me 2207 - manufacturing technology 1 - lab manual

P.A COLLEGE OF ENGINEERING AND TECHNOLOGY

POLLACHI – 641 002.

DEPARTMENT OF MECHANICAL ENGINEERING

SEMESTER – III

MANUFACTURING TECHNOLOGY LAB - I

(STUDENTS LAB MANUAL)

Name:

Reg No:

INDEX

S.No Date Name of the Experiment Mark Signature

1 STUDY OF LATHE

2MACHINING A WORK PIECE BY FACING, PLAIN TURNING AND STEP TURNING OPERATIONS USING A LATHE

3MACHINING A WORK PIECE BY TAPER TURNING OPERATION (COMPOUND REST METHOD) USING A LATHE

4MACHINING A WORK PIECE BY V- THREAD CUTTING AND KNURLING OPERATIONS USING A LATHE

5

MACHINING A WORK PIECE BY BORING AND

INTERNAL THREAD CUTTING OPERATIONS

USING A LATHE

6 STUDU OF SHEET METAL

7 FRUSTUM OF A CONE

8 TRAY

9 STUDU OF WELDING

10 HORIZONTAL WELDING

11 THE VERTICAL WELDING

12 THEOVERHEAD WELDING

13 SAND MOULDING PROCESS

TOTAL

FACULTY INCHARGE

A STUDY ON BASIC MACHINING

INTRODUCTION

Machining is the process of converting the given work piece into the required shape and size

with help of a machine tool. The most widely used machine tool is lathe. In simple words

machining is the process of removing certain material from the work piece.

LATHE

Lathe is the machine tool which is used to perform several operations on the work piece.

Lathe is useful in making several parts which is further assembled to make new machine.

Hence lathe is known as “mother of machines”.

BASIC WORKING PRINCIPLE OF LATHE

In lathe, the work piece is held in the chuck, a work holding device. The cutting tool is

mounted in the tool post. The chuck is rotated by means of power. When the chuck rotates,

the work piece also rotates. The tool is moved against the rotating work piece by giving small

amount of depth of cut. The material is removed in the form of chips. Continuous feed and

depth of cut is given until the required dimensions are obtained in the work piece.

TYPES OF LATHE MACHINES

There are different types of lathe machines, they are

1. Centre lathe

2. Tool room lathe

3. Bench lathe

4. Capstan lathe

5. Turret lathe

6. Automatic lathe

DESCRIPTION OF LATHE

Lathe is a machine which has several parts in it. They are

1. Bed

It is the base of the machine. On its left side, the head stock is mounted and on its

right it has movable casting known as tailstock. Its legs have holes to bolt down on

the ground.

2. Head stock

It consists of spindles, gears and speed changing levers. It is used to transmit the

motion to the job. It has two types one is the headstock driven by belt and the other

one is the gear driven.

3. Carriage

Carriage is used to carry a tool to bring in contact with the rotating work piece or to

with draw from such a contact. It operates on bed ways between the headstock and tail

stock.

4. Saddle

It is a ‘H’ shaped part fitted on the lathe bed. There is a hand wheel to move it on the

bed way. Cross slide, compound rest, tool post are fitted on this saddle.

a) Cross slide

It is on the upper slide of saddle in the form of dove tail. A hand wheel is provided

to drive the cross slide. It permits the cross wise movement of the tool (i.e.)

movement of tool towards or away from the operator

b) Compound rest

It is fitted over the cross slide on a turn table. It permits both parallel and angular

movements to cutting tool.

c) Tool post

It is fitted on the top most part of the compound rest. Tool is mounted on this tool

post. Cutting tool is fixed in it with the help of screws.

5. Apron

It is the hanging part in front of the carriage. It accommodates the mechanism of hand

and power feed to the cutting tool for carrying out different operations.

6. Lead screw

It is a long screw with ACME threads. It is used for transmitting power for automatic

feed or feed for thread cutting operation.

7. Tail stock

It is located at the right end of the lathe bed and it cn be positioned anywhere in the

bed. It is used for supporting lengthy jobs and also carries tool to carry out operations

such as tapping, drilling, reaming.

WORK HOLDING DEVICES

1. Lathe centers

They are used to support work. It has two categories of centers. Live center is one which is

fitted in the headstock spindle. Dead is another one which is fitted in the tail stock.

