The document discusses different types of mechanical joints used to connect parts in machinery. It describes three main types: bolted joints, which use bolts and nuts; screw joints, which use screws; and welded joints, which permanently fuse parts together. Welded joints include butt, corner, lap, tee, and edge joints. The document also discusses different welding processes like shielded metal arc welding, gas tungsten arc welding, gas metal arc welding, and submerged arc welding. It provides details on how each process works and its advantages and applications.

1. PRESENTATION OF DIFFERENT TYPES OF
JOINTS IN AN INDUSTRY
BY-
ABHISHEK CHOWDHURY

2. 1. INTRODUCTION
1.1 JOINTS-:
Joints are used to connect parts of a mechanism or machine. These
mechanical joints can be temporary or permanent depending on whether the
connection needs to be removed frequently or not removed at all.
1.1.1 Types of Mechanicaljoints-:
1. Bolted joint
2. Screw joint
3. Welded joint
I. Bolted joint-: A bolted joint is the most common temporary joint used in
the design of a system or machine. Like the name of the joint states, the joint
uses a bolt and screw to connect the two parts. The size of the bolt is
determined by the load required to ensure the connection is not severed
during operation of the system. A bolt is inserted through a non-threaded
hole drilled to the desired or engineered design and then a nut with washer
is screwed on the end of the bolt. This type of joint allows the maintenance
department to easily disassemble the joint when necessary.

3. -fig. 1 Bolted Joint
2. Screw joint-: A screw joint is another temporary joint used to assemble
two connections. This type of joint utilizes a screw only and is inserted
through a drilled hole of one arm of the connection. The other arm or
connection point is drilled to the desired size and then tapped with a device
that threads the hole to the same size as the screw. The screw is then inserted
and tightened down through the drilled arm and into the tapped hole of the
other arm of the connection. A screw joint is commonly used in soft metal
connections so wear can easily be repaired, such as in aluminum joints.
-Fig. 2 Screw joint

4. 3. Welded joint-: Welded joint is a permanent joint that connects
mechanical parts where disassembling is not necessary. The welded joint is
used on hard metal or steel joints where heavy loads are expected to put
stress on the connection. Welding the connection or mechanical joint does
not allow for easy disassembly.
Types of Welded joints-:
There are five types of welded joints-:
1. Butt joint:
In Butt welded type, the parts lie in the same plane and are joined at their edges.
2. Corner joint:
The parts in a corner joint form a right angle and are joined at the center ofthe angle.
3. Lap joint:
Lap joint consists of two overlapping parts.
4. Tee-joint:
In a Tee-joint, one joint is the right angle to the other joint in the approximate
shape of the letter “T”.
5.Edge joint:
The parts in edge joint are parallel with at least one of their edges in common and
the joint is made at the common edge(s).

5. -Fig. 3 Different Types of joints
2. What is welding??
Welding is a process in which two or more parts are joined permanently by
application of heat and pressure or heat.
2.1 Types of welding process-:
1. Fusion welding 2. Solid state welding
I. Fusionwelding-: In this process, base metal is melted by means of heat.
Often, in fusion welding operations, a filler metal is added to the molted
pool.
II. Solid state welding-: In this process, jointing parts taken place by
application of pressure alone or a combination of heat and pressure. No
filler material is used.

6. 2.1.1 Types of Fusion welding-:
1. Shielded metal arc welding
2. Gas tungsten arc welding
3. Gas metal arc welding
4. Submerged arc welding
2.1.2 Types of solid-state welding
1. Diffusion welding
2. Friction welding
3. Ultrasonic welding
2.1.3 Explanationof different types of fusion welding used-:
1. Shielded Metal Arc Welding (SMAW)-: Shielded Metal Arc Welding,
otherwise known as manual metal arc welding or flux shielded arc welding, is a
process that uses a flux-coated electrode to form the weld. As electricity passes
through the electrode, the flux forms a gas, which shields the electric arc in the
space between the electrode and the metal being welded, preventing
contamination from atmospheric gasses in the weld.

7. -Fig. 4 Shielded metal arc welding
Advantages-:
• Versatility - readily applied to a variety of applications and a wide choice of
electrodes
• Relative simplicity and portability of equipment
• Low cost
• Adaptable to confined spaces and remote locations
• Suitable for out-of-position welding
Disadvantages-:
• Not as productive as continuous wire processes
• Likely to be more costly to deposit a given quantity of metal
• Frequent stop/starts to change electrode
• Relatively high metal wastage (electrode stubs)
• Current limits are lower than for continuous or automatic processes (reduces
deposition rate).

