Working Principle of Vacuum Distillation

Vacuum Distillation works on the principle of simple distillation with few changes. According to this method, the desired liquid is distilled at a temperature lower than its boiling point by the application of vacuum.

When vacuum is applied, it means that the pressure above the liquid surface is lowered which enhances the rate of distillation. Liquid begins to boil when its vapour pressure is equal to the pressure above the system i.e., liquid surface.

Large-Scale (Industrial Scale) Apparatus :

Construction of Vacuum Distillation Small-scale (laboratory scale)

The small-scale (laboratory scale) apparatus consists of a two-necked flask condenser (known as Claisen flask), receiver, adapter and a vacuum pump. The liquid feed is boiled using a water bath or oil bath. A capillary tube is placed in one of the necks of Claisen flask. This tube prevents bumping and splashing of feed liquid. The tip of the tube should be dipped into the feed, so as to draw out the stream of air bubbles from the flask. A thermometer is inserted in the second neck of the Claisen flask. Claisen flask is connected to a condenser which in turn is connected to a receiver via an adapter.

The adapter has a provision for vacuum pump. A manometer (pressure gauge) is placed between the vacuum pump and the receiver so as to monitor the pressure change.

Working of Vacuum Distillation Small-scale (laboratory scale)

The liquid feed to be distilled is introduced into the Clause flask. Few porcelain pieces (glass beads) are added to the liquid feed to avoid bumping and splashing. Bumping is also minimized by the capillary tube that is inserted into one of the necks of the flask. The required vacuum is applied. The liquid feed is then boiled using a water bath or oil bath. The liquid feed boils when its vapour pressure becomes equal to the pressure above the system under the influence of vacuum.

The mixed vapours enter the condenser and gets condensed. They are then collected in the receiver. The temperature at which the liquid begins to boil is noted from the thermometer. This temperature is found to be lower than the boiling point of the liquid.

Large-Scale (Industrial Scale) Apparatus :

Construction of Vacuum Distillation Large-Scale (Industrial Scale) Apparatus

It is almost similar to apparatus used for simple distillation. The unit comprises the following essential parts,

1. Still

It consists of a large stainless steel or copper vessel, in which the liquid mixture to be distilled is placed. There is also a provision for thermometer. The hood of the still consists of an observation window to monitor the progress of the process. This observation window is also useful to see whether the liquid mixture to be distilled is at the right level or not. The hood also consists of a feed inlet. Steam is used as a heating medium which is circulated through the jacket. The base of the still is provided with a steam inlet and outlet.

2. Condenser

It is responsible for the condensation of vapours liberated from the still. It is made up of stainless steel and is covered with a jacket through which water is circulated in counter-current direction.

3. Receiver

Large scale distillation unit employs large metal containers made up of stainless steel. After condensation, the condensed vapours are carried into the receiver.

Working of Vacuum Distillation Large-Scale (Industrial Scale) Apparatus

The still is charged with the liquid mixture to be distilled, through a pipe from the reservoir for feed, at a controlled rate. Vacuum is applied by using a vacuum pump. Liquid mixture is heated with the aid of steam which is introduced into the jacket of the still. Under the influence of vacuum, the distillation temperature gets reduced and the liquid gets distilled at a temperature lower than its boiling point. The vapours are then fed to the condenser where they get condensed by the cool water circulating through the condenser jacket. The condensed vapours are then collected into the receiver.

Advantages of Vacuum Distillation

1. Application of vacuum reduces the distillation temperature to a greater extent. Hence, distillation occurs at a faster rate. As the distillation temperature is low, thermolabile substances can be distilled without any deterioration or decomposition of active constituents.

Disadvantages of Vacuum Distillation

1. Sudden application of vacuum to the hot boiling liquid may lead to foaming. However, excess foam formation can be avoided by the addition of anti- foaming agents such as capryl or octyl alcohol, silicones such as DC antifoam A etc.
2. Violent splashing of the liquid feed, may cause entrainment of feed molecules in the condenser. This can be avoided by inserting a thin capillary tube in one of the neck of the Claisen flask.
3. Vacuum distillation is not useful for the preparation of semi-solid or solid extract.

Applications of Vacuum Distillation

1. Substances which are susceptible to degradation at higher temperatures are termed thermolabile (heat-sensitive). The active constituents in a drug may deteriorate and become inactive, when they are subjected to extraction and concentration at higher temperatures. Hence, these substances are distilled by vacuum distillation.
2. The method can also be used to obtain granular and porous powders.