2. Chuck

It is a device used to hold a job. It is easily fitted on the thread cut on the end of head

stock spindle. Various types of chuck are

a) Two jaw chuck b) three jaw chuck c) four jaw chuck d) collet chuck

e) Magnetic chuck

3. Face plate

Three Jaw Universal self-centering chuck

Four Jaw Independent chuck

4. Catch plate

5. Lathe carriers or dog’s

6. Steady rest

7. Mandrel

8. Follower rest

CUTTING TOOLS USED

For making a finished job on lathe machine, various types of cutting tools are used. One of

them is single point cutting tool which is used to perform several operations on the work

piece. Various types of cutting tools are

1. FACING TOOL

It is used for facing the longitudinal ends of the job. Its shape is like a knife.

2. ROUGH TURNING TOOL

It is used to remove excess material from the work piece in quick time. It can be used

to give large depth of cut and work at coarse feed.

3. FINISHING TOOL

It is used for getting smooth finish on the work piece. Its point is a little more round.

4. RADIUS TOOL

Jobs which need round cutting are done with this tool. Its type is

a) Convex radius tool b) concave radius tool

5. PARTING TOOLS

It is used to cut the jobs into two parts. It is also used for grooving.

6. FORM TURNING TOOL

It is used for jobs which require both convex and concave turning.

7. THREAD CUTTING TOOL

It is used for making internal or external threads on the work piece. The tool nose is

designed with a definite profile for taking threads.

8. DRILL TOOL

It is used for making holes of various diameters on the job. Drill bit of various sizes of

diameter are available.

9. BORING TOOL

It used for enlarging the drill hole.

10. KNURLING TOOL

Drawing slanting or square projecting lines on the surface of a job is known as

knurling. It is used for making better grip on the surface of a job.

TOOL MATERIALS

The single point cutting tools are made of high speed steel. (H. S. S)

The main alloying elements in 18 – 4 – 1 HSS tools are 18 % tungsten, 4% chromium

and 1 % Vanadium. 5 to 10 % cobalt is also added to improve the heat resisting

properties of the tool.

General purpose hand cutting tools are usually made from carbon steel or tool steel.

Carbide tipped tools fixed in tool holders, are mostly used in production shops.

NOMENCLATURE OF SINGLE POINT CUTTING TOOL

CUTTING TOOL ANGLES

Top rake angle (back rake angle)

If the slope is given to the face or surface of the tool and if this slope is along the tools

length then it is called top rake angle. It is usually 15 to 20.

Side rake angle

If the slope is given to the face or top of the tool along the tools width then it is called

side rake angle. It lies between 6 and 15.

Clearance angle (relief angle)

Types: 1. Side clearance angle 2. End clearance angle.

They are provided to keep surface of the tool clear of the work piece.

Cutting edge angle

Types: 1. Side cutting edge angle – (generally 15) it is an angle, the side cutting edge

makes with the axis of the tool 2. End cutting edge angle – (from 7 to 15) it is an

angle, the end cutting edge makes with the width of the tool.

Lip angle (cutting angle)

It is the angle between the face and the end surface of the tool.

Nose angle

It is the angle between the side cutting edge and end cutting edge.

LATHE OPERATIONS

1. FACING

It is done for getting fine finish (good surface finish) on the face of the job.

Facing tool is set at an angle to the work piece.

The tool is fed from the centre of work piece towards the outer surface against

the rotating work piece.

Depth of cut is low for the facing operation.

2. PLAIN TURNING

It is done for reducing the diameter of the work piece.

A cutting tool with 70 setting angle is used for roughing operation.

More feed is given for rough turning while less feed is given for finishing.

Work piece is held in chuck and tool is set to center height of the work piece.

3. STEP TURNING

It is similar to the process of turning but in this case different diameter in step

of various sizes is taken on the work piece.

4. TAPER TURNING

It is different from the turning operation.

Taper is defined as uniform change in the diameter of a work piece measured

along its length.

Where D –

large Diameter

d – Small diameter

l – Length of taper

5. KNURLING

It is process of making serrations on the work piece.

Knurling tools of different shape and size are used to make grip on the work

piece. It has two hardened steel rollers.

