Mechanism of SIZE Reduction can occur via precipitation processes, mechanical processes, or different modes of size reduction. Precipitation involves dissolving a substance in a solvent and then precipitating it out finely with another miscible solvent where the substance is insoluble. Mechanical processes use grinding equipment like ball mills or roller mills under dry or wet conditions to produce materials for tablets, capsules, suspensions, or ointments. The main modes of size reduction are cutting, compression, impact, and attrition which break down materials using blades, pressure between rollers, high speed hammers or bars, or rubbing between surfaces.
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Mechanism of size reduction.pptx
1. TOPIC: Mechanism of SIZE Reduction
PHARMACEUTICAL ENGINEERING
Prepared by kashish Wilson
Assistant Professor,
MM College of Pharmacy,
MM(DU),Mullana Ambala
2. Precipitation process :
• Substances is dissolved in an appropriate solvent. Subsequently, it is finely precipitated by
the addition of another solvent.
• Which is miscible with the first, but in the later substance is insoluble.
• This method is suitable for the production of raw materials and bulk drugs.
Mechanical process:
The substances is subject to mechanical forces using grinding equipment.
E.g.: ball mill, roller mill.
Dry grinding or milling is used in the production of tablets, capsules.
Wet grinding is used in the preparation of suspensions, emulsions and
ointments.
3. Modes of size reduction:
Cutting: The material is cut by means of a sharp blades
Eg : cutter mill
Compression:
In this mode material is crushed between roller by the application of
pressure Eg : roller mill
Impact:
This involve the operation of hammer/bars at high speeds.
When a lump of material strikes the rotating hammers, the material splits
apart. Eg : fluid energy mill
Attrition: breaking down by the rubbing action between two surfaces.
Eg : fluid energy mill, ball mill