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Figure 1: Semi-Continuous Centrifuge.

Working Principle of Semi Continuous Centrifuge

Perforated semi-continuous centrifuge, also known as short cycle or automatic batch centrifuge works on the principle of filtration. The separation occurs through a filter medium (i.e., perforated wall) based on the difference in the densities of solid and liquid phases.

Construction of Semi Continuous Centrifuge

1. It consists of a vertical perforated basket which rotates on a horizontal axis (see Figure 1).
2. The slurry to be filtered is introduced from the feed tube.
3. Wash pipe (for washing the filter cake) is also introduced parallel to the feed pipe.
4. The feeder controls the thickness of the feed and automatically stops its supply.
5. When the discharge of crystals is desired, the hydraulic cylinder is attached in such a way that the discharge chute enters the basket from its sides.

Working of Semi Continuous Centrifuge

1. Feed is introduced in the basket through the feed tube.
2. The basket is allowed to rotate along the horizontal axis.
3. Due to the process of centrifugation, solids get retained in the filter in the basket and the filtrate leaves the basket from its outlet. The solid crystals are washed and the washed water is drained out which leaves from the outlet. The feeder maintains the feed thickness i.e., a thickness of 50-70 mm is preferred.
4. When the hydraulic cylinder is attached along with the discharge chute, the knife is lifted. It cuts the filter cake such that a layer of crystals is left back. This layer of crystals now sewed as a filter medium in the next cycle.
5. The feeder and the hydraulic cylinder makes the process semi-automatic, hence the name semi-automatic/semi- continuous centrifuge.
6. The crystals obtained contain 2-4

Advantages of Semi Continuous Centrifuge

1. Semi-continuous centrifuge is semi-automatic.

Disadvantages of Semi Continuous Centrifuge

1. Crystals may break while discharging.
2. Designing and operation of the centrifuge is complicated.
3. Increased labour requirement.
4. Higher power consumption.

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1. Hot chamber process and
2. Cold chamber process.

Hot Chamber Die Casting Process

In this process. the holding furnace for the molten metal is integrated within the die casting machine. Hot chamber die casting is mainly used for low melting point temperature materials.

Construction

1. Goose neck which is used to pump the molten metal into the cavity is made of grey, alloy or ductile iron ore of cast steel and is submerged into the holding furnace in which molten metal is stored.
2. One end of the goose neck is connected with a nozzle, this is connected with the sprue of stationary die of the machine.
3. Other end has a plunger made of alloy C.I.
4. Plunger is hydraulically operated and is responsible for the entry of the liquid metal into the casting cavity by developing the required pressure for the metal.

Operation

1. Initially, the die is closed.
2. Goose neck is filled with the liquid metal.
3. With the help of the plunger, the liquid metal is forced into the cavity and is allowed to solidify by holding it at the same pressure.
4. Die is opened and the cores are retracted if any.
5. Unused metal is returned back by moving the plunger.
6. Eject the casting and uncover the entry part by plunger. so that the liquid metal enters the goose neck.
7. Process is repeated for next casting.

Cold Chamber Die Casting Process

This process consists of pouring of molten metal into a shot chamber with the help of ladle for each casting cycle. It is commonly used for casting the materials with high melting point such as aluminium, brass. magnesium etc.

Construction

1. Cold chamber die casting machine consists of cylindrical chamber called as shot chamber with hydraulically operated piston or ram.
2. One end of the chamber is connected to the die of the machine.
3. A separate furnace is provided to melt the metal.
4. A small ladle is used to transfer the metal into the shot chamber.

Operation

1. Initially the die is closed after applying die lubricants over the walls of die cavity.
2. Metal in furnace is brought to molten state.
3. Then, molten metal is poured into the shot chamber by using auto ladle or manually operated ladle at the previously fixed instant of time in the casting cycle.
4. Hydraulic ram is operated so that the molten metal is forced into the die cavity with a pressure around 150 MPa. The same pressure is maintained until solidification is completed.
5. Die is then opened and the casting is taken out with the help of ejector pins.
6. Now the plunger moves back to its initial position. Same process is repeated for next casting.

Applications

1. It is used for casting high melting point alloys of aluminium, brass, copper and aluminium—zinc in manufacturing industry.
2. Industrial equipment’s like motor switches, rotor fan, electrical sockets, etc.

