Medical Plastic Injection Moulding: Key Requirements

The medical sector is one of the most demanding environments for the production of plastic components. Strict regulatory requirements, biocompatibility obligations, full batch traceability and zero tolerance for defects combine to make the choice of a moulding supplier a strategic decision, with direct consequences for the market release of the finished device.

This article sets out the requirements a moulding supplier must meet in order to operate in the medical field, the plastics most commonly used, and the criteria a medical device manufacturer should apply when selecting production partners.

The regulatory framework: MDR, ISO 13485 and quality system requirements

Regulation (EU) 2017/745 on medical devices (MDR), fully applicable since 2021, has introduced stricter obligations for device manufacturers and, indirectly, for their supply chain. These cover clinical evaluation, traceability through UDI (Unique Device Identification), post-market surveillance and technical documentation.

For a moulding supplier, the key quality system reference is ISO 13485, the international standard for quality management systems applied to medical devices. Unlike the more general ISO 9001, ISO 13485 sets specific requirements for risk management, control of special processes, component traceability and validation of production procedures.

A supplier without ISO 13485 certification can still manufacture components intended for medical use, but the device manufacturer will have to take on additional verification and control activities to demonstrate compliance. This makes certification far more than a formality: it acts as a natural selection filter that simplifies the entire supplier qualification process.

Biocompatibility: ISO 10993 and USP Class VI

When a plastic component comes into direct or indirect contact with the patient, material biocompatibility becomes a non-negotiable requirement. The two main references are ISO 10993, which defines the biological evaluation tests for medical devices, and USP Class VI certification under the United States Pharmacopeia, frequently required in Europe as well for materials intended for contact with biological tissues or fluids.

Biocompatibility is not an intrinsic property of the polymer itself, but of the specific commercial formulation. Two polypropylene granulates from different manufacturers may behave differently in biological terms because of additives, stabilisers and processing agents. For this reason, material selection cannot stop at the generic family (PP, PC, PA): it requires the specific commercial grade certified by the polymer producer to be defined.

A moulding supplier experienced in the medical field knows which certified grades are available on the market and is able to manage the supporting documentation — technical data sheets, certificates of analysis, declarations of conformity — needed to complete the technical file of the finished device.

The most widely used plastics in medical applications

Material selection depends on the function of the component, the type of patient contact, the intended sterilisation method and the service life of the device.

Polycarbonate (PC)

Transparent, impact-resistant and sterilisable by gamma radiation and ethylene oxide, polycarbonate is the reference material for electromedical device housings, transparent connectors, reusable syringes and any component where fluid visibility matters. Medical grades of PC are certified to USP Class VI and ISO 10993.

Polypropylene (PP)

PP is one of the most versatile polymers in single-use medical applications. Sample containers, test tubes, infusion set components, syringes and caps make extensive use of medical-grade PP. It withstands autoclave sterilisation up to 121 °C and offers an excellent cost-performance ratio for disposable components.

POM (acetal) and PA

These materials are used for mechanical components requiring dimensional precision, low friction and long-term stability. Typical applications include gears in diagnostic devices, peristaltic pump components, threaded connectors and mechanical valves. Their chemical resistance also makes them suitable for contact with disinfectant solutions.

PEEK

A high-performance technopolymer, PEEK is used in surgical applications that call for high mechanical strength, biocompatibility and stability under repeated sterilisation cycles. Surgical instrument components, implant inserts and endoscopic devices are typical fields of use. Its significantly higher cost limits its application to critical components.

Beyond the medical sector, PEEK is chosen wherever a high degree of reliability and production consistency is required, as well as for food-grade compatibility. On this front, we process several hundred kilograms of this high-value technopolymer every year.

Medical-grade TPE and TPU

Medical thermoplastic elastomers are used for seals, caps, soft-touch grips and components that require flexibility combined with biocompatibility. They are frequently paired with rigid components through overmoulding, producing multi-material parts in a single production cycle.

Production environment and contamination control

Not all medical components require cleanroom production. The cleanroom class needed depends on the type of finished device (in accordance with ISO 14644), its risk classification under MDR and the customer’s specific requirements. For many Class I and Class II components, production in a controlled environment with rigorous cleaning protocols can be sufficient, provided the procedures are documented and validated.

What makes the difference, more than the cleanroom itself, is systematic control of particulate and microbiological contamination throughout every stage of the process: material receipt and storage, processing, packaging and shipping. Strict batch changeover procedures, physical separation of medical production lines and dedicated staff training are equally important.

Traceability and documentation: the core of the process

In the medical field, every component must be traceable from the granulate batch used through to shipping, covering the specific production cycle, the recorded process parameters and the quality controls performed. This documentary chain is what makes it possible, when a non-conformity is detected downstream, to identify the source of the problem quickly and contain the recall. The PPAP approval process, although originally developed for the automotive industry, provides a robust methodological framework for medical applications too, and integrates well with ISO 13485 requirements.

The documentation typically required for a medical component includes: a material data sheet with biocompatibility certificates, the part’s DHF (Design History File), IQ/OQ/PQ process validation records, a dimensional control plan, first article inspection reports and certificates of analysis for every batch produced. Managing this documentary flow efficiently is a specific competence, built up over time.

How to choose the right supplier: the questions to ask

A medical device manufacturer qualifying a new moulding supplier should ask a number of key questions that go beyond simply checking certificates.

How many years of experience does the supplier have specifically in the medical field, rather than in moulding generally? Which end customers does it serve in the sector, where these can be disclosed, and for which device class? Is the quality system integrated across moulding, assembly and shipping, or are there handovers that introduce contamination risks? How is process validation managed when changes are made to the material, the mould or the process parameters? Are Good Manufacturing Practices (GMP) known and applied?

Other important areas to verify include the management of deviations and CAPAs, the ability to support customer and notified body audits, the robustness of the material supply chain (qualified suppliers, available second sources), and the willingness to sign medical-specific quality agreements defining mutual responsibilities.

A real-world case: the sniffer flange for operating theatres

One concrete example of an Akron component for the hospital environment is the sniffer flange for operating theatres, a technical part used in anaesthetic gas detection systems in surgical environments. The project called for the combined management of tight dimensional requirements, a technical material selected for chemical resistance and long-term stability, and process documentation consistent with the traceability needs of the hospital sector.

The added value of an integrated supplier becomes clear in projects of this kind, where collaboration between the customer’s engineering department and the supplier’s team begins at the co-design stage and continues through to final validation of the component in its real application.

Our approach to the medical sector

At Akron, we approach medical and paramedical projects by placing technical dialogue with the customer and rigorous documentation management at the centre of our work.

Our company certifications, in-house control of critical processes and vertical integration between design, mould construction, moulding and assembly allow us to act as a single technical point of contact for the entire production cycle of the component.

If you are evaluating a new supplier for plastic components intended for medical applications, or you have a project in development that requires specific expertise in this sector, contact us to arrange a preliminary technical meeting.