The tool is held in tool post and pressed against the rotating work piece.

Work piece is rotated at lower speed and small amount of feed is given.

6. DRILLING

It is a process of making a hole on the work piece

Job is held in chuck while the drill is held in the tail stock sleeve.

Feed is given by rotating the hand wheel in the tail stock which pushes the

tailstock sleeve.

CUTTING SPEED

It is the peripheral speed of the work past the cutting tool.

It is the speed at which metal is removed by the tool from the work piece.

It is expressed in meter / minute.

cutting speed=π ×diameter×R . P .M1000

=πDN1000

∈m /min

D – Diameter in mm

N – Spindle speed in rpm

FEED

It is defined as the rate of tool travel across a surface cutting it.

It is the distance of the tool advances for each revolution of the work piece.

It is expressed in mm/revolution.

DEPTH OF CUT

It is the perpendicular distance measured from the machined surface to the uncut

surface of work. It is expressed in mm.

de pth of cut=d1−¿ d2

2¿

d1 = diameter of work before machining

d2 = diameter of work after machining

SAFETY PRECAUTIONS

1) Job should be tightly held in the chuck.

2) If the job is held in between the centers, then apply grease on the nose of dead

center, otherwise it will burnt out due to excess heat.

3) Do not measure the job while it is rotating.

4) Do not leave the chuck key in the chuck.

5) Do not try to stop the lathe chuck or job with hands

6) Do not handle metal chips by hand.

7) Do not give more depth of cut while the job is rotating at high speed.

8) Tighten the tool I n the tool post.

9) Do not stand close to the rotating job or bring your face to it.

10) Do not reduce or increase the speed during the lathe operations.

Result :

EX.NO: MACHINING A WORK PIECE BY FACING, PLAIN TURNING AND STEP TURNING OPERATIONS USING A LATHE

AIM:

To machine a work piece by facing, plain turning and step turning operations using a lathe.

MATERIALS REQUIRED:

Mild steel polished round rod - 32 X 100 mm

TOOLS REQUIRED:

1. Lathe machine

2. Cutting tool

3. outside Caliper

4. Steel Rule

5. Vernier Caliper

PROCEDURE:

1. The given work piece is held firmly in a lathe chuck.2. The cutting tool is set in a tool post such that the point of the cutting tool

coincides with the lathe axis.3. The machine is switched on to revolve the work piece at the selected

speed.4. By giving Cross feed and longitudinal feed to the cutting tool, the facing

and turning operations are done respectively.5. The machine is switched off.6. The work piece is removed from the chuck and all the dimensions are

measured and checked.

GIVEN WORK PIECE (FIG: 1)

FINISHED WORK PIECE (FIG: 2)

RESULT:

The given work piece as shown in fig (1) is subjected to facing, plain turning and step turning operations to become a finished work piece as shown in fig (2).

EX.NO: MACHINING A WORK PIECE BY TAPER TURNING OPERATION (COMPOUND REST METHOD) USING A LATHE

AIM:

To machine a work piece by facing, plain turning and taper turning operation (compound rest method) using a lathe.

MATERIALS REQUIRED:


TOOLS REQUIRED:

1. Lathe machine 4.Steel Rule

2. Cutting tool 5.Vernier Caliper

3. Outside Caliper 6.Spanner

CALCULATION:

The taper angle is calculated using the following formula:

Taper angle () = tan−1( D−d

2l ) Where

D = large diameter of taper in mm

d = small diameter of taper in mm

l = length of tapered part in mm

= angle of taper

PROCEDURE:

1. The given work piece is held firmly in a lathe chuck.

2. The cutting tool is set in a tool post such that the point of the

Cutting tool coincides with the lathe axis.

3. The machine is switched on to revolve the work piece at the selected speed.

4. By giving Cross feed and longitudinal feed to the cutting tool, the facing and turning operations are done respectively.

5. The compound rest is swiveled for the calculated taper angle.6. By giving angular feed to the cutting tool through the compound slide the

taper turning operation is done. 7. The machine is switched off. 8. The work piece is removed from the chuck and all the dimensions are




RESULT:

The given work piece as shown in fig (1) is subjected to facing, plain turning and taper turning operation (compound rest method) to become a finished work piece as shown in fig (2).