Advantages

1. The castings produced by this method are of dense structure and have more dimensional accuracy.
2. Die components experiences less thermal stresses due to low temperature of molten metal.
3. Efficiency and life of the casting is more.

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Figure 1: Super Centrifuge.

Working Principle of Super Centrifuge

It works on the principle of sedimentation. It enables the separation of two immiscible liquid based on the difference in their densities. Due to the centrifugal force, the heavier liquid is thrown against the wall, while the lighter liquid forms the inner layer (near centre).

Construction of Super Centrifuge

1. It consists of a hollow cylindrical bowl.
2. The diameter ranges from is 1.75 – 5 inches with a length of 9-30 inches.
3. It is attached to a flexible spindle at the top and to a loose-fit bushing at the bottom.
4. The bowl is mounted in such a way that it can be rotated on its longitudinal axis.
5. The liquid which is to be separated is introduced into the bowl under pressure through the feed inlet.
6. Two outlet provisions are made at different heights at the top of the centrifuge.
7. Modified weirs can be used for simultaneous recovery’ of the separated liquids.

Working of Super Centrifuge

1. Feed is admitted at the bottom of the centrifuge through a feed nozzle under vacuum system.
2. Power is supplied to the entire system to rotate it in vertical manner.
3. The speed of rotation is up to 2000 rpm.
4. By the centrifugation process, the heavier liquid phase is thrown out against the wall, while the lighter liquid settles as an inner layer.
5. Hydraulic balance maintains the liquid-liquid interface (neutral zone) between two immiscible liquids.
6. Separated liquid phases are collected from the top of the bowl through outlets with the help of modified weirs.
7. Simultaneous removal of two immiscible liquids is possible enabling continuous operation.

Advantages of Super Centrifuge

1. Efficiency of separation is high.

Disadvantages of Super Centrifuge

1. Output is limited.

Modifications of Super Centrifuge

Tubular bowl centrifuge

1. Used for the separation of solids and liquids when solid content is low.
2. From a suspension, the solids get accumulated on the wall, while the liquid can be clarified from the top by centrifugal force.
3. If necessary, the deposited solid is collected at regular intervals.
4. Limited capacity.

Applications of Super Centrifuge

1. These are widely employed in food, biochemical and pharmaceutical industry.
2. Used to separate phases of emulsions.
3. Clarification of liquid can also be carried out.

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Figure illustrates the V-I charactefistics of a PN-junction diode. The charactefistics curve contains three distinct regions as,

1. Forward bias region
2. Reverse bias region
3. Breakdown region.

Forward Bias Region: On forward biasing, P side of the PN-junction is connected to the positive of the voltage supply and N side of the PN-junction is connected to the negative of the voltage supply. Simply, forward bias region is the characteristics of the diode for V > 0. From figure it can be seen that (in the FB region) initially, the diode current is very small because the barrier potential prevents the flow of current through it. If the applied voltage exceeds the barrier potential, then for a small increase in the voltage produces a shall) increase in the current. The voltage at which the current starts to increase rapidly is called cut-in or knee voltage of the diode. It is denoted as V_γ.

For silicon diode V_γ = 0.7 V and Germanium diode V_γ = 0.3V.

Reverse Bias Region: On reverse biasing, P side of the PN-junction is connected to the negative terminal of the voltage supply and N side of the PN-junction is connected to the positive terminal of the voltage supply. Simply, reverse bias region is the characteristics of the diode for V < 0. From figure it can be seen that (in RB region) the diode current is very small, almost equal to zero for all values of voltage less than the break down voltage V_Z. This is because in reverse bias the width of the potential barrier increases. As a consequence, the junction resistance becomes very high and practically no current flows through the circuit.

Breakdown Region: The diode enters the breakdown region when the magnitude of the reverse voltage exceeds a threshold value of that particular diode called the breakdown, voltage. In this region for very small variation in voltage the current increases rapidly as shown in figure. PN Diode should not be operated for V_R > V_BD because the diode will be damaged.

VI Characteristics of Ideal Diode

The deviation of V-I characteristics of pn junction diode from its ideal characteristics is illustrated below.

Figure 2.

The ideal and practical characteristics of p-n junction diode is shown in figure 2 (a) and (b) respectively.

