Precision injection molding technology plays a critical role in the manufacturing of medical devices, spanning from routine medical consumables to high-end implantable equipment. It covers various fields including diagnosis, treatment, and patient care. As the medical industry continues to demand higher levels of safety, reliability, and precision, the technical standards for precision injection molded parts and molds are also constantly advancing.
Diagnostic Equipment
Many core components of diagnostic devices rely on precision injection molding, such as fluid control units in blood analyzers and base structures of microfluidic chips in PCR instruments. These parts often feature complex structures and require extremely high dimensional accuracy, along with chemical resistance and biocompatibility.
Surgical Instruments and Consumables
Disposable scalpel handles, endoscopic structural components, and trocar housings are typically manufactured using medical-grade plastics through precision injection molding. Such parts must meet sterility requirements, and their surface finish often needs to reach a mirror-like level to prevent bacterial retention.
Implantable Medical Devices
Examples include for artificial joints, housings for pacemakers, and drug-delivery devices. These products demand strict biocompatibility, corrosion resistance, and long-term stability. High-performance engineering plastics such as PEEK and medical-grade PPSU are commonly used.
Drug Delivery Systems
Components like dose-control mechanisms in insulin pens and valve structures in inhalers require extremely high dimensional stability and assembly accuracy, typically controlled within micrometer-level tolerances to ensure precise dosing.
Material Selection Specificity
Mold steels must exhibit high hardness (above HRC 52), excellent wear resistance, and corrosion resistance. Commonly used materials include stainless steels such as S136 and NAK80. For liquid silicone rubber (LSR) molds, stricter material compatibility and thermal management capabilities are required.
Balancing Precision and Longevity
Medical device molds are typically required to endure over 500,000 cycles while maintaining precision stability. Key components such as cavities and ejector pins must be manufactured within tolerances of ±0.003 mm, and the fit clearance of guide pillars and bushings should not exceed 0.01 mm.
Runner and Thermal Management Design
Hot runner systems are often used in medical injection molding to reduce waste, but temperature fluctuations must be tightly controlled (within ±1°C). For transparent parts (such as reagent kit windows), techniques like sequential valve gating are employed to avoid flow marks and air bubbles.
Cleanliness and Surface Treatment
Molds must undergo mirror polishing (Ra ≤ 0.05 μm) and often receive coatings such as PVD or DLC to reduce friction coefficients. Some molds require built-in vacuum venting systems to prevent defects caused by trapped air.
Verification and Documentation
Molds must pass IQ/OQ/PQ (Installation/Operational/Performance Qualification) validations and retain comprehensive process data records to meet FDA and ISO 13485 traceability requirements. Mold flow analysis reports must be included as part of the technical documentation.
Special Process Adaptability
For implant-grade parts, molds must support sterile injection molding processes, including the use of self-lubricating materials to avoid mold release agents. Multi-material injection molds (e.g., hard-soft combination molds) are increasingly used in products such as respiratory masks.
With ongoing innovations in medical technology, precision injection molds are evolving toward greater intelligence and integration. For instance, new molds equipped with sensors can monitor cavity pressure and temperature in real time and enable remote maintenance via IoT technologies. These advancements not only enhance the quality of medical devices but also provide a manufacturing foundation for personalized healthcare.
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