REVISION 2015 - Ma’din poly

3027(S3) / 4029(S4)

LAB MANUAL ON

(Sheet metal & Welding)

REVISION 2015

DEPARTMENT OF

MECHANICALENGINEERING

[WORKSHOP PRACTICE III & IV]

SYLLABUS

COURSE TITLE : WORK SHOP PRACTICE-III

COURSE CODE : 3027

COURSE CATEGORY : B

PERIODS/ WEEK : 6

PERIODS/ SEMESTER : 90

CREDIT : 3

TIME SCHEDULE

MODULE TOPIC PERIODS

1 Machine Shop. 24 2 Fitting 24 3 Sheet metal , Aluminum fabrication. 22 4 Welding 20

TOTAL 90

Course Distribution:

Course Total periods per semester

Module Name of Module Outcome Instructional Test

Total

no.

1 Theory :

1 Machine Shop. 2 3 24

3 Practical :21

Theory :

2 Fitting 4 3 24

Practical :21

Sheet metal , Aluminum

Theory :

3 5 3 22

fabrication.

Practical :21

Theory :

4 Welding 6 3 20

Practical :21

Total periods per semester 90

Remarks based on feedback from students, faculty, industry (revision 2010)

GENERAL INFORMATION: *Class is divided into 2 batches (Batch I and Batch II). For Batch I –it is M/c. Shop and Fitting shop and for Batch II- it is Sheet metal, Aluminum fabrication And welding. This syllabus should be continued for Semester IV also by interchanging the batch of students.

COURSE OUTCOME :

Sl.No. Sub Student will be able to

1 Work on Lathes.

1 2 Work on shaper machine.

3 Work on drilling machine.

4 Understand the fitting practice and use of gauges.

2 5 Work in sheet metal shop and aluminum fabrication

6 Work on welding machine.

CONTENT DETAILS

MODULE I MACHINE SHOP

Understand the safety precautions 1.1.0 Lathe work

1.1.1 Familiarization with lathes- principal parts, work holding device, measuring instruments, accessories & attachments 1.1.2 Plain turning to the given accuracy - Practice with Precision measuring devices - use of digital vernier and Micrometer 1.1.3 Taper turning 1.1.4 Form turning (ball and curve) 1.1.5 Combination of above operations (taper, ball and curve)

1.2.0 Work on shaper 1.2.1 Familiarize with the parts, accessories and attachments. 1.2.2 Simple operations on Shaper (Planning) 1.2.3 Shaping of a rectangular block 1.2.4 Shaping a ‘V’ in a rectangular block

1.3.0 Work on drilling machine 1.3.1 Familiarization of drilling machine parts 1.3.2 Marking and drilling holes 1.3.3 Boring and counter boring 1.3.4 Reaming 1.3.5 Combination works

MODULE II FITTING PRACTICE

2.1 Study of measuring gauges-dial gauges, feeler gauges, thread gauges 2.2 Working from a given blue print exercises involving marking filing, drilling, reaming

andtapping to an accuracy of 0.02mm (T- joint, V-joint, Single dovetail joint)

MODULE III SHEET METAL & ALUMINIUM FABRICATION

3.1 Understand safety precautions. 3.2 Familiarization of sheet metal tools – scribers, dividers, trammel points, set square, punches –

prick punches, centre punches – hand Grover, rivet, chisels, hammers, riveting hammers, ball peen hammers – mallet, snip shears, pliers, hand seamers (tongs) files, stakes. Measuring instruments in sheet metal - folding rule, common rule, steel circumference rule, vernier calipers, micrometer, combination set, Thickness gauges – Plate gauge.

MODULE IV WELDING

4.1 Safety precautions 4.2 Study of various tools and equipments used in the welding shop for both arc welding and gas

welding (review) 4.3.0 Practice work

4.3.1. D.C. arc welding (review of practice) 4.3.2. A.C. arc welding (review of practice) 4.3.3. Gas welding (review of practice) 4.3.4. Horizontal, flat, vertical and over head welding 4.3.5. Edge preparation of welded joint such as V, double V. 4.3.6. Pipe welding – linear and round 4.3.7. Flame cutting

GENERAL INFORMATION:

*Class is divided into 2 batches (Batch I and Batch II). For Batch I –it is M/c. Shop and Fitting shop and for Batch II- it is Sheet metal, Aluminum fabrication and welding This syllabus should be continued for Semester IV also by interchanging the batch of students.