EX.NO: MACHINING A WORK PIECE BY TAPER TURNING OPERATION (TAPER TURNING ATTACHMENT METHOD) USING A LATHE

AIM:

To machine a work piece by facing, plain turning and taper turning operation (Taper turning attachment method) using a lathe.

MATERIALS REQUIRED:


TOOLS REQUIRED:

1. Lathe machine with taper turning attachment

2. Cutting tool 5.Vernier Caliper

3. Outside Caliper 6.Spanner

4. Steel Rule

CALCULATION:

The taper angle is calculated using the following formula:

Taper angle () = tan−1( D−d

2l ) Where

D = large diameter of taper in mm

d = small diameter of taper in mm

l = length of tapered part in mm

= angle of taper

PROCEDURE:






5. The taper turning attachment is attached and set for the calculated taper angle.

6. By giving angular feed to the cutting tool the taper turning operation is done.

7. The machine is switched off. 8. The work piece is removed from the chuck and all the dimensions are




RESULT:

The given work piece as shown in fig (1) is subjected to facing, plain turning and taper turning operation (Taper turning attachment method) to become a finished work piece as shown in fig (2).

EX.NO: MACHINING A WORK PIECE BY V- THREAD CUTTING AND KNURLING OPERATIONS USING A LATHE

AIM:

To machine a work piece by facing, plain turning, knurling and external thread cutting operations using a lathe.

MATERIALS REQUIRED:


TOOLS REQUIRED:

1. Lathe machine 5.Outside Caliper

2. Turning tool 6.Steel Rule

3. Knurling tool 7.Vernier Caliper

4. External V – thread cutting tool

CALCULATION:

The number of teeth on change gears is calculated using the following formula:

Driver teeth/ Driven teeth = Pitch of the work / pitch of the lead screw

PROCEDURE:






5. The speed of the work piece is reduced.6. The knurling operation is done using knurling tool. 7. The machine is switched off and the change gears of calculated teeth(as

per calculation) are connected.8. Again the machine is switched on.9. The external thread cutting operation is done using external V–thread

cutting tool by engaging thread cutting mechanism.10. The machine is switched off.

11. The work piece is removed from the chuck and all the dimensions are measured and checked.



RESULT:

The given work piece as shown in fig (1) is subjected to facing, plain turning, knurling and external thread cutting operations to become a finished work piece as shown in fig (2).

EX.NO: MACHINING A WORK PIECE BY BORING AND INTERNAL

THREAD CUTTING OPERATIONS USING A LATHE

AIM:

To machine a work piece by facing, plain turning, boring and internal thread

cutting operations using a lathe.

MATERIALS REQUIRED:


TOOLS REQUIRED:

1. Lathe machine 5.Outside Caliper2. Turning tool 6.Steel Rule3. Boring tool 7.Vernier Caliper4. Internal V – thread cutting tool

CALCULATION:

The number of teeth on change gears is calculated using the following

formula: Driver teeth/ Driven teeth = Pitch of the work / pitch of the lead screw.

PROCEDURE:






5. The speed of the work piece is reduced.6. The boring operation is done using boring tool. 7. The machine is switched off and the change gears of calculated teeth(as

per calculation) are connected.8. Again the machine is switched on.9. The internal thread cutting operation is done using internal V–thread

cutting tool by engaging thread cutting mechanism.10. The machine is switched off.

11. The work piece is removed from the chuck and all the

Dimensions are measured and checked.



RESULT:

The given work piece as shown in fig (1) is subjected to facing, plain turning, boring and internal thread cutting operations to become a finished work piece as shown in fig (2).

STUDY ON SHEET METAL

INTRODUCTION

Sheet metal work is the working on the metal of 16 gauge to 30 gauge with hand tools

and simple machines into different forms by cutting, forming into shapes and joining.

APPLICATION OF SHEET METAL

It is used for making hoppers, funnels, various ducts chimneys, ventilating pipes,

machine tool guards, boilers etc. It is extensively used in major industries like air craft

manufacturing, ship building, automobile body building and fabrication of ducts in air

conditioning equipments.

