centrifugal casting, investment casting, lost wax process, special casting process, stir casting

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1.5 Carbon Dioxide moulding,
Shell moulding, Investment casting, Hot-
cold chamber die casting, Centrifugal
casting , stir casting

2. Carbon-Dioxide Gas Molding
• Rapid hardening process
• Mould material contains pure dry silica sand
free from clay, 3-5% sodium silicate as binder
and moisture content generally less than
3%.
• After packing, carbon dioxide gas at about 1.3-
1.5 kg/cm2 pressure is forced for 20 t0 30 sec.
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3. Various methods
of gassing mould
and cores
in CO2 moulding
Single probe cover probe
Manifold and
multiple probe
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4. Gassing mould after
drawing out pattern
Gassing previously
stripped cores
Gassing through hollow
pattern
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6. Advantages
• This process has many advantages in comparison to
other forms of castings some of them are as follows:
• Compared to other casting methods cores and molds
are strong
• Reduces fuel cost since gas is used instead of other
costly heating generating elements
• Reduces large requirement for number of mold boxes
and core dryers
• Provides great dimensional tolerance and accuracy in
production
• Moisture is completely eliminated from the molding
sand
• This process can be fully automated.
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How are they
manufacturing this
componets?

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9. Shell mould casting
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10. Shell mould casting
• Fine silica sand and (3–6%) thermosetting
phenolic resin and liquid catalyst.
• Cast iron pattern heated to 230 to 315 °C
• Inverted- few mins- inverted excess sand will
drop
• 10 to 20 mm thickness
• Combined shells as mould
Examples: Gear housings, cylinder heads and connecting
rods, crank shaft. It is also used to make high-precision
molding cores.
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11. Shell Molding
Casting process in which the mold is a thin shell of
sand held together by thermosetting resin binder
Figure 11.5 Steps in shell-molding: (1) a match-plate or cope-and-drag metal
pattern is heated and placed over a box containing sand mixed with
thermosetting resin.
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12. Shell Molding
Steps in shell-molding: (2) box is inverted so that sand and resin fall onto the
hot pattern, causing a layer of the mixture to partially cure on the surface to
form a hard shell; (3) box is repositioned so that loose uncured particles
drop away;
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13. Shell Molding
Steps in shell-molding: (4) sand shell is heated in oven for several minutes to
complete curing; (5) shell mold is stripped from the pattern;
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14. Shell Molding
Steps in shell-molding: (6) two halves of the shell mold are assembled, supported
by sand or metal shot in a box, and pouring is accomplished; (7) the finished
casting with sprue removed.
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19. Crankshaft in engine
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20. Advantages
1.High suitable for thin sections like petrol engine cylinder.
2)Excellent surface finish.
3)Dimensional accuracy of order of 0.002 to 0.003 mm.
4)Negligible machining and cleaning cost.
5)Occupies less floor space. 6)Skill-ness required is less.
7)Molds formed by this process can be stored until required.
8)Better quality of casting assured. 9)Mass production.
Disadvantages
The main disadvantages of shell molding are:
1)Higher pattern cost, resin cost. 2) Not economical for small
runs. 3) Dust-extraction problem.
4) Complicated jobs and jobs of various sizes cannot be easily
shell molded. 5)Specialized equipment is required. 6) Resin
binder is an expensive material.7) Limited for small size.
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21. video
• 6. Shell Molding
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Identify the componet
and its manufacturing
process..

