mt-i manual

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UNIT I

LATHE

INTRODUCTION:

Lathe is the father of all machine tool. It is a basic machine tool

probably the most important one of all, lathe was actually the first

machine tool.

Lathe is a particular type of machine tool in which the work is held

and rotated against a suitable cutting tool for the purpose of producingsurface of revolution in any material.

LATHE SPECIFICATIONS:

In order to specify a lathe, a number of parameters could be

used on the specific applications. However, the major elements used for

specifications should invariably be based on the components that would

be manufactured in the lathe. The sum of lathe specifications is,

L=Distance between centers.

A=Swing diameter over bed.

B=Swing diameter over carriage.

R=Radius.

H=Height of center from bed

DISTANCE BETWEEN CENTERS (L):

This would be specifying the maximum length of the job that can beturned in the lathe.

SWING DIAMETER OVER BED (A):

This specifies the maximum diameter of the job that can be turned in

the lathe machine generally restricted to small length jobs.

SWING DIAMETER OVER CARRIAGE (B):

This specifies the maximum diameter of job that can be turned in thelathe machines with the job across the cross slide.

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Other factors should also be specified to fully describe the lathe machine.

1. Horse power of the motor

2. Feed range

3. Accuracy achieved

4. Cutting speed range

5. Screw cutting capacity

6. Spindle nose diameter

PARTS OF ENGINE LATHE OR CENTER LATHE:

The principal parts of an engine lathe are,

1. Bed,2. Head stock,

3. Tail stock,

4. Carriage,

4.1. Saddle,

4.2. Cross slide,

4.3. Compound rest,

4.4. Tool post,4.5. Apron.

5. Feed Mechanism,

6. Thread cutting mechanism.

CARRIERS AND CATCH PLATES:

Carriers and catch plates are used to drive a work piece when it is

held between two centers. Carriers or driving dogs are attached to the end

of the work piece by a setscrew, and catch plates are either screwed or

bolted to the nose of the headstock spindle.

CHUCK:

A chuck is one of the most important devices for holding and rotating

a piece of work in a lathe. Work piece of short length, and large diameter or

irregular shapes, which cannot be conveniently mounted between centers,

are held quickly and rigidly in a chuck.

TYPES OF CHUCKS:

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1. Four jaw independent chuck

2. Three jaw universal chuck

3. Air or hydraulic operated chuck

4. Magnetic chuck5. Collet chuck

6. Combination chuck

7. Drill chuck

FACE PLATE:

A faceplate consists of a circular disk bored out and threaded to fit

the nose of the lathe spindle. This has the radial, plain and T slots for

holding work by bolts and clamps.ANGLE PLATE:

This is a cast iron plate having two faces machined to make them

absolutely at right angles to each other. Holes and slots are provided on

both faces so that it may be clamped on a faceplate and can hold the work

piece on the face by bolts and clamps.

MANDRELS:

A mandrel is a device for holding and rotating a hollow piece of work

that has been previously drilled or bored. The work revolves with the

mandrel which is mounted between two centers.

PLAIN MANDREL:

The plain mandrel this type of mandrel is most commonly used in

shops and finds wide application where a large number of identical pieces

having standard size holes are required to be mounted on it.

STEP MANDREL:

A step mandrel having steps of different diameters may be employed

to drive different work pieces having different sizes of holes without

replacing the mandrel each time. This type of mandrel is suitable for

turning collars, washers and odd size jobs used in repairing workshops.

COOLER MANDREL:

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A cooler mandrel having solid coolers is used for turning work pieces

having holes of larger diameter, usually above 100 mm. This construction

reduces weight and fits better than a solid mandrel of equal size.

SCREWED MANDREL:

A screwed mandrel is threaded at one end with a collar. Work pieces

having internal threads are screwed on to it against the collar for

machining.

CONE MANDREL:

A cone mandrel consists of a solid attached to the one end of the

body, and a sliding cone, which can be adjusted by turning a nut at athreaded end.

GANG MANDREL:

This has a fixed collar at one end and a movable collar at the

threaded end, which may be adjusted, to this position by a nut. The

mandrel is used to hole a set of hollow work piece between two collars by

tightening the nut.

EXPANSION MANDREL:

There are different types of expansion mandrels. The mandrel

consists of tapered pin, which is driven into a sleeve that is parallel outside

and tapered inside the sleeve has three longitudinal slots, two of which are

cut nearly through, and the third splits it completely.

RESTS:

A rest is a mechanical device which supports a long slender workpiece, which is turned between centers or by a clutch, at some

intermediate point to prevent bending of the work piece due to its own

weight and vibrations set up due to the cutting force that acts on it.

STEADY REST:

A steady rest shown in Fig consists of a cast iron base, which may be

made to slide on the loath bed ways and clamped at any desired position

where a support is necessary.

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FOLLOWER REST:

A follower rest consists of a C like casting two adjustable jaws

which support the work piece. The rest is bolted to the back end of the

carriage and moves with it.

