Tablet compression ; Compression – Consolidation - Compaction Heckal’s plot

1. TabletCompression
Compression– Consolidation-Compaction
By
Vinod D Ramani
Bhagwan Mahavir college of Pharmacy, Surat

6. 6
Tablets are made by compressing the formulation
ingredientas containing the drugs along with the
excipients on stamping machines.
It is also called a press or simply compression
machine.
Tablets compression

7. 7

8. 8
Basic Components of
tablet press
• For holding and feeding the granulation
Hopper
• It defines the shape and size of the tablet.
Dies
• Helps to compress the granulation
Punches(Upper & Lower)
• It guides the movement of the punches
CamTrack
• It is used to move the granulation from the hopper to the die.
Feeding Mechanism (Feed Frame)

9. 9

10. 10
Feed Frame

11. 11
Types of tablet
press
Tablet Press
Single Punch
Multi Station
Press
Comment !!

12. 12
Single Punch
Machine
Upper &
Lower Collar
Collar
Locker

14. 14
Other Components of
tablet press
• Part of the machine which holds the
granulation
Turret
• It is the part of the machine holding the dies.
DieTable

15. 15
Factors affecting output of the
tablet machine
No ofTooling sets
No of compression stations
Rotational speed of the tablet press

16. 16
Compression
Machine Tooling
One tooling set consists of 2 punches and a die
The two punches includes the upper and the
lower punch.
There are three types of tooling

17. CLASSIFICATION OF MULTI-STATION PRESS
TOOLING
TSM STANDARD
 TSM is acronym for the “TABLET SPECIFICATION MANUAL”, widely recognized and exclusive in the
United States.
 TSM tooling specifications are the sole reference on U.S. manufacturing standards for tablets and tablet
tooling.
 Established by the American Pharmacists Association (APhA).
 TSM tooling specifications are the only published standards for the tablet compression industry.
EU STANDARD
 EU, is short for “EUROSTANDARD” considered as the European standard and also globally applicable.
 EU, more widely used than the TSM.
 EU, or Euronorm standard tool configurations are not published or governed by any organization or
association.
 The EU standard is the most common tooling configuration used outside the U.S.

18. Basics of
Tablet tooling
 Tablet compression machines are made in
keeping in view the type of dies and punches
will be used on them, The dies and punches
and their setup on compression machine is
called tooling, it is classified as B and D mainly.
 The B tooling dies and punch can be further
have specifications as BB
 D tooling can also be dies and punches can be
utilised on B tooling machine which is called as
DB

19. Types of
Tooling
available
‘B’ -Tooling
‘D’ –Tooling
‘BB’ -Tooling
‘DB’ –Tooling

20. 20
Types of tooling and
specifications
• Length = 5.25 inch
• Barrel diameter = 0.75 inch
• Head Diameter = 1 inch
BBTooling
• It has the same specifications as BB tooling
• Only difference is that lower punch is 3.56 inch long
BTooling
• Length = 5.25 inch
• Barrel diameter = 1.0 inch
• Head Diameter = 1.25 inch
DTooling

21. TOOLING TERMINOLOGIES

22.  Head: The end of the punch that guides it through the cam track of tablet
machine during Rotation.
 Head flat (Dwell Flat): The flat area of the head that receives the
compression force from Rollers (in upper punches) and determines the
weight and ejection height (in lower punches).
 Outside head Angle: The area gets in touch with the roller prior to head
flat , while Compression.
 Inside Head Angle: This is the area, which pulls down the lower punches
after ejection and lifts the upper punches after compression.
 Neck: The relived area between the head and barrel, which provides
clearance for the cams.
 Barrel: This area guides the punch (while going up and down) with
reference to turret guides.
 Stem: The area of the punch opposite the head, beginning at the tip and
extending to the point where the full diameter of the barrel begins. If the
chamfer is present the barrel usually reaches its full diameter just above
the chamfer.
PunchTerminology

