Principle:
It's an “Agitator Mixer”.
It works on the mechanism of Shear and Convective Mixing.
This type of mixer employs a stationary container to hold the material and brings about mixing by means of moving screws, paddles or blades.
They cause folding, kneading, tearing and mixing of the materials.
Construction:
The construction of a planetary mixer is shown in the above diagram.
It consists of a vertical cylindrical bowl.
The bowl consists of an upper cylindrical section and a lower hemispherical section.
The bowl can be moved up and down whereas the mixing head with the drive is stationary.
This bowl can be removed, either by raising the blade above the bowl or lowering it beneath the blade.
The eccentrically placed mixing mechanism rotates around its own axis. This axis also makes a rotating movement in the bowl.
There is very little place between the blade and the wall of the container.
Working:
In this mixer, the mixing arm (agitator) moves around its own axis and around the central axis (like a planet), so that it reaches every spot of the vessel.
The blade (beater) is shaped in such a way that there is very little clearance between the blade and the wall of the container. Therefore, it creates minimum dead space during mixing i.e. it left no material unmixed.
The blade tears the mass apart.
Shear is applied between the moving blade and the stationary wall.
The plates in the blade are sloped. This facilitates the powder making an upward movement. This causes tumbling (convective) motion in the powder.
At the beginning, the blade moves slowly for premixing and after sometime at higher speed for active mixing.
The bowl is emptied by scooping or by a dumping mechanism.
Uses:
Semi-Solid mixing.
Preparation of ointments, pastes, creams etc.
Commonly used in bakeries for bread making.
Advantages:
Minimum dead space during mixing.
Suitable for solid-solid and semisolid mixing.
Speed can be adjusted.
Easy to clean and unload the material.
Disadvantages:
Require high energy.
Batch type only: No continuous operation.
Limited size.
Commonly Asked Questions:
Define Mixing. With help of a diagram describe the principle, construction and working of the Planetary Mixer..
Write a short note on Planetary Mixer.