TYPES:

1. Speed lathe

a. Woodworking

b. Centering

c. Polishingd. Spinning

2. Engine lathe

a. Belt drive

b .Individual motor drive

c. Gear head lathe

3. Bench lathe

4. Tool room lathe5. Capstan and turret lathe

6. Special purpose

a. Wheel latheb. T. Lathe

c. Gap. Bed lathe

d. Duplicating lathe

7. Automatic lathe

THE ENGINE LATHE OR CENTER LATHE:

The term engine lathe is associated with the lathe owing to the fed

that early lathe was driven by steam engines It has all parts.

THE BENCH LATHE:

This is a small lathe usually mounted on bench it has similarly all the

parts of an engine lathe or speed lathe and it only difference is being in thesize. This is used for small and precision work.

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THE TOOL ROOM LATHE:

A tool room lathe having the features similar to an engine lathe is

much more accurately built and has wide range of spindle speed ranging

from a very few to quite high speed unto 2500 rpm. This lathe is mainlyused for precision works on tools, dies, and gauges and in machinery work.

THE CAPSTAN AND TURRET LATHE:

These lathes are developed of the engine lathe and are used for

product on work. The distinguishing features of this type of lathe is that

the tailstock of an engine lathe is replaced by a hexagonal turret on the

face of which multiple tools may be fitted and feed into the work in the

proper sequence.

SPECIAL PURPOSE LATHE:

As the name implies they are used for special purpose and the jobs,

which cannot be accommodated or conveniently machined on a standard

lathe. The wheel lathe is made for finishing the journal and turning the

traded on the railroad carriage and locomotive wheel. The gab bed lathe in

which a section of the bed is adjacent to the headstock of the bed is

recoverable is used to sluing extra large diameter piece. The T lathe a new

member of the lathe family is intended for machining of rotor for jet

engines.

AUTOMATIC LATHE:

These are high speed heavy duty mass production lathe with

complete automatic controls once the tools are set and the machine

started it performs automatically all the operation to finish the job.

TOOLS:

A cutting tool may be used either for cutting a part as with a knife or

for remaining the chips parts are produced by removing the metal mostly in

the form of small ships removal in the metal cutting process may be

performed wither by cutting tools having distinct cutting edges or by

abrasively sticks abrasive cloth etc,

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All cutting tools can be divided into 2 groups

1. Single point cutting tool

2. Multi point cutting tool

SINGLE POINT CUTTING TOOLS:Single point cutting tool has a sharpened cutting part its point and

shaft; the point of the too bounded by the base. The side flank or major

flank or end slank or minor flank or and it base. The side cutting edges of a

tool is form by the interaction of the base and the side flank. The end

cutting edge, a tool into form by the intersection of the base and the flank,

the chip and cut from the work piece by the side cutting edges. The paint a

where the end and side cutting edge met is called nose of tool.

LATHE OPERATIONS:

TURNING:

Turning is the further most generally used operation is the lathe. In

ties the work held in spindle is rotated which the tool is fed part the work

piece in a direction parallel in the axis of rotation. The surface generated is

the cylindrical shape

FACING:

Facing is the operation of machining the ends of a piece of work to

produce flat Surface Square with the axis. The operation involves feeding

the tool parallel to the axis of rotation of the work piece.

TAPER TURNING:

Taper may be turned in a lathe by feeding the tool at an angle to the

axis of the work piece. Which taper is essential that the tool cuttings edge

should be accurately on the centre line of the work piece otherwise correct

taper will not be obtained

By a broad nose form tool By setting over to the tailstock center

By swiveling the compound rest By a taper turning attachment.

By combing longitudinal and cross feed in a lather.

THREAD CUTTING:

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Thread cutting is one of the most important operations performed in

a lathe. When the job is reduced between centers or by a chuck. The

longitudinal feed should be equal to the pitch of the thread to be cut per

revolution of the work piece.

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FACING PLAIN TURNING AND STEP TURNING

Ex. No:Date:

AIM:

To obtain the required shape and size of the work piece by turning

and facing operation.

MATERIALS SUPPLIED:

Cylindrical work piece of diameter _______mm and length_________ mm mild steel rod.

TOOLS REQUIRED:

1. Lathe

2. Cutting tool

3. Vernier caliper

4. Try square

5. Scriber

6. Vernier height gauge

SEQUENCE OF OPERATIONS:

1. Checking

2. Work piece

3. Tool setting

4. Facing

5. Turning

6. Taper turning

7. Chamfering

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WORKING STEPS:

1. The mild steel rod is cut approximately to the given dimensions.

2. Then the work piece is held in the chuck such that no eccentricityand run out occurs. It is done by using the marking block.

3. Then the work piece is fitted tightly with the help of chuck key in

the chuck.

4. The single point cutting tool is placed on tool post and it is

always aligned such that it coincides with the axis of the dead

centre

5. The tool is fixed tightly with the help of tool post key

6. Now the constant speed is applied to the work piece

7. Then the tool tip is brought to the centre of work piece

8. The facing operation is done by giving cross feed by moving

carriage and tool post by moving from centre and the turningoperation is done by giving longitudinal feed.The chamfering is

done to the edges of work piece.

9. The work piece is clamped on the other side for machining.

10. The operations are repeated to make step turning to the given

size.

11. Then the work piece is checked for required dimensions withthe help of vernier caliper.

RESULT:

Thus the required size and shape of the given work piece is

obtained.

