High-Shear Mixing versus High-Pressure Homogenization

High shear mixing and high-pressure homogenization are both methods of particle size reduction, homogenization and emulsification. Both methods are based primarily on shear force. However, they have differing advantages and one or the other may be better suited based on your application.

What is shear force?

Shear force is any force parallel to a material's surface. In a liquid, this results in friction between fluid particles, that can result in particle size reduction.

In high shear mixing, the shear force is generated through methods like high-speed blades or a rotor stator. In rotor stator, two pieces work together. The stator is stationary, and it sits around the rotating rotor to generate shear force.

High-pressure homogenization creates shear by propelling the sample through a narrow tube. For instance, the Y-shaped diamond interaction chamber splits the liquid sample in two and collides it with itself. The narrow section before collision generates shear. Homogenization also generates additional forces, like the impact from the samples colliding and cavitation.

Pros and Cons

High shear mixing has the capacity to handle larger volumes and more viscous samples than high-pressure homogenization. High shear mixing can be the more affordable option. However, high-pressure homogenization has a narrower distribution size, a smaller particle size, and is generally the more precise option.

High shear mixing can handle larger beginning particle size, while high-pressure homogenization can reach smaller ending particle sizes. This is one reason for some applications processing begins with high shear mixing or sonication and ends with high-pressure homogenization. This can reduce the starting particle size for high-pressure homogenization and reduce processing time.

High-pressure homogenization is typically faster processing, and results will be much more uniform. This is because all the sample goes through the same process, while in high shear mixing, processing for the sample differs based on the distance of each part of the sample from the blades or rotor stator.