PRINCIPLE INVOLVED

Generally all sheet metal work patterns are based on the development of the surfaces

of a number of geometrical models like prism, cylinder, pyramid and cone. Besides

development of surfaces, geometrical projections are also used for sheet metal work.

GENERAL 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 metal and then the sheet is cut. Then it is

folded or rolled to the required shape before the joints are made by welding or any other form

of fastening.

SPECIFICATION OF SHEET METAL

The sheets are specified by standard gauge numbers. Each gauge designates a definite

thickness. The gauge number can be identified by standard wire gauge or SWG.

SWG 10 12 14 16 18 20 22 24 26 30

Thickness (mm) 3.2 2.6 2.0 1.6 1.2 0.9 0.7 0.6 0.4 0.3

METALS USED IN SHEET METAL WORK

The most commonly used sheet metals are

a. Black iron – used for making tanks, pans and stove pipes etc.

b. Galvanized iron – used for making pans, buckets, furnaces, heating ducts, cabinets

etc.

c. Stainless steel – domestic appliances such as vessels since it is anticorrosive, it is

well suited for handling of liquid helium, hydrogen, nitrogen and oxygen that exists at

cryogenic state.

d. Copper – used for making cutters, expansion joints, roof flashing and hoods.

e. Aluminium – used for making house hold appliances, refrigerator trays, vessels used

in chemical and food industries, electrical industries, structural applications etc.

f. Tin plate – used for making roofs, food containers, dairy equipments, furnace fittings,

cans and pans etc.

g. Lead – used for lining in tank, flooring in chemical plants. And also in battery paltes.

TOOLS USED IN SHEET METAL WORK

I. Cutting tools

a. Chisels

They are used for cutting sheets, rivets, bolts and chipping operations. Though

there are many types of chisels available, round nose chisel and flat nose

chisel are used for sheet metal work.

b. Snips or Shears

Snips are hand shears; varying in length from 200mm to 600mm. 200mm to

250 mm length is most commonly used. Straight end and curved snips are

mostly used for cutting along outside curves and straight lines, trimming along

inside curves respectively.

II. Striking tools

a. Hammers

They are used for hollowing, stretching, leveling, riveting, strengthening of

sheet metal joints etc. the mostly used hammers are ball peen hammer, straight

peen hammer, riveting hammer, mallet etc.

b. Punches

It is used for marking out work locating centers etc. the widely used punches

are dot punch, hollow punch and center punch.

III. Supporting tools

Stakes

They are the sheet metal worker’s anvil used for bending, hemming, seaming,

forming etc, using hammers or mallet.

IV. Bending tools

Pliers: They are used for bending the sheet metal to the required shape. It also

used for holding and cutting the sheet metal. Flat nose pliers and round nose pliers

are used in the sheet metal work for forming and holding.

V. Layout tools

Steel rules: It is used for measuring and laying out small work. It can measure

with an accuracy of upto 0.5mm.

Scriber: It is long wire steel with its one end sharply pointed and hardened to

scratch line sheet metal for laying out patterns.

Dividers: It is used for drawing circles or arcs on sheet metal. They are used to

mark a desired distance between two points and to divide lines into equal parts.

Sheet Metal gauge: It is used to find the thickness of the sheet metal. The various

gauges are standard wire gauge, Birham wire gauge and American wire gauge.

VI. Other Tools

a. Groover: The process of joining two sheet metal jobs, their ends are grooved

with the help of grooving tools and this is known as grooving.

b. Hand dolly: It is a steel bock rectangular in shape and fitted with a handle in

the bottom of the block.

SHEET METAL OPERATIONS

The major types are

Shearing, Bending, Drawing, Squeezing.

Shearing:

Bending:

It means that the metal is stressed beyond the elastic limit. So that the metal is bent into right

angle and forming occurs when complete items or parts are shaped. It incorporates angle

bending, roll bending, and roll forming and seaming.

Drawing:

It is the operation of producing cup shaped components from the sheet metal by many

number of punching strokes. It is performed by placing a metal blank over a stationary die

and exerting a calculated pressure from a punch against the blank.

Squeezing:

It is the one of the methods of forming ductile material. Riveting, cold heading and rotary

swaging are very common process of squeezing. Rivets are used to join two or more sheets of

metal together.

SHEET METAL JOINTS

Sheet metal working incorporates a wide variety of hems and seams.

