Manufacturing Processes

1. MAJU,ISLAMABAD
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2. MANUFACTURING PROCESSES-I
PROJECT NAME:
WELDING PROCESSES
GROUP MEMEBERS:
1 . A B U B A K R AY U B
2 . WAQ A S A S H R A F
3. HAFEEZ-UR-REHMAN
4 . B I L A L J AV E D
5. SALMAN AZIZ
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3. CLASSIFICATION OF ASSEMBLY PROCESSES
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4. What is Welding?
Welding is a materials joining process in which two or
more parts are coalesced at their contacting surfaces by a
suitable application of heat and/or pressure
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5. TERMS
1) Filler Material: Facilitate coalescence, Increase bulk and strength.
2) Weldment: The assemblage of parts that are joined by welding is called a
weldment.
3) Faying Surfaces: Surfaces in contact or in close proximity that are to be
joined.
4) Welding Fixture: Holds and clamps the components in fixed position for
welding.
5) Welding positioner: Hold the parts, can also moves the assemblage to the
desired position for welding.
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6. ARC (AW)
RESISTANCE (RW)
FUSION
WELDING
TYPES OF WELDING
PROCESSES
OXYFUEL (OFW)
OTHER
ELECTRON
BEAM
LASER
BEAM
DIFFUSION (DFW)
SOLID STATE
WELDING
FRICTION (FRW)
ULTRASONIC
(USW)
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7. V E R S AT I L I T Y O F W E L D I N G
The principal applications of welding are:
1. Construction, such as buildings and bridges
2. Piping, pressure vessels, boilers, and storage
tanks
3. Shipbuilding
4. Aircraft and Aerospace
5. Automotive and Railroad
6. They can be performed at construction sites, in
shipyards, at customers’ plants, and in
automotive repair shops
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8. The Weld Joint: It is the junction of the edges or surfaces of
parts that have been joined by welding.
Types of Joints
• Butt Joint
• Corner Joint
• Lap Joint
• Tee Joint
• Edge Joint
Types of Welds
• Fillet Weld
• Groove Weld
• Plug Weld
• Slot Weld
• Spot Weld
• Seam Weld
• Flange Weld
• Surfacing Weld
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9. (a) butt, (b) corner, (c) lap, (d) tee, and (e) edge
Various
forms of fillet welds
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10. Some typical groove welds
Plug and Slot Welds
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11. a) SPOT WELD and
b) SEAM WELD
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12. PHYSICS OF WELDING
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13. PHYSICAL RELATIONSHIPS
There are two physical relationships that allow fusion welding to be performed.
“ Power
transferred to the
work per unit
surface area ”
Power
Density
PD = P/A
(Watt/mm^2)
Physical
relationships
Heat Balance
Equations
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Hw (net heat used by the
welding operation)=Um*V
(Joules)
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14. EFFECT OF TIME
• Inverse Relation (PD is inversely proportion to time of melting)
• If power density is too low, the heat is conducted into the work as rapidly
as it is added at the surface, and melting never occurs.
• The minimum power density required to melt most metals in welding is
about 10 W/mm^2.
• Differences in the range of PD among different welding processes.(See
Table on next slide)
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15. • For metallurgical reasons, it is desirable to melt the metal
with minimum energy, and high power densities are generally
preferable.
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16. Heat required to melt depends upon:
• Metal’s volumetric specific heat
• The melting point of metal
• Metals heat of fusion
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17. 
The unit Energy for melting is given by,
Eq # A
 Not all the energy Generated by Heat
source is used to melt the weld metal
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18. HEAT BALANCE EQUATION and
Heat Transfer Mechanism
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19. • Heat Energy available for welding is given by:
Hw= f 1*f 2*H
• f1 and f2 are proportions
•H = total Heat generated by the welding process
• Heat balance will be (from Eq # A)
Hw= Um*V
• Rate form
RHw=f 1*f 2*RH= Um*Aw*v
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20. FUSION WELDED JOINT, ZONES AND GRAIN STRUCTURE
Figure (a)
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21. Figure(b)
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22. Cont.
• Fusion Zone
(Completely Melted)
• Epitaxial Grain Growth (Atoms from the molten pool
solidify on preexisting lattice sites)
• Weld Interface (Narrow boundary)
• Heat Effected Zone (Welding failures occur)
• Unaffected Base Metal (residual stresses)
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