Compression and compaction

05/01/23 RAGHAVENDRA KUMAR GUNDA

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COMPRESSION AND

COMPACTION ENERGY INVOLVED IN COMPACTION TABLET STRENGTH CRUSHING STRENGTH FRIABILITY LAMINATION

Presented by:RAGHAVENDRA KUMAR GUNDA

GUIDED BYProf.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


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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


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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.


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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


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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)


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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


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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


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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)


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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


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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 includingHARDNESSBENDING STRENGTHFRIABILITYFRACTURE RESISTANCECRUSHING STRENGTHFLEXURE (or) BREAKING STRENGTH


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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.


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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)


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SURFACE CRUSHING STRENGTH

VICKER’S TEST

Pfizer Tablet Hardness Tester Monsanto Tablet Hardness Tester

Stokes Digital Tablet Hardness Tester

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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


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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


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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

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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

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REASONS Entrapment of Air& Elastic Compression ruptures the bonds

Defective Punches & Dies

High Speed of Compression

Incorrect setup of press

OVERDRYING of Granules

PREVENTIVE MEASURESOperating 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


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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


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BIBLIOGRAPHY1. 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

http://www.pharmainfo.net/

http://www.wikipedia.com/


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Education

Compression and compaction