8. Applications-:
Shielded metal arc welding is one of the world's most popular welding processes,
accounting for over half of all welding in some countries.
Because of its versatility and simplicity, it is particularly dominant in the
maintenance and repair industry, and is heavily used in the construction of steel
structures and in industrial fabrication.
In recent years its use has declined as flux-cored arc welding has expanded in the
construction industry and gas metal arc welding has become more popular in
industrial environments.
However, becauseof the low equipment costand wide applicability, the process will
likely remain popular, especially among amateurs and small businesses where
specialized welding processes are uneconomical and unnecessary.
2. Gas Tungsten Arc Welding (GTAW)-:
Gas tungsten arc welding (GTAW) is an electric arc welding process that
produces an arc between a non-consumable electrode and the work to be welded.
The weld is shielded from the atmosphere by a shielding gas that forms an
envelope around the weld area.
The GTAW processis versatile and canbe used onferrous and nonferrous metals.
An arc is produced between a nonconsumable electrode and the work to be
welded. The weld is shielded from the atmosphere by a shielding gas that forms

9. an envelope around the weld area. Argon and helium are the two mostcommonly
used shielding gases used for GTAW.
-Fig. 6 Gas Tungsten Arc Welding
Advantages-:
o No flux is used
o No danger of flux entrapment when the welding of refrigerator or air
conditioner takes place.
o Better control by the operator because of better visibility.
o Very few splatters. Very high quality and smooth welds.
Disadvantages-:
o Under similar conditions MIG welding is much more faster process.
o Tungsten if gone to the molten weld then it can contaminate the pool.
o Equipment’s are costly.
Applications-:
o Aluminium, magnesium, copper alloys can be welded easily. Inconel,
carbon steels, stainless steels can be welded.
o Thin parts and sheet metals can be welded easily.

10. o Can sealing, instrument diaphragms and transistor cases can be welded
very efficiently.
o Expansion bellows and other delicate parts can joined.
o Atomic energy, aircraft, chemical and instrument industries use this
welding process.
o Rocket motor chamber fabrication welding can be done by this process.
3. Gas Metal Arc Welding (GMAW)-:
Gas metal arc welding (GMAW) is a high-speed, economical process that is
sometimes referred to as metal inert gas (MIG) welding.
In this process, an arc is struck between the base metal and a continuously supplied
consumable electrode, which provides filler metal for the weld.
The electrode is bare, containing no coating or core. The shielding, to protect the
molten metal from reacting with constituents of the atmosphere, is supplied by an
external gas, usually containing one of a mixture of the following: helium, argon, or
carbon dioxide.
A significant amount of fume can be generated when welding with this process.
Most of the fume generated during GMAW is derived from the consumption of the
electrode and not from the base metal.

11. -Fig. 7 Gas Metal Arc Welding
Advantages-:
1. Low costequipment.
2. Low costconsumables.
3. High deposition rates.
4. Low hydrogen deposits.
5. Can weld almost all metals.
6. Low levels of spatter.
Disadvantages-:
1. Sensitive to contaminants – The process can only handle low to moderate
levels of surface contaminants such as rust, mill scale, dirt, oil and paint. All
these have potential to create problems such as porosity, incomplete fusion,
bad bead appearance and even cracking.
2. Portability – Moving the welding equipment may not be that tough, but you
also have to handle the high-pressure cylinders that contain the shielding gas.
Proper care must be taken.

12. 3. Sensitive to wind – The shielding gas used for MIG welding can easily be
blown away when welding outdoors. Even inside, a fan or a wind draft of as
low as 5mph can be enough to cause porosity.
4. Lack of fusion – Due to the ability to weld at low currents this process has
the potential for lack of fusion when running in short circuit mode. Make sure
you always use the correct procedure for the thickness of material you are
welding. There is a reason why the American Welding Society does not have
pre-qualified procedures using the short-circuit mode of metal transfer.
Applications-:
o Production of car bodies.
o Fabrication of structures.
o Shipbuilding.
o Pressure vessels.
o Tanks, pipes, domestic equipment, general.
o Heavy electrical engineering and the aircraft engine manufacturing
industries.
4. Submerged Arc Welding -:
Submerged-arc welding (SAW) involves the formation of an arc between a
continuously fed electrode and the workpiece. A blanket of powdered flux, which
generates a protective gas shield and a slag (and may also be used to add alloying
elements to the weld pool), protects the weld zone. A shielding gas is not required.
The arc is submerged beneath the flux blanket and is not normally visible during
welding.

13. -Fig. 8 Submerged Arc Welding
Advantages-:
o This welding process has high deposit rate.
o Very little welding fume is seen.
o No edge preparation is needed.
o This process is applicable indoor as well as outdoor.
o No chance of weld spatter as it is submerged in flux blanket.
Disadvantages-:
o Operation is limited to some specific metals.
o The application is limited to straight seams and pipes and vessels.
o The flux handling can be tough.
o Health issue can be caused because of the flux.
o Slag removal is needed after welding.

14. Applications-:
o Joining of pressure vessels such as boilers.
o Many structural shapes, earth moving equipment, pipes.
o Railroad construction, locomotives and ship building.
o Repairing machine parts.