RAILWAY WORKSHOP SEMINAR

S e m i n a r r e p o r t | 1
RAILWAY WORKSHOP JHANSI
INTRODUCTION
Jhansi Workshop is the biggest Wagon Repair Workshop of Indian Railways. It is
spread in area of 3.4 lakh square meter. The Covered area is 65000 square meter. The
Railway Board Wagon POH target for Jhansi workshop is 610 wagons per month which is
approximately 16 % of the wagon POH done in Indian Railways. Jhansi Workshop
undertakes POH of BOXN, BCN, BOBYN, BOBRN, BTPN and All types of defence
wagons i.e. DBKM, BWTN and BFAT etc. In addition, Jhansi workshop undertakes
Rehabilitation of 75 BOXN wagons per month. This is approximately 14% of the Rehab
work done by all Workshops of IR.
Jhansi workshop is a major POH wagon workshop being the largest workshop in the
Indian Railways, and handling 22% of the Indian Railway wagon-POH arising. It deal with
air brake stock, UIC stock and 4-wheeler tank wagon stock, with bulk of the outturn
pertaining to air brake stock. The out turn of air brake stock requires feed of 11 rakes per
month. This feed is received from NKJ and Bhusawal yards of WCR and CR.
North Central Railway caters to two heavy density over saturated electrified A routes
i.e. Ghaziabad Mughalsarai and Palwal Agra Bina. Line capacity utilization on these sections
has gone upto 170%. N C Railway has over all electrification of 52% of B.G. track and hauls
approximately 87% of its traffic on electric traction. North Central Railway runs
approx. 280 Mail/Express, 109 Passengers EMU-MEMU and an average POL 366.5 (Goods
+ coaching) daily on electric traction.
BRIEF HISTORY OF RAILWAY WORKSHOP JHANSI
(a). 1889 Commencement of Construction of Jhansi Workshop.
(b). 1895 Steam Loco, Coach & Wagon Repair activities started by Indian Midland
Railways.
(c). 1910 Take Over by G.I.P. Railway (Great Indian Peninsula Railway)
(d). 1930 Loco Repair transferred from Jhansi to Parel Workshop.
(e). 1961 Introduction of Incentive Scheme.
(f). 1990 Introduction of POH of BOX ‘N’/ BCN wagons.

(g). 1997 Discontinuation of coach POH.
(h). 2001 ISO 9001: 2000 Certificate awarded to Jhansi workshop.
(i). 2008
[i]. Coach MLR Workshop sanctioned at a cost of Rs. 83.67 crores.
[ii]. Modernization Project sanctioned at a cost of Rs. 71.44 crores.
(j). 2009
[i]. POH of Tower Wagons started on regular basis.
[ii]. Stainless Steel wagons BOXNR turned out from May 2009 Rehabilitation
[iii]. Outturn increased from 50 per month in 2008-09 to 75 per month in 2009-10.
(k) 2010 GM Observation Car, RA Furnishing, RA Air conditioning
(l) 2011 Commencement of Turn Key Projects. BRN Conversion for Rail loading
DMT
(m) 2012
[i]. Conversion of BOXN to BOXNHAM started. First ever Rake of BOXNHAM in India
Railway has been flagged of on 25.05.12.
[ii]. Work of Turnkey Projects in progress, MBFU of Kanpur based ART has been
converted in to Air brake with BMBS.
STATISTICS OF JHANSIWORKSHOP
(a). Established 1895
(b). Total area 3.4 Lakh square meter
(c). Covered area 65000 square meter
(d). Approximately no. of worker 6135
(e). Total machine and plant 576+
(f). Electric load 531253KW/month
(g). Budget sanctioned 171635100 Rs/-
(h). Average wagon holding 920
(i). Total outturn per day 24.5
(j). Outturn of tank wagon 105 per month
(k). Outturn of BOX-N/BCN 476 per month
(l). Average working days of a wagon 6 days
(m). P.O.H. unit cost of wagon 260000 Rs/-

