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1. Mechanical Technology

2. 1. Rolling
2. Forging
3. Extrusion

3. It is deformation
process in which
work thickness is
reduced by
compressive
forces exerted by
two opposing
rollers.
Rolling
Flat Rolling

4. Rollers perform two main functions:
1. Pull the work into the gap between them by friction
between work piece and rollers.
2. Simultaneously squeeze the work to reduce it’s cross
section.

5. Based on work
piece geometry :
1. Flat rolling - It is
used to reduce
thickness of a
rectangular cross
section
Types of Rolling

6. 2. Shape rolling-
In this process square
cross section is formed
into a shape such as an I-
beam

7. Based on work
temperature :
1. Hot Rolling –
It is most
common due to
the large amount
of deformation
required.

8. 2. Cold rolling –
Produces finished
sheet and plate stock.
High surface finish
than hot rolling

9. Nomenclatureof FlatRolling
Side view of flat rolling, indicating before and after thicknesses, work
velocities, angle of contact with rolls, and other features.

10. Rolling Industry

11.  It has been suggested that Leonardo Da Vinci
invented the first rolling mill.
 But what exactly is a rolling mill?
A rolling mill is a unit in which a metal forming
process takes place. During this process various metal
materials get passed through a massive pair of rolls, or
material handling equipment.

12. Various configuration / arrangement of rolling mills
Tandem Rolling MillCluster Mill
Four-High Rolling
Mill
Three-High Rolling
Mill
Two-High Rolling
Mill

13.  Bulk deformation process used to form threads on
cylindrical parts by rolling them between two dies.
 Performed by cold working in thread rolling machines
 Advantages over thread cutting (machining):
1. Higher production rates
2. Better material utilization
3. Stronger threads and better fatigue resistance due to
work hardening

15. Forging is deformation process
in which work is compressed
between two dies or by
hammer.
It is oldest of the metal forming
operations, dating from about
5000 B C
Types:
1. Hot forging
2. Cold forging
Forging

16.  Engine crankshafts
 Connecting rods
 Gears
 Aircraft structural components
 Jet engine turbine parts

17. Advantages
 Decrease in yield
strength, which means
that it is easier to work.
 Elevated temperatures
increase diffusion
between the metals.
 Pores may reduce in size
or close completely
during deformation.
 Undesirable reactions
between the metal and
the surrounding
atmosphere.
 Less precise tolerances
due to thermal
contraction and warping
from uneven cooling.
 Grain structure may vary
throughout the metal.
Disadvantages

18. Advantages
 Better surface finish.
 Better reproducibility and
interchangeability.
 No Heating required.
 Directional properties can
be imparted into the
metal.
 Higher forces are required.
 Heavier and more powerful
equipment and stronger
tooling are required.
 Metal is less ductile and
Undesirable residual stress
may be produced.
 Metal surfaces must be
clean and scale-free.
Disadvantages

19. 1. Drawing out
In this operation in which the metal get elongated
with a reduction in the cross sectional area. For this
purpose, the force is applied in the direction
perpendicular to the length of the axis.

20. In this operation, cross sectional area of the work piece
increases by decreasing length. For this purpose force is
applied in the direction parallel to the length of the axis
2. Upsetting

21. 1. Smith forging
Traditional operation,
done by manual
hammering in open
dies.
Types of Forging

22. 2. Drop Forging or Impression
Done by serious of blows by means drop hammers die contains cavity or
impression that is imparted to work during this process flash is created.
Types:
1. Gravity drop hammers - impact energy from falling weight of a heavy
ram.
2. Power drop hammers - accelerate the ram by pressurized air or steam.

23. 3. Machine forging
In case of drop and press forging the material would be
continuously drawn out where as in this case only upsetting
take place.
Even though the drop and press forge are done by machine,
historically upsetting process is called machine forging.

24. 3. Press forging
similar to the drop forging except force is applied continuously
(squeezing type).

25. •It is a manufacturing process, in which a block of metal enclosed in a
container is forced to flow through the opening of a die.
•The metal is subjected to plastic deformation & it undergoes reduction &
elongation.
•Basically it is an adaption of Open Die forging.
Uses: Manufacture of solid & hollow sections from non ferrous metals &
alloys, Sliding doors, tubing having various cross sections, door & window
frames.
Extrusion

26.  By Direction:
i. Direct / Forward
ii. Indirect / Backward
 By operating temperature:
i. Hot
ii. Cold
 By equipment:
i. Horizontal
ii. Vertical

27. •It is a process in which the metal billet, placed in a container
is forced by a ram to pass through a die.
•In this type the direction of flow of metal is, in same as that of
movement of ram.
•The punch closely fits the die cavity to prevent backward flow
of the material.
Direct Extrusion

28. •It is a process in which a hollow ram containing the die is
forced into the container, containing metal.
•Hollow ram limits the applied load.
•The movement of metal is opposite to the direction of ram
motion.
In-direct Extrusion

29. •It is done at fairly high temperatures,
approximately 50 to 75% of the melting
point of the metal.
•Die life and components are effected
due to the high temperatures and
pressures, which makes lubrication
necessary.
•Pressures Ranges: 35-700 Mpa.
Types
1. Lubricated
2. Non Lubricated
3. Hydrostatic
Hot Extrusion

30. •Cold extrusion is the
process done at room
temperature or slightly
elevated temperatures.
•This process can be used
for materials that can
withstand the stresses
created by extrusion.
Cold Extrusion

31. •A manufacturing process in
which a small shot of solid
material is placed in the die and
is impacted by a ram, which
causes cold flow in the material.
•It may be either direct or
indirect extrusion and it is
usually performed on a high-
speed mechanical press.
Impact extrusion

32. •The layout of operating machine is horizontal and
movement of billet as well as of ram is horizontal in
direction.
•15-50 MN capacity.
•It is mostly used for commercial extrusion of bars and
shapes.
Horizontal extrusion

33. •The movement of billet
and ram is vertical in
orientation.
•3-20 MN capacity.
•Mainly used in the
production of thin-wall
tubing.
Vertical extrusion

34.  It is defined as the ratio of the initial cross-sectional
area , Ao, of the billet to the final cross-sectional area ,
Af, after extrusion.
 R ~ 40:1 for hot extrusion of steels.
 R ~ 400:1 for aluminum.

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