The File is very useful for mechanical department it describes casting and forging processes you should not miss it

1. Forming
Processes
Amr Eaid El-Ashmony
Sec 5
Doctor / Ahmed Elbahi

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Ch.1 Casting processes
1-Write short notes clearly and briefly (with neat sketches) on:
- Expendable molds:
Expendable molds are made of sand, plaster, ceramics, and similar
materials and are mixed with various binders (bonding agents) for
improved properties. A typical sand mold consists of 90% sand, 7%
clay, and 3% Water. These materials are refractories (that is, they are
capable of withstanding the high temperatures of molten metals). After
the casting has solidified, the mold is broken up to remove the casting.
-Permanent Molds
Permanent molds, which are made of metals that maintain
their strength at high temperatures. They are used repeatedly
and are designed in such a Way that the casting can be
removed easily and the mold used for the next casting.
- Composite Molds
Composite molds, which are made of two or more different materials
(such as sand, graphite, and metal) combining the advantages of each
material. These molds have a permanent and an expendable portio

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2-What are the advantages and disadvantages of the Casting
Processes:
3-Descibe and explain clearly and briefly (with neat sketches)
outline of production steps in sand casting
Placing pattern into sand to make an imprint and making gate system
Remove pattern and pouring metals into cup allow metal to cool
And break the sand mold and get the casting

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4-Explain and discuss clearly and briefly (with neat
sketches) the major features of molds in sand casting
1. The flask, which
supports the mold
2. A pouring basin or
pouring cup, into
which the molten metal
is poured.
3. A sprue, through
which the molten metal
flows downward.
4. The runner system, which has channels that carry the molten metal
from the sprue to the mold cavity. Gates are the inlets into the mold
cavity
5- Explain and discuss clearly and briefly (with neat sketches)
Schematic illustration of operations for sand casting

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6- Describe and explain Shell Molding casting (with neat sketches)
showing its product:
The shell thus formed constitutes one half of the mold. -Two such
halves are placed over one another to make the complete mold. -The
sands used in shell molding process are usually finer than the same
used in sand casting.
7- Describe and explain Ceramic-mold Casting (with neat
sketches) showing its products

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The ceramic-mold casting process (also called cope-and-drag
investment casting) is similar to the plaster-mold process, except that
it uses refractory mold materials suitable for high temperature
applications. Typical parts made are impellers, cutters for machining
operations, dies for metalworking, and molds for making plastic and
rubber Components. Parts weighing as much as 700 kg have been cast
by this process.
8- Describe and explain Investment Casting (with neat
sketches) showing its products

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9- Write short notes clearly and briefly (with neat sketches) on:
- Vacuum Casting:
Vacuum - casting process, or counter gravity low pressure (CL)
process is suitable particularly for thin-walled (0.75 mm) complex
shapes with uniform properties. Typical parts made are super alloy
gas-turbine components with walls as thin as 0.5 mm.
- Slush Casting:
A solidified skin develops in a casting and becomes thicker with time.
Hollow castings with thin walls can be made this principle: a process
called slush casting. This process is suitable for small production runs
is used for making ornamental and decorative objects and toys from
low-melting point metals such as zinc, tin, and lead alloys.
- Pressure Casting:
The molten metal is forced upward by gas pressure into a
Graphite or metal mold. The pressure is maintained until the metal has
solidified completely in the mold. The molten metal also may be forced
upward by vacuum, which also removes dissolved gases and produces
a casting with lower porosity. Pressure casting generally is used for
high-quality castings, such as steel railroad-car wheels.

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- Die Casting:
Typical parts made by die casting are housings, and appliance
components, and toys. Equipment costs, particularly the cost of dies,
are somewhat high, but labor costs are generally low, because the
process is semi- or fully automated. Die casting is economical for
large production runs in the die-casting process, molten metal is
forced into the die cavity at pressures ranging from 0.7 to 700 MPa.
10-Describe and explain Squeeze casting process (with neat
sketches) showing its products:
The squeeze-casting (or liquid-metal forging) process involves the
solidification of molten metal under high pressure. Typical products
made are automotive components and mortar bodies (a short- barreled
cannon). The machinery includes a die, punch, and ejector pin.

