Manufacturing Science Firstyear File

8/9/2019 Manufacturing Science Firstyear File

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INDEX SR

NO NAME OF EXPERIMENT DATE SIGN REMA

RK 1. Design of pattern of desired

casting.2. Pattern making using a given

design of pattern.3. Making mould for a desired

casting -Bearing Block, Machinevice moving jaw.

4. Mould sand testing(a) Permeability test (b)Moisture content test.

5. Study of oil fired tilting furnaceand melting of metal for acasting.

6. Study of jigs and fixtures anddrilling of holes with the help of

jigs.7. Tube bending on Tube Bending

Machine.8. Study of Power Press and to

perform Blanking and piercingoperation.


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PATTERN MAKING SHOP

OBJECT: To make the pattern for the moving jaw of a machine vice.

MATERIAL REQUIRED-Soft wood (Deodar, teak).

TOOLS REQUIRED-Tools required for making pattern is as follows-

1. RIP SAW : It s size is determined by its length which is about 12 to

20 cm wide near the handle and 6 to 10 cm near the tip. It cuts the

wood along the grains. The cutting action starts from near the and

gradually the whole length, or a major part of it, is used in theoperation. The pressure is applied in the forward stroke and relieved

during the backward stroke. It carries about 2 teeth per cm length of the blade.

2. CROSS CUT SAW : It is primarily designed for cutting across the

grains of woodwork. Its blade is 50 cm to 70 cm long and carries 3 to

4 points per cm. A blade with finer pitch is preferred for hard woodand that having coarse pitch for soft wood.

3. COMPASS SAW : It carries a tapered blade, which is long narrow.

The blade length usually varies from 25 to 40 cm and the width from

2.5 cm at tip to 5 cm near the handle. The blade is quite flexible andthus, it can be used easily for straight or curved cuts on outside or on

inside of the wood. For internal cutting a hole is first drilled and then

the saw blade inserted in it to commence the cut. Its blade containsabout 12 teeth per cm length.

4. FIRMER CHISEL : It is a general purpose chisel and is used for

taking wider cuts and finishing flat surfaces inside the groove. It

carries a wide blade, the common widths varying from 3mm to


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38mm at the cutting edge; the blade has a rectangular cross section

such that the longer side of the rectangle represents the width andthe smaller side the thickness of the blade at that point.

5. DOVETAIL CHISEL : It has a long carbon steel blade with abeveled back. The shape enables reduction of blade thickness on the

sides due to which it can enter sharp corners to finish them. Such arequirement usually occurs in case of dovetail joint and other V-

shaped grooves.

6. MORTISE CHISEL : It is used for taking heavy and deep cuts in

more stock removal, as in case of making mortises. It is available in

various assorted sizes, the maximum width of blade in commonlyused chisel being up to 15mm. The blade thickness varies from 6 to

15mm.

7. TRY SQUARE : It is used measuring and setting out dimensions,

testing the finish of a planed surface, draw parallel lines at right

angle to a planed surface, draw mutually perpendicular lines over a

plane surface and test squareness of two adjacent surfaces. Itconsists of a steel blade fitted into a wooden or metallic stock at

right angles. The inner surfaces, i.e. the surface that runs the job it is

provided with a brass liner. The blade carries graduation either in

inches and their parts or centimeters and millimeters.

8. MARKING GAUGE : It is made of wood and is very prominent tool

for marking. The stem is a long bar of wood of square or rectangular

cross section. The side faces are made a little curved. One of thecurved sides faces carries graduations. A sliding piece, called stock,

also made of wood, carries a brass liner at the face of it which istowards the scribing pin fitted in the stem. It is this face of the stock,

which remains in contact with the job surface during marking. The

thumbscrew helps in tightening the stock over the stem at any


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distance from the scribing pin. It is used to scribe lines parallel to and

at any desired distance from a finished face or edge.

10. WOOD TURNING LATHE :

Construction :

The wood turning lathe consists of cast iron body, a head

stock, tool rest, live and dead centers and a speed control device.

The bed carries horizontal ways as its top on which the tailstock and

tool rest move. They can be clamped at any desired place along

these ways. The work pieces are either clamped between two

centers. The live on the headstock spindle and the dead centre in the

tail stock, or on a face plate. The operation done the former case is

known as turning between centers. The different types of tools used

in wood turning lathe are : -

a) SCRAPING TOOLS: the most common used chisels in lathe

operations are round nose, square nose, spear point, diamond nose.