HEM: a hem is an edge or border made by folding.

Types of Hem: single hem, double hem, wired edge.

Double Hem

SEAM: A seam is a joining made by fastening two edges together.

Types of seam: Single Seam, Double Seam, Grooved Seam.

SHEET METAL PATTERN DEVELOPMENT METHODS

In order to fabricate an object out of sheet metal it is necessary to know the exact shape and

size of the sheet metal required. For that a pattern which is the flat outline of the object

should be prepared. The objects like cylinder, cone, prism, pyramids etc. are developed from

the development of surfaces.

The following are methods used to make patterns in the sheet metal

1. Parallel line method

2. Radial line method

3. Triangulation method

Development of cylinder using parallel line method

Cylinder is wrapped around the paper. When the paper is opened, it is rectangular of size.

Radial line method

It is used for the development of cones and pyramids in which the apex is taken as center and

its slant edge or generator as the radius for its development.

SAFETY PRECAUTIONS

1. Heavy sheets must be handled by using gloves.2. Check whether head portion of the mallet and hammer should be

tightly fixed to the handle.3. Respective snips should be used according to the sheet thickness.4. Burrs should be removed in the edges of the sheet metal after the

cutting process.5. Do not let sheet metal slip through your hands.6. While cutting operation, blade should be perpendicular to the job and

along the marking line.7. Adequate care should be taken while folding, hemming, seaming

operations.8. Waste materials should be cleaned by using wire brush.9. Necessary sheet metal working tools should be collectively selected

and handled because that avoids confusion.10.High force should not be applied while leveling the plate because that

leads to malleability state of sheet metal.

EX. NO: RECTANGULAR TRAY

DATE:

AIM

To make a Rectangular Tray from the given sheet metal.

MATERIAL SUPPLIED

26 gauge Galvanized Iron (G.I) sheet.

TOOLS REQUIRED

1. Steel Rule

2. Mallet

3. Scriber

4. Divider

5. Snips

6. Ball Peen Hammer

7. Stakes

WORKING PROCEDURE

1. First the work pieces must be thoroughly cleaned to remove rust, scale and other

foreign material.

2. The size of the given sheet is checked for its dimensions using a steel rule.

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

4. The dimensions are marked as shown in figure.

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

6. A single hemming is made on the four sides of the tray as shown in fig.

7. These four sides of the tray are bent to 90 degrees using stakes anvil.

8. Finally all the corners of the tray are joined.

RESULT

Thus the rectangular Tray is made from the given sheet metal.

EX. NO: FRUSTUM OF A CONE

DATE:

AIM

To make a Cone Frustum from the given sheet metal.

MATERIAL SUPPLIED

26 gauge Galvanized Iron (G.I) sheet.

TOOLS REQUIRED

1. Steel Rule2. Mallet3. Scriber4. Divider5. Snips6. Ball Peen Hammer7. Stakes8. ProtractorWORKING PROCEDURE

First the work pieces must be thoroughly cleaned to remove rust, scale and other foreign

material.

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

2. The required shape is first produced in a paper which is used for reproducing the exact

size on the sheet metal.

3. The slanting angle of the sector is calculated by using the formula 360X(R/L).Where, R

is a base circle radius and L is a slant height.

4. The required shape is cut from the paper.

5. Then the exact shape of the paper cut is placed on the G.I sheet, so that the same size

can be reproduced on the sheet metal using scriber.

6. Then the sheet is folded using funnel stake to make cone shape.

7. Then edges of the folded portion are joined together by seaming process using

groover.

RESULT

Thus the cone frustum is made from the given sheet metal.

WELDING EXCERCISES

INTRODUCTION

Welding is one of the metal joining processes.

In welding, metals are used by the application of heat with or without the application of pressure.

During welding the edges of the metal pieces are heated to a high temperature so that they either melt or brought to a plastic condition and then allowed to cool.

Type of welding

1. Plastic welding

2. Fusion welding

PLASTIC WELDING:

The piece of metal to be joined are heated to the plastic state and then forced together

by external force without the filler material.

Note: Filler material is used to fill the gap between the joint surfaces.