TEXT BOOKS

1. Mechanical Workshop Practice by K. C. John (PHI Learning Private Limited)

2. Mechanical Workshop & Laboratory Manual by K. C. John

REFERENCE

1. Workshop Technology Vol. I by S K Hajra Choudhary

2. Workshop Technology Vol. II by S K Hajra Choudhary

COURSE TITLE : WORK SHOP PRACTICE – IV & MINI PROJECT

COURSE CODE : 4029

COURSE CATEGORY : A

PERIODS/ WEEK : 6

PERIODS/ SEMESTER : 90

CREDIT : 5

GENERAL INFORMATION:

Same as for Semester-III

Batches I and II are to be interchanged to compensate.

Student should work 35 periods (5days) for completing mini project

One of the exercise done in the workshop should be related to the industrial product. Eg.

Fabrication of Nut & Bolt, Bucket, Office tray, etc and maintenance of available machinery in the

workshop/ lab will be treated as mini project

Group work for students can be assigned to undertake repair and maintenance works

At the end of the semester each student shall prepare a report on mini project for evaluation

certified by the Head of department. TEXT BOOKS

1. Mechanical Workshop Practice by K. C. John (PHI Learning Private Limited) 2. Mechanical Workshop & Laboratory Manual by K. C. John REFERENCE

1. Workshop Technology Vol. I by S K Hajra Choudhary 2. Workshop Technology Vol. II by S K Hajra Choudhary

SAFETY PRECAUTION

❖ Always wear protective clothing. Do not wear loose dress.

❖ Wear hard leather shoes or safety shoes. Do not wear sandals or rubber shoes.

❖ Must be wear goggles, helmet, Apron, hand gloves and leg guard.

❖ If you don’t have knowledge about working of a machine, you should not operate it

without the help of a person who known it’s working.

❖ Use suitable tools or machines for your work.

❖ When carrying tools, point the sharp edge downwards.

❖ A machine must always be operated by one student at a time.

❖ Do not leave any tools, materials or waste on the bench, machine or floor after

working.

❖ Never adopt a casual attitude in the workshop and always be conscious of the

potential hazards.

❖ Take additional care when carrying or moving any potentially hazardous material or

substance.

❖ Ensure that all safety equipment remains accessible to the workshop personnel at all

times.

❖ Clean machines after use.

CONTENTS

TOPICS PAGE NO.

SHEETMETAL 2 - 9

WELDING 10 - 14

Work Shop Practice III & IV

1 MADIN POLY TECHNIC COLLEGE

DIVEDERS

BENCH VICE

TRAMMEL POINT



SHEET METAL

INTRODUCTION

Sheet metal work is generally regarded as the working of metal from 16gauge down to

30gauge, with hand tools and simple machines in to various forms, by cutting forming in to shape,

and joining. It has its own significance as a use full trade in engineering works and also for our day to

day requirements. Common examples of sheet metalwork are hoppers, canister, guards, covers, pipes,

hoods, funnels, bends, boxes, etc. such articles are found less expensive, lighter in weight and at many

place they easily replace the use of the castings or forgings.

In sheet metalwork knowledge of geometry, mensurations and properties of metal is most

essential. Since nearly all patterns comes from development of the surface of the a number of

geometrical models such as cylinder, prism cone and pyramid a good pattern properly means saving

of time and money.

In sheet metal work, sheet metal used black iron, galvanized iron, stainless steel, copper,

brass, zinc, aluminum, tin plate and lead. The sheet is specified by standard gauge. Each gauge

designate a definite thickness. The larger the specified by standard gauge numbers. It is very essential

to know the different uses and applications of these metal sheets.

SHEET METAL HAND TOOLS

WORK BENCH

A fitting process can be done at various places, but most of the important operation of fitting

are generally carried out on a table called work bench. The work bench is a strong , heavy and rigid

table made up of hard wood. The size of the work bench required is about 150 to 180cm length ,

nearly 90cm width and approximately 76 to 84cm height.

BENCH VICE

The most commonly used in the engineers parallel jaw bench vice some times called fitters vice

.It must be firmly fixed to the bench with coach screws, with nuts and bolts. The vice essentially

consists of cast iron body ,a fixed jaw, a movable jaw ,both made of cast steel, a handle, a square

threaded screw, a nut all made of mild steel. separate cast steel plates known as jaw plates are fixed

to the jaws by means of set screws and they can be replaced when concern. The holding faces of the

jaw plates have teeth for holding the work firmly but this has some disadvantages for soft metal witch

maybe damaged when firmly held between faces protective grips or clamps witch can be made of led

,fiber ,tin - plate, etc are there for usually fitted over the jaw to prevent the serrations damaging the

surfaces of the finished work. The movement of the vice is caused by the movement of the screw

through the nut fixed under the movable jaw and the screw is provided with a collar inside to prevent

it form coming out of jaw when revolved. The size of vice is known by the width of its jaws. The

width suitable for common work varies from 82 to 140 mm, the maximum opening being 95 and 180

mm.