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TAPER TURNING USING COMPOUND REST, TAILSTOCK SETOVER

DRAWING:

All Dimensions are in mm

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TAPER TURNING USING COMPOUND REST, TAILSTOCK SETOVER

Ex. No:

Date:

AIM:

To obtain the required shape and size of the work piece by taper

turning operation using compound rest & Tailstock set over method.

MATERIALS SUPPLIED:

Cylindrical work piece of diameter_________mm and length_________

mm mild steel rod.

TOOLS REQUIRED:

1. Lathe

2. Cutting tool

3. Vernier caliper

4. Try square

5. Scriber



1. Checking

2. Work piece setting

3. Tool setting

4. Facing

5. Turning

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6. Taper turning

WORKING STEPS:

1. The given work piece is checked for its dimension.

2. The work piece is held in the chuck. Chuck key is used to tighten

the job firmly, ensuring centering of work piece.

3. The single point cutting tool is held in the tool post and tightens

the nuts using Tool post key.

4. Facing is done with cutting tool moving from the centre of work

piece towards outside. It is one until the required length of the job

is obtained.

5. Turning is done to reduce the diameter of the job. Sufficient depth

of cut is given and it is done until the required diameter of the job

is obtained.

6. Next step taper turning is done on the work piece, as per the taper

angle already calculated. Then the compound rest base is

swiveled and set at half taper angle. Cutting tool is moved at an

angle to the lathe axis. Tool is moved by the compound rest hand

wheel.

7. For chamfering to be done at the end of the work piece, the tool is

held at 45 0 to the lathe axis and is fed against the rotating workspice.

8. Finally the dimension of work piece is again checked.

RESULT:

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obtained.

SINGLE AND MULTI START V THREAD

CUTTING AND KNURLING

DRAWING:

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SINGLE AND MULTI START V THREAD

CUTTING AND KNURLING

Ex. No:

Date:

AIM: To obtain the required shape and size of the work piece by turning

and thread cutting.

MATERIALS SUPPLIED:

Cylindrical work piece of diameter_________mm and

length__________mm mild steel rod.

TOOLS REQUIRED:1. Lathe

2. Cutting tool

3. Vernier caliper

4. Try square

5. Scriber



1. Checking


3. Tool setting

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4. Facing

5. Turning

6. Chamfering

7. Thread cutting.

WORKING STEPS:


2. The work piece is held in the chuck. Chuck key is used to tightenthe job firmly, ensuring centering of work piece.


the nuts using spanner.



is obtained.

5. Turning is done to reduce the diameter of the job. Sufficient depth

of cit is given and it is done until the required diameter of the job

is obtained.

6. For chamfering to be done at the end of the work piece, the tool is

held at 45 0 to the lathe axis and is fed against the rotating work

spice.

7. The cutting tool in the tool post is taken out. Thread cutting tool is

held in the tool post and tightened the nuts.

8. For right hand thread the lead screw rotates in clock wise direction

and for left thread, it rotates in anti clock wise direction. The

carriage is engaged to lead screw and automatic feed is given.

9. Suitable depth is given and thread is cut on the work spice.

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10. Finally the dimension of work piece and pitch of the thread are

again checked.

RESULT:


obtained.

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Ex. No:Date:

AIM:

To obtain the required shape and size of the work piece by Facing,

plain turning and Boring and internal threading.

MATERIALS SUPPLIED :

Cylindrical work piece of diameter_______ mm and length_______ mm

mild steel rod.

TOOLS REQUIRED:

1. Lathe

2. Cutting tool

3. Vernier caliper

4. Try square

5. Scriber


7. Boring tool and internal thread cutting tool.


1. Checking


3. Tool setting

4. Facing

5. Turning

6. Boring

7. Thread cutting.

WORKING STEPS:

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2. The work piece is held in the chuck. Chuck key is used to tighten

the job firmly, ensuring centering of work piece.


the nuts using spanner.



is obtained.

5. Turning is done to reduce the diameter of the job. Sufficient depthof cit is given and it is done until the required diameter of the job

is obtained.

6. Fix the boring tool in the tail stock.

7. Slowly given the feed by rotating the wheel in the tailstock which

moves the tool longitudinally to producing a boring.

8. Fix the internal threading tool, to cut the internal thread.

9. Finally the dimension of work piece is again checked.

RESULT:


obtained.

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UNIT II

WELDING EXCERCIES

WELDING

INTRODUCTION

Welding is the metal joining method wherein localized coalescence is

produced either by heating the metal to suitable temperatures, with or

without use of filler metal or by application of pressure.

The filler material has similar composition and melting point temperatures

as the base metal. It is used to fill gap between the joint surfaces.

TYPES OF WELDING

1. PLASTIC WELDING :

The pieces of metal to be joined are heated to the plastic state and then

forced together by external pressure without the filler material.

a. FORGE WELDING :

The work pieces are placed in a forge or other appropriate furnace and

heated within the area to be joined to the plastic condition. Then parts arequickly superimposed and worked into a complete union by hand or power

hammering or by pressing together.

b. RESISTNACE WELDING:

In resistance welding, a heavy electric current is passed through the metals

to be joined over limited area, causing them to be locally heated to plastic

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state and the welding is completed by the application of pressure for the

prescribed period of time.