ELECTRIC LOCOMOTIVE
An electric locomotive is a locomotive powered by electricity from overhead lines, a
third rail or on-board energy storage such as a battery or fuel cell. Electric locomotives with
on-board fuelled prime movers, such as diesel engines or gas turbines, are classed as
dieselelectric
or gas turbine-electric locomotives because the electric generator/motor combination
serves only as a power transmission system. Electricity is used to eliminate smoke and take
advantage of the high efficiency of electric motors, but the cost of electrification means that
usually only heavily used lines can be electrified.
Electric Loco Shed (Jhansi)
Electric Loco Shed, Jhansi designed for a holding of 100 locos was established in
1987 with an initial holding of 17 locos. Present holding of the shed is 207 locomotives i.e.
90 WAG/7 (45 BHEL & 45 CLW make) and 117 WAG/5 (74 BHEL & 43 CLW make)
locomotive. This includes 45 Nos. newly built BHEL make WAG/7 locos and 09 no. CLW
make WAG-7 loco added to the fleet. These newly received locomotives are having some
special features viz., Crew Friendly Cab with FRP cabinet for Driver Desk and Air
conditioning & Stick type Master Controller.
ELS/JHS was the first shed in Indian Railways to acquire three prestigious
International Standards viz., ISO-14001:2004, OHSAS-18001 & ISO-9001:2008 together

WAGON REPAIRING PROCESS
INTRODUCTION
Various processes which are carried out once a wagon reaches in the workshop
premises are as follows:
(a). Firstly wagon come in pocket yard.
(b). Senior Section Engineer (S.S.E) of inspection department inspect deeply the wagon
and that time coding is done according to work.
(c). Light Repair- 1
(d). H/Repair- 6
(e). Under Frame- 5
(f). RE Floor- 6RF
(g). RE Roofing- 6RR
(h). Re Hab- RH
(i). For Condemn- U/Inspection
(j). In the yard noted that which wagon required POH, ROH & NPOH.
(k). In the inspection department the repairable part of wagon marked.
(l). From the yard the box is directly send in stripping shop.
(m). All corrosive parts separated by cutting operation and clean well.
(n). After parts is clean well and then according to work demand wagon is send to different
shops.
(o). Usually vacuum brake wagon sending in BWR shop, Heavy repairable wagon sending
in BNR-I and BNR-II and Re Hab wagon is send in Re habitation shop.
(p). Firstly in shop the BP of wagon and centre pivot pin of wagon is cut and after cut the
lifting the wagon and lowered on tassels by separating of body parts of wagon.
(q). After dismantle of wagon is sending in wagon shop and the wheel is sending in wheel
shop for the new profile with Ultrasonic Testing (U.S.T).
(r). After then lower the body parts on tassels air brake parts like as Auxiliary
Reservoir(A.R.), Controlling Reservoir(C.R.), Brake Power(B.P.), Distributor
Valve(D.V.), Dirt collector, Angle cock is separated.

Fig. 2.1: Rail Wagon
(s). All parts of air brake are sending in the air brake shop, all air brake steam tested on 10
kg/cm2.
(t). All parts after handling assemble in a wagon to make a perfect BOXN.
(u). According to painting schedule paint is done on wagon.
(v). After doing Stenciling the writing work on wagon is done.
(w). After complete this operation/s the testing of air brake is done by single wagon test
ring (S.W.T.R.).

