Description of Construction, Working and Application of Pharmaceutical Machinery Such as Rotary Tablet Machine, Fluidized Bed Coater, Fluid Energy Mill and Humidifier.

Description of Construction, Working and Application of Pharmaceutical Machinery Such as Rotary Tablet Machine, Fluidized Bed Coater, Fluid Energy Mill and Humidifier.

1. EXPERIMENT NO. 1

Description of Construction, Working and Application of
Pharmaceutical Machinery Such as Rotary Tablet
Machine, Fluidized Bed Coater, Fluid Energy Mill and
Humidifier.
















S. I MAKRANI
Assistant Professor
Department of Pharmaceutics
Ali Allana College of Pharmacy Akkalkuwa.




Pharmaceutical
Engineering
Practical

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EXPERIMENT NO. 1
Aim:
Description of Construction, Working and Application of Pharmaceutical Machinery Such
as Rotary Tablet Machine, Fluidized Bed Coater, Fluid Energy Mill and Humidifier.
References:
1) Md. Rageeb Md. Usman, Prerna K. Mahajan, Dr. Mohammed Zuber Shaikh, Dr. Neelesh
Chaubey, Keerthy H. S. Practical Book of Pharmaceutical Engineering, first edition July 2018,
published by Nirali Prakashan, page no 53-66
2) C.V.S Subrahmanyam. J. Thimma Setty, Sarasija Suresh,V. Kusum Devi, Pharmaceutical
Engineering: Principles and practices Vallabh Prakashan, latest edition ,Page no 158-160

3)………………..

Requirements:
Rotary tablet machine, Fluidized bed coater, Fluid energy mill, Humidifier
Rotary tablet machine:
Principle:
Rotary tablet machine is used for high production of tablets. Tablet press also referred to as
tableting machine, pharmaceutical tablet press, and tablet compressing machine or tablet
punching machine is a mechanical device that compresses powders into tablets of uniform size,
shape, and weight containing approximately the same quantity of Active Pharmaceutical
Ingredient (API) and excipients. All tablet presses employs the same basic principle of
compression.
Theory:
Types/Classification of Tablet Press:
Tablet press can be classified into:
1. Single punch/single station/eccentric presses.
2. Multi-station/rotary presses.

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(A) Single punch/single station/eccentric presses:
Construction:
Parts of a single punch tablet press:
1. Hopper: This is connected to the feed shoe and it is where the granules/powder Mixtures are
poured into prior to tableting or compression. The hopper can be filled manually or by using
mechanical equipment during subsequent tableting.
2. Die cavity: The die cavity is where the powder granules are compressed into tablet. The die
determines the diameter of the tablet, The size of the tablet, To some extent the thickness of the
tablet.
5. Punches: This comprises upper and lower punch and they Compress the powder into tablets of
various shapes within the die.
4.Cam truck: This guides the position/movement of the punches.
Tablet adjuster : This is used to adjust the volume of the powder to be compressed and So
determine the weight of the tablet.
Ejection adiuster : This facilities the ejection of the tablet from the die cavity after
Compression. In the production of tablet using single punch, the upper punch compresses The
powder into tablets while the lower punch ejects the table

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Fig 1: Components/ functional parts of a single punch tablet press
Working:
The events involved in tablet production can be divided into 3 stages.
(a) Filing
The upper punch is raised and lower punch drops to create a cavity in the die. The feed shoe
moves over the die cavity and granules fall into the die cavity under the Influence of gravity
from the hopper.
(b) Compression:
The feed shoe moves out of the way and the hopper punch descends to compress the
granules/powder mixture into tablets by progressive reduction of the porosity of the die content
and forcing of the particles into close contact with one another.
(c) Ejection:

