Size reduction, or comminution, involves breaking down drugs and substances into smaller particles or powders through methods like precipitation and mechanical processes. While it offers advantages like improved drug absorption and stability, it also carries risks such as drug degradation and contamination. Various theories explain the energy dynamics in size reduction, including Rittinger's, Bond's, and Kick's theories, which apply differently based on material properties and desired particle size.

1. SIZE REDUCTION
Dr. Laxmikant R Zawar

2. SIZE REDUCTION
Definition
Size reduction or comminution is the process of
reducing drugs (vegetable and chemical
substances) into smaller pieces, coarse particles or
fine powder.

4. PROCESS OF SIZE REDUCTION
1.Precipitation Method
2.Mechanical Process

5. IMPORTANCE/ ADVANTAGE
1. Content Uniformity
2. Uniform Flow
3. Effective Extraction of Drugs
4. Effective Drying
5. Improved Physical Stability
6. Improved Dissolution Rate
7. Improved rate of Absorption

6. DISADVANTAGES
1.Drug Degradation
2.Poor Mixing
3.Contamination

7. FACTORS AFFECTING SIZE
REDUCTION
1.Hardness
2.Toughness
3.Stickiness
4.Material Structure
5.Moisture Content

8. FACTORS AFFECTING SIZE
REDUCTION
6.SofteningTemperature
7. Purity Required
8.Physiological Effect
9.Ratio of Feed Size to Product Size
10.Bulk Density

9. PRINCIPLES OF SIZE
REDUCTION (MECHANISMS)
Mechanism Description Machine (Example)
Cutting Material is cut by sharp blade Cutter Mill
Compression Material is crushed between roller by pressure Roller Mill
Impact Material breaks by hammer or bars at high speed Hammer Mill
Ball Mill
Moving particle strikes against a stationary surface Fluid Energy Mill
Attrition Break down of material by rubbing action
between two surfaces
Ball Mill
Fluid Energy Mill
Impact & Attrition
Combined
Ball Mill
Fluid Energy Mill

11. CLASSIFICATION OF SIZE REDUCTION EQUIPMENT'S

12. HAMMER MILL
Principle
Construction
Working
Advantages
Disadvantages
Uses

13. HAMMER MILL

16. BALL MILL
Principle
Construction
Working
Advantages
Disadvantages
Uses

17. BALL MILL

20. FLUID ENERGY MILL
Principle
Construction
Working
Advantaged
Disadvantages
Uses

21. FLUID ENERGY MILL

22. EDGE RUNNER MILL
Principle
Construction
Working
Advantages
Disadvantages
Uses

23. EDGE RUNNER MILL

24. END RUNNER MILL
Principle
Construction
Working
Advantages
Disadvantages
Uses

25. END RUNNER MILL

26. THEORIES OF SIZE REDUCTION
A number of theories have been proposed to
establish a relationship between energy input and
the degree of size reduction produced.
1. Rittinger’s theory
2. Bond’s theory
3. Kick’s theory

27. RITTINGER’S THEORY
Rittinger’s theory suggests that energy required in a size
reduction process is proportional to the new surface area
produced.
where, E = energy required for size reduction
 KR = Rittinger’s constant
 Si = initial specific surface area
 Sn = final specific surface area
Application: It is most applicable in size reducing brittle materials
undergoing fine milling.

28. BOND’STHEORY
Bond’s theory states that the energy used in crack propagation is
proportional to the new crack length produced.
where, E = energy required for size reduction
 KB = Bond’s work index
 di = initial diameter of particles
 dn = final diameter of particles
Application: This law is useful in rough mill sizing. The work
index is useful in comparing the efficiency of milling operations.

29. KICK’STHEORY
Kick’s theory states that the energy used in deforming (or
fracturing) a set of particles of equivalent shape is proportional
to the ratio of change of size/diameter
where, E = energy required for size reduction
 KK = Kick’s constant
 di = initial diameter of particles
 dn = final diameter of particles
Application: For crushing of large particles Kick’s theory most
useful.

30. ThankYou