Compression and compaction

02/10/16 RAGHAVENDRA KUMAR GUNDA1

COMPRESSION AND COMPACTION
ENERGY INVOLVED IN COMPACTION
TABLET STRENGTH
CRUSHING STRENGTH
FRIABILITY
LAMINATION
Presented by:
RAGHAVENDRA KUMAR GUNDA
GUIDED BY
Prof.A.M.S.SUDHAKAR BABU SIR M.PHARM., M.B.A.,Ph.D
PRINCIPAL & HOD
DEPARTMENT OF PHARMACEUTICS
A.M.REDDY MEMORIAL COLLEGE OF PHARMACY

COMPRESSION: The process
of applying pressure to a material i.e,
results reduction in the bulk volume of
the material as a result of displacement of
gaseous phase
CONSOLIDATION: It is an increase
in mechanical strength of a material resulting
from particle –particle interactions
COMPACTION: It is the general
term used to describe the situation in which
material is subjected to some level of
MECHANICAL FORCE
PRESSURE: The force acting on
unit area of a surface , (or) The ratio of
Force to Area. It is measured in Pascals
ENERGY: A measure of a system’s
ability to do work. It is measured in Joules

Tablet Machines, Roll Compacters, Extruders are required a high
Input of MECHANICAL WORK
As the upper punch enters the Die, begins to apply force to
granulation; A small qty of energy needed to Rearrange the particles to
pack with less Void
As the process of compaction continues ( i.e both Compression
&Consolidation) energy is expended to over come DIEWALL
FRICTION& To increase the specific surface area as
Fragmentation Deformation occurs.
The ways in which work done is converted into other forms of energy
. The work requirement is a key factor in machine design& any
proportion of applied energy stored in a product retains as
DESTRUCTIVE CAPABILITY.

That necessary to overcome Friction between
Particles
That necessary to overcome Friction between
Particles& Machine parts
That required to cause brittle fracture with in the
material
That required to induce ELASTIC (Or) PLASTIC
DEFORMATION
That associated with MACHANICAL OPERATIONS of
various parts

The energy expenditure is the sum of the energy
dissipated as HEAT, The energy of reversible
ELASTIC STRAIN, The energy of COMPRESSION
ETOTAL = ECOMPRESSION + EHEAT +EELASTIC
The energy expended in the compression of granule to reduce the void &
To form a tablet is the product of Force& Distance.
The energy is determined by measuring lower punch force&
displacement of upper punch. And plotting the Compressional force a
function of Displacement.
The energy used to compress Tablet and To overcome Die wall
friction is equivalent to Area Under the Force-Displacement Curve
(AUC 1 g cm = 2.3X 10-5 cal)

If the granules ate Lubricated, The Die Wall Friction is thus reduced&
Less force is required to produce given Displacement& more Upper
punch Force is Transmitted to Lower punch

According to Experimental reports of NELSON &ASSOCIATES, the energy
expenditure in LUBRICATED& UN LUBRICATED SULPHATHIAZOLE
GRANULATION
Lubrication reduces the energy to 75% . Proved experimentally by
taking .4 gm lubricated the results are compared with un lubricated
sulphathiazole granules compressed at 1700 kg/cm2. The difference in
AUC is equal to .8 cal
The total work was calculated using formula
DMAX
WT = ∫ F.dD
DF=0

COMPRESSION UNLUBRICATED LUBRICATED
COMPRESSION 1.5 1.5
OVERCOMING DIE
WALL FRICTION
0.8 -
UPPER PUNCH
WITHDRAWAL
1.2 -
TABLET EJECTION 5.1 0.5
TOTAL 8.6 2.0
ENERGY EXPENDED (Cal)

FORCE- DISPLACEMENT CURVES ( F-D CURVES)
Distinctive F-D curves related to the Stress/ Strain
properties of meterials involved shows the more sensitive method
for evaluating the LUBRICANT EFFICIENCY.
The wider utility of F-D curves is the exemplified by their
application to the selection of a best BINDER
For example: GELATIN*, STARCH, METHYL CELLULOSE FOR SULPHONAMIDE TABLET

RELATION BETWEEN TEMPERATURE& ENERGY EXPENDED
According to HIGUCHI HYPOTHESIS , By
assuming that only energy expended in the process of
forming a tablet caused rise in temperature, estimated the
temperature rise to be approximately 5°c
The energy expended in the process of tablet ejection, that
needed to overcome Die Wall Friction& that were used to
remove up from die
STRENGTH OF TABLETS
The MECHANICAL STRENGTH of tablets has been described in a variety of ways including
HARDNESS
BENDING STRENGTH
FRIABILITY
FRACTURE RESISTANCE
CRUSHING STRENGTH
FLEXURE (or) BREAKING STRENGTH

The Mechanical Strength of tablets is an imp property of this form of
Drug Presentation& plays substantial role in both
PRODUCT DEVELOPMENT & CONTROL
The mechanical strength is primarily due to two events that occur
during COMPRESSION: The formation of Interparticulate bonds
& A reduction in porosity sed Density
The most popular estimate of tablet strength has been
CRUSHING STRENGTH SC In industry mechanical
strength is most often referred as TABLET HARDNESS/
more precisely CRUSHING STENGTH
BROOK & MARSHALL have described as the compressional force
(fc) that when applied diametrically to a tablet just fractures it. It was
measured in Kg. A SC OF 4Kg is considerable as minimum satisfactory.