ELECTRICAL REPAIR & TESTING ROOM
CEILING FAN (1-ɸ INDUCTION MOTOR)
INTRODUCTION
A ceiling fan is a mechanical fan, usually electrically powered, suspended from
the ceiling of a room, that uses hub-mountedrotating paddles to circulate air. A ceiling fan
rotates much more slowly than an electric desk fan; it cools people effectively by introducing
slow movement into the otherwise still, hot air of a room, inducing evaporative cooling. Fans
never actually cool air, unlike air-conditioning equipment, but use significantly less power
(cooling air is thermodynamically expensive). Conversely, a ceiling fan can also be used to
reduce the stratification of warm air in a room by forcing it down to affect both occupants'
sensations and thermostat readings, thereby improving climate control energy efficiency.
Fig. 3.1: Construction of Fan
WORKING AND CONSTRUCTION OF CEILING FAN
The ceiling fan motor works on principle of single phase induction motor using capacitor.
Working of capacitor start motor: The stator consists of the main winding and a starting winding
(auxiliary). The starting winding is connected in parallel with the main winding and is placed
physically at right angles to it. A 90-degree electrical phase difference between the two windings
is obtained by connecting the auxiliary winding in series with a capacitor and starting switch.
When the motor is first energized, the starting switch is closed. This places the capacitor in series
with the auxiliary winding. The capacitor is of such value that the auxiliary circuit is effectively

resistive-capacitive circuit (referred to as capacitive reactance and expressed as XC). In this
circuit the current leads the line voltage by about 45° (because XC about equals R). The main
winding has enough resistance-inductance (referred to as inductive reactance and expressed as
XL) to cause the current to lag the line voltage by about 45° (because XL about equals R).
The currents in each winding are therefore 90° out of phase - so are the magnetic fields
that are generated. The effect is that the two windings act like a two-phase stator and produce the
rotating field required to start the motor. When nearly full speed is obtained, a centrifugal device
(the starting switch) cuts out the starting winding. The motor then runs as a plain single-phase
induction motor. Since the auxiliary winding is only a light winding, the motor does not develop
sufficient torque to start heavy loads. Split-phase motors, therefore, come only in small sizes.
REPAIRING OF CEILING FAN
Steps for repairing ceiling fan
(a). Start by turning off the circuit breaker to the fan.
(b). Next, remove the cover on the fan housing or the globe light so you can access the
switch, and unscrew the nut on the outside of the switch that holds it on.
(c). Pull the switch out of the housing from the inside, leaving the wires attached.
(d). Examine the switch to see if the chain can be reattached.
(e). If not, carefully note the colors of the wires and the terminal each attaches to (take a
picture with a digital camera or cell phone or draw a diagram of the switch).
(f). Detach the wires and take the switch—along with the model and make of the fan—with
you to the home center for a replacement. Be sure to match the number of speeds, switch
size, and wattage.
(g). To install the new switch if the wires attach directly to the terminals, bend each wire
around the corresponding terminal in a clockwise direction, and tighten up the screws.
(h). If the switch has wires that attach using twist-on connectors (commonly called wire
nuts), strip 1/2” to 3/4” of insulation from each wire, wrap them together in a clockwise
direction, and twist the connector on in a clockwise direction so it is secure and the bare
wire is covered.
(i). Insert the switch in the hole in the fan housing from the inside and thread the nut on the
outside.
(j). Attach the housing cover or the globe light

MACHINE SHOP
INTRODUCTION
Every machine needs proper care and with the time there parts get worn out, so these
parts needs to replaced or maintained. This function performed in Machine shop. Here
different parts of machines are repaired. This shop has many heavy machines. For example
lathe machine, milling, shaper, grinding, radial drilling etc.
LATHE MACHINE
It is commonly known as the mother of all other machine tool. The main function of a
lathe is to remove metal from a job to give it the required shape and size. The job is secure1y
and rigid1y held in the chuck or in between centre on the lathe machine and then turn it
against a single point cutting tool which will remove metal from the job in the form of chips.
Lathe can be used to carry out other operations also, such as drilling, reaming, boring, taper
turning, knurling, screw thread cutting, grinding etc.
CENTRE OR ENGINE LATHE
This lathe is the important member of the lathe family and is the most widely used.
Similar to the speed lathe, the engine lathe has all the basic parts, e.g., bed, headstock, and
tailstock. But its headstock is much more robust in construction and contains additional
mechanism for driving the lathe spindle at multiple speeds.The engine lathe can feed the
cutting tool both in cross and longitudinal direction with reference to the lathe axis with the
help of a carriage, feed rod and lead screw. The power may be transmitted by means of belt,
electric motor or through gears.
Fig. 4.1: Centre lathe

