MIXING EQUIPMENT
OVERCOMING MIXING CHALLENGES IN MEDTECH APPLICATIONS
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ontact mixing, also known as mechanical agitation, can range from stirring with a stick, glass stirrer, electric stirrer with blades, impellers or paddles, or magnetic stirrer. However, when mixing liquids, pastes, and powders, medical device manufacturers may experience issues with this approach, typically variance between operators, difficulty validating the process, poor dispersion, or a high defect rate. Contact mixing offers a lack of traceability and process control that is undesirable for any medical device assembly process. Productivity is another challenge MedTech manufacturers may want to address with a new mixing approach: increasing throughput or reducing waste. A manual mixing process may have numerous weighing or decanting steps, as well as requiring mixing by hand. If there is a high filler content or heavy fillers in the mixture, the operator may risk repetitive strain injury (RSI) following long periods of hand mixing.
IMPROVING MIXING QUALITY With contact mixing, quality and repeatability issues can occur when the paddle or stirrer introduces air into the mixture, mixing differs between operators, or contamination occurs between batches. Incomplete mixing can risk serious defects, particularly in adhesives applications where insufficient mixing of a two-part adhesive can result in incomplete cure, and therefore a product that cannot withstand its intended environmental conditions.
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The medical device and pharmaceutical market requires the fast, homogenous mixing of materials for many applications, for example during drug development and delivery or when creating medical implants. Traditional contact mixing brings challenges for medical device manufacturers who must avoid contamination, meet stringent quality standards, and ensure patient safety to the highest levels. These challenges can be resolved with a non- contact planetary mixing technology. Here Kevin Brownsill, head of Technical: Learning and Development at adhesives supplier Intertronics, discusses common issues with industrial mixing in medical device applications, and explains how to address them.
Furthermore, it may be difficult to achieve a homogenous mix manually with certain material types. For example, combining materials with differing viscosities, or when adding solids such as conductive powders, catalysts, phosphors, fillers or even nanoparticles, into liquids or pastes. Another challenge of contact mixing is that rollers, blades or propellors can cause physical damage to the components of a mixture. This can be a particular problem in applications where MedTech manufacturers are mixing delicate materials, such as enzymes or nanostructures.
PLANETARY CENTRIFUGAL MIXERS One alternative to contact mixing is using a planetary centrifugal mixer. This is a non-contact mixing method that combines revolution and
rotation within a set radius to achieve a fast, homogenous mix. Rotation is typically at ~1,000s of RPM, generating mixing forces of about 400 G. Users mix in their own containers (with sizes ranging from 12 ml to 20 litre), to mix, disperse, and degas materials in seconds to minutes. Planetary centrifugal mixers can be programmed with different ratios of revolution and rotation —“recipes” — for example to add more rotation for the defoaming function or more mixing for a more centrifugal action. Altering the speed and mode can help with mixing difficult materials, some of which may require a 10 or even 20 step program.
THE BENEFITS OF NON-CONTACT MIXING One of the key benefits in medical device assembly is that planetary centrifugal mixers are closed
Summer 2025 UKManufacturing
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