Plastic welding further categorized by the following:-

1. Forge welding

2. Resistance welding

3. Thermit welding

FORGE WELDING

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

the area to be joined to the plastic condition. Then parts are quickly superimposed and

worked into a complete union by hand or power hammering or by pressing together.

Example > lap welding, Butt welding,”V” welding

RESISTANCE WELDING

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

joined over limited area causing them to locally heated to plastic state and the welding is

completed by the application of pressure for prescribed period time.

Example > Spot welding, Projection welding, Seam welding Butt welding.

THERMIT WELDING

Thermit welding 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.

FUSION WELDING

The fusion welding is categorized as follows

1. Gas welding

2. Electric welding

3. Thermit welding(without pressure)

Gas welding

Gas welding is the process in which the required heat to melt the surface is

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

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

Oxy-acetylene Welding

In oxy-acetylene gas welding process, a flame is produced by burning mixture

of oxygen and acetylene to get a flame temperature up to 3500°C in two stages.

Types of flames

The ratio of oxygen and acetylene in the mixture leads to any one of the following

flames.

Neutral flame

Oxidizing flame

Carburizing flame

Neutral flame:

This flame has equal volumes of oxygen and acetylene.

According to the application this flame is used to weld steel, stainless steel and

cast iron.

Oxidizing flame

It has more volumes of oxygen than acetylene.

This flame is used to weld copper and copper alloys.

Carburizing flame

It has more volumes of acetylene than oxygen.

This flame is used to weld monel metal, low carbon steel and alloy steel.

FILLER MATERIAL

It is the metal that is added to the metal that is added to the weld pool to assist in

filling the gap. Filler material forms an integral part of the weld. The filler metal is usually

available in the rod form.

ARC WELDING

In arc welding process, the source of heat is electricity

In arc welding process, coalescence is produced by heating the work piece.

With an electric arc stick between an electrode and the work piece.

Welding may be carried out in air or in an inert atmosphere.

Principle of Arc welding:

The electricity is important thing in arc welding.

The electricity 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 the arc melts the metals to be joined are fused together.

The electrodes are used in arc welding as a filler rod.

The electrodes are made of metallic wire called core wire.

It is coated uniformly with a protective coating called flux while fluxing an electrode

about 20 mm of length is left bare at one end for holding it using electric holder.

It is used to transmit full current from electrode holder to the front end of the

electrode coating.

The size or diameter of the core wire will depend upon the amount of weld metal to

be deposited and on the type of joint.

TOOLS USED IN ARC WELDING:

1. Electric holder

2. Chipping hammer

3. Wire brush

4. Hand screen

5. Helmet

6. Tongs

7. Goggles

8. Hand gloves

1. Electrode holder

It is the device used for mechanical holding the electrode and conducting the current

to it.

Electrode holder should be light to minimize fatigue in cured by the welder.

Jams are made to hold the bare of the electrode in either a vertical or an angular

position.

2. Chipping hammer

A chipping hammer is chisel shaped one and it is used to remove slag from the weld

bed.

3. Wire brush

A wire brush made up of shift steel wire, embedded in wood, removes small

particulars of slag from the weld after the chipping hammer has done its job.

4. Hand screen

It is protective device used in arc welding, a hand shield is held in the hand of the

welder and it is fitted with a suitable fitter lens.

5. Helmet

It is used for shielding and protecting the face and neck of the welder and it fitted with

fitter lens.

6. Tongs

Tongs are used to handle the hot metal – welding job while cleaning, they are also

used to hold the metal for hammering.

7. Goggles

Chipping goggles are used to protect the eyes while chipping the slag. They are fitted

while a plain glass to see the area to be cleaned.

8. Hand gloves

Hand gloves are used to protect the hands from the electric shocks, arc radiation and

hot spatters.

EX.NO. THE HORIZONTAL WELDING

Aim:

To arc weld two metal piece of mild steel to get the Horizontal Welding.

Tools Required:

1. Electrode 2. Welding transformer3. Gloves4. Tong5. Chipping hammer6. Wire brush7. Welding shield8. Electrode holder

Procedure:

The mild steel plates to be joined are first cleaned. Using the wire brush to remove dust & rust.

The edges and surface to be welded using the wire brush to remove dust and rust. The edge and surface to be welded are then filled or ground to get the required dimension.