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The upper punch retracts and the lower punch moves upwards to eject the compressed tablet. The
whole events repeat over and over again unit the feed material is exhausted
Advantages of Single Punch Tablet Press:
1. The single punch structure is rational and small.
2. Easy to operate and it operates at a high utilization ratio.
3. It can manufacture odd shaped products with a diameter of up to 20 mm
4. It is ideal for development of tablets and small batch production.
Single punch tablet press utilizes a high amount of pressure to reduce weight variations between
tablets while maintaining a low noise level at the same time.
(B) Multi-Station Press
Multi-station press is a mechanical device that unlike the single punch tablet Press has several
tooling station which rotates to compress granules/powder mixture into tablet of uniform size,
shape (depending on the punch design) and uniform weight. It was developed to increase the
output of tablets. In rotary press, the compaction force on the fill material is exerted by both the
upper and lower punches leaving the powder granules to be compressed in the middle.
Construction
Hopper: The hopper holds the granules/powder mixture (API plus recipients) that are to be
compressed into tablets.
Die cavity: This is where the powder granules is compressed into tablets and it determines the
diameter of the tablets, the size of the tablets and to some extent the thickness of the tablets.
Feed paddle: Helps to force the feed the granules into the dies especially during faster rotation.
Punches: This comprises the upper and the lower punches. They move within the die bore to
compress granules into tablets.
Lower cam track: This guides the lower punch during the filling stage so that the die bore is
over filled to allow accurate adjustment.
Cam tracks: This guides the movement of both the upper and lower punches.
Dept of fill/capacity control : This adjusts the lower punch track during the latter part of the fill
stage to ensure that the appropriate quantity of granules remains within the die prior to
compression.

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Pre-compression rollers: This roller gives the granules an initial compression force to get rid of
excess air that might be entrapped in the die.
Main compression: This roller applies the final compression force needed for the formation of
tablet.
Ejection cam: Guides the lower punch upwards facilitating the ejection of tablet from the die
cavity after compression.
Take off Blade: This is fitted in front of the feeder housing and it deflects the tablet
down the discharge chute.
Discharge chute: This 1s where the tablet passes through for collection after being deflected by
the take-off blade.

Fig. 2: Components/Functional Parts of a Rotary Press
Working:
The process is essentially the same as the single press in that the tablets are produced by
compression between upper and lower punches within a die. In a multiple station press, there are
many sets of tools (punches and dies) and these are accurately aligned in such a way that the
whole head comprising die table and turrets uniformly rotate in the horizontal plane.
Filling: Material to be formed into tablets is placed/fed into the fixed hopper which then feeds a
fixed frame that fills several dies simultaneously as the die table rotates.

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Compression: Compression, as with the single station press, is performed by the punches which
are controlled by cam tracks and rollers that guide the movement of the punches as the table
rotates. The compression sequence starts by the lower cam guide pulling a lower punch to the
bottom of the dies. This action allows particular die to be overfilled with powder. The lower
punch will then rise according to a weight control process at which point excess powder is
removed by a swipe blade. The blade pushes material into the oncoming die.
The lower punch drops slightly allowing the upper punch to penetrate into the die and contact the
upper surface of the powder. This is the point at which compression begins.
In modern presses, there is a pre-compression step in which both punches are forced by pre-
compression rollers to squeeze the powder to form a tablet within the die. As the table rotates, so
the punches are engaged by the main compression rollers which are substantial rolls, exerting a
massive force on the powder. Both punches have forces applied and both move to compres the
tablet (unlike the single table press in which only the upper punch moves during the compression
step).
Ejection:
After the full compressive force has been applied, the upper punch is withdrawn by the upper
raising cam, and the lower punch also rises to bring the tablet above the surface of the die (and
die table). At this point the tablet is fully formed and is swept off the die table from the feed
frame towards a chute and container located beneath the die table to catch the tablets.
The lower punch will then be engaged by the pull-down cam to be withdrawn to the bottom of
the die, and the whole process starts again.
Advantages of Rotary Press:
1. High productivity can be gained with a minimal amount of labour while saving money.
2. Rotary press has an output of between 9000 - 234000 tab/hour thus saves time and meets up
with the high demand of tablet dosage form.
3. The powder filled cavity can be automatically managed by a moving feeder.
4. Rotary press decreases waste of valuable formulation in non-specific tablets.
5. The machine allows independent control of both weight and hardness.
Fluidized bed coater:
The fluidized bed coater used to coat particles, spheres, granules, and tablets. Systems been
developed for use with a variety of coating formulations, including aqueous/organic solvents, hot
saturated solutions and hot melts.

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Principle:
In this process, the spray is done inside a hollow cylinder from the bottom or top or may be from
side and pellets are allowed in small quantity to enter the hollow cylindrical tube.
Construction
Fluid bed processor systems (distinct types of spray systems)
(a) Top spray
(b) Bottom spray
(c) Tangential spray

Fig 3. Practical action of different sprays in fluid bed equipment

Top Spray in Fluid Bed Coating Machine:
With top spray coating in the fluid bed (batch and continuous), particles are fluidized in the flow
of heated air, which is introduced into the product container via a base plate.
The coating liquid is sprayed into the fluid bed from above against the air flow (counter Current)
by means of a nozzle. Drying takes place as the particles continue to move upward in the air flow.
Small droplets and a low viscosity of the spray medium ensure that the distribution is uniform.
The product is continuously fed into one Side of the machine an and is transported onwards via
the sieve bottom by means of the air flow. Depending on the application, the system is sub-
divided into pre-heating Zones, spray zones and drying zone The dry and coated particles are
continuously extracted