ShaperMachine
Shaper is a reciprocating type of machine tool in which the ram moves the cutting tool
backwards and forwards in a straight line. These surfaces may be horizontal, Vertical, or
inclined. A shaper is used to generate flat (plane) surfaces by means of a single point cutting
tool similar to a lathe tool. A single point cutting tool is held in the tool holder, which is
mounted on the ram. The work piece is rigidly held in a vice or clamped directly on the table.
The table may be supported at the outer end. The ram reciprocates and thus cutting tool held
in tool holder moves forward and backward over the work piece. In a standard shaper, cutting
of material takes place during the forward stroke of the ram. The backward stroke remains
idle and no cutting takes place during this stroke. The feed is given to the work piece and
depth of cut is adjusted by moving the tool downward towards the work piece. The time
taken during the idle stroke is less as compared to forward cutting stroke and this is obtained
by quick return mechanism.
Fig. 4.2: Shaper Machine
Radial Drilling Machine
The radial drilling machine consists of a heavy, round vertical column supporting a
horizontal arm that carries the drill head. Arm can be raised or lowered on the column and
can also be swung around to any position over the work and can be locked in any position.
The drill head containing mechanism for rotating and feeding the drill is mounted on a radial

arm and can be moved horizontally on the guide-ways and clamped at any desired position.
These adjustments of arm and drilling head permit the operator to locate the drill quickly over
any point on the work. The table of radial drilling machine may also be rotated through 360
deg. The maximum size of hole that the machine can drill is not more than 50 mm. Powerful
drive motors are geared directly into the head of the machine and a wide range of power
feeds are available as well as sensitive and geared manual feeds. The radial drilling machine
is used primarily for drilling medium to large and heavy work pieces.
Fig. 4.5: Radial Drilling Machine
Slotting Machine
The slotter or slotting machine is also a reciprocating type of machine tool similar to a
shaper or a planer. It may be considered as a vertical shaper. The chief difference between a
shaper and a slotter is the direction of the cutting action. The machine operates in a manner
similar to the shaper, however, the tool moves vertically rather than in a horizontal direction.
The job is held stationary. The slotter has a vertical ram and a hand or power operated rotary
table.
Fig. 4.6: Slotting Machine

Grinding Machine
Grinding is a material removal and surface generation process used to shape and
finish components made of metals and other materials. The precision and surface finish
obtained through grinding can be up to ten times better than with either turning or milling
usually a rotating wheel brought into controlled contact with a work surface. The grinding
wheel is composed of abrasive grains held together in a binder. These abrasive grains act as
cutting tools, removing tiny chips of material from the work. As these abrasive grains wear
and become dull, the added resistance leads to fracture of the grains or weakening of their
bond. The dull pieces break away, revealing sharp new grains that continue cutting.
The requirements for efficient grinding include:
(a). Abrasive components which are harder than the work.
(b). Shock- and heat-resistant abrasive wheels.
(c). Abrasives that is friable. That is, they are capable of controlled fracturing.
Fig. 4.7: Grinding Machine