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c. THERMIT WELDING:

It is a fusion process in which weld is effected by pouring super

heated liquid Thermit Steel, around the parts to be united with or without

the pressure.

2. FUSION WELDING :

a. GAS WELDING :

Gas welding is a process in which the required heat to melt the surfaces is

supplied by a high temperature flame obtained by a mixture of two gases.

Usually the mixture of oxygen and acetylene is used for welding purpose.

b. OXY-ACETYLENE WELDING :

In oxy-acetylene welding Oxygen and Acetylene are the two gases used for

producing flame. The Oxygen is manly used for supporting the combustion

intensity.

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TYPES OF FLAMES:

1. Neutral Flame (Oxygen, Acetylene in equal proportions)2. Oxidizing Flame (excess of Oxygen)

3. Reducing Flame (excess of Acetylene)

WELDING TECHNIQUES :

There are two techniques in gas welding, depending upon the ways in

which the welding rod and the welding torch are used.

(i) Leftward technique or Forehand welding method

(ii) Rightward technique or Backhand welding method.

(I) LEFTWARD TECHNIQUE :

1. The welder holds welding torch in his right hand and filler rod in the

left hand.

2. The welding flame is directed away form the finished weld.

ADVANTAGES:

1. The flame is pointed in the direction of welding; it preheats the edges

of joint.

2. Good control and neat appearance arc characteristics are ensured in

the leftward technique.

(II) RIGHTWARD TECHNIQUE :

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1. Here the welding torch is held in the right hand of the welder and the

filler rod in the left.

2. The welding flame is directed towards the finished weld (i.e. opposite

to that when employing the leftward technique)ADVANTAGES:

1. As the flame is always directed towards the solidified weld, it results

in annealing effect and better mechanical properties are obtained.

2. Very little agitation is produced because torch moves in a straight

line.

FILLER METAL:

It is the material that is added to the weld pool to assist in filling the gap.

Filler metal forms an integral part of the weld. The filler metal is usuallyavailable in rod form. These rods are called filler rods.

FLUXES:

During the welding, if the metal is heated in air, oxygen in the air combines

with the metal to form oxides which result in poor quality, low strength

welds or in some cases may even make welding impossible. In order to

avoid these problems, a flux is added during the welding. This flux preventsoxidation by preventing oxygen from contacting the weld zone.

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PRINCIPLE OF ARC WELDING:

The heat required for joining the metals is obtained from an electric arc.

The electric motor generator or transformer sets are used to supply high

electric current and the electrodes are used to produce the necessary arc.

The electrode serves as the filler rod and arc metals the surfaces so that

the metals to be joined are fused together.

The transformer type welding machine produces AC current. It takes power

directly from power supply and to produce high current and low voltage to

the welding. It is least expensive.

Motor generator type welding machine produces DC current to welding

machine. This current is having straight or reversed polarity. The polarity

selected for welding depends on the electrode arc used in the welding.

WELDING BEAD CLEANING ACCESSORIES:

1. Chipping Hammer

2. Wire Brush

3. Hand Screen

4. Helmet

5. Tongs

6. Goggles

7. Hand Gloves

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ADVANTAGES OF ARC WELDING:

1. Flux shielded manual metal arc welding is the simplest of all the arc

welding processes.

2. The equipment can be portable and the cost is fairly low.

3. This process finds innumerable applications, because of the

availability of a wide variety of electrodes.

4. A big range of metals and their alloys can be welded.

DISADVANTAGES OF ARC WELDING:

1. Because of the limited length of each electrode and brittle flux

coating on it, mechanization is difficult.

2. In welding long joints (in pressure vessels), as one electrode finishes,

the weld is to be progressed with the next electrode. Unless properly

cared, a defect (like slag inclusion or insufficient penetration) may

occur at the place where welding is restarted with the new electrode.

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HORIZONTAL, VERTICAL AND OVERHEADWELDING

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HORIZONTAL, VERTICAL AND OVERHEADWELDING

Aim:

To make a joint at various position of welds like horizontal, vertical

and overhead type by using arc welding on the given work piece.

Material supplied:

Mild steel plate of size - 3 Nos.

Tools Required:

Welding Transformer, Electrodes, Tongs, Chipping Hammer, WireBrush, Gloves, Apron, Shield, Goggles, and Earth clamps.

Sequence of Operations:

1. Edge preparation (Removal of Rust, Scale etc.,)2. Tacking3. Welding4. Cooling5. Chipping6. Cleaning

Working Steps:

1. The given pieces are checked and cleaned by using a wire brush.

2. The electrode is fixed in the electrode holder and the two pieces are

placed one over the other

3. The electrode angle is 45 and in horizontal position while welding

the two pieces.

4. The arc length for this joint is of Medium arc.

5. Then another plate is positioned with the adjacent side and position

the electrode at vertically and welds at the entire length.

6. Then another plate is placed and the electrode will performed from

the underside of the joining plats.

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7. The welding is carried out throughout the length.

8. After welding, slag which remains on the pieces are removed by the

help of chipping hammer.

