

Material compatibility is critical for overmolding success. Common pairings include:

• TPE over PC or ABS: For ergonomic grips or chemical-resistant surfaces
• Silicone over PEEK: For implantable or high-temperature applications
• COC over PP: For diagnostics with fluidic and optical functionality
• TPU over PC: For ruggedized and sterilizable enclosures

All materials must meet ISO 10993 or USP Class VI biocompatibility standards, and withstand sterilization methods such as gamma, EtO, or autoclave, depending on device classification.

Technical Considerations

Medical overmolding is more complex than standard injection molding. Key considerations include:

1. Adhesion Between Materials

Proper chemical and mechanical bonding is essential. Some polymers naturally adhere, while others require surface treatment (plasma, corona, or primers) to achieve durable interfacial bonding.

2. Tooling Design

Molds must be precisely engineered to support multi-shot processes or accommodate substrate loading without distortion. Flash control and venting are particularly critical in cleanroom environments.

3. Dimensional Control

Overmolding can introduce warpage or dimensional shift due to differing shrinkage rates. Moldflow simulations and precision tooling help compensate for these variables.

4. Cleanroom Integration

For Class I–III medical devices, overmolding often occurs in ISO Class 7 or 8 cleanrooms. Equipment must be validated, and all materials traceable per ISO 13485 standards.

Validation and Regulatory Compliance

As with any process in medical manufacturing, overmolding must be fully validated through:

• Design of Experiments (DOE)
• Installation Qualification (IQ)
• Operational Qualification (OQ)
• Performance Qualification (PQ)
• Documented traceability and batch control

These are essential for compliance with ISO 13485, FDA QSR, and EU MDR requirements, especially for critical components.

Benefits of Medical Overmolding

• Enhanced Product Integrity – Reduces part count, risk of assembly failure, and contamination
• Improved Patient Experience – Ergonomic, soft-touch, and color-coded elements
• Sterilization Compatibility – Material bonding avoids adhesives that may degrade under sterilization
• Scalability – Automated molding is ideal for high-volume medical production
• Regulatory Efficiency – Fewer assemblies, less testing, and streamlined documentation

Overmolding Capabilities at Optimold

At Optimold, together with our sister company Micro Systems, we offer fully integrated medical overmolding services, from design through validation and production:

• Multi-shot and overmold tooling with sub-micron precision
• All-electric injection molding machines from 30t to 300t
• ISO Class 7 and 8 cleanroom molding
• Complete validation protocols (FAT, IQ, OQ, PQ)
• Global reach with UK and Singapore facilities
• ISO 13485 & ISO 9001 certified systems

Our capabilities support rapid prototyping and scalable production, offering OEMs a single partner for ultra-precision tooling and validated overmolding solutions.

Medical overmolding combines engineering precision, material science, and validated manufacturing to deliver high-performance components that are safer, stronger, and easier to use. As medical devices grow more sophisticated and patient-focused, overmolding stands out as a key technology that supports both innovation and compliance.

For OEMs looking to reduce risk, streamline design, and improve device functionality, overmolding is a smart and scalable solution—especially when supported by a trusted, ISO 13485-certified manufacturing partner.

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Injection molding is a highly versatile and precise manufacturing process widely used in producing plastic components for drug delivery devices. These devices—including inhalers, auto-injectors, insulin pens, and nebulizers—require stringent quality, reliability, and biocompatibility standards to ensure safe and effective medication administration.

Why Injection Molding is Essential for Drug Delivery Devices

Drug delivery systems often demand complex geometries, multi-material components, and tight tolerances that traditional manufacturing methods struggle to achieve. The technology offers:

• High Precision and Consistency: Critical for dose accuracy and device reliability.
• Complex Multi-Material Molding: Supports overmolding and 2-shot molding for integrated seals, grips, and flexible components.
• Scalability: From prototypes to high-volume production with minimal cost variation.
• Material Versatility: Compatible with medical-grade polymers like polycarbonate, polypropylene, and cyclic olefin copolymers.

Key Considerations in Medical Molding for Drug Delivery

• Regulatory Compliance: Devices must meet ISO 13485 standards and FDA regulations, requiring validated processes and cleanroom molding environments.
• Biocompatibility: Use of FDA-approved, sterilizable polymers that are safe for patient contact.
• Precision Tooling: Ultra-precise molds are essential to achieve consistent part dimensions and functional integrity.
• Assembly and Integration: Injection molding often pairs with secondary operations like ultrasonic welding, insert molding, or component assembly to produce ready-to-use drug delivery devices.

Advances in Injection Molding for Drug Delivery

Innovations such as micro-injection molding enable the production of tiny, highly intricate parts used in microfluidic drug delivery and wearable injectors. Additionally, multi-shot molding techniques allow seamless integration of soft-touch grips or seals directly into rigid housings, reducing assembly steps and improving device durability.

Optimold’s Expertise in Drug Delivery Injection Molding

Optimold, together with Micro Systems, combines over 20 years of experience in medical injection molding with ISO 13485-certified processes and cleanroom facilities to manufacture critical components for drug delivery devices. Our turnkey solutions—from design-for-manufacturing (DfM) and mold tooling to validated production and assembly—ensure rapid development cycles and compliance with global regulatory demands. Supported by advanced metrology and comprehensive validation protocols, we deliver reliable, high-quality parts that enhance patient safety and device performance.