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24. INVESTMENT CASTING or LOST
WAX PROCESS
or CERAMIC SHELL
INVESTMENT CASTING
• Wax is coated with refractory material to make
a mould after which the wax is melted away
prior to pouring the molten metal.
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27. Step 1
• Wax patterns are produced; with a help of
special steel dies. Wax is injected at 1500F at a
pressure range of 7 – 70 kg/cm2.
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28. Step 2
• (2) Several patterns are attached to a sprue to
form a pattern tree;
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29. Step 3
• The pattern tree is coated with a thin layer of
ceramic slurry material.
Ceramic slurry
Fine grained refractory
powders of Zircon (ZrSiO4),
Alumina (Al2O3), Fused Silica
(SiO2) and a liquid chemical
binder (Alcohol based Silicon
Ester).
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30. Step 4
• The full mould is formed by covering the
coated tree with sufficient thickness.
• To strengthen it is coated with a fine zircon
powder.
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31. Step 5
• The mould is held in an inverted position and
heated to melt the wax and permit it to drip out
of the cavity;
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32. Step 6
• The mould is preheated to a high temperature,
which ensures that all contaminants are
eliminated from the mould; it also permits the
liquid metal to flow more easily into the
detailed cavity; the molten metal is poured; it
solidifies.
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33. Step 7
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34. Step 7
• The mold is broken away from the finished
casting. Parts are separated from the sprue.
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35. • Applications:
• Nozzles, vanes,gas turbines
• Aerospace industry parts
• Scientific instruments
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36. • Advantages:
• Complex shape can be made.
• Good surface finish.
• Unmachinable alloys can be cast.
• NO of castings can be made at a time.
• Can obtain directional solidification
components.(high strength)
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37. • Disadvantages:
• Only small size is possible.
• More expensive.
• Location of hole is impossible.
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38. Video
• 7. Investment Casting Animation
• If time permits play this(15.How Its Made -
103 Lost Wax Process Casting)
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39. Ceramic moulding
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To Remove the binder in the
mould it is heated to 980˚C in
furnace.

40. Ceramic moulding
• Ceramic as a mould material.
• Ceramic slurry prepared by mixing of
fine grained refractory powders of Zircon
(ZrSiO4), Alumina (Al2O3), Fused Silica (SiO2)
and a liquid chemical binder (Alcohol based
Silicon Ester) for making the mould
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41. Ceramic moulding
• A little Vibration helps to fills the cavity.
• To remove the binder in the mould it is heated
to 980˚C in furnace.
• Applications:
• used to make tooling, especially drop forging
dies, but also injection molding dies, die
casting dies, glass molds, stamping dies, and
extrusion dies.
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42. Advantages and disadvantages
• Highest precision and extremely high finish are
obtained.
• Suitable for all types of cast metals including
highly reactive metals such as titanium and
uranium.
• The castings do not require any riser, venting and
chilling as the cooling rate is very slow.
• A ordinary wood metal or epoxy pattern enough.
• Disadvantages:
• The process is expensive because the mould material is
costly.
• Impractical to control dimensional tolerances across the
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How can you
produce these
components?

44. Pressure die casting
• The molten metal is forced into the die assembly
under pressure, with a help of compressed air. The
pressure varies from 3 to 5 Mpa.
• The metal occupies nook and corner of the die
cavity.
• The die is water cooled and the metal become
solidifies immediately.
• Now the die is opened. The casting is removed by
ejector pins.
• This process is suitable for casting lead,
magnesium, tin, brass.
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45. Applications of die casting
Used to produce
• Household equipments such as washing machine
parts, vaccum cleaner body, fan case etc
• Automobile parts such as fuel pump, carburetor
body, crank case etc
• Components for telephones, television sets,
speakers, microphones.
• Toys such as electric trains, model air crafts etc.
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46. Advantages and disadvantags
• Advantages: Very accurate castings. Good
surface finish. High production rate. Defects is
less.
• Disadvantages: only small parts can be made.
Only non-ferrous metals can be cast.
Equipment is high cost.
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47. Hot chamber die casting
• Tin 230°C, lead 327 °C, zinc 420°C.
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b
pressure varies from 3 to 5Mpa
permanent mould casting

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50. video
• 9.hotchamber
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51. Hot chamber die casting
• Burner is used to heat the metals like zinc, tin
or lead.
• Gooseneck is submerged.
• Plunger is moved.
• Pressure of 3-5Mpa.
• Water cooled die- solidifications-ejection.
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52. Advantages & disadvantages
• It is a simple machine and no moving parts.
• Disadvantages:
• Low production rate.
• Machine life is low due to the attached
furnace.
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53. Cold chamber die casting
• There is no melting unit in the machine and
the molten metal is poured though a ladle.
• The temperature of the molten metal is lower
compared to the hot chamber casting, so that the
pressure applied is much higher (70-200Mpa) than
the hot chamber casting.
• Melting temparature
Al-660 °C,
Magnesium – 650 °C
Brass-940 °C.
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permanent mould casting

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pressure varies from 70 – 200 Mpa

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57. video
• 10.coldchamber
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permanent mould casting
mould cavity fills with no force other than
gravity

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• The die is heated and then sprayed with a refractory
coating, and closed. The coating both helps control the
temperature of the die during manufacture and it also
assists in the removal of the casting.
• Molten metal is then manually poured into the die,
(although in some cases a machine can be used) and
allowed to solidify.
• The die is then opened and the cast parts either
removed by hand or in some cases ejector pins are used
on the mechanised machines.
• Finally, the scrap, which includes the gate, runners,
sprues and flash, is removed from the casting(s).
The castings are then processed to remove sharp edges
and excess material, then blast cleaned (if required) prior
to despatch to the customer.