They are used for shaping different contours in faceplate work. Also

they are used in turning between centers; the round nose chisel forshaping of curved surfaces and square nose for plain cylindrical

surfaces.

Theory :

DEFINITION: A pattern may be defined as a replica or facsimile model

of the desired casting which, when packed or embedded in a suitable

moulding material, produces a cavity called mould. This cavity when

filled with molten metal produced the desired casting after the

solidification of the poured metal.

PA TTERN M AKI NG M A TERIAL

The common materials used for pattern making are :


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1. W OOD : It is the most common material used for pattern making.

The wood selected for pattern making should be straight grained,free from knots and other natural defects and should not carry sap

wood. The common wood used for pattern making is : -

(i)Pine (ii) Deodar (iii) Teak (iv) Mahogany

Advantages:-

(i) It is cheap and available in abundance.(ii) It can be easily shaped into forms and intricate designs.

(iii) Its manipulation is easy because of lightness in weight.(iv) Good surface finish can be easily obtained by only planning and

sanding.

Disadvantages:

(i) It wears out quickly due to its low resistance to send abrasion. Assuch a wooden pattern cannot stand a long constant use.

(ii) It is very susceptible to moisture, which may lead to its warpingor splitting. This needs its careful storing in a dry place and the

application of preservatives.

2. METALS: Metals used for with advantage, as the pattern material,

only when the number of castings to be made is very high and acloser dimensional accuracy is desired. They have a much longer life

than wooden pattern and eliminate the inherent disadvantage of

wood to a greater extent. But they have certain disadvantages. They

are as follows :

(a) They are costlier than wood, and therefore cannot be used withadvantage, where a smaller number of castings are to be made.

For giving different shapes and fine surfaces finish they need

machining.


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(b) Most of them are very heavy and in case f large castings theweight of the pattern always poses a problem in its manipulation.

(c) A large number of them have a tendency to get rusted. Commonmetals for purpose of pattern making are cast iron, brass,aluminum, white metal, etc.

3. PLASTER: Plaster of Paris or gypsum cement is advantageously

used as a pattern material since it can be easily cast into intricate

shapes and can be easily worked also. Its expansion can be easilycontrolled and it carries a very high compression strength. Its specific

use is in making small patterns and core boxes involving intricate

shape and closer dimensional control.4. PLASTICS: Plastics are gradually gaining favour as pattern materialsdue their following specific characteristics :

(a) Lightness in weight(b) High strength(c) High resistance to wear(d) Fine surface(e) High resistance to corrosion due to moisture(f) Low solid shrinkage(g) Very reasonable cost

5. W AX: Wax patterns are exclusively used in investment casting. For

this a die or metal mould is made in two halves into which the

heated wax is poured. The die is kept cool by circulating water

around it. As the wax sets on cooling the die parts are separated andthe wax pattern are taken out.

PATTERN ALLOW ANCES


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A pattern is always made larger than the required size of the

casting in order to allow for various factors, such as follows : -1) SHRINKAGE ALLOW ANCE: most of the metal used in castingwork contract during cooling from pouring temperature to roomtemperature. This contraction takes place in forms, viz, liquid

contraction, solidifying contraction and solid contraction. The first

two are compensated by gates and risers and the last one byproviding allowances in the patterns. The amount of contraction

varies with different metals and therefore their corresponding alsodiffers. The prominent factors, which influence the metal contraction

are the following :

(a) Pouring temperature of molten metal.(b) Type of mould material.(c) Moulding method.(d) Mould resistance to shrinkage of metal.(e) The metal of which the casting is to be made.

Thus, the correct amount of shrinkage allowance for a particular

casting can be obtained only after duly taking into consideration all

the factors.2) MACHINE ALLOW ANCE: A casting may require machining all

over or on certain specified portions depending upon the

assembly condition and the operation it has to perform. Such

portion or surface is marked duly in the working drawings. The

corresponding portion or surface on the pattern are givenadequate allowance, in addition to the shrinkage allowance, by

increasing the metal thickness there to compensate for theloss of metal due to machining on the surface. The amount of

this allowance depends on the method to be employed,

method of casting used, size and shape of casting and the

degree of finish required on the machined portion. Ferrous

metals need more Allowance than the non-ferrous metals.


