Physics of tablet compression

tablet fabrication mechanism

1. PHYSICS OF TABLET COMPRESSION Presented By Mr. Shubham Radhesham Biyani M. Pharmacy (pharmaceutics) Guided By Prof. Mr. Chate sir SCHOOL OF PHARMACY S R T M UNIVERSITY NANDED 430616

2. CONTEN Ts Introduction Difference between compression consolidation Properties of powder/granule Compression cycle / process of compression Forces involved in compression Compaction profile Equation for compression study references

3. Introduction It is also known as ‘ physics of compaction’ . It may be stated as compression- consolidation of two phases ( solid - gas ) . compression:- It is the reduction in bulk volume of material due to displacement of gaseous phase . Consolidation :- It is increase in mechanical strength of material due particle – particle interaction .

4. Difference between compression consolidation compaction consolidation 1. It is defines as the formation of solid specimen of defined geometry by powder compression. 1 It is increase in mechanical strength of material from particle – particle interaction . 2. The compression takes place in a die by the action of two punches , the lower and upper by which compression force is applied .

5. Properties of powder/granule While studying physics of compression considering following ‘s factor :– Angle of repose Bulk density Tapped density Hausner ratio carr’s index or percentage compressibility etc of material….

6. Compression cycle / process of compression In pharmaceutical tableting , an appropriate volume of granules in die cavity is compressed between an upper & lower punch to consolidate the material into a single solid matrix , which is finally ejected from die cavity as a tablet ….

7. Events in process of compression transitional repacking or particle rearrangement Deformation at point of contact Fragmentation Bonding Decompression Ejection

8. Transitional repacking or particle rearrangement Particle size distribution determines initial repacking.. During initial stage of compression , particle subjected to low pressure , during this particle moves with respect to each other & smaller particle enters in voids between larger particle.. As result volume decreases & density increases spherical particle undergoes lesser rearrangement than irregular particle…

9. Deformation at point of contact When a force is applied on a material deformation occur . If the deformation disappear completely (return to original shape) upon release of stress , it is said to be ‘ elastic deformation’ A deformation that not recover completely after removal of stress known as ‘ plastic deformation’. The force required initial plastic deformation is known as ‘yield stress’ When granule particle so closely no further filling voids occurs ,hence further increase of compression force cause deformation at point of contact …

10. Fragmentation Compression forces increases particle starts fragmentation because of high load , particle breaks into smaller fragment leading to formation of new bonding area. Fragmentation undergoes densification & infiltration of small fragments into voids .

11. Bonding cold welding :- When particle approach each other unsatisfied forces present on their surface leads formation of strong attractive forces called ‘cold welding’.. Fusion bonding:- Particle irregular in shape heat transmission leads increase mechanical strength . Factor affecting bonding:- Chemical nature of material Available surface Presence of surface contaminant

12. Decompression The success or failure of intact tablet depends on stress induced by ‘ elastic rebounds ’ & the association deformation produced during decompression & ejection . Capping is due to unaxial relaxation in die cavity .. Ejection As the lower punch rises & pushed tablet upward , there is continues residual die wall pressure & energy may be expanded due to die wall friction.

13. Forces involved in compression Frictional forces Distribution forces Radial forces Ejection forces

14. Compaction profile Force –time profile Force – displacement profile Die wall force profile

15. Equation for compression study

16. references Aulton, M. E. (2007).  Alton's pharmaceutics: The design and manufacture of medicines . Edinburgh: Churchill Livingstone. Pharmaceutical dosage forms: Tablets. Vol. I. Edited by HH Lieberman ...