In medical device assembly, ensuring precision, quality, and contamination control is paramount. Swelling fluids have emerged as crucial tools in this domain, offering significant advantages.
There are two common methods of joining silicone tubing or parts: lubricating with isopropyl alcohol (IPA) or silicone oils and swelling with elastomer swelling agents
These specialised fluids play a vital role in assembling medical devices, addressing challenges related to contamination control, ease of assembly, and overall quality. This article explores the benefits of swelling fluids in the context of medical device assembly.
Understanding swelling fluids
Swelling fluids are chemical agents designed to temporarily expand silicone and other elastomeric materials for easier assembly of components. When applied to silicone parts, these fluids cause the material to swell, increasing its volume and reducing its durometer (hardness). This temporary state allows for the seamless fitting of parts that would otherwise be difficult to assemble due to tight-fitting components.
Making connections easier
For many medical device manufacturers, silicone elastomers are the preferred tubing material due to their remarkable physical properties: durability, flexibility, low cost, structural versatility, resistance to bacterial growth, low extractables, and ease of sterilisation.
Hexane, as a VOC, contributes to poor air quality
However, mating complex silicone tubing onto parts made of harder materials can be problematic because silicone, while flexible, will not generally expand or stretch without assistance and has a high coefficient of friction, making it difficult to slide onto fittings.
Chemical formulations, such as swelling agents, can make connecting silicone tubing quicker and easier. There are two common methods of joining silicone tubing or parts: lubricating with isopropyl alcohol (IPA) or silicone oils and swelling with elastomer swelling agents.
Isopropyl alcohol (IPA)
Ultra-pure IPA can lubricate silicone tubes for assembly. While it evaporates without residue, it dries slowly, increasing assembly cycle time. IPA is of little help when assembling thin-wall tubing, which can collapse or fold, making it difficult to slide onto fittings. Incomplete drying can also lead to problems later.
Silicone oils
Lubricating with silicone oils is effective but messy, as the oil stays on surfaces indefinitely and can migrate through the factory, capturing dirt from the environment. Medical-grade silicone oils are expensive and, like IPA, do not help with the assembly of thin-wall tubing.
Engineered swelling fluids
Engineered swelling agents are the superior choice, allowing tubing to easily slide over barbed fittings or other connectors. The two most common swelling agents are hexane and engineered silicone swelling fluid.
Hexane has a strong odour, requires proper ventilation or PPE, and can remove surface coatings or damage components. As a VOC, it also contributes to poor air quality.
Unlike silicone oils, which are messy and can capture dirt from the environment, engineered swelling fluids offer a cleaner and more efficient alternative
Engineered silicone swelling fluids are a better choice. When a silicone tube is soaked in the fluid, it swells uniformly, expanding the elastomer quickly and predictably.
The entire swelling process can often be done in less than a minute, with tubing dimensions expanding just enough for easy assembly. The engineered swelling fluid evaporates quickly and completely, allowing the tubing to recover its original properties and form a tight, leak-proof grip over the fitting.
Benefits of engineered swelling fluids in medical device assembly
Engineered swelling fluids have been widely adopted in the medical device industry due to their superior performance and safety profile. These fluids are engineered to provide controlled swelling of silicone parts, ensuring consistent and reliable results. Key features of engineered swelling fluids include:
Faster assembly
The use of engineered swelling fluids significantly improves assembly times by making it easier to insert silicone tubing over rigid fittings. By reducing the hardness of silicone parts, these fluids simplify the assembly process, making it more time efficient and less labor-intensive.
This enhancement in the assembly process boosts productivity and contributes to a more efficient manufacturing environment
The application of swelling fluids allows for easier manipulation and insertion of silicone components, streamlining the assembly workflow.
This enhancement in the assembly process boosts productivity and contributes to a more efficient manufacturing environment.
Enhanced assembly precision
The use of engineered swelling fluids significantly reduces waste and the number of scrapped parts by preventing tubing damage during manufacturing. These fluids provide controlled swelling, ensuring predictable and uniform expansion of silicone parts.