1. When diode is forward biased.

(i) For ideal p-n diode, the forward resistance is zero. As a result, the diode acts as short circuit i.e., V = 0 and is remain unchanged for any value of ‘I’.

(ii) The practical p-n diode offers small forward resistance (i.e., static and dynamic resistance). Hence as voltage increases beyond barrier potential current also increases rapidly as shown in figure (b).

2. When diode is reverse biased.

(i) The ideal p-n diode offers infinite resistance. In this case the diode acts as open circuit i.e., current flowing through the diode is zero and the reverse voltage becomes infinite. An ideal diode does not undergo any breakdown, since the current is zero for any value of reverse voltage.

(ii) In a practical p-n diode, for an applied reverse voltage small amount of current flows due to minority charge carriers in both the regions. When the voltage increases above breakdown voltage (V_BD). The maximum reverse saturation current flows in diode. As a consequence it gets destroyed.

Note: PN Junction diode should be operated for V_R < V_BD.

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Among all the machine tools, the jig boring machine is most accurate (accuracy ranges from 0.0025 mm) and precise. These machines are mainly used to manufacture components which need a greater degree of accuracy like jigs. fixtures, tools, etc. A typical diagram of jig boring machine is shown in the figure.

Parts of Jig Boring Machine

Bed:

It is a box type and rigid construction. It acts as main supporting member. It supports a vertical colunm at the back and saddle at the front.

Table and Saddle:

The saddle is mounted on the base. It gives cross-feed to the work. The table is mounted over the saddle and it can be adjusted cross-wise. The table and saddle is provided with measurement reading and clamping mechanisms. A separate motor supplies power for the movement of table and saddle.

Spindle Head:

It slides in front of the column. It houses drive gear box, quill and feed gear box for the spindle. An indicator device is provided on spindle head, to measure the boring depth accurately. The driving mechanism provided to it is capable of giving speeds ranging from 300-1500 revolutions per minute. The quill is attached to it. which slides in the housing.

Column:

It is a hollow vertical structure. The colunm is provided with vertical guideways and it supports spindle head. The spindle head slides on the vertical guideways of the column. It houses the counter weights, to balance the spindle head.

These machines are characterized by,

1. Provision of highest accuracy through rigidity.

2. Locating and spacing holes by accurate measuring of distance.

3. Low thermal expansion.

A jig boring machine is visually similar to the vertical milling machine but not in case of operation and accuracy. To avoid deflections and vibrations, the spindle and other components of the machine are made extremely rigid. Antifriction bearings are used to run the spindle and housings of the spindle are made of invar to avoid its expansion during working at various temperatures. These machines are operated at temperature controlled rooms to avoid inaccuracy in the machine and work.

Types of Jig Boring Machine

The jig boring machines are classified into two types. They are,

Vertical Milling Machine Type:

This machine is visually similar to vertical milling machine it consists of a spindle, column, bed, work table. The spindle is arranged in the vertical axis and the work table is mounted on the bed in front of the column. The table can be moved in parallel, perpendicular and combined directions with respect to column face.

Planer Type:

This machine is designed in such a way that it consists of vertical columns on both sides of the work table which is mounted on the base. The table can be moved to and fro for adjusting the work. A cross rail is arranged on two vertical columns in the form of a bridge and the spindle is mounted on it. In this machine, the movements of the table (longitudinal) and spindle along with cross rail (cross) are used to locate the hole.

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Radial drilling machines are most suitable for drilling on large and heavy workpieces and can drill holes up to 50 mm in diameter. The radial and vertical motion of the arm. horizontal motion of drill head over radial arm makes the machine more versatile.

Parts of Radial Drilling Machine

The main parts of a radial dulling machine are as follows,

Base:

It is a heavy rectangular structure made of graded steel whose upper surface is accurately finished and provided with T slots to clamp work holding devices or to mount heavy works directly. On one end of the base has a vertical column is supported and on another end is mounted with a work table. The base is designed in such a way that it can tolerate heavy vibrations produced while drilling.

Column:

It is a vertical cylindrical structure mounted on the base and is equipped with the motor on top of the column and an elevating screw to provide vertical motion to radial arm in either direction.

Radial Arm:

It is a horizontal extension mounted on the vertical column and can slide vertically on the guideways provided on the column and also can swing around the column tip to 180° or more. Guideways are provided oui front vertical face upon which drill head is slid.