Milling machine
A milling machine is a machine tool that removes metal as the work is fed against a
rotating multipoint cutter. The milling cutter rotates at high speed and it removes metal at a
very fast rate with the help of multiple cutting edges. One or more number of cutters can be
mounted simultaneously on the arbour of milling machine. This is the reason that a milling
machine finds wide application in production work. Milling machine is used for machining
flat surfaces, contoured surfaces, surfaces of revolution, external and internal threads, and
helical surfaces of various cross-sections. In many applications, due to its higher production
rate and accuracy, milling machine has even replaced shapers and slottersAs the workpiece
moves against the cutting edges of milling cutter, metal is removed in form chips of trochoid
shape. Machined surface is formed in one or more passes of the work. The work to be
machined is held in a vice, a rotary table, a three jaw chuck, an index head, between centres,
in a special fixture or bolted to machine table. The rotatory speed of the cutting tool and the
feed rate of the work piece depend upon the type of material being machined.
Fig. 4.8: Milling machine

COMPRESSOR SHOP
Introduction of Air Compressor
Air compressor is a machine, suck low pressure low temperature air form atmosphere
and compressor it to high pressure and high temperature by reciprocating or rotary motion
of compressor. It is driven by external source like as prime mover. The compressor used
for supplying large amount of air to machine.
Use of CompressedAir
(a). To start large diesel engine.
(b). To clean workshop machine.
(c). To operate blast furnaces.
(d). To operate lift, reams and pump.
(e). To inject drill, hammer, air brake for locomotive and water sprays.
(f). For supercharging of I.C. engine.
(g). For filling the air in tube of tire.
(h). To cool large building.
Classification Of Air Compressors
Reciprocating Air Compressor
Single Stage Reciprocating Compressor
Construction
(a). It consists of cylinder and piston assembly.
(b). Assembly of crank shaft and connecting rod.
(c). Inlet and delivery valve etc.
Fig. 6.2: Reciprocating Compressor

Working
(a). The single stage reciprocating compressor is shown in figure.
(b). The single stage reciprocating compressor working is same as engine.
(c). During the downward motion of the piston, the pressure inside the cylinder falls
below the
(d). Atmospheric pressure and the inlet valve is opened due to the pressure.
(e). As the piston starts moving upward, the inlet valve is closed and the pressure is
increasing continuously until the pressure inside the cylinder is above the pressure of
delivery side which to the receiver.
(f). Then delivery valve open and air transfer to receiver.
(g). The cycle is repeated.
Two stage compressor(Multi stage compressor)
Construction
It consists of two cylinders, one is L.P. (Low pressure) and another is H.P. (High pressure).
Two parallel cylinders are connected by inter-cooler.
Working
(a). The two stage compressor diagram shown in figure.
Fig. 6.3: Multistage Compressor
(b). In the two- stage air compressor with inter-cooler, the air is first taken into low
pressure (L.P.) cylinder; this air is compressed in to the cylinder.
(c). Then this air is passing to inter-cooler.
(d). The air is cooled at constant pressure to its original temperature by cold water.

(e). When the air cooled to original temperature, the cooling perfect due to constant
pressure.
(f). The cooled air is passed to high pressure (H.P.) cylinder.
(g). For second stage, the H.P. cylinder compressed to final pressure then delivered to
receiver at constant pressure.
(h). The indicated diagram of H.P. and L.P. cylinder shown in figure.
ROTARY COMPRESSOR
Screw compressor
Construction
(a). In screw compressor, the suction and delivery valve replaced by port and a piston
replaced by helical screw.
(b). It consists of two helical screws which are mesh with each other.
(c). An electrical motor drives a male rotor and female are driven by male rotor.
Working
(a). The screw compressor is shown in figure.
(b). The screw compressor is driven by external source like electric motor.
(c). When the male rotor shaft is rotate then female is mesh with male gear.
Fig. 6.4: Screw Compressor
(d). The air, gas is drawn into the inlet port, the rotor is continuous to turn inter lobe space
increase in size, and gas, air flow continuously into compressor.
(e). Male lobe with female inter lobe space on the suction end and progressively
compresses the air in axial direction of discharge proof.
(f). At the point determine by the designed built in volume ratio, the discharge port is
uncovered and the compressed air is discharge.
(g). The cycle is repeated.