23. Punch
Terminology
 Tip: This determines size, shape & profile
 Tip face: This area of punch is where the tablet is formed. Good surface
finish is required here to get quality tablets.
 Working length: This distance between bottom of the cup and the head
flat is called as working length which determines weight and thickness of
the tablet.
 Overall length: Distance between top of the cup and the head flat.
 Key Angle: The relationship of the punch key to the tablet shape. The keys
position is influenced by the tablet shape, take-off angle, and turret
rotation.
 Domed Heads: Increases the dwell time and hence help to achieve the
better tablet hardness.
 Dwell time – The time punches spends below the pressure roller while
rotating in the machine.
 Clearance: Die bore dia – punch tip dia = Clearance.
 Hardness: Usually measured in HRC (Rockwell ‘C’ scale) and optimum
readings are as follows:
PunchTerminology

24. Die
Terminology
 Die.O.D.: The outside diameter of the die, which is compatible with
the die pockets in the press.
 Die Height:The overall height of the die.
 Die Bore: The cavity where the tablet is made. The Cavity’s shape and
size determine the same form of tablet.
 Chamfer: Entry angle of the die bore.
 Taper dies: dies with tapered bore on one or both sides. They are used
for easy ejection of tablets (mainly for double layered tablets.
 Die Groove: The groove around the periphery of the die, which allows
the die to be fixed in the press.
 Lined (Insert) Dies: Dies fitted with a linear insert made from a much
harder, more wear resistant material such as tungsten carbide and
ceramic.
DieTerminology

25. SHAPES OF PUNCHES/TABLET IN REGULAR USE
 Round
 Geometric
 Convex
 Convex & Bevel
 Oval
 Modified Oval
 Capsule
 Modified Capsule
 Compound Cup
 Flat Faced
 Flat Faced Bevel Edged
 Flat Faced Radius Edged
 Deep Concave (Round/Capsule)
 Extra Deep
 Modified Ball
 Shallow Concave (Round/Capsule)
 Standard Concave (Round/Capsule)

26. SHAPES OF PUNCHES/TABLET IN REGULAR
USE

27. SHAPES OF PUNCHES/TABLET IN REGULAR USE

28. Type ofSteel
used for
construction of
die and
Punches
(hardened
steel)
 STEEL HARDNESS
 OHNS O1 58-59
 HCHC D2 59-60
 HCHC D3 61-62

29. TCM
specification
looks like

30. TCM
Brands
Cadmach
Manesty
Killian
Korsch
Sejong
Ronchi

31. Advance
Tooling
Designs

32. Advance
Tooling
Designs

33. Stages of
Tablet
Compression
Filling
Metering
Compression
Ejection

34. Stages of
Tablet
Compression

36. Stages of
Tablet
Compression
FILLING
 The filling stage of tablet compression process
involves transfer of granules to the compressing
machine punch-die cavity.
 The punch die cavity is composed of upper
punch, die and lower punch. The position of
lower punch within the die determines the
volume of the punch-die cavity.
 This volume must be appropriately sized for the
weight of granulation to be compressed into
tablets.
 The granulation is overfilled on the die table
(turret) to ensure complete filling of the
punch-die cavity volume.

37. Stages of
Tablet
Compression
METERING/WEIGHT ASDJUSTMENT
The metering stage of the tablet compressing process
involves removal of excess granulation from the
compressing machine.
This stage enables the exact weight (volume) of
granulation to be compressed into tablets.
The exact weight of granulation is controlled by the
height of the lower punch in the die. The height of
the lower punch is controlled by the metering cam
(also called the dosage cam).
The lower punch is raised to the appropriate level in the
die to provide the exact weight of granulation in the
punch-die cavity. The excess granulation is scraped
from the surface of the die table.

38. Stages of
Tablet
Compression
COMPRESSION
The compression stage of the tablet forms the tablet.
This stage involves bringing together the upper and lower
punches under pressure within the die to form the tablet.
As the punches enter the compression stage, the upper and
lower punches move between two large wheels called pressure
rolls. These pressure rolls push the punches together to form
the tablet.
The distance between the upper and lower punches
determines the thickness and the hardness of the tablet.
When the punches are close together, a thin and hard tablet
is created. When the punches are farther apart, the tablet
made is softer and thicker.
The proper balance of thickness and hardness
determines the optimum roll distance for any specific
product. These adjustments are made while keeping the
tablet weight constant.

