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Factors That Determine High Shear vs. Low Shear Mixing

Processing plants need rotating mixers that can handle different compositions and materials to meet a desired endpoint. When mixing impellers rotate in a batch, they generate shear, or stress, on the materials, to mix them together. The viscosity and other properties of liquids, as well as the presence of solids, determine the force needed to combine the materials. The amount of shear is dictated by the blade design and rotational speed. Mixers can use either high shear mixing or low shear mixing to incorporate the disparate materials into one mixture, depending on your needs.

High Shear Mixing

Shear forces are caused by one force pushing part of a mixture while another force pushes a different part of the mixture in the opposite direction in a parallel field. The higher the shear force is, the better the materials can incorporate together, even mixtures with viscous liquids and solids. 

High shear mixers have a high-speed rotor that forces the mixture outward against a stator to generate shear. These mixers mix, rotate, and agitate the batch. One particular type of high shear mixing, called dispersion, uses high levels of horsepower to create even higher levels of shear. In addition to combining the mixture, high shear forces also ensure the materials are evenly distributed within the batch.

Low Shear Mixing

Low shear mixing is a gentler, less forceful mixing process. This process is ideal for miscible materials that don’t need a lot of energy or force to combine. It also can handle delicate materials—including adhesives, polymers, and structured food products—and materials with large particle sizes that shouldn’t be broken down during mixing. If the shear rate gets too high, the materials can start to suffer from shear degradation.

Low shear mixing processes feature a wide variety of different rotor blade designs, and they use the flow and turbulence in the tank to help incorporate the materials. 

Applications for High and Low Shear Mixing

High shear mixing and low shear mixing each meet the needs of different applications. High shear mixing equipment uses include:

• Emulsifying and homogenizing liquid-liquid compounds
• Dispersing powders into liquid compounds
• Mixing liquid-liquid mixtures with materials that have different viscosity levels
• Dispersing and suspending solids in liquids
• Reducing particle sizes in mixtures

Low shear mixing processes are reserved for mixtures that need gentler handling or require less force to achieve the desired result. Popular applications include:

• Combining miscible liquids and fluids
• Flavoring
• Increasing the efficiency of heating mixtures
• Maintaining suspension of particles
• Mixing liquid chemicals

Working With Highland: Leveraging Software to Optimize the Mix

The key to optimal low and high shear mixing isn’t just the hardware—it’s also the software. High-quality shear mixing software can model the different factors that impact sanitary mixing processes, including heat transfer, reactions, and turbulence.

Using this modeling, Fluent software can present a wide range of industrial functions, such as airflow over aircraft wings, semiconductor manufacturing, and more. New iterations of software are also user-friendly, in that they can easily be used by new and experienced operators. Users follow task-based workflow guides to speedily create simulation processes with accurate results based on different meshes, different blade radius and shape parameters, and more.

Fluent also uses a Mosaic meshing technology as part of its patent-pending high-speed system. This technology combines different boundary layer meshes to create a unique mesh. This ensures faster and more accurate flow resolution based on the models.

With this software, Highland can test different mixing scenarios and blade configurations to optimize the process and time requirements for every batch, design blades with the right radii and shapes to speed up mixing, create better consistency, and create customized equipment for each of our customers. 

Contact Us Today for High Shear and Low Shear Mixing Solutions

High shear and low shear mixing processes each play an important role in manufacturing. Different mixtures may need to be homogenized, while others need consistently suspended solids. High shear, or very forceful, mixing processes uses high-speed impellers, and low shear mixing processes use flow, turbulence, and rotational force to combined miscible goods. 

At Highland Equipment, we specialize in testing and designing high shear mixing and low shear mixing equipment. Every product is customized and thoroughly modeled to create the optimal shear mixing force for each of our customer’s needs. Request a quote today to get the customized mixing tools your facility needs.