Planetary mixers have set of rotating blades that sweep off-axis to the drive motor within a tank. One blade scours the surface of the tank while the other disperses the mixture. Most planetary mixers have two mixing blades that rotate around individual shafts and, further, a center axis. The net effect is intermixing, stirring, and shear. In terms of applications, planetary mixers are used to process adhesives, chemicals, construction materials, cosmetics, food and beverages, ore and minerals, paints and coatings, pulp and paper, plastics, pharmaceuticals, and wastewater.
Planetary mixers differ in terms of operating configuration. Devices are designed for industrial or laboratory use, and there a variety of choices for mounting style. Planetary mixers have batch or continuous-process modes. Batch mixing is the simplest mode of operation. The planetary mixer is filled with a medium and mixing is allowed to proceed. When the mixing has finished, the contents are emptied for downstream processing. The mixer is then cleaned and refilled, and mixing begins again. With continuous-feed planetary mixers, the sample being mixed is continuously added and mixed fluid is continuously removed. The device can be run for long periods of time without being shut down.
Product specifications for planetary mixers include media type and operating capacity. There are three choices for media type: liquid, liquid with suspended solids and powder or granular. Media viscosity, a measure of a fluid’s thickness, is important to consider when choosing planetary mixers for processing liquids or liquids with suspended solids. As a rule, thicker materials require more energy for mixing, homogenizing, or blending. In terms of operating capacity, volume capacity and feed rate are important parameters. Capacity is the volume of product that a planetary mixer can accommodate. Feed rate is the volume that can be processed over a given period of time.
Additional specifications for planetary mixers include mixer location, mix rate and motor speed, operating temperature and pressure, and application. There are four choices for mixer location: in-line, top entry, side entry, and bottom entry. In-line mixers are mounted on the process line. Top-entry devices are mounted through an entry port at the top of the process material tank. Conversely, bottom-entry mixers are mounted through an entry port at the bottom of the process material tank. Normally, side-entry planetary mixers are mounted through a nozzle on the side of the tank or chest. The nozzle is near the bottom of the tank so that mixing is possible at reduced liquid levels during filling or emptying.