9. Allow the work piece to cool and then chipped pieces are once againbrushed and are cooled by means of sand or air.

Result:

Thus the desired joint at various position of welds like horizontal,

vertical and overhead type by using arc welding on the given work piece.

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GAS CUTTING AND GAS WELDING

DRAWING:


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GAS CUTTING AND GAS WELDINGEx. No:Date:

AIM:

To cut and joint given metal sheets in gas welding

MATERIAL SUPPLIED:

Mild Steel Plate of size X X mm 2 Nos.

TOOLS REQUIRED:

1. Oxygen and acetylene gas cylinders with pressure regulators and

pressure gauges.

2. Gas welding torch

3. Filler rod

4. Safety gloves

5. Goggle

6. Chipping hammer

7. Wire brush


1. Edge preparation (Removal of rust, scale etc)

2. Tacking

3. Welding

4. Cooling5. Chipping

6. Cleaning

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DRAWING:

b

a a t

All Dimensions are in

mm

38

BA

A B


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WORKING STEPS:

10. The given pieces are checked and cleaned by using a wirebrush.

11. The given work pieces are positioned with the work holding

device.

12. The oxy acetylene torch focused on the material at the

required position , first the plate material melted at approximately

1300 C and the torch pointed out at the cutting portion of the entire

length of the plate.13. Allow the work piece to cool, and once again brushed and are

cooled by means of sand or air.

14. Set the two work pieces in correct position like butt joint and

tack at both ends of the work pieces.

15. After welding, slag which remains on the pieces are removed

by the help of chipping hammer.

16. Allow the work piece to cool, and then chipped pieces are onceagain brushed and are cooled by means of sand or air.

Result:

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The two metal sheets are welded in gas welding. Thus the gas

cutting and gas welding is done on the given metal sheets.

BRAZING INTRODUCTION- for demonstrationpurpose

Brazing is the process of joining metals with a nonferrous filter metal

that has a melting point below that of the metals being joined. By AWSdefinition, the melting point of the filler metal will be above 800 0F (427 0C).

Below this temperature are the solders. The filler metal must wet the

surfaces to be joined, that is, there must be a molecular attraction between

the molten filler material and the materials being joined. The brazing alloy,

when heated to the proper temperature, flows into the small joint

clearances by capillary action. A limited amount of alloying occurs between

the filler metal and the base metal at elevated temperature. As a result,the strength of the joint when properly made may exceed that of the base

material. The strength is attributed to three sources, atomic forces between

the metals at the interface; alloying, which comes from diffusion of the

metals at the interface; and inter granular penetration.

The heat for brazing may be provided in many different ways, the most

common o f which are by torch, induction furnace, and hot dipping.

TYPES OF BRAZING:

1. TORCH BRAZING:

Torch brazing is one of the oldest and most widely used methods of heating

for brazing; it is versatile and adaptable to most jobs. It is especially good

for repair work in the field and for small-lot jobs in the shop. As it is a

manual operation, torch brazing may have high labor costs, and the skill

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and judgment of the torch operator will determine the quality of work.

Torch brazing may be done with the use of natural gas and oxygen, air and

acetylene, butane, propane, MAPP, and the regular oxyacetylene.

2. INDUCTION BRAZING:

The heat of induction brazing is furnished by an AC coil placed in close

proximity to the joint. The high-frequency current is usually provided by a

solid-state oscillator that produces a frequency of 200, 000 to 5, 000, 000

Hz. These alternating high-frequency currents induce opposing currents in

the work, which, by electrical resistance, develop the heat. This method

has the advantage of providing good heat distribution, accurate heat

control, uniformity of results, and speed. It is especially good for certain

types of repetitive work that require close control.

3. FURNACE BRAZING :

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5. PASTE BRAZING:

A newer development in brazing is paste brazing. Anyone who has done

any brazing knows there is some skill involved. After the appropriate type

and amount of flux and filler metal are selected, the appropriate

temperature must be chosen. Too little flux means the base metal will not

be sufficiently cleaned, resulting in a weak joint. To ensure strong joints,

excessive flux is often used, this wastes material , requires more cleaning,

and can erode parts and fixtures.

6. PASTE ALLOY PROCESS:

Paste alloys are designed to overcome the problems given in the previous

paragraph. Paste alloys are blends of filler metal in powdered form and a

flux that are held in suspension by a paste-type binder. Premixing of flux

and filler ensures the proper proportions of each and keeps the alloy

localized to the joint area. Pastes rely on capillary action to spread the

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metal and flux over the joint area. Paste brazing filler materials are

available in silver, nickel, copper and gold based formulations.

7. BRAZE WELDING :

Braze welding is similar to brazing in that the base metal is not melted but

joined by an alloy of lower melting point. The main difference is that in

braze welding the alloy is not drawn into the joint by capillary action. A

braze-welded joint is prepared very much lik a joint is prepared for welding

except that an effort should be made to avoid sharp corners, because they

are easily overheated and may also be points of stress concentration.

BRAZING FLUXES:

Generally, fluxes are available in 3 forms namely powder, paste or liquid.

Of the three, paste is most commonly used, although powdered flux is

frequently mixed with water or alcohol to give a paste like consistency.