RootBlower(Lobe Type)
Construction
(a). It consist of two rotor driven by externally, one of the rotor is connected to drive and
another is driven by first rotor.
(b). A very small clearance is provided between the casing and rotor to prevent wear.
Then increase the pressure ratio.
Working
(a). The root blower is shown in figure.
(b). The volume of air Vs at atmospheric pressure is trapped between the left hand rotor
and casing.
Fig. 6.5: Root Blower
(c). At the same time, high pressure air rushes back from the receiver and mix irreversibly
with blower air V until pressure equalized.
(d). Then air is delivered to receiver.
(e). If two rotor has two lobes then air delivered is 4V and if three lobes then 6V per
revaluation.
(f). The delivery of air into receiver is not continuously even the rotor revolves with
uniform speed.
(g). The procedure is repeated.
Vane compressor
Construction
(a). It consists of a rotor located eccentrically in a cylindrical casing.
(b). The rotor carries a set of spring located vane in the lot of rotor.

(c). It consists of vane, spring, casing, rotor etc.
Working
The vane compressor is shown in figure.
Fig. 6.6: Vane Compressor
(a). The volume of air V1 at atmospheric pressure P1, is trapped between two vanes in root
blower.
(b). As the rotation processed, the trapped air is first compressed reversibly from
condition 1 to d as the compression take place due to decrease in volume provide for
trapped air.
(c). Thus the air is compressed irreversibly from the pressure Pd to P2.
(d). The air is delivered to receiver after the equalization of the pressure in receiver.
Centrifugal Compressor
Construction
(a). It consists of rotating impeller, diffuser, casing, driven shaft, impeller eye etc.
(b). The impeller can run at speed 20,000 to 30,000 r.p.m.
(c). The diffuser is important part of compressor which surrounding the impeller and
provides diverging passage for air flow thus increasing the pressure air.
Working
(a). The centrifugal compressor is shown in figure.
(b). The impeller rotate with the shaft at high speed and air is drawn into the impeller eye
in an axial direction.
(c). The air flow radially outward through the impeller passed due to centrifugal force.
Fig. 6.7: Centrifugal Compressor

(d). The air leaves the impeller tip with high velocity and enters the diffuser.
(e). The diffuser reduce the high velocity thus by diffuser process of air in the diffuser,
kinetic energy is converted in to pressure energy.
(f). The flow from the diffuser is collected in a spiral passage from which it is discharged
form compressor.
(g). The procedure is repeated.
APPLICATION OF COMPRESSOR
Application of reciprocating compressor
(a). To spray painting shop.
(b). In workshop, for cleaning the machine.
(c). In automobile service station for cleaning the vehicle.
(d). For operation of pneumatic tools.
(e). Blast in blast furnace.
(f). Boosting of I.C. engine.
Application of rotary compressor
(a). Petrol chemical factory.
(b). Refrigeration factory.
(c). Supercharging of petrol and diesel engine.
(d). Oil refinery plant.

CRANESHED
INTRODUCTION
A crane is a type of machine, generally equipped with a hoist, wire ropes or chains,
and sheaves, that can be used both to lift and lower materials and to move them horizontally.
It uses one or more simple to create mechanical advantage and thus move loads beyond the
normal capability of a human.
Basic Lifting Parts Of The Crane
(a). Lever
(b). Pulley
(c). The hydraulic cylinder
(d). A balance crane contains a horizontal beam (the lever) pivoted about a point called
the fulcrum.
(e). A jib crane contains a tilted strut (the jib) that supports a fixed pulley block. Cables
are wrapped multiple times round the fixed block and round another block attached to
the load.
(f). For stability, the sum of all moments about any point such as the base of the crane
must equate to zero.
TYPES OF CRANE
On the basis of modern crane study and advancement there are two basic types of cranes:-
1. Fixed crane
2. Mobile or movable crane
(a). A fixed crane is the type of crane which lift the loads without any appreciable
movement.
(b). A mobile crane is the type of crane which moves from one place to another as
well as movement of the crane basic tools.
TYPES OF FIXED CRANE
TOWER CRANE
The tower crane is a modern form of balance crane. Fixed to the ground (and
sometimes attached to the sides of structures as well), tower cranes often give the best

