Cleaners and carrier fluids: Preventing contamination in medical device production

Modern cleaning and coating fluid technologies and associated vapour degreasing equipment provide consistent and reliable device cleaning. However, these modern cleaning fluids offer added benefits beyond this

Many medical device manufacturers need production materials that not only work efficiently but are also cleanroom compatible. In addition, they must stay profitable without compromising product quality or their customer's requirements. They must meet stringent quality controls and support validated cleanroom manufacturing processes all while maintaining the bottom line. Modern cleaning and carrier fluids meet all of those demands by helping cleanroom production managers produce medical devices more quickly and efficiently.

Nearly all medical devices require cleaning during manufacture. It is important to remove particulate, oils or inorganic contamination resulting from the manufacturing process. Most medical devices require high levels of cleanliness to ensure proper sterilisation of finished product and ultimately patient safety and product performance. This is especially true for those with complex assemblies, intricate shapes and delicate parts.

Vapour degreasing not only cleans effectively, it also creates opportunities for other cleanroom manufacturing efficiencies

Modern solvent-based cleaning fluids, when used inside a vapour degreaser, provide consistent and reliable device cleaning. In addition to the simplicity of operation, a major advantage of using a vapour degreaser is the small footprint relative to the amount of production output. A small footprint means the vapour degreaser takes up less space while sustaining high output, allowing for lower overall operating costs in the expensive cleanroom environment.

Modern vapour degreasing fluids

The unique low-boiling cleaning fluids feature high densities, low surface tensions and low viscosities. Together with a vapour degreaser, these factors combine to completely dissolve contaminants and remove particulates. In addition to thorough cleaning, modern cleaning fluids offer added benefits.

When used with a vapour degreaser, modern cleaning fluids do not get trapped in tight spaces or deep grooves inside the devices. The parts come out of the vapour degreaser clean and dry without any residue, spots or stains. Plus, they leave the degreaser ready for the next step in the process - whether sterilising or coating. When applying coatings or ink-based markings, it's imperative that the parts be completely clean and dry before applying. The presence of water, moisture, oils or particulates on parts after cleaning will negatively impact the coating quality, and may lead to expensive rework or scrapping of parts.

Unlike aqueous cleaning that requires engineers to ensure the chemistry of water, detergents, and other additives are consistent and bioburden-free, modern solvent-based cleaning fluids in a vapour degreaser remain consistently pure. Plus, there are no stabilisers or acid acceptance testing required as with older chlorinated solvents. Since there is no need for complicated process controls at every stage in the cleaning process, production managers get peace of mind that there is no variation in the cleaning fluid chemistry. This makes initial product validation, and ongoing process controls for operation of the cleanroom much simpler and less costly.

Many conditions can cause bioburden, but water is the primary growth medium for bacteria. Even trace amounts of moisture can allow the growth of bacteria and create related bioburden issues, compromising the ability to properly sterilise the medical devices prior to shipment. Modern solvent-based cleaners do not contain any water, ensuring a pyrogen-free cleaning environment. This simplifies subsequent device sterilisation and also eliminates the potential of recleaning, repackaging, or even scrapping devices that have been affected by bioburden, ultimately reducing time and expense.

Today's sophisticated medical devices are made from a variety of materials. These include metals, ceramics, and plastics. Although metals, especially stainless steel, titanium, and nitinol are preferred materials for many device applications, device designers are also using a wide range of polymers including polypropylene, polyethene, and polystyrene as well as nylon, polyethene terephthalate (PET), polyimide, polycarbonate (PC), acrylonitrile butadiene, polyether ether ketone (PEEK), and polyurethane.

A small footprint means the vapour degreaser takes up less space while sustaining high output

In addition, devices constructed with mixed materials of metals and polymers are also common. Modern cleaning fluids offer high enough solvency (or Kb value) to selectively clean contamination from the devices without damaging substrates or dislodging delicate components. Production managers can confidently choose a single cleaning fluid that effectively cleans all materials without damage, therefore streamlining processes and reducing cleaning fluid inventories.

Lastly, modern cleaning fluids are constantly recycled through the vapour degreaser. The cleaning fluid is purified, recycled and re-used hundreds or even thousands of times without fine-tuning the formulation. This ensures consistency without any unexpected variances to manage. Plus, when it is time for disposal, the vapour degreaser concentrates the soil and contaminants, minimising the amount and frequency of waste disposal.

Modern carrier fluids for coating

Vapour degreasing not only cleans effectively, but it also creates opportunities for other cleanroom manufacturing efficiencies. For example, it is possible to design vapour degreasing cleaning equipment with a second-step surface treatment for the application of a lubricant or a speciality film. Both processes may be done in line, again saving on valuable and expensive cleanroom floor space. Vapour degreasing systems are not geometry-sensitive, meaning if the components will fit in the machine, the machine will clean or coat it. This is beneficial because it reduces the need for expensive fixtures and is an extremely forgiving process even when cleaning and/or coating large quantities of parts.

Currently, there are a number of modern fluids with formulations that not only clean, but multi-task in other applications beyond cleaning. The most common is a cleaner that may also serve as a carrier fluid for the application of medical-grade lubricants like PTFE, silicone or even pharmaceutical surface treatments. Such processes are finding common use in the manufacture of hypodermic needles and needles for sutures. These modern, advanced fluids are typically non-flammable, making them safer in the cleanroom, and much less risky for handling and storage. It's easy to see why these nonflammable fluids are a preferred choice of production managers and environmental health and safety officers alike.

Conclusion

Modern cleaning and coating fluid technologies and associated vapour degreasing equipment have brought new attention to their value in manufacturing medical devices. They are well suited for use in cleanroom manufacturing and assembly areas and ensure compliance with both strict bioburden and process controls.

Perfecting and validating a cleaning method that works effectively on intricate parts is vital to ensure patient safety and reliable cleaning validation. Modern vapour degreasers, when used in combination with non-pyrogenic cleaning fluids are an excellent way to clean and coat parts effectively and without introducing bioburden. They are also a safe and effective carrier fluid for deposition of silicone, PTFE lubricant and pharmaceutical coatings. Many modern cleaning and carrier fluids make required ISO-10993 certification easier and because they quickly dry from parts without any reside, are fully compatible with most sterilisation processes.

However, it is important to work with a cleaning and carrier fluid supplier who has experience in the special requirements associated with manufacturing in cleanroom environments and have technical engineers who work closely with end-users at the design stage of a project to ensure they are specifying the best product for their applications. When specifying a cleaning or carrier fluid, look for a supplier that can provide expert advice. One who helps simplify the selection process, provides lab testing, and offers multiple options such as off-the-shelf and customised formulations to ensure selection of the right cleaning or carrier fluid for your specific needs.


Written by Jay Tourigny

N.B. This article is featured in the May 2020 issue of Cleanroom Technology. The latest digital edition is available here.

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