BRAZING FILLER METALS:

Brazing filler metals are divided into seven classifications. In order of

popularity, these are silver, copper, copper-zinc, copper-phosphorus,

aluminium-silicon, copper-gold, and magnesium. These alloys are produced

in many forms such as wire, rods, coated sheets, and powder. Frequently,

brazing alloys are performed into rings or special shapes to simplify

placement of the correct amount at the joint.

ADVANTAGES OF BRAZING:

Brazing is well suited to mass-production techniques for joining both

ferrous and non-ferrous metals. Some of the principal advantages are

1. Dissimilar metals can be joined easily.

2. Assembles can be joined in a virtually stress-free condition.

3. Complex assemblies can be joined in several steps by using filler

metals with progressively lower melting temperatures.

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4. Materials of different thickness can be joined easily.

5. Brazed joints require little or no finishing other than flux removal.

LIMITATIONS OF BRAZING:

1. Joint design is somewhat limited if strength is a factor.

2. Joining is generally limited to sheet-metal thicknesses and relatively

small assembles.

3. Cost of joint preparation can be high.

UNIT III

SHEET METAL WORK

INTRODUCTION

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Sheet metal work is working on the metal of 16 gauges to 30 gauges,

with hand tools and simple machines into different forms by cutting,

forming into shape and joining.

Sheet metal work is one of the major applications in engineering

industry. It has its own significance as a useful trade in engineering work.

APPLICATION OF SHEET METAL

Sheet metal work is used for making

Hoppers

Funnels

Various ducts

Chimneys

Ventilating pipes

Machine tool guards

Boiler etc.

PROCEDURE FOR SHEET METAL WORK

The exact size and shape of the sheet to be cut is given by the

development of the concerned object.

The development is drawn on a flat sheet of metal and then the sheet

is cut.

The cut sheet is folded or rolled to the required shape before the

joints are made by welding or any form of fastening.

METAL USED IN SHEET METAL WORK

a. Black iron

b. Galvanized iron

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2. STRIKING TOOLS

(a)Hammers (b) Punches

(a) Hammers: Hammers are used in sheet metal work for following,

raising, Stretching or throwing off. The following hammers are

mostly used in sheet metal work.

(i) Riveting hammers

(ii) Raising hammers

(iii) Setting hammers

(b) Punches: In sheet metal work, punch is used for marking out work

locating centers etc. The following two types of punches are

widely used.

(i) Prick punch

(ii) Centre punch.

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3. SUPPORTING TOOLS

Stacks: Stacks are nothing but sheet metal workers anvils used for

bending, seaming or forming, using a hammer or mallet. The

following fig. shows different shapes and sizes of stakes.

4. BENDING TOOLS

Pliers: Pliers are mainly used for bending the sheet metal to the

required shape. It is also used for holding and cutting the sheet

metal. Flat nose pliers and round nose pliers are used in sheet metal

work for forming and holding.

5. LAYOUT TOOLS.

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3. Marking

4. Cutting

5. Hemming

6. Bending

7. Riveting

WORKING STEPS:

1. The size of the given sheet is checked using a steel rule.

2. Then the sheet is leveled on the leveling plate using a mallet.

3. The dimensions are marked as shown in fig

4. The sheet is cut as per the marked dimensions by straight snips.

5. Then a single hemming is made on the four sides of tray as shown

in fig.

6. These four sides of the tray are bent to 90 0 using stakes anvil.

7. Finally the corners of the tray are joined by riveting.

RESULT:

A tray is made from the given metal sheet.

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5. Folding.

6. Hemming

7. Soldering .

WORKING STEPS:

1. The size of the given sheet metal is checked for its dimensions

using steel rule.

2. The required developed of surface is being made on the white

paper which is overlapped on the sheet metal.

3. The marking is done on the sheet metal as per the development

being done on the paper.

4. Now using straight snips, unwanted materials are removed.

5. Now fold and bend the work piece to make the funnel shape and

joint is made on the work piece.

6. Then using groove, locked grooved joint is made for about 5mm.

Also, hemming is done in the bottom of the funnel.

7. In between top face and bottom face, butt joint is made using

solder.

8. Finally, trimming and finishing operation are being carried out.

RESULT:

The funnel of the required dimensions is made from the given

metal sheet.

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UNIT IV

PREPARATION OF SAND MOULD

INTRODUCTION

Producing Components by casting has been used since the earliest days of

civilization. Lot of shapes and sizes can be prepared in a casting process.

To make the casting of a component, a cavity of desired shape is t be

produced in which the molten metal is poured.

Mould is the cavity to the required shape made in modeling sand or other

material. The process of modeling consists of all operations done to make a

mould.

PATTERN:

Pattern is the model used to get required casting. It is used to

produce the moduld cavity in sand.

FOUNDRY:

The place where modeling and casting are done is known as foundry.

MOULDING SAND OR GREEN SAND:

It is a maximum of sand and additives such as water, bentonite,

inoculent, sodium silicate etc, used to create mould cavity.

COMPONENTS REQUIRED FOR MOULDING:

The following components are essential for producing mould.