Now the metal plates to be welded are placed in proper position on a cathode plate (that is a metal plate).

The welding electrode is held using an electrode holder and tack welds at two places are made such that the position of the plates do not change while welding (The planes should be at 90° to each other).

Now the electrode is made to touch the metal plates and then electrodes is separated to leave a small gap. (3 to 4 mm) between its tips and the metal plates. This initiates an arc. Once the arc is initiated, the electrode is moved along the length of the metal pieces. For completing the welding process on one side.

Using tongs, the metal plates welded on one side is over turned. Welding is now carried out on this side also in the previously explained manner.

After welding, the plates are allowed to cool for some time. Using a chipping hammer, oxides are removed to complete the exercise.

RESULT:

Thus the two mild steel plates are welded to get the Horizontal Welding.

EX.NO THE VERTICAL WELDING

Aim:

To arc weld two metal piece of mild steel to get the Vertical Welding.

Tools Required:


Procedure:

The mild steel plates to be welded are first cleaned. Using the wire brush to remove dust & rust. The edges and then filed or ground to get the required dimension.

Now the metal plates to be welded are placed in proper position on a cathode plate (that is a metal plate).

The welding electrode is held using an electrode holder and tack welds at two places are made such that the positions of the plates do not change while welding.

Now the electrode is made to touch the metal plates and then electrodes is separated to leave a small gap. (3 to 4 mm) between its (electrode) tips and the metal plates. This initiates an arc. Once the arc is initiated, the electrode is moved along the length of the metal pieces. For completing the welding process on one side.

Using tongs, the metal plates welded on one side is over turned. Welding is now carried out on this side also in the previously explained manner.

After welding, the plates are allowed to cool for some time. Using a chipping hammer, oxides are removed to complete the exercise.

RESULT:

Thus the two mild steel plates are welded to get the Vertical Welding.

EX.NO. THE OVERHEAD WELDING

Aim:

To arc weld two metal piece of mild steel to get the Overhead Welding.

Tools Required:


Procedure:

The mild steel plates to be joined are first cleaned. The edge and surface to be welded are then filled or ground to get the required

dimension. Now the metal plates to be welded are placed in position on metal plate. The welding electrode is held using an electrode holder and tack welds at two

places are made such that the position of the plates do not change while welding.

Now the electrode is made to touch the metal plates and then electrodes is separated to leave a small gap. (3 to 4 mm) between its tips and the metal plates.

This initiates an arc. Once the arc is initiated, the electrode is moved along the length of the metal

pieces. For completing the welding process on one side. Using tongs, the metal plates welded on one side is over turned. Welding is

now carried out on the other side. After welding, the plates are allowed to cool for some time. Using a chipping

hammer, oxides are removed to complete the exercise.

RESULT:

Thus the two mild steel plates are welded to get the Overhead Welding.

EX NO: MAKING A GREEN SAND MOULD

AIM:

To make a green sand mould using a given pattern.

MATERIALS REQUIRED:

1. Pattern

2. Moulding sand

3. Parting sand.

TOOLS REQUIRED:

1. Moulding boxes 6.Sprue pin2. Moulding board 7. Riser pin3. Shovel 8. Strike off bar4. Trowel 9. Draw spike5. Rammers 10. Vent rod

GIVEN PATTERN (FIG: 1)

FINISHED MOULD (FIG: 2)

PROCEDURE:

1. The given pattern is placed on the moulding board.2. Parting sand is applied over the pattern and the moulding board.3. The drag is placed on the moulding board such that the pattern is at the

center of the drag box.4. The prepared moulding sand is filled and evenly rammed in the drag box.5. Excess sand is removed using strike off bar.6. The drag box is turned upside down.7. The cope box is placed on the drag box.8. The sprue pin and riser pin are kept at the respective positions.9. The parting sand is applied at the parting plane 10. The green sand is filled and rammed in the cope box.11. Vent holes are made in the cope box.12. Sprue and riser pins are removed from the cope box.13. The cope box is kept aside and the pattern is removed using draw spike.14. The cope box is placed over the drag box.

RESULT:The green sand mould cavity is prepared as shown in fig (2) by using the

given pattern as shown in fig (1).

me 2207 - manufacturing technology 1 - lab manual

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