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11-Describe and explain cold-chamber die-casting process showing
its products:
In the cold-chamber process), molten metal is poured into the injection
cylinder (shot chamber). The chamber is not heated-hence the term
cold chamber. The metal is forced into the die cavity at pressures
usually ranging from 20 to 70 Mpa.
12-Descibe and explain Hot -chamber die-casting process (with
neat sketches) showing its products:
-The hot-chamber process involves the use of a piston, which forces
A certain volume of metal into the die cavity through nozzle.
-Pressures range up to 35 MPa, with an average of about 15 MPa.
-The metal is held under pressure until it solidifies in the die.
-To improve die life and to aid in rapid metal cooling (thereby
reducing cycle time) dies usually are cooled by circulating water or oil
through various passageways in the die block

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13-Descibe and explain centrifugal-casting process showing its
Products:
The centrifugal-casting process utilizes inertial forces (caused by
rotation) to distribute the molten metal into the mold cavities. There
are three types of centrifugal casting: true centrifugal casting, semi
centrifugal casting, and centrifuging. The products are tubes with
many thicknesses
14-Descibe and explain the semi centrifugal casting process (with
neat sketches) showing its products:
An example of semi centrifugal casting is shown. This method is used
to cast parts with rotational symmetry, such as a wheel with spokes.

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15-Explain and discuss clearly and briefly 8 defects in sand casting
process (with neat sketch):
1-Misrun
2-cold shot
3-shrinkage cavity

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4-sand blow
5-pin holes

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6-penetration
7-mold shift

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16-Explain Electric arc furnaces
The source of heat is a continuous electric arc that is formed between
the electrodes and the charged metal. Temperatures as high as 1925°C
are generated.
Consisting of three graphite electrodes, the electrodes can be as large
as 750 mm in diameter and 1.5 to 2.5 m in length; their height in the
furnace can be adjusted in response to the amount of metal present
and the amount of wear of the electrodes.
17- Explain Induction Furnaces
Induction furnace consists of a Crucible completely
Surrounded with a water-Cooled copper coil through which a high- frequency
current passes.
This furnace has excellent mixing characteristics for alloying and adding a new
charge of metal because of the strong electromagnetic stirring action during
induction heating

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18- Explain crucibles furnaces
They are used extensively throughout history and heated with various
fuels, such as commercial gases, fuel oil, and fossil fuel, as well as
electricity. Crucible furnaces may be stationary, tilting, or movable.

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19- Explain Cupolas furnaces
They are basically vertical, refractory-lined steel vessels charged with
alternating layers of metal, coke, and flux
Although they require major investments and replaced by induction
furnaces, cupolas operate continuously, have high melting rates, and
produce large amounts of molten metal.

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Ch2. Forging Processes
1- Describe Open-die forging showing its products and
explain with neat sketches:
Open-die forging can be depicted by a solid work piece placed
between two flat dies and reduced in height by compressing it also
called upsetting or flat die forging the deformation (plastic
deformation) of a work piece under
Frictionless
2-explain with neat sketches cogging (drawing out):
-Cogging is basically an open-die forging operation in which the
thickness of a bar is reduced by successive forging steps (bites) at
specific intervals.

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3- Explain Impression-die and showing its products:
The work piece takes the shape of the die cavity while being forged
between two shaped dies
4- What are Stages in forging a connecting rod for an
internal engine with neat sketches?
The blank to be forged is prepared by
(a) Cropping from an extruded or drawn bar stock
(B) Preforming from operations such as powder metallurgy; (c)
casting
(d) Using a preformed blank from a prior forging operation. The blank
is placed on the lower die, and as the upper die begins to descend, the
blank’s shape gradually changes-as is shown for the forging
Of a connecting rod