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(i) Moulding Sand(Green sand)

(ii) Moulding Boxes

(iii) Pattern

(iv) Moulding tools

MOULDING SAND

Composition

It is a special type of sand used for making mould. Moulding

sand has three constituents. They are

(i) Sand (ii) Binder (iii) Additive

SAND:

It has silica, clay and moisture. Silica is the main constituent of sand.

Silica has 80 to 90 % silicon dioxide. Silicon gives refractoriness to the

sand.

CLAY:

Clay is another constituent of sand. Clay gives more bonding strength

to the sand. Generally sand has 5 to 20 % clay. Moisture is the water added

to the sand. It gives the bonding action. In general 2 to 8 % water is added

to the sand.

BINDERS:

Binders are added to the moulding sand to bring the property of thecohesiveness. The binder binds the sand grains together and brings

strength. There are three types of binders.

a) Clay type binders eg: Bentonite

b) Organic binders eg.Resin

c) Inorganic binders eg. Sodium silicate.

ADDITIVE:

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MOULDING TOOLS:

1. Shovel2. Sieve

3. Trowel

4. Rammers

5. Sprue pin

6. Strike off bar

7. Lifter

8. Gate cutter9. Runner

10. Riser

11. Vent rod

12. Draw spike

13. Bellow

ADVANTAGES OF SAND CASTING:

1. Use is widespread; technology well developed

2. Materials are inexpensive, capable of holding detail and

resist deformation when heated.

3. Process is suitable for ferrous and non-ferrous metal casting.

4. Handles a more diverse range of products than any other

casting method.

5. High levels of sand reuse are achievable.

LIMITATIONS OF SAND CASTING

1. Typically limited to one or more a small number moduls per

box.

2. Sand: metal ratio is relatively high.

3. High level of waste is typically generated, particularly sand,

bag house dust and spent shot.

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SOLID PATTERN

DRAWING:


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MOULD WITH SOLID PATTERNEx. No:

Date:

AIM:

To make the mould of solid pattern

MATERIAL REQUIRED:

Molding sand, Parting sand, facing sand, Gear pattern, molding boxes

etc.

TOOLS REQUIRED:

1. Shovel

2. Sieve

3. Trowel

4. Rammers

5. Sprue pin

6. Strike off bar

7. Lifter

8. Gate cutter

9. Runner

10. Riser

11. Vent rod

12. Draw spike

13. Bellow


1. Sand preparation

2. Core preparation

3. Placing the pattern on the moulding board.

4. Ramming of drag

5. Placing runner and riser

6. Ramming of cope

7. Removal of pattern, runner, riser

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8. Gate cutting.

WORKING STEPS:

1. The gear pattern is placed on the moulding board.

2. A suitable core is prepared and placed in the hole of the

gear pattern.

3. Clay washing is done inside the drag surface.

4. Parting sand is applied over the pattern.

5. Box is filled with smooth moulding sand and proper ramming

is done using flat and peen rammer.

6. Excess sand is removed using the strike off bar.

7. The drag is turned upside down.

8. The cope is placed on the drag after doing clay wash.

9. The runner and riser are placed over the pattern.

10. After applying parting sand, moulding, sand is filled over

the part ten.

11. Ramming is done to get a rigid mould.

12. Using strike off bar excess sand is removed.

13. Vent holes are made using vent rod.

14. Runner and riser are removed and a funnel shape is

made on the runner hole.

15. Cope is kept aside and the pattern is removed using draw

spike

16. The cope is placed on the drag.

RESULT:

Thus the gear mould is prepared and ready for casting.

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MOULD WITH SPLIT PATTERN

DRAWING:

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All Dimensions are inmm

MOULD WITH SPLIT PATTERNSEx. No:Date:

AIM:

To prepare a sand mould using a split pattern.

MATERIAL REQUIRED:

Moulding sand, Parting sand, Facing sand, Gear pattern, Moulding

boxes etc.

TOOLS REQUIRED:

1. Showel

2. Sieve

3. Trowel4. Rammers

5. Sprue pin

6. Strike off bar

7. Lifter

8. Gate cutter

9. Runner

10. Riser11. Vent rod

12. Draw spike

13. Bellow


1. Sand preparation

2. Core preparation

3. Placing the pattern on the moulding board

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4. Ramming of drag


6. Ramming of cope

7. Removal of pattern, runner, riser8. Gate cutting.

WORKING STEPS:

1. The mould box, pattern, tools, and the table /floor are cleaned.

2. The drag is filled with green sand after positioning lower part of

the pattern on the table.

3. The green sand is rammed carefully and the excess sand is

struck off.

4. Till the drag upside down and sprinkle river sand on top of it.

5. The cope is positioned on the top of the drag and upper part of

the pattern is positioned carefully.

6. Position the sprue pin and riser pin, then the fill cope with sand

ramming is done and the excess sand is struck off.

7. Remove the sprue pin and the riser pin carefully

8. Apply water on the edges of the pattern and remove them

carefully using the draw spike, then finish the cavity.

9. Vent holes are made using vent wire.

10. A funnel shaped opening and gate is made to pour the

molten metal.

RESULT:

Thus the mould cavity of the given split pattern is obtained.

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MOULD WITH LOOSE PIECE PATTERNS

DRAWING:

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MOULD WITH LOOSE PIECE PATTERNSEx. No:Date:

AIM:

To prepare a sand mould using a loose piece pattern.