TRY SQUARE SCRIBER

FILE



STEEL RULE

This is particularly useful in measuring and laying out small work. Steel rules are made of

spring steel on stainless steel. The reading accuracy of the steel rule is 0.5mm.

TRAMMEL POINT

The trammel points, consists of two straight, removable legs tapered to needle points and attached to

separate heads. These heads or holders slide on wood or steel bars or beams and are held in place by

thumb screws. A special clamp for a pencil can be attached to one of the points. The trammel points

are used to raw large arc and circles that are beyond the limit of dividers.

DIVIDERS

Dividers are used for scribing circles, arcs and transferring and stepping of distance. Dividers are

available with firm joints and spring joints

The try square is a precision instrument which is used to check squareness (angles of 900) of a

surface. Try square are made of hardened steel .The main parts of try square are stock and blade.

SCRIBER

A scriber is a pointed tool used for marking lines on metals. Scribers are made from high

carbon steel and the points are hardened and tempered.

FILES

The most widely used hand tool in an engineering shop is the file. A file is a hardened piece

of high grade steel with standing row of teeth. The cuts all metals except hardened steel. The

file consists of the following parts, tip or point, face or side, tang, edge, heel, shoulder, tang,

handle, ferrule.

Files are classified according to four principal factors, sizes, shape, grade and

typesof cut of teeth.

COMBINATION SET

Combination set can used for different types of work, like lay out work ,measurement and

checking of angles. The main parts are protractor head , square head ,centre head and a rule.



SHEET METAL OPERATIONS

1. LAYING OUT OF PATTERNS

The first operation for a sheet metal work is the preparation of the development of the object

to be made .The development with the allowance for joints, is called the pattern stretch out of the

object to be shaped. The accuracy of the shape of the object mainly depends on the accuracy of

geometry of the pattern.

To find the development –patterns of objects, basically there are four methods. Parallel line

method. Radial line method , Triangulation method, Approximate method.

2. MEASURING AND MARKING:

A standard size sheet metal may have to be cut i to several smaller pieces, each being

sufficient for making component. Overall dimensions, length and breadth of the required small pieces

are marked on the large sheet with the help of making tools including steel rule, a straight edge. try

square, wing compass and a scriber. In mass production the making can be done using a template and

a scriber or scratch awl.

3. CLEANING: Sometimes blank surface need proper cleaning before being worked. For this purpose pickling

process is issued. Pickling involves immersing the blanks in a hot bath of dilute sulphuric acid. After

sufficient time these blanks are taken out from the pickling bath and are washed in a stream of water

and then dried.

4. CUTTING AND SHEARING: The simplest way of cutting a sheet metal is by chisel and

hammer. The cutting of sheet metal by two parallel edge moving in opposite directions, as in case of

hand shears (snips) or by means of machine shears is commonly termed as shearing.

Basic shearing operations are given below.

a. Cutting off: Seperating a piece from the blank by cutting along a single line.

B .Blanking : Cutting and seperating required shape from a sheet metal blank, using puch and die (the

remaining part of the clank is crap)

c .Punching: Producing circular holes in a sheet metal by punch and die (Punched out piece of sheet is

the scrap). On the other hand producing holes of any shape is termed as piercing.

d. Notching : Removing metal from the edges or corners of seams are known as notching. Types of

notches are straight notch or slit, square notch, slant notch, V notch.

e. Slitting : Cutting along a number of parallel lines to form slits, using snips or rotary blades.

F .Lancing : Makes a cut part away across a strip.

g. Nibbling : Continuous cutting along a contour using a portable shearing machine called nibbler.



HAND GROOVER

RIVET SET

SOLDERING IRON



h. Trimming : Operation of cutting away excess metal from a work piece ,after completion of the

forming operation.

5. EDGE FORMING AND WIRING:

The edges of sheet metal articles need to be folded to increase the strength and to eliminate

the sharp edges of sheet(An edge or border made by folding is also known as hem).

