Roller compactors are used in the pharmaceutical industry to densify fine powders into solid compacts like flakes or sheets. They have replaced slugging as the preferred dry granulation method. A roller compactor consists of a feeding system, compaction unit between two counter-rotating rolls, and a size reduction unit. It provides pre-densification, improves flowability, and compresses particles into larger agglomerates quickly and efficiently. Key design considerations include the roller assembly type, side sealing method, feeding mechanism, roller surface, and roller orientation. Roller compaction offers benefits like improved flow and stability but can impact dissolution if not formulated properly.

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ROLL COMPACTOR
By Kailash choudhary

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INTRODUCTION
There are two dry granulation methods in
the pharmaceutical industry: slugging and
roll compaction. During the 1950s–1970s,
dry granulation was mainly performed by
slugging; however,
nowadays, roll compaction is the preferred
method because it offers greater
production capacity, and simplified and
continuous processing

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ROLE OF ROLL COMPACTOR
Roller Compactors are used to force fine
powders between two counter rotating rolls
and presses the raw materials into a solid
compact (flakes, sheets, strips).It is quick &
efficient way to provide pre-densification
and improve followability of the primary
powder, it compresses small size particle
into large agglomerates.

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GENERAL VIEW
.
01) Feed hopper 02) screw feeder 03) vacuum system with filter 04) Roller unit 05) Flake crusher
06) Pre- granulator 07) fine granulator 08) frame 09) control panel 10) switch cabinet

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PROCESS FLOW CHART

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BASIC FLOW CHART

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EQUIPMENT COMPONENTS
A roller compactor generally consists of three major
units.
A ) Feeding system and Screw feeder
B ) Compaction unit
C ) Size reduction unit

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EQUIPMENT COMPONENTS
A ) feeding system and Screw feeder

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A). A feeding system is divided in four parts
Material is filled into feed hopper 01)
manually from the top . Thus the material
falls down in the direction of rotating chopper
and 02) band screw 03) of the feed hopper.
The material transported evenly downwards
through the hopper in the direction of 04)
screw feeder
EQUIPMENT COMPONENTS

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B) Screw feeder: it helps to carry material to the rollers and it
somewhat de aerates the material. Generally three types of screw
feeder used in industrial practice.
a) Vertical b) Inclined c)Horizontal
EQUIPMENT COMPONENTS

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2). Screw feeder
.
EQUIPMENT COMPONENTS

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B). A compaction unit, where powder is compacted
between two counter rotating rolls to a ribbon by
applying a force.
EQUIPMENT COMPONENTS

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C). A size reduction unit, for milling the ribbons to
the desired particle size.
EQUIPMENT COMPONENTS

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schematic of roller compaction process

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ROLLER COMPACTOR DESIGN
Basically the design can be classified into
five major characteristics of the design :
1) Roller assembly
2) Side sealing
3) Feeding mechanism
4) Roller surface type
5) Roll layout

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01) Roller Assembly
Roller assembly can be divided into two
categories:
1) one is equipped with a fixed gap : When a
fixed gap is installed, the amount of powder
drawn in into the compaction area between
the rolls is inconsistent, which results in
different forces applied to the powder bed.
Like in slugging, this will cause large
fluctuations in the ribbon and granulate
properties.

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1) one is equipped with a fixed gap :
01) ROLLER ASSEMBLY

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01) ROLLER ASSEMBLY
02) the other one with a floating gap:
the distance between the rolls change according
to the amount of powder provided. The force
applied to the powder remains constant. This
ensures that property fluctuations in the granules
are reduced to a minimum

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02) the other one with a floating gap:
01) ROLLER ASSEMBLY

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02) SIDE SEALING
Sealing on either end of the roller gap is necessary
to stop powder from flowing away from the space
between the two roller. There can be two type of
sealing
01) Side plate assembly/check plate: The side
plate made of PTFE (Polytetrafluoroethylene)-
platelet to avoid metal- metal friction and wear
02) Rim roll assembly: the one roller with rims on
both side and other roller runs within cavity of this
rims. imagine male and female fitting whereby one
fits within the other .
Note : This allow the resistance to high transversal
pressure without losing the sealing capability

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02) SIDE SEALING

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Side plate assembly/check plate Rim roll assembly
02) SIDE SEALING

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03) FEEDING MECHANISM
The Feeding mechanism can be by gravity or by
force feeding using method a hopper guide the
powder material to region between the two roller
and the hopper is filled up with powder material
The force feeding system is usually applied using
screw whish is placed inside a hopper and the
screw end is directed to the space between the two
rollers.
The screw pushes powder material inside the
hopper toward the roll compaction region and this
reduces the effect of air entrainment in feeding
region

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04) ROLLER SURFACE TYPE
There are four type of roll:
1) Milled- shape(Square/ pocketed)
2) Corrugated - shape(plain)
3) Knurled- shape(Diamond)
4) Plain- shape(plain/Smooth)

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 Milled- shape(Square)
Product between squared roller, Compaction & Pre-compacted material after roller
04) ROLLER SURFACE TYPE

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 Plain- shape(plain)
Product being stuck in slip area Pre-compacted material after roller
04) ROLLER SURFACE TYPE

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 Microscope image of powder before compaction
MCC 101 Mannitol 200SD
04) ROLLER SURFACE TYPE

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 Microscope image of powder after compaction
MCC 101 Mannitol 200SD
04) ROLLER SURFACE TYPE

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05) ROLLER LAYOUT
Three type of roller orientation are commercially
available
A) Vertical orientation: Direct bypass through rolls
is minimised because material movement is not
govern by gravity feeding system , Due to the
advantage of less bypass of material, this is
preferred for low dose product.
B). Inclined orientation: In Inclined orientation
(Position between horizontal and vertical) such type
design reduce bypass of material up to 10 to 15 %
C) Horizontal orientation: This is most commonly
used design, in this material loss is high from bypass

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05) ROLLER LAYOUT

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Vertical orientation
05) ROLLER LAYOUT

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Horizontal orientation
05) ROLLER LAYOUT

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Inclined orientation
05) ROLLER LAYOUT

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Advantage
• Roll compaction improve powder flow properties
• To avoid wet granulation this may induced
degradation
• To improve final product stability
• To prevent segregation
• To reduce bulk volume of final blend hence
improves transportation efficiencies
• To reduce environment potential hazards and
ensures safety

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Disadvantage
• Roll compaction densifies the powder or particle
which can adversely affects the dissolution of
product
• The powder to be compacted must be
compressible or have to add compressible
excipient or additive to the formulation.
• The various process parameter involved in roller
compaction process and its interrelation are given
in figure.

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Roller process parameter

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Problem and Remedies

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