MATERIAL REQUIRED:

Moulding sand, Parting sand, facing sand, Gear pattern, Molding

boxes etc.

TOOLS REQUIRED:

1. Showel

2. Sieve

3. Trowel

4. Rammers

5. Sprue pin6. Strike off bar

7. Lifter

8. Gate cutter

9. Runner

10. Riser

11. Vent rod

12. Draw spike

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13. Bellow


1. Sand preparation

2. Core preparation


4. Ramming of drag


6. Ramming of cope


8. Gate cutting.

WORKING STEPS:

1. The mould box, pattern, tools, and the table /floor are cleaned.

2. The drag is filled with green sand after positioning lower part of

the pattern on the table.

3. The green sand is rammed carefully and the excess sand is

struck off.

4. Till the drag upside down and sprinkle river sand on top of it.5. The cope is positioned on the top of the drag and upper part of

the pattern is positioned carefully.

6. Position the sprue pin and riser pin, then the fill cope with sand

ramming is done and the excess sand is struck off.

7. Remove the sprue pin and the riser pin carefully

8. Apply water on the edges of the pattern and remove them

carefully using the draw spike, then finish the cavity.

9. Vent holes are made using vent wire.

10. A funnel shaped opening and gate is made to pour the

molten metal.

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RESULT:

Thus the mould cavity of the given loose piece pattern is

obtained.

MOULD WITH COREEx. No:Date:

AIM:

To prepare a sand mould with core.

MATERIAL REQUIRED:

Moulding sand, parting sand, facing sand, Gear pattern, molding

boxes etc.

TOOLS REQUIRED:

14. Shovel15. Sieve

16. Trowel

17. Rammers

18. Sprue pin

19. Strike off bar

20. Lifter

21. Gate cutter

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22. Runner

23. Riser

24. Vent rod

25. Draw spike26. Bellow


9. Sand preparation

10. Core preparation


12. Ramming of drag


14. Ramming of cope


16. Gate cutting.

WORKING STEPS:

17. The mould box, pattern, tools and the table / floor arecleaned.

18. The drag is filled with green sand after positioning the

pattern on the table.

19. The green sand is rammed carefully and the excess sand

is struck off. Place the core to provide the hollow portion of the

mould.

20. Tilt the drag upside down and sprinkle river sand on top

of it.

21. The cope positioned on top of the drag positioned

carefully.

22. Position the sprue pin and riser pin, then fill the cope

with sand and ramming is done and the excess sand is struck

off.

23. Remove the sprue pin and the riser pin carefully.

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The moulding material is loaded into a hopper from which it is transferred

to aheating section by a feeding device where the temperature is raised to

150 0 C - 370 0 C. The material melts and is forced by an injection ram or by

plunger through a nozzle and sprue in a closed mould which forms the part. There are two types of injection moulding and it is given below.

RAM OR PLUNGER TYPE INJECTION MOULDING:

The ram and plunger type injection moulding has two units.

1. Injection unit

2. Clamping unit.

So it may be split in order to eject the finished component.

Initially, the polymer is filled in a hopper. Then it goes to the heating

section where the polymer is melted and the pressure is increased. The

heated material is injected by the ram under pressure. So, the heated

material is forced to fill in mould cavity through the nozzle to get the

required shape of the plastics. Here, the mould is water-cooled type.

SCREW TYPE INJECTION MOULDING:

In this type also, there are two units to split and eject the finished

component such as

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1. Injection unit

2. Clamping unit

The injection unit has hopper, screw and heating section. In clamping

section, it has mould.

In screw type moulding machine, initially the pellets are fed into thehopper. The resins are pushed along with the heated reciprocating screw.

The screw is moved forward to force the plastic material into the mould.

The screw itself is moving backwards and allowing the accumulation of

enough material to fill the mould.

The rotation of the screw provides the plasticizing action by shearing and

frictional effects. The axial motion of the screw provides the filling action.

The jet moulding process is used to find the problems occurred in injection

moulding process. The reaction moulding is the recent development in

injection moulding. In reaction moulding, the low viscosity monomers are

used in the mould. A chemical reaction takes place between resins at low

temperature and a polymer is created.

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In jet moulding, the plastic is preheated about 93 0 C in the cylinder

surrounding the nozzle. The reaction moulding is suitable for the production

of polyurethane moulding.

ADVANTAGES OF INJECTION MOULDING :

1. High production capacity and less material losses.

2. Low cost and less finishing operation.

3. It is used for making complex threads and thin walled parts.

4. Accuracy becomes 0.025 mm.

5. Wide range of shapes can be moulded.

APPLICATIONS:

1. It is used in making parts of complex threads.

2. Production of Intricate shapes like thin walled parts.

3. Production of typical parts like cups, containers, tool handles, toys,

knobs, plumbing fittings.

4. Production of electrical and communication components like

telephone receivers.

LIMITATIONS:

1. Equipment of cylinder and die should be non-corrosive.

2. Reliable temperature controls are essential.

The injection capacity of injection moulding machines ranges from 12,000

mm 3 to 2.2 X 10 6 mm 3 .

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mt-i manual

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