6.JOINT MAKING:

Several methods are used for joining sheet metal parts together .The most commonly used

methods are (a) Seaming (b) Riveting (c)Soldering (d)Welding (e) Brazing (f)Screwed fastening.

a. Seaming : A seam is a joint made by the fastening of two edges of two pieces of metal together

.The types of seams are Lap seam, Grooved seam, Single seam, Double seam ,Double grooved seam,

Dove tail seam, Burred bottom or Flanged seam.

b. Riveting :It is a process of joining permanently two pieces of sheet metal with rivets.

c. Soldering: It is the process by which metallic meterials are joined with the help of another liquefied

metal (solder).The melting point of the solder is lower than that of the meterials being joined.

JOINING TOOLS

The tools exclusively used for making and finishing joints are ; (a)Hand groover (b)Rivet set (c)

Soldering irons.

Hand groover are used to flatten and shape joints made in the sheet metal. The tool has a groove

of required width and depth like a die .For shaping the second head of a rivet, a riveting tool called

rivet set is used .This can convert the rough shape of a rivet formed by hammering to a smooth round

head by final hammering over the tool.

A soldering iron consist of a copper block fixed on an iron rod with a wooden handle. The

purpose of the copper block is to act as a heat source for melting and spreading the solder at the

joining area. The soldering iron is heated using furnace, blower or by electrical resistance.



WELDING INTRODUCTION

The welding is a process by which metals are joined by heating them to a suitable temperature with or

without the application of pressure and addition of filler material. Welding processes are employed in most

of the modern fabrication works and industries.

TYPES OF WELDING

The welding process is broadly divided into the following two groups

1. Pressure Welding or plastic welding: In this process, the ends of the material piece to be joined are

heated to plastic state and are joined together by applying pressure on them. No additional filler metal is

used.

Examples for pressure welding are

(i)Forge welding (ii) Resistance welding (iii) cold pressure welding (iv) pressure Gas Welding etc.

2. Non Pressure or Fusion Welding: In this process, the material at the joint is heated to molten state and

allowed to solidify. Thus the parts are joined together without the application of any pressure. Fusion

welding involves the use of additional filler metal through electrode. It involves the following main process

are

(i) Gas welding (ii) Arc welding (iii) Thermit welding (iv)Braze welding etc.,

(i)Forge welding: It is the oldest method of all the welding process. The metal parts to the welder are

heated in blacksmith furnace to a plastic state and the pressed together by hand of power hammer. Though

the process is very slow, yet it is conveniently used for joining parts of mild steel, wrought iron and low

carbon steels.

(ii)Electric resistance welding: This is also a type of pressure welding. I t is used for joining pieces of

sheet metal or wire. It is usually adopted for mass production. In this case, welding heat is obtained at the

location of the desired weld by electrical resistance through the metal pieces to a relatively short duration,

low voltage high amperage electric current. When the area to be welding is sufficiently heated, the pressure

varying from 25 to 55 MP is applied to the joining area by suitable electrodes until the weld is solid. The

amount of heat generated by the resistance of the metal pieces at the point of contact is given by

H= I2Rt

Where, H = Total heat generate in the work, in Watt, in Watt – second

I = Current, in amperes

R = Resistance of the metal being welded, in ohms, and

T = Time during which electric current flows, in seconds.

Examples for electric resistance welding process are as follows.,

(a) Spot welding (b) projection welding (c) seam welding (d) butt welding

(a)Spot Welding: The spot welding is used for welding lap joints, joining components made from plate

material having 0.02 mm to 1.25 mm in thickness. The plate thickness limited be the pressure and current

capacity of the available spot welding machine. The plates to be joined together are placed are placed

between the two electrodes tips of copper or copper alloy. A low voltage and high amperage current is

passed between electrodes, causing the metal temperature to be raised to welding temperature. The heat

generated by the electric current is rapidly transferred from the outer faces of the plates to the electrodes

which are water cooled. The pressure is applied which squeezes the metal together and thus completes the

weld.



(b)Projection welding : It is similar to spot welding except that one of the metal pieces to the welding has

projections on its surfaces at the points were the welds are to be made. These projections should extent

about 1mm above the surface to be welded. The projections are easily made with punch presses by

embossing. The contact between the two metal pieces to be melted and flattened, allowing the two surfaces

to come together, the melted projections become the weld.

