Principles of Rotor Stator Homogenization

Since prehistory, mankind has devised clever ways to crush — and blend — various substances. From simple mortar and pestle combinations to water-driven gristmills, the benefits of grinding and mixing have long been obvious.

The goal is always the same: to render large, inconsistently sized particles — from cells, to grains, to stones — into relatively uniformly sized particles. In a word, the goal is homogenization. When a substance is homogenized, a majority of its constituents are transformed into particles of roughly the same size and shape. Think bulky corn transformed into fine cornmeal, or rocks converted to gravel.

Depending on the substance — and the industry — homogenization can be used to alter the physical properties of a given raw material; to facilitate blending, dispersion, or even emulsification. In modern industry, these mills are sometimes used to disrupt living cells, to release their contents and harvest various substances of interest, such as organelles.

We no longer rely on muscle power or gravity to power our mills, but many of the ancient principles harnessed by our ancestors still apply. The rotor-stator mill, for example, is still used by numerous industries to homogenize any number of substances. There are a variety of ways to achieve homogenization, and the appropriate machinery is often dictated by the raw material itself. Properties to consider include viscosity, coarseness of the media to be milled, and other factors, such as hardness.

A Superior Choice

Also called colloid mills, rotor-stator homogenizers are often the superior alternative to such choices as blade homogenizers (think home blenders), or bead homogenizers. Rotor-stator mills use a combination of forces, including hydraulic and mechanical shear, and cavitation, to render larger, inconsistently sized particles smaller and more uniform in size.

Rotor-stator mills can also be used to facilitate blending, dispersion (seamlessly mixing one substance into another), and emulsification (the blending of two otherwise immiscible substances, such as oil and water, to form a stable substance known as an emulsion.) Today’s sophisticated rotor-stator homogenizers offer a wide range of designs, speeds, sizes, etc.

 

In a rotor-stator, the rotor consists of a blade-like structures that spins within a non-moving tube (the stator). As raw materials are drawn through the spinning blades of the rotor, they are size-reduced into uniform-size particles. Variable-speed drives make it possible to control rotor speeds, ranging from 11,000 up to 45,000 rpms, depending on your unique homogenizing challenges. Volumes ranging from minuscule (0.2 mL) to large (20 L) can be efficiently processed, using the appropriate rotor-stator combination.