Engineered swelling fluids are free from harmful residues, ensuring a contamination-free environment in medical device manufacturing
This controlled expansion enhances assembly precision, allowing components to fit together with minimal force and reducing the risk of damage or misalignment. This precision is crucial in medical devices, where even minor deviations can affect functionality and safety. By ensuring precise and gentle assembly, engineered swelling fluids help maintain the exacting standards of quality and efficiency in medical device manufacturing.
Improved contamination control
Engineered swelling fluids are free from harmful residues, ensuring a contamination-free environment in medical device manufacturing.
Contamination control is critical, and engineered swelling fluids play a vital role in supporting a cleaner assembly process. By reducing the need for excessive handling and mechanical force, engineered swelling fluids allow components to fit together more easily, minimising the risk of introducing contaminants.
Engineered swelling fluids boast excellent materials compatibility, making them suitable for use with a wide range of tubing materials
Unlike silicone oils, which are messy and can capture dirt from the environment, engineered swelling fluids offer a cleaner and more efficient alternative.
Medical-grade silicone oils are not only expensive but also ineffective for assembling thin-wall tubing, while engineered swelling fluids provide an efficient and contamination-free solution. This ensures a higher standard of cleanliness and reliability in the final medical devices.
Excellent materials compatibility
Engineered swelling fluids boast excellent materials compatibility, making them suitable for use with a wide range of tubing materials, including silicone, polyethylene, and polyimide. Their unique formulation ensures that they effectively expand these materials without causing any adverse effects on other polymers.
Safety is a paramount concern in medical device manufacturing, and engineered swelling fluids are specifically formulated to be non-flammable
This broad compatibility is particularly helpful in medical device manufacturing, where diverse materials are often used in complex assemblies. By ensuring that all components remain unaffected during the swelling process, engineered swelling fluids provide a reliable solution for precise and safe assembly, enhancing the overall quality and durability of the final products.
Non-flammable and safe
Safety is a paramount concern in medical device manufacturing, and engineered swelling fluids are specifically formulated to be non-flammable, significantly reducing the risk of fire hazards in the assembly area. This non-flammability not only enhances workplace safety but also ensures compliance with stringent regulatory standards for medical device production environments. By incorporating non-flammable swelling fluids, manufacturers can maintain a safer assembly environment while adhering to critical safety regulations.
Enhanced worker safety
Engineered swelling fluids reduce the amount of force needed to insert a tube onto a connector, helping workers avoid potential injuries like carpal tunnel syndrome. With minimal skin and eye irritation and low toxicity, these fluids are a safer choice compared to hexane. This not only enhances productivity but also minimises the risk of worker strain and repetitive stress injuries, contributing to a healthier and more efficient workplace.
Easier validation
Engineered swelling fluids offer an easier way to validate medical device assembly processes by selectively swelling the targeted silicone components without affecting other polymers or materials. This precision allows for controlled, repeatable swelling of tubing, which simplifies the qualification and validation processes. By ensuring that the swelling effect is precise and consistent, engineered swelling fluids facilitate a more straightforward validation of assembly procedures, reducing the complexity and time needed for ensuring that devices meet regulatory and performance standards. This streamlining of the validation process not only enhances efficiency but also supports rigorous quality assurance in medical device manufacturing.
High-quality results
Engineered swelling fluids contribute to the production of high-quality medical devices by ensuring the secure and reliable fit of components. The temporary swelling effect ensures that parts are assembled with the least amount of force, eliminating gaps and ensuring a tight seal. This is particularly important in devices that require hermetic sealing or precise alignment of components to function correctly.
Conclusion
Engineered swelling fluids provide enhanced design flexibility and an effective and efficient way to join silicone, polyurethane, or other thermoelastic tubing to fittings and moulded parts. Using an engineered swelling fluid helps simplify medical device assembly, increasing throughput and boosting overall productivity. Many engineered swelling fluids are an easy-to-handle and reliable alternative to aggressive solvents such as hexane. Consulting with a company specialising in medical lubricating and coating technology can help you choose the best engineered swelling fluid for each individual application.
Top image: Endotracheal Tube