2. (i)Gas Welding:

It is a fusion welding process, in which metals are fused by a gas flame and thus joined. A

gas flame is obtained with the combustion of a fuel gas and oxygen. To make a suitable flame for welding

and cutting oxygen is used as a supporter of combustion. The commonly using fuel gases are acetylene,

hydrogen, coal, LPG etc...

Oxy- Acetylene Welding

Oxy-acetylene welding is a method of joining metals by heating them to the melting point using of mixture

of oxygen and acetylene gas in this welding a additional metal called filler metal or filler rod added to the

welding in the form of welding rod. The composition of filler rod is usually the nearly the same as that of

part being welded.

OXY-ACETYLENE WELDING EQUIPMENTS &ACCESSORIES

Oxygen Cylinder: It is a cylindrical container for storing and supplying compressed oxygen for gas

welding and cutting process. Cylinders are painted in black color and cylinder valve are right hand threaded.

Acetylene Cylinder : It is steel cylinder, filled with a porous substance created a number of small cells in a

cylinder. These cells are filled with acetylene gas under pressure, cylinder painted maroon color and that

outlet valve left hand threads.

Pressure Regulator: Regulators are generally used for reducing the high pressure in let of cylinder to a

suitable, stable working pressure for welding purpose.

Hose Pipes: These are used to carry gas from regulator to the blow pipe. These are made of strong canvas

rubber having good flexibility. Hose pips which carry oxygen are black color and acetylene are maroon.

Welding Blowpipe: Blow pipe is a device which is used for mixing oxygen and fuel gas in required

quantity and producing a flame for welding purpose.

Filler rod: pieces of wires of rod of standard diameter and length used as filler metal in the join during gas

welding process are called filler rod or welding rod.

Goggles: They are used protect the eyes from invasion of flame like high illumination, hot etc.

Spark Lighter: It is used to ignite the gases to avoid danger.

Tip Cleaner: It is a wire with a rough end surface whose diameter corresponds to the diameter of the tip

passage. It removes the metal particles and other impurities from nozzle tip

(ii) ARC WELDING: Here the source of heat is an electric arc. The main types of arc welding are:

(i)Metal inert gas(MIG) welding (ii) Tungsten inert gas(TIG) welding (iii)metal arc welding etc.,



(i)TIG welding: in this process the arc is formed between the water cooled tungsten electrode (non

consumable) and welding job in a atmosphere of an inert gas.

(ii)MIG welding: in this process the arc is formed between a continuous automatically feed

metallic consumable electrode and welding job in an atmosphere of an inert gas.

ARC WELDING EQUIPMENT AND ACCESSORIES:

The following accessories are used for electric arc welding.

1. AC or DC welding machine. 8. Face Shield. 15. Flat file.

2. Electrode. 9. Safety Goggles. 16. Hammers.

3. Electrode holder. 10. Hand gloves. 17. Flat chisel.

4. Cable and Cable connector. 11. Apron. 18. Hack saw with

blade.

5. Chipping Hammer. 12. Sledge Hammer 19. Scriber.

6. Earth Clamp. 13. Punch. 20. Centre punch.

7. Wire Brush. 14. Tongs.

(iii) THERMIT WELDING:

Thermit welding is the only welding process employing an exothermal chemical reaction

(thermit reaction) for the purpose of developing a high temperature. It is a fusion process in which weld is

affected by pouring super heated liquid thermit steel around the parts to be weld.

Welding Positions: The positions of welding joint line in respect of the ground axis indicate the welding

position. Important welding positions are, (1) Flat position (2) Horizontal position (3) Vertical position (4)

over head position

Edge preparation: To obtain sound weld, good edge preparation particularly essential, the edges of the

work pieces must be clean and free of dirt, oil, grease, paint, or scale formation. For many types of joints

chamfers are needed. Depending up on the length of work pieces and availability of machinery, chamfers

may be produced by milling, shaping, sawing, filling or flame cutting. The preparation of edges depends

upon the thickness of metal being welded.

Types of welded joint: The relative position of the two pieces being joined determined the types of joints.

Five basic types of joints are used in welding. These are (1) butt joint (2) corner joint (3) tee joint (4) lap

joint (5) edge joint.

Flame Cutting: The cutting metal by means of flame has many advantages over other methods, especially

when the metal is of regular shape. When using oxy-acetylene, a special torch or cutting blow pipe

necessary. At a temperature of approximately 900 Degree Celsius iron and steel easily combine with the

oxygen to form oxides, burning rapidly away, it is the disintegration of the formation of the oxides that

produce the cut.

REVISION 2015 - Ma’din poly

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