Wednesday, 7 December 2011

Shear Mixer

Shear mixer is a type of pharmaceutical machine which is used to disperse or transport, one phase or ingredient of liquid, solid, gas into a major regular phase of liquid, along which it would generally be incapable of mixing. Apart from pharmaceutical industry, shear mixers are used in adhesives, chemical, cosmetic, and plastics industries for emulsification, homogenization, particle size reduction and dispersion. These mixers are highly efficient and very quick in operation. Employment of interchangeable work heads allows machine to mix, emulsify, homogenize, solubilize, suspend, disperse and disintegrate solids.
Types of Shear Mixers
  • Batch High Shear Mixer
  • In-line Shear Mixer
Working of High Shear Mixers Any type of liquid experiences shear when a certain area of fluid moves with different velocity contingent to the next surface area. Rotating impeller or high speed rotor, or a series of such impellers or in-line rotors, usually powered by an electric motor, to "work" the fluid, creating flow and shear are used in shear mixers. The speed of the fluid over diameter of the rotor is high as compared to velocity at the middle of the rotor, which develops shear.

A fixed constituent known as stator is used along with the rotor. Stator is employed so that a gap can be created between rotor and itself resulting in a high shear zone for the materials while they move out of the rotor. The combination of rotor and stator is referred to as the mixing head or generator. Numerous generators can be included in a high shear rotor-stator.

Important Factors To Be Considered
  • The diameter of the rotor and its rotational speed
  • The distance between the rotor and the stator
  • The time in the mixer
  • The number of generators in the series
  • The number of rows of teeth and their angle
  • The width of the openings between teeth.