Full_Assembly_Bowls.jpgMedical device manufacturers can easily avoid expense by choosing an injection molder experience in the medical industry.  The injection molder will have the facility, equipment and trained personnel for this type of manufacturing along with relationships with vendors to provide quality materials and resources.  Included in this are the specialized skills like design for manufacturability, mold building and material knowledge for a more efficiently engineered and manufactured product.

Quality operational controls are a primary requirement for medical injection molding.  FDA registration and ISO 13485 certification are required to maintain these quality system operational standards.  

FDA Registration is necessary when producing and distributing medical devices intended for commercial distribution in the US are required to obtain a registration with the FDA.  This requires the Quality Management System to be in compliance with the rules established under FDA Quality System Regulation (QSR) as established under the 21 Code of Federal Regulation (CFR) Part 820 (Medical Devices).  With this FDA registration not only components that are distributed to a finished device manufacturer; but to manufacture finished good devices or components that are packaged or labeled for commercial distribution of health-related purposes to an end user.   

ISO 13485:2003:  This mandates maintaining quality procedures while emphasizing documentation in order to verify procedures that provide controlled conditions for the activities and processes needing to be performed. This includes risk management activities and full lot traceability.     

Material Selection for Your Medical Device

Because medical devices in the US are regulated by the Food and Drug Administration (FDA), they are classified into three classes:  Class I, Class II and Class III - depending upon critical risk factors.  Each device class requires a different level of regulation and compliance.

When choosing a plastic for medical devices or components, design considerations are important.  Material selection, production process and part geometry are interdependent.  Usage conditions such as temperature, chemical contact and resistance, applied stresses during use, transparency/opacity, color (some items use color to aid in identification), aesthetics, water absorption, lubricity and wear resistance need to be considered.      

For example, if the device is going to be used by a surgeon it should be light and have good ergonomics and functionality.   Drug deliver products comprised of needles, tubing, bags, manifolds, Y-sites, clips and connectors are mainly disposable,  so csot and other considerations like excellent chemical resistance, flexibility, transparency and clarity, sterilization resistance and toughness must be considered. Endoscopy uses a lot of electronics and ancillary products like cameras, light sources, monitors and recording equipment.  Electric, power and thermal management is very important for these types of products including durability and toughness. 

Medical components and devices may have complex shapes that cannot be molded directly.  The plastic parts will need to be separately made and joined together with adhesives or by welding.  Changes in the plastics from welding process must be considered as well as the  introduction of adhesives and the chemicals used in them. 

Also a very important material consideration for medical device and components is sterilization method and material compatibility including is this a single vs repeat sterilization process.  

Medical Grade Plastics

The effort to evaluate these factors is reduced by using the medical grades of  plastics. The manufacturers of these plastics likely already had a significant number of the studies done which means a reduction of time and cost for commercialization. 

Polyethyelene Material has low heat deflection temperatures making them unsuitable for steam and autoclave sterilization.   Applications and uses include containers, packaging films, pouches, lidstock, breather patches and headers for bags.  UHMWPE is used as the wear bearing surface of hip and knee arthroplasty ad total joint replacement.

Polypropylene material is adequately stabilized and can survive the radiation stabilization process with antioxidant remaining so as to protect the sterilized product from more degradation.   Polypropylene has a melting temperature high enough for autoclave applications.

Polystyrene material is a colorless, hard plastic with limited flexibility.  This can be transparent or can be made in various colors.  It is economical and used for producing plastic assembly kits, plastic cutlery, and many other common objects where a fairly rigid, economical plastic is desired.  This is not recommended for steam and autoclave sterilization, but retain their properties after exposure to one normal EtO sterilization cycle as well as gamma radiation, UV light sterilization and electron beam due to its high aromatic content.  Although some color changes have been found after e-beam sterilization.  This material has been used in diagnostic instruments and disposable laboratory ware like petri dishes, tissue culture components, flasks, pipettes and other medical devices.

Polycarbonate material is impact resistant, clear, high heat resistance, dimensional stability, resistant to UV light, flame retardant properties.  Gamma and EtO sterilization can be done.  Ultrasonic welding can be used.  Typical applications include: reservoirs, high-pressure syringes, artery cannulas, stopcocks, luers, centrifugal force separators, blood filter housings, dialyzer housings: glucose meters, pumps, insulin pens, surgical device handles and housings.

PEEK also known as polyetheretherketone is a thermoplastic with extraordinary mechanical properties. PEEK is highly resistant to thermal degradation as well as resistant to both organic and aqueous environments.  Outstanding wear resistance and has very good dielectric strength, volume resistivity, tracking resistance an excellent radiation resistance.

Experts  at Crescent Industries

Crescent Industries offers decades of industry-leading injection molding solutions and product delivery. If your company needs custom injection molding for your next project – visit our website at www.crescentind.com.

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Topics: custom injection molding