Drill Head:

It is a heavy rigid casting mounted on the guideways of the radial arm and can slide along the guideways to alter the position of the spindle according to the workpiece. It acts as a housing for all the mechanisms of speed and feed.

Spindle Speed and Drive Mechanism:

In most of the cases, a constant speed motor is directly mounted on top of the drill head and spindle obtains multiple speeds and feeds through motor via gear trains. In some cases, the motor is mounted on another side of the radial arm to partially balance the weight of the drill head. And is connected to spindle through bevel gears.

Advantages of Radial Drilling Machine

1. The arrangement is simple and any improvements or modifications can be done easily.
2. More than two holes can be drilled at a time with the help of proper jigs.
3. The various operations such as tapping. reaming. boring, counter-boring, trepanning, spot facing, counter-sinking, etc.. can also be done on this machine.
4. It does not requires highly skilled operator.
5. The cost of operation is less and is a quick process.
6. The work table and base of machine has capacity to accommodate different sizes and various types of jobs.

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Figure 1: Bag Filter.

Bag Filter equipment is not meant for actual size separation process. Instead, it is used as an auxiliary equipment with cyclone separator or air separator for the separation of fines and dust particles.

Working Principle of Bag Filter

Air-containing fines or dust particles obtained from the milled powder is forcefully introduced into the bag filters. These filters are made up of cotton or wool fabric. Air is introduced under the influence of suction applied on the opposite side of the feed inlet. This enables in the separation of particles. The particles stick to the walls of the bags. Air supply is cut off and the filters are shaken vigorously at high speed. As a result, dust particles adhering to the walls of the filters fall off and are collected from the conical base into a hopper.

Construction of Bag Filter

Bag filters consist of a number of cylindrical bags made up of cotton or wool fabric. These bags are suspended in a sheet of metal container which is tapered at the base. A hopper is placed by the side of the sheet metal container in continuation with the conical base of the container. On the top of the unit, a suction fan is present to maintain a pressure less than the atmospheric pressure. A bell crank lever arrangement is present which consists of a shaft operated by means of a cam. The cam presses the bell crank lever back and forth which in turn changes the position of the damper, which controls the motion of the bell crank lever. Hence, it aids in controlling two steps; filtering and shaking. A suction fan is present beside the damper. A hopper is present at the bottom of the filter to collect the dust particles.

Working of Bag Filter

The working of the bag filters involves the following two steps.

Filtering :

During this stage, air containing the dust particles is introduced into the bag filter through a hopper placed at the side of the sheet metal container. The air ascends into the filter bags under the influence of suction created by means of a suction fan present on top of the bag filters. This leads to reduction in pressure. The suction fan maintains the entire unit at a pressure lower than the atmospheric pressure. As the air laden with dust particles ascend dust particles remain inside the filter bags and the air passes upwards towards the top portion of the equipment. Due to the presence of air inside the bags, they remain completely stretched (taut) during the filtering stage. Drilling this period, the shaft with a cam is rotated at a very low speed. The cam does not press the bell crank lever. Due to this, the damper remains in place so that the filter bag comes in contact with the suction. As the feed inlet is closed, there is no contact between the filter bags and the atmosphere.

Shaking :

After few minutes, the shaft is rotated at a very high speed. The cam attached to the shaft presses the bell crank lever. Due to this, the damper changes its position and thus vacuum is cut off as there is no contact between the filter bags and suction. The feed inlet opens and the filter bags come in contact with the atmosphere. When dust laden air (considering the above condition) is introduced into the bag filters, it results in violent jerking of the bags. The dust panicles adhering to the walls of the filter bags fall into the conical base and are collected into a hopper (or chute) at regular intervals of time.

Advantages of Bag Filter

1. Fines generated during milling operation can be removed by bag filters, when other methods of separation cannot be employed.
2. The process is completely automatic, does not require manual labour.
3. The equipment can also be designed to promote very large filtering surface per unit floor space.

Applications of Bag Filter

1. Bag filters are used in association with other size separation equipment such as cyclone separator, air separator in order to remove dust or fines.
2. It can also be attached to a fluid energy mill discharge for the removal of fines.
3. Used to remove dust.

Example: Household vacuum cleaner works on the same principle.