combination of height and lifting capacity and are used in the construction of tall buildings.
Specification:
Lifting Capacity: - max 25t.
Working Radius: - 70 m to 75m.
Tower crane is generally used for high rise infrastructure and project.
SELF-ERECTING CRANE
Specification:
Lifting Capacity: - max 6t to 8t.
Working Radius: - 45m.
Use:
It is mainly used on construction –site to transport the material from one place to other place.
HAMMERHEAD CRANE
The "hammerhead", or giant cantilever, crane is a fixed-jib crane consisting of a steelbraced
tower on which revolves a large, horizontal, double cantilever; the forward part of this
cantilever or jib carries the lifting trolley, the jib is extended backwards in order to form a
support for the machinery and counter-balancing weight.
Specifications:
Lifting capacity: - max 350tons.
Working radius: - up to 70m.
Use: Ship-yard work including construction of ship and heavy duty building construction.
30
OVERHEAD CRANE
(a). Overhead Crane can build top running cranes, under running cranes, double girder
cranes, and single girder cranes ranging from:
(b). Capacities - 1/4 ton through 100 tons
(c). Spans - 5' through 125‘
(d). Use: The most common overhead crane use is in the steel industry.

WELDING SHOP
INTRODUCTION
Welding is a process for joining two similar or dissimilar metals by fusion. It joins
different metals/alloys, with or without the application of pressure and with or without the
use of filler metal. The fusion of metal takes place by means of heat. The heat may be
generated either from combustion of gases, electric arc, electric resistance or by chemical
reaction. During some type of welding processes, pressure may also be employed, but this is
not an essential requirement for all welding processes. Welding provides a permanent joint
but it normally affects the metallurgy of the components. It is therefore usually accompanied
by post weld heat treatment for most of the critical components. The welding is widely used
as a fabrication and repairing process in industries. Some of the typical applications of
welding include the fabrication of ships, pressure vessels, automobile bodies, off-shore
platform, bridges, welded pipes, sealing of nuclear fuel and explosives, etc.
WELDING POSITIONS
There are four types of welding positions:
(a). Flat or down hand position.
(b). Horizontal position.
(c). Vertical position.
(d). Overhead position.
Fig. 8.1: Types of joints
TYPES OF WELDING JOINTS
(a). Butt joint
(b). Corner and Tee joint
(c). Lap joint
(d). Edge joint
CLASSIFICATION OF WELDING PROCESSES

OXY ACETYLENE GAS WELDING
In this process, acetylene is mixed with oxygen in correct proportions in the welding
torch and ignited. The flame resulting at the tip of the torch is sufficiently hot to melt and join
the parent metal. The oxy-acetylene flame reaches a temperature of about 3300°C and thus
can melt most of the ferrous and non-ferrous metals in common use. A filler metal rod or
welding rod is generally added to the molten metal pool to build up the seam slightly for
greater strength.
Oxy Acetylene Welding Setup
Acetylene and oxygen gas is stored in compressed gas cylinders. These gas cylinders
differ widely in capacity, design and colour code. However, in most of the countries, the
standard size of these cylinders is 6 to 7 m3 and is painted black for oxygen and maroon for
acetylene. An acetylene cylinder is filled with some absorptive material, which is saturated
with a chemical solvent acetone. Acetone has the ability to absorb a large volume of
acetylene and release it as the pressure falls. If large quantities of acetylene gas are being
consumed, it is much cheaper to generate the gas at the place of use with the help of
acetylene gas generators. Acetylene gas is generated by carbide-to-water method.
Fig. 8.3: Oxy-Acetylene Welding