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Similarly large and slender castings need more allowance than

the shorter ones. This allowance varies from 1.5 mm to 16 mmbut 3mm allowance is quite common for small and medium

size castings.

3) DRAFT ALLOW ANCE: All patterns are given a slight taper on allvertical surfaces i.e. the surface parallel to the direction of theirwithdrawal from the mould. This taper is known as DRAFT

ALLOWANCE. It can be expressed in terms of linear measures, it isprovided in both internal surfaces is more than on external

surfaces. The amount of draft on internal surfaces is more than

external surfaces. The purpose of providing this taper or draft is tofacilitate easy withdrawal of pattern from the mould without

damaging the surface and edges of the latter. The amount variesfrom 10 mm to 25 mm per meter on the external surfaces and

from 40 mm to 70 mm per meter on the internal surfaces. The

factors affecting this amount are the design of pattern, its vertical

height, method of moulding.

4) RAPPING AND SHAPING ALLOW ANCE: When a pattern is to bewithdrawn from the mould, it is first rapped or shaken, by striking

over it from side to side, so it s surface may be free of the mould

cavity increase a little and a negative allowance is to be provided

on the pattern to compensate the same. However, it may be

considered negligible for all practical purposes in small andmedium sized castings.

5) DISTORTION

ALLO

WANCE

:

The tendency of distortion is notcommon in all the castings. Only castings which have an irregular

shape and some design that the contraction is not uniform

throughout will distort during cooling on account of the setting up

of thermal stresses in them. Such an effect can be easily seen in

some dome shaped or u shaped castings. To eliminate this defect


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an opposite distortion is provided on the pattern, so that the

effect is neutralized and the correct casting is obtained.6) MOULD W ALL MOVEMENT ALLOW ANCE: Movement of mould

wall in sand mould takes place on account of the excessive heatand the static pressure exerted on the surface layer of sand which

comes in contact with the molten metal. Graphitisation of another

cause of mould wall movement on case of ferrous casting. Thismovement of mould walls, obviously affects the ultimate size of

the castings and needs to be compensated by providingcorresponding allowances in the patter and by controlling the

density and temperature of the molten and composition of the

moulding sand.

TYPE OF PATTERN

1) SOLID OR SINGLE PIECE PATTERN : A single piece pattern is thepattern, is made in one- piece and carries no joint, partition orloose pieces, Depending upon the shape, it can be moulded in one

or two boxes. This pattern is the cheapest but its use can be done

to a limited extent of production only since its moulding involves alarge number of manual operations like gate cutting, providingrunners and risers and the like.

2) TW O-PIECE OR SPLIT PATTERN : many times the design of castingoffers difficulty in mould making and withdrawal of pattern, if thesolid pattern is used. For such castings, split or two piece pattern

are employed. They are made in two parts, which are joined at theparting line by means dowels. While moulding, one part of the

pattern is continued by the drag and the other cope.

3) MULTIPIECE PATTERN : casting having a more complicated designthan two parts in order to facilitate an easy moulding and

withdrawal of the pattern may consist of 3, 4 or more number of

parts, depending on their design.


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4) MATCH PLATE PATTERN : these patterns are used where a rapidproduction of small and accurate castings is desired on a largescale. These patterns find a great favor in machine moulding.

There construction cost is quiet high, but the same is easilycompensated by a high rate of production, greater dimensional

accuracy and minimum requirement for matching in the casting.

These patterns are made in 2 pieces; one piece mounted on oneside and the other side of the plate; called matching plate. The

plate may carry only one pattern, or a group of pattern mountedon the same way on its 2 sides. The plate may be of wood, steel,

magnesium, or aluminium.

5) GATE PATTERN : they are also used in mass production of smallcastings. For such castings multi-cavity moulds are produced i.e. a

single sand mould carries a number of cavities. Pattern of thesecastings are connected to each other by means of gate formers,

which provide suitable channels, or gates in sand for feeding the

molten metal to these cavities. A single runner can be used for

feeding all the cavities. This enables a considerable saving in

moulding time and a uniform feeding of molten metal. For smallquantities, these patterns may be made of wood, but for large

production metallic pattern are preferred.