The tablet hardness have been associated with other properties like
Density, Porosity, Concentration of Binder. It generally increases
depend upon Shape, Chemical Properties, Binding agent, Pressure
applied during Compression (general range 300-3000 Kg/Sq.Cm in
hydraulic presses)
SC determinations are useful for determining needed pressure adjustment on tablet machine for
getting appropriate tablet& to meet Dissolution Specifiactions
The resistance of tablets to Capping, Abrasion, Breakage under conditions of Storage,
Transportation, Handling before usage depends upon its HARDNESS
It may be described by Knudsen equation
Sc = Kd-a
Where
SC = crushing strength
D = mean particle diameter
K= constant
a= material dependant property
ST = 2Fc/ DH ST = Tensile strength
D = Diameter of tablet
H = Thickness of Tablet

wf = 2(∫FdZ)/ DH
F = Force applied to Tablet
Z = deformation resulting from it
Many Crushing Strength Testers are described in the Literature, several are available
Commercially. Comparison between the have been described. The widely used are
HORIZONTAL
CRUSHING
STRENGTH
MONSANTO HARDNESS TESTER( STOKES MECHANISM
STRONG COBB TESTER (PNEUMATIC MECHANISM)
PFIZER TESTER(PLIERS MECHANISM)
ERWEKA TESTER(COUNTER WEIGHT PRINCIPLE)
SCHLEUNIGER TESTER(COUNTER WEIGHT PRINCIPLE)

SURFACE
CRUSHING
STRENGTH
VICKER’S TEST
Pfizer Tablet Hardness
Tester Monsanto Tablet Hardness Teste
Stokes Digital Tablet Hardness Tester

02/10/16 17
From the reports relate to crushing strength, The crushing strength is directly proportional to
Disintegration Time, log FA & Inversely proportional with porosity over normal range of
Compressional Forces
From the results of Shotton, Gandetron suggested that the granular size will influences the
TABLET STRENGTH.
Smaller size
Greater the strength
The presence of lubricants, can nullify the failure due to weakening of
Interparticulate bonds. The Inherent cohesiveness of particles se consolidation
Stronger Tablets having high Microporosity
They may Trap Air in tablets
It can Rise the CAPPING at granular boundaries

Presence of Thin Film of Binder at the surface
Lead to Failure across the Granules
Tablet with se TABLET STRENGTH
FRIABILITY test is performed to evaluate the ability of tablet to withstand wear& tear in
Packing & Transportation. The most popular version (commercially available) is the
ROCHE FRIABILATOR
THE APPARATUS consists of a Plastic Chamber, which is divided into two
parts& revolves at a speed of 25 rpm

F = 100(1- W0 / W)
Describes the practical use of Indentation Hardness and Tensile
Strength data to define 3 dimensional indicates {STRAIN INDEX,
BONDING INDEX , BRITTLE FRACTURE INDEX } were used to
quantify the relative Tabletting Performance (Especially Lamination
Tendency) of both Single Components& Mixtures
F= 0.8 – 1%
Plastic Chamber

02/10/16 20
One of the more common problems encountered in Compaction is
that the tablet structure fails on Ejection from Die
The partial r complete separation of Top r Bottom surface of the
tablet from the body is called CAPPING
In other cases the tablet splits into a number of layers
(LAMINATES). The phenomenon of separation of various layers
known as LAMINATION. This is due to Inadequate removal of
Air from the Granules in the Die Cavity before& during Compression
Excessive fines in the Granules
entrap the Air with in the Tablet
Which Tend pack poorly
MASSIVE ELASTIC RECOVERY give force inherent
variation in Compressional Stress

REASONS
Entrapment of Air& Elastic Compression ruptures the bonds
Defective Punches & Dies
High Speed of Compression
Incorrect setup of press
OVERDRYING of Granules
PREVENTIVE MEASURES
Operating at high speed under partial vacuum
Use of Slow Compressional rates& Multi Stage Compression Press
The Technique which se the association of weakly bonded contributing factor
Instances
Choice of Addition of Excipients which provide a Matrix of PLASTICALLY
DEFORMING material for stress relief
Loading& Unloading of mass by utilization of Large Compressional rolls,
Precompression, Slow press speeds also reduce the Lamination
Lubricants, compression mechanism, Moisture levels, Tooling Geometry all
contribute for overcoming Lamination all take into consideration

Setting Dies & Punches properly
Reduce the percentage of fines
Punches should be either BUFFED/POLISHED before use
Defective Punches are replaced
Regulate the speed of machine to desired level
Regulate the pressure on punches so as to maintain a proper degree of compression

BIBLIOGRAPHY
1. THEORY AND PRACTICE OF INDUSTRIAL PHARMACY BY LEON LACHMAN
2. A TEXT BOOK OF TUITORIAL PHARMACY BY COOPER& GUNNS
3. BENTLY’S TEXT BOOK OF PHARMACY
4. ANSEL’S PHARMACEUTICAL DOSAGE FORMS AND DRUG DELIVERY SYSTEMS
5. AULTON’S PHARMACEUTICS
6. PHARMACEUTICAL DOSAGEFORMS TABLET VOLUMES-II
7. REMINGTON’S PHARMACEUTICAL SCIENCES
8. MODERN PHARMACEUTICS BY CHRISTOPPHER.T.RHODES (M-D SERIES)
9. FMC MATERIAL
10. WWW.PHARMAINFO.NET
11. WWW.WIKIPEDIA.COM

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