METAL INERT GAS WELDING
Metal inert gas arc welding (MIG) or more appropriately called as gas metal arc
welding (GMAW) utilizes a consumable electrode. MIG welding uses a welding wire that is
feed automatically at a constant speed as an electrode. A short arc is generated between the
base metal and the wire. The resulting heat from the arc melts the welding wire and joins the
base metals together. Since the wire is fed automatically at a constant rate, this method is
called semiautomatic arc welding.
During the welding process, either inert gases or active gas shields the weld from the
atmosphere and prevents oxidation of the base metal. The type of inert gas used depends on
the base material to be welded. For most steels welds, carbon dioxide is used a shield gas.
The power supplies are always of the constant voltage type only. The current from the
welding machine is changed by the rate of feeding of the electrode wire. Normally DC arc
welding machines are used for GMAW with electrode positive (DCRP).
Fig. 8.4: Mig Welding Set Up
TUNGSTEN INERT GAS WELDING
In this process a non-consumable tungsten electrode is used with an envelope of inert
shielding gas around it. The shielding gas protects the tungsten electrode and the molten
metal weld pool from the atmospheric contamination. The shielding gases generally used are
argon, helium or their mixtures. Both AC and DC power source can be used for TIG welding.
DC is preferred for welding of copper, copper alloys, nickel and stainless steel whereas DC

reverse polarity (DCRP) or AC is used for welding aluminium, magnesium or their alloys.
Fig. 8.5: Tig Welding Set Up
WELDING DEFECTS
Lack of Penetration
It is the failure of the filler metal to penetrate into the joint. It is due to
(a). Inadequate de-slagging.
(b). Incorrect edge penetration.
(c). Incorrect welding technique.
Lack of Fusion
Lack of fusion is the failure of the filler metal to fuse with the parent metal.
(a). Too fast a travel
(b). Incorrect welding technique
(c). Insufficient heat
Porosity
It is a group of small holes throughout the weld metal. It is caused by the trapping of gas. It is
caused by the trapping of gas during the welding process, due to
(a). Chemicals in the metal
(b). Dampness

(c). Too rapid cooling of the weld.
Slag Inclusion
It is the entrapment of slag or other impurities in the weld. It is caused by
(a). Slag from previous runs not being cleaned away,
(b). Insufficient cleaning and preparation of the base metal before welding commences.
Undercuts
These are grooves or slots along the edges of the weld caused by
(a). Too fast a travel
(b). Bad welding technique
(c). Too great a heat build-up.
Cracking
It is the formation of cracks either in the weld metal or in the parent metal. It is due
(a). Unsuitable parent metals used in the weld
(b). Bad welding technique.
Poor Weld Bead Appearance
If the width of weld bead deposited is not uniform or straight, then the weld bead is
termed as poor. It is due to improper arc length, improper welding technique, damaged
electrode coating and poor electrode and earthing connections.
Distortion
Distortion is due to high cooling rate, small diameter electrode, poor clamping and slow arc
travel speed.
Overlays
These consist of metal that has flowed on to the parent metal without fusing with the defect is
due to
(a). Contamination of the surface of the parent metal
(b). Insufficient heat
Blowholes
These are large holes in the weld caused by
(a). Gas being trapped, due to moisture.
(b). Contamination of either the filler or parent metals.
Burn Through

It is the collapse of the weld pool due to
(a). Too great a heat concentration
(b). Poor edge preparation.
Excessive Penetration
It is where the weld metal protrudes through the root of the weld. It is caused by
(a). Incorrect edge preparation
(b). Too big a heat concentration
(c). Too slow a travel.
Fig. 8.6: Types of Welding Defects

RAILWAY WORKSHOP SEMINAR

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (20)

Similar to RAILWAY WORKSHOP SEMINAR

Similar to RAILWAY WORKSHOP SEMINAR (20)

Recently uploaded

Recently uploaded (20)

RAILWAY WORKSHOP SEMINAR