6) SKELETON PATTERN : when the size of the castings is very large,but easy to shape and only a few numbers are to be made, it is in

economical to make a large solid pattern of that size. In suchcases, a pattern consisting of a wooden frame and strips is made,

called skeleton pattern. It is filled with loam sand and rammed.The surplus sand is removed by means of a strickle.

7) SW EEP PATTERN : sweep can be advantageously used forpreparing mould so flarge symmetrical castings, particularly of

circular cross-section. This affects a great save in time, labour and

material. The full equipment consist of a base, suitably placed in


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the sand mass, a vertical spindle and a wooden template called

sweep. The outer end of the sweep carries the contourcorresponding to the shape of the desired castings. The sweep is

rotated about the spindle to form the cavity. Then the sweep andthe spindle are removed, leaving the base in the sand the hole

made by removal of spindle, is patched up filling the sand.

8) FOLLOW BOARD PATTERN : a follow board is a wooden boardused to support a pattern during moulding; it acts as a seat for the

pattern. Such single piece pattern, which have an odd shape orvery thin wall require a follow board.

9) SEGMENTAL PATTERN : these patterns are used for preparingmoulds of large circular castings, avoiding the use of a solidpattern of the exact size. In principle they work like a sweep but

the difference is that a sweep is given a continuous revolvingmotion to generate the desired shape, where as the segmental

pattern is portion of a solid pattern itself and the mould is

prepared in parts by it. It is mounted on a central pivot and after

preparing the part mould in one position; the segment is moved

to the next position. The operation is repeated till the completemould is ready.

CORE BOXES

Core boxes are made for making core. They are either made single orin 2 parts. Their classification is, generally according to the shape of

the core or the method of making the core. The common types of core boxes are :

1) HALF CORE BOX: to prepare the core into halve which are lateron cemented together to form the complete core.


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2) DUMP CORE BOX: used to prepare complete core in it generallyrectangular cores are prepared in these boxes. In constructionit is similar to half core box.

3) SPLIT CORE BOX: it is made in 2 parts, which can be joinedtogether by means of dowels to form the complete cavity for

making the core.

4) STRICKLE TYPE CORE BOX: it is used to form cores of irregular orunsymmetrical shapes.

5) LOOSE PIECE CORE BOX: it is used to prepare, in same core box,the 2 halves of a core are non-identical in shape and size.

PROCEDURE

1. Cut a rectangular piece of length 95 mm, width 66 mm andthickness 12 mm. Make the edges at right angles with the

help of tri-square and file.

2. Finish the top surface of the job with sand paper.3. Mark the required dimensions on both the sides of the job.4. Cut the job with the crosscut saw according to the given

dimensions.5. Make the groove on the top of the job with the help of a

firmer and mortise chisel.

6. Finish the surface with the help of sand paper.


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Hydraulic Pipe Bending Machine

OBJECT: To perform pipe bending operation with the help of

Hydraulic Pipe

Bending

Machine .

TOOLS: A hallow GI pipe of inch diameter, bending machine.

THEORY: The tooling used is bending operation results in the metal

being formed in localized area only the localized stress occurs only in

the bend radius. The remaining part of the blank is not stressedduring bending the metal on the outside of the bent radius is

stretched or elongated. The metal on the inside of bend radius isstretched or elongated. The metal on the inside is compressed. If

pipe fracturing occurs during bending its coiling occurs at the outside

of the bend surface of the bend. This wrecking also has to be taken into a current when designing parts and processes but visually loss of a

concern then is outside bend fracture. During bending one area of blank is usually held stationary by a press plate a pad. A leveal region

of the blank is bent and the change in contour. This free metal

movement is often called swinging and a characteristic common onlyto bending operation. In design of a bending die the swinging action

must be predicted so that no abstracts are placed in the way.Because of the related movement the larger area of the plant is

usually held stationary and the smaller blank area is allowed to

move.

Types of Bending Operations :

Angle of b ending bending at sharp angles. Curling - edge is curled around. Fo rming -bending along a curved die. Plunging -localized bending to form a hole.


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Precautions :

(i) Force should be applied slowly on the hand.(ii) Rod should be fastened correctly.

MOULDING AND CASTING

INTRODUCTION

The moulding is the process of making a cavity (or mould) outof sand by means of a pattern. The molten metal is poured intothe mould to produce casting. Some time a casting is to be made

hollow or with cavity in it. Such type of casting requires the use of cores.A core is defined as a sand shape which is exactly similar tothe cavities or holes to be provided in the casting s. The cores aregenerally made separately i.e., they are not moulded with thewith the pattern. The process of making cores is called coremaking.