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Bottom Spray in Fluid Bed Systems (Wurster coating):
Unlike in top bed fluid bed equipment, here a spraying nozzle is in the bottom section. In the
Wurster process, a complete sealing of the surface can be achieved with a low uses of coating
substance. The spray nozzle is fitted in the base plate resulting in a spray pattern that is
concurrent with the air feed. By using a Wurster cylinder and a base plate with different
perforations, the particles to be coated are accelerated inside the Wurster tube and fed through
the spray cone concurrently. As the particles continue travelling upwards, they dry and fall
outside the Wurster tube back towards the base plate. They are guided from the outside back to
the inside of the tube where they are once again accelerated by the spray
This produces an extremely even film. Particles of different sizes are evenly coated.
i) Bottom spray coating is uniquely identified with the following features
(ii) Spraying nozzle is located at the bottom of a fluidization chamber.
(iii) Minimal spray drying due to the short distance between nozzle and particles.
iv) High coating efficiency and uniformity.
Bottom Spray Coating (Continuous fluid bed) Particularly suitable for protective coatings/colour
coatings where the products throughput rates are high. The product is continuously fed into one
side of the machine and is transported onwards via the sieve bottom by means of the air flow.
Depending on the application, the system is sub-divided into pre-heating zones, spray zones and
drying zones whereby spraying can take place from below in the form of a bottom spray. The dry
and coated particles are continuously extracted.
Tangential Spray Coating (Rotor pellet coating):
Ideal for coating with high solid content. The product is set into a spiral motion by means of a
rotating base plate, which has air fed into the powder bed at its edge. The spray nozzle is
arranged tangentially to the rotor disc and also sprays concurrently into the powder bed. Very
thick film layers can be applied by means of the rotor method.

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Fig. 4. Main types of spray nozzle positions in fluid bed system
Working of Wurster Coater:
The basic concept in Wurster coating is to separate the particles in the fluid bed from one another
in an air (gas) stream. While the particles are suspended, a coating formulation is sprayed from
the bottom of the bed up onto the particles (bottom-up spray). The process takes place inside a
specially modified fluid bed that is divided into two zones by a partition.
The inner area is a high velocity zone that separates the particles and pneumatically transports
them past the spray nozzle. After passing the nozzle, the particles enter the expanded area of the
chamber, slow down and fall back into the outer section of the fluid bed product bowl. The
coating dries while the particles are suspended to prevent agglomeration from occurring when
they enter the tranquil part of the bed. The coated particles in the tranquil storage area remain
fluidized just enough to allow them to continue moving towards the bottom of the bowl. When
the particles reach the bottom, they are drawn back into the high velocity air stream and the cycle
is repeated. This process continues until the desired level of coating has been achieved.
Applications:
1. A top spray coating fluid bed process Is common in fine chemical industry, animal feed and
food processing.
2. A bottom spray fluid bed process is commonly used in powder and granules coating in the
pharmaceutical industry.
3. It provides a uniform and excellent coating on every material.

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4.Again in this process, to ensure efficiency and high. quality of the final product, it is important
to monitor all process variables. This helps to maintain them to a certain level where an optimal
result can be realized.
5. The bottom spray in a fluid bed system ensures an even and uniform coating, hence, an
optimal film quality.
Fluid Energy Mill:
The fluid energy mill mainly used to grind the sensitive materials to the fine powder the
mechanism of impact and attrition forces applied by the air or inert gas from the nozzle presents
in the chamber.
Principle:
It works mainly on the principle of attrition and impact.
Construction:
The main basic parts present in the fluidized energy mill are as follows:
1. The inlet by which the solid material is introduced into the chamber which is made up from
stainless steel.
2. The nozzles by which the air and the inert gas is introduced into the chamber at high pressure.
3. The classifier from which the fine reduced particles are collected.
It consists of a loop of pipe which has a diameter of 20 to 200 mm, depending on the overall
height of the loop, which may be up to about 2 m. There is an inlet for the feed and a series of
nozzles for the inlet of air or an inert gas. It also has an outlet with a classifier which allows the
air to escape but prevents to pass until they become sufficiently fine.