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5- Describe and explain (with neat sketches) Closed-die
Forging showing its products and capabilities:
The process shown in Fig. (a) An also is referred to as closed die
forging in which flash forms. -In true closed-die forging, flash does not
form (hence the term fleshless forging), and the work piece completely
fills the die cavity (Fig. b). Consequently, the forging pressure is very
high, and accurate control of the blank volume and proper die design
are essential to producing a forging with the desired dimensional
tolerances
6- What are sequences of steps of a typical forging
operation?
1. Prepare a slug, billet, or preform by shearing (cropping),
sawing or cutting off.
2. For hot forging, heat the work piece in a suitable furnace
and then, descale it with a wire brush, water jet, or by
scraping. 3. For hot forging, preheat and lubricate the dies;
for cold forging, lubricate the blank. 4. Forge the billet in
appropriate dies. Remove any excess material (such as flash)
by trimming, machining, or grinding 5. Clean the forging,

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check its dimensions, and (if necessary machine it to final
dimensions and specified tolerances. 6. Perform additional
operations, such as straightening and heat treating for
improving mechanical properties.
Inspect the forging for external and internal defects.
7- Write short notes (with neat sketches) on the following
forging processes:
-Coining
-It is a closed-die forging process used in the minting of coins,
medallions, jewelry and marking parts with letters and number
-Heading
Heading (Also called upset forging), is an upsetting operation,
performed on the end of a round rod or wire in order to increase the
cross section
Products are nails, bolt heads, screws, rivets, and various other
fasteners.

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-Piercing
This is a process of indenting (but not breaking through) the surface of
a work piece (confined in a die cavity) with a punch in order to
produce a cavity or an impression
-Tube Swaging
The internal diameter and/or the thickness of the tube is
reduced with a mandrel (the final wall thickness of the tube
depends on the mandrel diameter) or without mandrels (the
increase in wall thickness in the die gap

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8-Describe and explain clearly and briefly (with neat
sketches) Forging Defects:
In addition to surface cracks as Forging Defects:
1-If there is an insufficient volume of material to fill the die cavity
completely, the web may buckle during forging and develop laps
2- On the other hand, if the web is too thick, the excess material flows
past the already formed portions of the forging and develops internal
cracks
9- Write short notes clearly and briefly (with neat sketches)
on the following forging machines showing their
capabilities:
- Hydraulic Presses
A hydraulic press consists of a frame with two
Or four columns, pistons, cylinders), rams, and
Hydraulic pumps driven by electric motors

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- Mechanical presses
mechanical presses, are of either crank or eccentric type .
The speed varies from a maximum at the center of the stroke to zero at
the bottom of the stroke; (stroke limited. ) The energy is generated by a
large flywheel powered by electric motor. The force available depends
on the stroke position and becomes extremely high at the end of the
stroke. Thus, proper setup is essential to avoid breaking the dies or
equipment components.
- Screw Presses
They derive their energy from a flywheel (energy limited). The forging
load is transmitted through a large vertical screw, and the ram comes
to a stop when the flywheel energy is dissipated. If the dies do not
close at the end of the cycle, the operation is repeated until the forging
is completed.

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-Hammers
Hammers derive their energy from the potential energy of the ram,
which is converted into kinetic energy; hence, they are energy limited.
To complete the forging, several successive blows usually are made in
the same die. Hammers are available in a variety of designs and are
the most versatile and the least expensive type of forging equipment
The Types of hammers
1. Drop Hammers.
In power drop hammers, the ram’s down stroke is accelerated by
steam, air, or hydraulic pressure at about 750 kPa. Ram weights range
from 225 to 22,500 kg, with energy capacities reaching 1150 kJ. In the
operation of gravity drop hammers (a process called drop forging), the
energy is derived from the free-falling ram.
2. Counterblow Hammers
These hammers have two rams that simultaneously approach each
other horizontally or vertically to forge the part. As in open-die
forging operations, the part may be rotated between blows for proper
shaping of the work piece during forging. Counterblow hammers
operate at high speeds and transmit less vibration to their bases.
Capacities range up to 1200 kJ.
3. High-energy-rate Forging Machines.
The ram is accelerated rapidly by inert gas at high pressure and the
part is forged in one blow at a very high speed.