MOULDING MATERIALS

Following are the moulding materials commonly used infoundry practice :

1.Moulding sand, 2.Sand binders,and3.Additive materials.

MOULDING SAND

The principal material used in making a mould is sand. The Sand

is defined as the granular particles resulting from thebreakdown of rocks. Quartz and other silica rocks are the source of

silica sand, which is commonly used for moulding. The sand is found

in nature on the bottoms and banks of rivers, lakes and larger

bodies of water. The silica sand comprises from 50 to 95% of the


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total material in any moulding sand. A good moulding sand

contains the following ingredients.Silica sand(SiO 2)- 80.8%

Alumina (Al 2O3) - 14.9%

Iron oxide(Fe 2O3) - 1.3%Combined water - 4 to 6%

Other inert materials- 1.5%

SAND BINDERS

Any material added to the sand or provided by nature in thesand imparts cohesiveness to it, is called a binder. The binderhold the sand grain together, imparts strength, resistance toerosion and breakage and degree of collapsibility.The binders areclassified as :

1.Clay- type binders,2.Organic-type binders, and3.Inorganic type binders.The clay is natural earthy material, which becomes plastic when

moltened. The fire clay is a clay-type binder and widely used

with silica sand.

The organic-type binders are mostly produced from vegetables

wood. For example, molasses (from sugarcane), starches (from maizecorn and potatoes), dextrines (intermediate product in the

degradation of starch), linseed oil (from flax seed), resins (from

trees), pitch (from coal).They are mainly used in making oil sands forcores.

The inorganic binders include Portland cement, bentonites (a

form of clay), fire clays (kaolinite), sodium silicate and iron oxide.


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These binders have considerable strength at high temperatures.They may be used to obtain green strength, baked strength, hotStrength or smooth finish.

SAND ADDITIVES

Materials, which do not promote binding action, when added to

the sand by facing the mould or by mixing with heap of sand forimproving sum special feature is called a sand additive. Some

Commonly used additives are sea coal, wood flour and silica flour.The sea coal is a finely pulverized bituminous coal. It improves

the surface finish, aids in cleaning of casting and prevent burning

on sand.The wood flour is a finely pulverized or ground soft wood. It

Improves finish, prevent burning in, aids cleaning and improves

collapsibility.

The silica flour is a finely ground silica sand of less than 54

microns. It fills interstices (voids ) and thus reduces metal

penetration.

PROPERTIES OF MOULDING SAND

The moulding sand must posses the following properties :

P orosity or p ermeability : It is that property of sand, whichpermits the steam and other gases to pass through the sand mould. When hot molten metal is poured into the

sand mould, it evolves a great amount of steam and othergases while coming in contact with moist sand. If these

gases do not escape completely through the mould, the

casting will contain gas holes and pores. Thus the sand

from which the mould is made must be sufficiently

porous or permeable.


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P lasticity : It is that property of sand due to which it flows to all portion of the moulding box or flask and

acquires a predetermined shape under ramming pressure

and retains this shape when pressure is removed. The sandmust have sufficient plasticity to produce a good mould.

The plasticity is increased by adding water and clay to

sand.

Ad hesiveness : It is that property of sand due to whichit adheres or clings to the sides moulding box. A good

sand have sufficient adhesiveness so that heavy sand

masses can be successfully held in the moulding box or flax

without any danger of its falling out when the flask is

Removed.

C ohesiveness : It that property of sand due to whichthe sand grain sticks together during ramming. It may be

defined as the strength of moulding sand. It is of the

following three types :

a) GREEN STRENGTH: The green sand, after water has mixedto it, must have adequate strength and plasticity formaking and handling of the mould. The green strength

depends upon the grain shape and size, amount and type of

clay and the moisture content.

b) DRY STRENGTH: When the molten metal is poured, the sandadjacent to the hot metal quickly loses its water as steam.The dry sand must have strength to resist erosion and alsothe metallostatic pressure of the molten metal, otherwisethe mould may enlarge.


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The natural sand is one,which contains sufficient clay as minedfrom the sand pit so that it can be used directly. It needs only to betempered and conditioned. Since the natural sands have theadvantages of simplicity in their preparation, handling and use,

therefore these are used for most of the ferrous and non-ferrouscastings.