Injection molding is a foundational technology in the manufacture of modern drug delivery devices, offering precision, material versatility, and scalable production while meeting stringent medical standards. Partnering with experienced contract manufacturers like Optimold ensures that your drug delivery systems are produced with the quality and reliability required for today’s healthcare market.

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As medical devices continue to evolve in complexity, functionality, and user-centric design, the demand for integrated multi-material solutions has surged. One process at the forefront of this evolution is 2K injection molding—a highly controlled, precision manufacturing method enabling the production of dual-material or dual-color components in a single tool cycle. For regulated markets such as drug delivery, diagnostics, ophthalmics, and minimally invasive technologies, 2K molding delivers critical advantages in form, function, and regulatory compliance.

What is 2K Molding?

Also referred to as two-shot injection molding, 2K molding is a fully automated process where two distinct polymers are injected sequentially or simultaneously into a single mold. These materials may differ in rigidity, color, chemical resistance, or tactile properties—allowing for high-performance, single-assembly components without secondary bonding or assembly steps.

This process is distinct from traditional overmolding, as 2K molding occurs within the same machine cycle, using rotating platen, core-back, or index plate systems to position the substrate and allow precise overmolding of the secondary material.

Medical Applications of 2K Molding

2K molding is particularly suited to medical and pharmaceutical device manufacturing, where precision, cleanability, chemical resistance, and user interaction are all critical. Common applications include:

• Auto-injectors with rigid internal structure and soft overmolded grips
• Inhaler bodies combining transparent viewing windows with robust housing
• IV connectors and valves with integrated seals
• Wearable drug delivery systems with dual-material enclosures and interfaces
• Ophthalmic packaging with compliant closures and rigid optical zones
• Microfluidic diagnostic cartridges integrating optical windows and fluidic pathways

Each of these applications benefits from permanent bonding, biocompatibility, and sterility assurance provided by 2K molding under validated cleanroom conditions.

Key Technical Advantages

1. Precision Material Bonding

With tool-controlled polymer interface formation, the process ensures strong interlayer adhesion without adhesives. This is crucial for parts requiring leak-tight seals, consistent mechanical interfaces, or optical clarity across polymer boundaries.

2. Regulatory-Compliant Cleanroom Integration

For medical applications, 2K processes can be fully validated (FAT, IQ, OQ, PQ) and executed in ISO Class 7 and 8 cleanroom environments, as required under ISO 13485 and FDA QSR guidelines.

3. Design for Function

2K allows engineers to design for tactile function (e.g., grip, actuation), patient safety (e.g., color coding), or integrated mechanical properties—without sacrificing dimensional accuracy or increasing part count.

4. Reduced Bioburden and Contamination Risk

By eliminating assembly and adhesive bonding, 2K molding reduces contamination risk and minimizes the need for downstream aseptic processing, a major benefit in diagnostics and implantables.

5. Cost and Supply Chain Efficiency

Combining parts during molding reduces labor, assembly, and logistics—delivering lower total part cost and shorter time to market for validated, patient-ready assemblies.

Materials Selection in 2K Molding

Choosing compatible materials is critical. Common medical-grade pairings include:

• PC + TPE (rigid/soft) for ergonomic enclosures
• COC + PP for diagnostic cartridges
• PC + ABS for structural and aesthetic integration
• PEEK + TPU for high-temperature or implantable components

Each pairing must be vetted for chemical bonding compatibility, sterilization resistance, and biocompatibility (USP Class VI or ISO 10993) depending on device classification.

Tooling and Process Requirements

Effective 2K molding demands advanced tooling and tight process control:

• Multi-component mold design (rotary platen, core-back, or transfer systems)
• Dual-barrel injection molding machines with precise temperature and pressure regulation
• Advanced simulation tools (e.g., Moldflow) to analyze interface bonding and shrinkage
• Tooling tolerances in the micron range to maintain part integrity and regulatory compliance
• In-mold robotics for part transfer or insert placement

2K Molding at Optimold

Optimold, together with its sister company Micro System offer a fully integrated, ISO 13485-certified manufacturing platform for medical-grade 2K molding, with world-class capabilities in:

• Ultra-precision mold tooling (sub-micron accuracy)
• 2K injection molding from 30t to 300t, with all-electric and twin-shot machines
• ISO Class 7 cleanroom production for regulated medical products
• Comprehensive validation protocols: FAT, IQ, OQ, PQ
• Advanced metrology and optical inspection for complex micro features
• 24/5 and 24/7 production availability across UK and Singapore facilities

By integrating design, tooling, validation, and production under one group, we reduce risk, speed up development, and support long-term manufacturing scalability for global OEMs.

2K injection molding has become a critical enabler of next-generation medical and diagnostic devices. It supports the integration of multiple functions, improves patient usability, and reduces assembly risks—all within a fully validated, cleanroom-compliant process.

When executed by a qualified, ISO 13485-certified partner, 2K molding delivers measurable value across product performance, regulatory assurance, and commercial viability—making it a smart investment for forward-thinking medical OEMs.

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