39. Stages of
Tablet
Compression
EJECTION
 The ejection stage of the tablet compressing process
involves removal of the tablet from the lower
punch-die station.
In this stage, the upper punch retracts from the die
cavity and rises above the turret table. Then the lower
punch rises in the die, which in turn pushes the tablet
upward to the top surface of the die table and out of
the die cavity.
 A scraper (also called takeoff scraper or tablet rake-
off) then pushes the tablet off the die table away from
the compressing machine into the collection container
through discharging chute.

40. Post
Compression
Equipment
Tablet deduster or definger.
This equipment removes excessive dust or fringes from
the tablets by means of gentle agitation and vacuum.
Metal detector
This equipment detects metal fragments within the
tablet.
Tablet weight checker
This equipment automatically weighs individual tablets
and rejects out-of-specification tablet weights.

41. Physics Of
Tablet
Compression
1. Compression
2. Consolidation
3. Compaction
4. Process of compression
5. Forces involved in Compression

42. Physics Of
Tablet
Compression
Compression
Compression means a reduction in the bulk volume of a material as
a result of the removal of the gaseous phase (air) by applied pressure.
Consolidation
Consolidation is an increase in the mechanical strength of a
material resulting from particle-particle interactions.
Compaction
Compaction of powders is the general term used to describe the
situation in which these materials are subjected to some level of
mechanical force.
 The physics of compaction may be simply stated as "the
compression and consolidation of a two-phase (particulate solid-
gas) system due to the applied force."

43. Physics Of
Tablet
Compression

44. Consolidation
An increase in the mechanical strength of the material
resulting from particle or particle interaction. (Increasing in
mechanical strength of the mass)
Consolidation Process
Cold welding: When the surface of two particles
approach each other closely enough, (e.g. at separation of
less than 50nm) their free surface energies result in strong
attractive force, this process known as cold welding.
Fusion bonding: Contacts of particles at multiple points
upon application of load, produces heat which causes fusion
or melting. If this heat is not dissipated, the local rise in
temperature could be sufficient to cause melting of the contact
area of the particles.
Upon removal of load it gets solidified giving rise to
fusion bonding & increase the mechanical strength of mass.

45. .
The process of compression.
REMOVAL OF PRESSURE

46. Transitional repacking/particle rearrangement.

47. Deformation
• The force required to initiate a plastic deformation is called as yield stress
or elastic limit.

49. Fragmentation and deformation.
Fragmentation do not occur when applied stress-
• is balanced by a plastic deformation.
• change in shape.
• sliding of groups of particle (viscoelastic flow).

50. After fragmentation of the particles, as the pressure increases, formation of
new bonds between the particles at the contact area occurs. The hypothesis
favouring for the increasing mechanical strength of a bed of powder when
subjected to rising compressive forces can be explained by the following
theory.
Bonding Mechanism
There are three theories about the bonding of particles in the tablet by
compression
I.Mechanical theory
II.Intermolecular force theory
III. Liquid-Film surface theory
❖ Bonding Of Particles

51. The mechanical theory
• It occurs between irregularly shaped particles.
• The mechanical theory proposes that, under pressure the individual
particles undergo Elastic / Plastic deformation and the particle
boundaries that the edges of the particle intermesh forming a
mechanical Bond.
• Mechanical interlocking is not a major mechanism of bonding in
pharmaceutical tableting.
❖ Bonding Of Particles

52. • The Molecules at the surface of solids have unsatisfied forces which
interact with the other particle in true contact.
• According to this theory, under compressional pressure the molecules at
the points of true contact between new clean surfaces of the granules are
close enough so that vanderwaals forces interact to consolidate the
particles.
• Material containing plenty OH group may also create hydrogen bond
between molecules. E.g. microcrystalline cellulose is believed to undergo
significant hydrogen bonding during tablet compression
• The intermolecular forces theory and the liquid-surface film theory are
believed to be the major bonding mechanisms in tablet compression
 Intermolecular force theory

53. Ejection.
Portion under strain caps strain > shear strength.

54. 3 stages of force necessary to eject a finished table
1. Peak force required to initiate ejection.
2. Small force required to push tablet up to die- wall .
3. Decline force as tablet emerge from die.