The synthetic sand is one, which is artificially compounded bymixing sand grains and selected type of clay. These sands have theadvantages of lower cast in larger volume; wide spread availabilityand the possibility of sand reclamation and reuse.

The special sand contains mixtures of inorganic compounds.

Though these sands cost more, yet they offer better hightemperature stability than ordinary silica sand. These sandsproduce better cast surface. The special sands used most often arezircon, olivine, chromotte, and chrome magnesite.

The moulding sands, according to their use, further classified asbelow :

1) Green sand . The sand in its natural or moist state is calledgreen sand. It is also called tempered sand. It is a mixture of silica sand with 20 to 30 percent clay having total amount of water from 6 to 10 percent. The mould prepared with this sandare called green sand moulds. The molten metal is poured inthe green sand moulds without any prior baking. The greensand moulds are used for small size castings of ferrous andnon-ferrous metals.

2) Dry sand. The green sand moulds when baked or dried before

pouring the molten metal are called dry sand moulds. Thesand in this condition is called dry sand. The dry sand mouldshave greater strength, rigidity and thermal stability. Thesemould are used for large and heavy casting.

3) Loam sand. A mixture of 50 percent sand grains and 50percent clay is called loam sand. It is used for loam moulding


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of large grey-iron castings.4) Facing Sand . Sand use for facing of the moulding is called

facing sand .It is specially prepared sand from silica sand andclay, without the addition of used sand. The thickness of layer of

facing sand in a mould ranges from 20 to 30 mm and isused directly next to the surface of the pattern .Since it comescontact with the molten metal when poured, therefore it mustpossess high strength and refractoriness .

5) Backing or floor sand. Sand used to back up the facing sand

and not used next to the pattern, is called backing sand. the

sand, which has been repeatedly used, may be employed for

this purpose. It is sometimes called black sand because of its

black colour.

6) System sand. Sand employed in mechanical sand preparation

and handling system is called system sand .this sand has high

strength, permeability and refractoriness .

7) Parting sand. Sand employed on the faces of the pattern

before moulding is called parting sand. The function of the

parting sand is that when the pattern is withdrawn, the face of

the mould impression is damaged by adhesion of grains of

or section of the mould. The parting sand consists of dried

silica sand, sea sand or burnt sand.

8) Core sand. sand used for the preparation of cores is called

core sand. It is sometimes called oil sand. It is the silica sandmixed with linseed oil or any other oil as binder.


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9) Molasses sand. Sand, which carries molasses as a binder iscalled molasses sand. It is very useful for making moulds of small castings of intricate shapes and their sections. Thecores are also made from this sand.

PREPARATION OF MOULDING SAND

The preparation of sand is required in order to good castings. Itconsists of mixing sand, tempering of sand, conditioning of

sand. The efficient mixing of sand ingredients in proper ratio is

very important. It may be done manually or mechanically. Thenatural sand does not possess all qualities, which the

moulding sand should posses. It is, therefore, necessary that thenatural sand should be mixed with other sands or other

substances (such as clay, coal, dust etc.), which posses that

characteristics in a high degree. The clay is a necessary bond to

the moulding sand and coal dust is the most widely used

substance. The process of mixing consists of removing of all

foreign particles such as fins, nails, etc. From the sand grain by

passing it through a sieve or by magnetic separators. The sandingredients are mixed either by hand or by sand mixing

machines. The mixing is continued till there is a uniform

distribution of ingredients. The more uniform is this

distribution; the better is the quality of sand.

The preparation of moulding sand by adding water in properproportion is known as tempering of sand. The exact amount of

water to temper a given amount of sand is impossible to state,because, the sand conditions always vary. It can be mastered onlythrough practical experience.

The preparation of moulding sand so that it becomes suitable formoulding purposes is called conditioning of sand. The properconditioning of sand accomplishes uniform distribution of binder


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around the sand grains, control the moisture content, eliminatesforeign particles and aerates the sand so that it flows readily aroundand takes up the detail of the pattern.

METHODS OF MOULDING

The various methods used in making the mould are as follows : 1. Bench moulding . The moulding done on a bench of a

convenient height to the moulder, is called bench moulding.It is usually used for small castings, which are light in

weight.