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Grinding is defined as the process of removing metal in small quantities, by using an abrasive wheel called grinding wheel. In order to bring the workpiece to required size and shape, to obtain quality of work surface and dimensional accuracy grinding process is used. The metal removal is carried out in small quantities, which bring the machining process to desired accuracy. The microscopic examination of removed chips are similar to that of machined metal chips. The unique surface finish and accuracy in size is obtained by the grinding process.

This process, also removes material in a small area where machining is impossible. It is an efficient method of removing material from the machine parts, which are hardened. Due to high hardness of abrasives, complex profiles can be produced with extremely low pressure. Extremely smooth finish at bearing surface can be produced only by this process.

Elements of Grinding

The basic elements of a grinding process include (see Figure 1),

1. Workpiece Material :

Workpiece being ground is firmly held against the rotating grinding wheel, to remove the unwanted metal.

Various parameters of workpiece such as shape, size, stiffness, hardness, chemical and thermal properties have impact on the quality of grinding.

2. Grinding Wheel :

It is the cutting tool, made up of abrasive materials, which should be harder than the workpiece material. The grinding wheel should possess the following properties for better accuracy and surface finish,

1. High hardness and stiffness
2. Low heat sensitivity
3. High wear resistance
4. Better grain size
5. Good structure of bond
6. Highly resistant to thermal and chemical effects.

3. Grinding Machine :

The machine structure provides the static and dynamic constraints between the tool and the workpiece. Type of machines to be selected depends upon the type of operations to be performed.

A perfectly designed grinding machine should experience less vibrations and provide high accuracy movements. Thus, the specification, design and manufacturing of the grinding machine, influence its performance.

4. Kinematics :

Kinematics of grinding process includes the geometry and motions governing the movement or engagement between the workpiece and grinding wheel.

5. Dressing Conditions :

The factors which affect the dressing conditions are type of tool, cooling medium, lubrication, speed and feed, maintenance, etc.

6. Grinding Fluid (Coolant) :

Grinding fluid is used to reduce the wheel wear, cool the workpiece and flush away the swarf (fine chips and abrasive particles). Flow rate, velocity, pressure, physical, chemical and thermal properties of grinding fluid affects its effectiveness.

Advantages of Grinding

1. It can be employed for materials, which are too hard to machine by other processes.
2. Better surface finish and smooth surfaces can be obtained.
3. The pressure required during grinding process is less.
4. Complex profiles can be produced accurately.
5. The grinding wheels have self sharpening property.
6. High cutting speeds can be employed.
7. High material removal rate.
8. The abrasives can sustain at high temperatures.
9. High dimensional accuracy up to ± 0.02 mm can be obtained.

Disadvantages of Grinding

1. High cost of tool, power and labour is required.
2. The value of the operation lies in the quality of finish obtained and accuracy of the product, but not in the amount of material removed.
3. The time taken in removing a certain quantity of stock through grinding operation is more.
4. The grinding wheels wear out more quickly than other types of cutting tools.
5. Incorrect grinding leads to glazing and clogging.

Applications of Grinding

1. It is used for sharpening the cutting tools.
2. It is used for grinding threads.
3. It is used for machining hard surface, which are difficult to machine by HSS and carbide tools.
4. It is used for rapid stock removal from the workpiece.

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Working Principle of End Runner Mill

End Runner Mill works on the principle of compression and shearing stress offered to the feed by the heavy weight steel pestle. However, its use has become obsolete.

Construction of End Runner Mill

It is basically a mechanical mortar and pestle. The shallow mortar is made up of bed of stones or mild steel. The pestle has a flat bottom and is cylindrical and dumb bell shaped. The pestle is arranged eccentrically on the shallow mortar. The pestle carries a hinged arm so that it facilitates in emptying the feed and for cleaning the device just by raising the pestle. Inside the shallow mortar, a scrapper is arranged which brings the feed material towards the grinding surface.

Working of End Runner Mill

Feed material is introduced in the mortar and the motor is switched on. The mortar revolves, which leads to the rotation of the pestle. This rotation is due to the friction produced between the contacting surfaces of the mortar and the pestle. The scrapper brings the material towards the grinding zone. The material is size reduced by crushing and shearing phenomena. The product is collected and then sieved to obtain the desired particle size.

Advantages of End Runner Mill

1. It is a laboratory scale mill.

Disadvantages of End Runner Mill

1. Unbroken drugs or those in slightly broken conditions cannot be milled by end runner mill.

Applications of End Runner Mill

1. Brittle and crystalline feed materials are size reduced to fine powder.

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