55. Various Forces involved in Compression
1. Frictional Forces
2. Distribution Forces
3. Radial Forces
4. Ejection Forces
Frictional Forces: are interparticulate friction & Die wall Friction.
reduced Glidants
E.g. Colloidal silica
Lubricants
E.g. Mag. Stearate
Distribution Forces: Most investigational of fundamental of tableting
have been carried out on single punch presses with hydraulic Press.
Ejection Forces: Radial die wall forces & die wall friction also affects
ejection of the compressed tablet from die. The force necessary to eject
a finished tablet is known as Ejection Force. Variation also occurs in
ejection force when lubrication is inadequate.

56. Measurement of
compression
forces
 Strain gauge

57. Measurement of
compression
forces
 Strain gauge

58. Measurement of
compression
forces
 Piezo – Electric Cell

59. Measurement of
compression
forces
 Piezo – Electric Cell

60. Heckal’s plot
 The heckel analysis is a most popular method
of determining the volume reduction under the
compression pressure in pharmacy.
 Powder packing with increasing compression
load is normally attributed to particle
rearrangement, elastic and plastic deformation
and particle fragmentation.
 Heckel analysis is based on the assumption that
powder bed densification follows first order
kinetics.

61. Heckal’s plot
 In heckel equation the decrease in porosity of powder bed as the
compression force increases is assumed to follow the following
equation:
 Where, D= ρave / ρtrue
 ρave = the average density of the powder bed.
 ρtrue = true density of the powder.
 (1-D) = porosity.
 K = constant.
Upon integration:
In heckel plot we draw ln[1/1-D] as a function of compression
pressure P.

62. Types of
Heckal’s plot
 Type A Heckel plot:
 For plastic deforming bodies. It is possible to distinguish
the three different types of powder behavior by
compressing different size fraction of the same
material. For plastically deforming materials the Heckel
plots, drawn from different size fractions remain
parallel over the entire pressure range.
 Examples: MCC, Starch

63. Types of
Heckal’s plot
 Type B Heckel plot:
 For fragmenting materials. For fragmenting materials,
the plots become coincidental as the compression
pressure increases.
 Examples: Lactose, Sucrose.

64. Types of
Heckal’s plot
 Type C Heckel plots:
 After initial linear part the plots become coincidental
because the material packing fraction approaches unity
at quite low compressive stress level.
 Examples: Fatty acids or Lactose mixed with high
percentage of fatty acids.

65. Heckal’s plot
Significance of Heckel Plots:
 The Heckel constant k, has been related to the
reciprocal of the mean yield pressure, which is the
minimum pressure required to cause deformation of
the material under compression.
 The intercept of the curve portion of the curve at low
pressure represents a value due to densification by
particle rearrangement.
 The intercept obtained from the slope of the upper
portion of the curve is a reflection of the densification
after consolidation.
 A large value of the Heckel constant indicates the onset
of plastic deformation at relatively low pressure.
 A Heckel plot permits an interpretation of the
mechanism of bonding

66. Heckal’s plot
Weakness of Heckel Plots:
 Shape of the plot is very sensitive for small errors in the
determination of powder true density.
 Linear part of the plot is sometimes difficult to
determine.
 Heckel plot determination need very accurate data.
 Even the deformation of the tablet compression
machine has to be recorded.

67. References:
- Keith marshall 1987,Compression and consolidation of powderd solids,
Leon lachman, Herbert a.Liberman, & Joseph kanig ,The theory and
practice of industrial pharmacy, third edition varghese publication
house,bombay, pp.66,68,70-88.
Eugene parrott , 2007,Compression,Herbert A.Liberman, Leon
Lachman & Joseph B.Schwartz ,Pharmaceutical dosage forms, tablets,
volume ii,pp.201-241.
Stanforth J.N, Aulton’s pharmaceutics the design and manufacturing
of medicine,third edition, Churchill livingstone elsevier,pp.176,177.
Subrahmanyam C.V. ,Micromeritics, Textbook Of Physical
Pharmaceutics, Second Edition,vallabh prakashan,delhi,Pp-180-234.
Gilbert S. Banker , Christopher T. Rhodes, Modern
Pharmaceutics , Fourth Edition.Pp.408-409.
www.google.com