2. Floor moulding. The moulding done on the foundry floor iscalled floor moulding. In this method, the foundry floor

itself acts as a drag and it may be covered with a cope on themould may be cast open. It is used for all medium sized and

large castings.

3. Pit moulding. The moulding done in a pit instead of a flaskis called pit moulding. It is used for extremely large castings.

The pit acts as a drag part of the flask and a separate cope isused above it. The sides of the pit are brick lined and on the

bottom there is a thick layer of cinders with connecting vent

pipes to the floor level. Since pit moulds can resist highpressure developed by hot gases, therefore it greatly saves

pattern expenses.

4. Machine moulding. The moulding done by machine iscalled machine moulding. The moulding machine perform

the number of operations which the moulder does by hand.

The ramming of sand, rolling the moulding over, forming

the gate and drawing out of pattern can be done by these


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machines much better and more efficiently than by hand.

5. Sweep moulding. The moulding done by using a sweeppattern is called sweep moulding. It is used for making

moulds of large size and symmetrical in shape particularlyof circular section.

CASTING

The sand moulds may be used for casting ferrous and non-

ferrous metals, but these moulds can be used only once, because

the moulds are destroyed after the metal has solidified. This will

increased the cast of production. The sand moulds also, cannot

maintain better tolerances and smooth surface finish. In order to

meet these requirements, following casting methods may be used :

Permanent mould casting Semi-permanent mould casting, Slush casting,

Die casting, Centrifugal casting, Investment or last wax casting, and Shell moulding process.

DESIGN OF CASTING

An engineer must know how to design the casting so that theyCan effectively and efficiently render the desired service and can

be produce easily and economically. In order to design a casting,

the following factors must be taken into consideration :


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PROCEDURE:

1- Take a sample of green sand,50gm weight the sand with theWeighing mechanism and take calculated amount of sand.

2- Place the sand in the cylinder of moisture tester .3- Add in it calcium carbide in required proportion one bowl.4- Shake the cylinder well fir few seconds.5- The amount of moisture present in the sand

RESULT: The given sample of sand containing moisture content 5.5% istested.

PRECAUTION :

1- Sand is to be homogeneous.2- Proper weighing of moisture should be3- Accurate weighing sand and proper amount of calcium carbide

should be taken.4- Mixing should be well .


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Power Press

OBJECT: -Study of Pow er Press and to perform Blanking and Piercing

operation.THEORY: -The constructional feature of power press is almost thesame as ram instead of driven by hand it is driven by power thePOWER PRESS may be designated as mechanical or hydraulicaccording to the type of working mechanism used to transmit powerto ram. In this mechanism, the rotary motion obtained from anelectric motor is converted into reciprocating movement of the ramby using different mechanical devices. In a hydraulic press the fluid

under high pressure is pumped on one side of the piston and then onthe other in a hydraulic cylinder to device. The reciprocatingmovement of a power press driven by crank and converting rodmechanism. The working of the press is similar to that of a handpress the punch is fitted on the end of ram and die is attached on thehole, the flywheel mounted on the end of crankshaft stores up theenergy for maintaining a constant downward speed of the ram whenthe sheet metal is pressed between the punch and the die.

Pow er Press Parts

The different parts of power press are described below :

Base : The base is the supporting member of press and providesarrangement for tilting and clamping the frame.

Frame : All press except the straight side types have C shapedframe to take up the vertical thrust of ram.

Bo lster Plate : The bolster plate is a flate plate fitted on thebase for supporting the die block.

Ram : The ram is the reciprocating member of the press that iswithin press and guide.

Pitman : The pitman is the connecting rod in crank or electricpower press.


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Crank Eccentric or Other Driven Mechanism : The rotarymovement of the motor is converted into the reciprocatingmovement of the ram, crank and connecting rod.

Flywheel : The flywheel is mounted at the end of the driving

shaft and is connected to it through a clutch. The flywheel isdirectly connected with the electric motor.

Clutch : The clutch is used for connecting and disconnecting themoving shaft with the flywheel.

Brakes : The brakes are used to stop the movement of thedriving shaft immedeately after it is disconnecting from theflywheel.

Result:- Both surfaces of given metal piece were grinded.

Precauti o ns: 1. In order to avoid chattering of the wheel it should be

correctly mounted at ram at prescribed speed.2. Face of wheel should be flat and dressed properly.3. Small depth of cut should be given.

Documents

Manufacturing Science Firstyear File