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61. YoucaN
How can you
produce this
flywheel?

62. Centrifugal casting
• Centrifugal casting refers to several casting
methods in which the mold is rotated at high
speed so that centrifugal force distributes the
molten metal to the outer regions of the die
cavity.
• 30 to 300 rpm.
• The group includes (1) true centrifugal casting,
(2) semi-centrifugal casting, and (3) centrifuge
casting.
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63. True centrifugal casting
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64. True centrifugal casting
• True centrifugal method of casting is used to
produce hollow castings with a round hole.
• No cores are used.
• Mould is rotated about the axis of the hole.
• Axis may be vertical, horizontal or inclined.
• Speed of rotating should be high enough to
hold the metal on to the mould wall till it
solidifies.
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65. True centrifugal casting
• If low speed means slipiing of metals occurs.
• Centrifugal force
– For horizonal moulds 65-75 times of gravity.
– For vertical moulds 100 times of gravity.
• Products:
– Pipes
– Oil engine cylinders
– Piston ring stock
– Bearing bushes
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66. True Centrifugal Casting OR
De lavaud process
De lavaud process concept diagram
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67. De lavaud process
De lavaud process
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68. De lavaud process:
• Poured in to the rotating mould.
• Centrifugal force that causes the metal to take
the shape of the mould cavity.
• Without core we can manufacture a hollow
section.
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69. video
• 8.Centrifugal_Casting_the_Process
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70. Advantages & disadvantages
• Advantages:
• Core is not required. High rate of production.
Pattern, runner and riser are not required. Thin
casting can be made. Castings have uniform
physical properties.
• Limitations: It is suitable for only
cylindrical parts only. Cost of equipment is
high.
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71. Semi centrifugal casting
concept diagram for semi centrifugal casting
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72. concept diagram for semi centrifugal casting
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73. Semi centrifugal casting
• Centrifugal force is used to produce solid
castings.
• Outer side parts have high density.
• Finally the centre part is machined away.
• Used to produce:
• Wheels, pulleys, flywheel.
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74. Semi centrifugal casting
• Here a core(sand core) is used to form the
central cavity(as the hub of the wheel).
• These are normally vertical type machines.
• Spinning speed is not to be high as true
centrifugal casting.
• A linear speed of the order of 180-200mpm
(meter per minute).
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75. semi centrifugal casting
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76. Flywheel production in semi centrifugal
process
Stack moulding:
When castings in multiple
layers one above the other are
produced in one mould, the
method is called stack
moulding.
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Stack casting is used for small casting.
It requires less floor space in the foundary.
A common sprue is used to pour all moulds.

78. Flywheel- Energy storage device
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79. Centrifuged
casting
• Non symmetrical parts can
be cast in a group of moulds
arranged in a circle to
balance each other.
• The axis of the mould and
that of rotation do not
coincide with each other.
• Centrifuging helps in proper
feeding of castings resulting
in clean, close grained
castings.
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80. Centrifuged casting
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81. Stir casting process
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82. Stir casting process
• Stir casting is a process is used to prepare an adequate
homogenous particle distribution throughout the
molten material.
• The stainless steel stirrer blade was coated with
zirconia to avoid the reaction between stainless steel
and Al alloys at higher temperatures.
• The Argon gas was supplied into the near the crucible
during the stirring to avoid the formation of oxide
layer on the surface of matrix melt.
• The Stirring speed 450 – 1000 rpm was maintained
throughout work.
• The mixture is allowed to solidify in the preheated
(300°C) steel die.(RHA- Rice Husk Ash)
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83. Stir casting process
• Advantages:
• High mechanical strength.
• The cost of preparing composites materials
using a casting method is about one third to
one half that of a competitive method. So the
high volume of production is possible.
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85. Slush casting process
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Identify the casting
process shown in fig
?

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