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Fig. 5: Fluid Energy Mill
Working
In the operation of a fluid energy mill, gas of high energy content is introduced into a pulverizing
chamber. The air or inert gas is introduced with a very high pressure through the nozzle. Solids
are introduced into air stream through the inlet. Due to the high degree of terbulence, impact and
attritional forces occurs between the particles. The fine particles are collected through a classifier.
Fluid energy mill reduce the particles to 1 to 20 micron. To get very fine powder even up to 5
micron the material is pretreated to reduce the particle size to the order of 100 mesh and then
passed through fluid energy mill. A size-reduction unit depending for its action on collisions
between the particles, the energy being supplied by a compressed fluid, (e.g, air or steam) that
enters the grinding chamber at high speed. Suchmills will give a product of 5 micron or less.
Types of Pulverizer
There are two main classes of pulverizers
1. Air swept pulverizer.
2. Air impact pulverizer.

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Air swept pulverizers use air to transport particles to the pulverizing section of the apparatus. Air
impact pulverizers use high speed air to pulverization of the particles. The products from both air
swept and air impact pulverizers produces oversize particles and no need of further sieving or
classifying.
Air Swept Pulverizer
The particles along with air are fed into the mill inlet. The beater plates support the hammers and
distribute the particles around the periphery of the grinding chamber. The hammers grind the
solid against the liner of the grinding chamber. The beater plates rotate between 1600 and 7000
rpm (revolutions per minute) to reduce the size of the incoming particles. The classifier plate
separates the fine product and exit through the discharge outlet. The material is back feed to the
mill inlet through the recycle housing.
Air Impact Pulverizer
In air impact pulverizers superheated steam or compressed air produces the force that reduces the
size of large particles. It results in the smashing of the particles into smaller particles.
Pharmaceutical applications :
1. Pulverizer are commonly used for chemicals, pigments and food processing. The micro scale
air impact pulverizer is used in laboratories, where small samples are needed.
2. Fluid energy mills are used because of their advantages in fine grinding, The mill is used to
grind heat sensitive material to fine powder.
3.They have been used for the fine grinding of fruits, kaolin, zircon, titanium and calcium,
alumina, but the energy consumed per ton of milled product is high.
4. It is also an object to provide grinding of dry solids.
The mill is used to grind those drugs in which high degree of purity is required.
Humidifier:
A humidifier is a device that increases humidity (moisture) in a single room or an entire building.
Principle:
In cooling and humidification process the moisture is added to the air by passing it Over the
stream or spray of water which is at temperature lower than the dry bulb temperature of the air.
When the ordinary air passes over the stream of water, the particles of water prese sent within the
stream tend to get evaporated by giving up the heat to the stream, the evaporated water is
absorbed by the air so its moisture content increases, thus the humidity increases. At the same

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time, since the temperature of the absorbed moisture is less than the DB bulb temperature of the
air, there is reduction in the overall temperature of the air. Since the heat is released in the stream
or spray of water, its temperature increases.
One of the most popular applications of cooling and humidification is the evaporative cooler,
also called as the desert cooler. The evaporative cooler is the sort or big box inside which is a
small water tank, small water pump and the fan. The water from the tank is Circulated by the
pump and is also sprayed inside the box. The tan blows strong currents of air over the water
sprays, thus cooling the air and humidifying it simultaneously.
Construction and Working:
Types of Humidifiers
There are many different ways to raise the humidity at home. For example, we can puta pan of
water on the stove or on the radiator, or we hang wet towells near a heater duct but most people
use a mechanical humidifier to do the job.
Four most popular technologies are:
1. Steam:
Often referred to as a "vaporizer", a steam humidifier boils water and releases the warm Steam
into the room. This is the simplest, and therefore the least expensive, technology for adding
moisture to the air. You can find inexpensive impeller models for less than $10 at discount stores.
Another advantage of this technology is that you can use a medicated inhalant with the unit to
help reduce coughs.
2. Impeller
In this humidifier, a rotating disc flings water at a comb-like diffuser. The diffuser breaks the
water into fine droplets that float into the air. You normally see these droplets as a cool fog
exiting the humidifier
Ultrasonic:
An ultrasonic humidifier uses a metal diaphragm vibrating at an ultrasonic frequency, much like
the element in a high-frequency speaker, to create water droplets. An ultrasonic humidifier is
usually silent, and also produces a cool fog.
3. Wick/Evaporative System
The wick system uses a paper, cloth or foam wick or sheet to draw water out of the reservoir.
The higher the relative humidity, the harder it is to evaporate water from the filter, is type of

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humidifier is self-regulating, as humidity increases, the humidifier's water- vapor output
naturally decreases.