IT IS 5th unit of Manufacturing Science 1 hope u all like it..........................

1. Saurabh srivastava
Shane alam
Srikant kumar
Sujeet kumar thakur
Vinod rajbhar
Vishvesh kumar pandey

2. The process by which a liquid material is usually
poured into a mold, which contains a hollow cavity of
the desired shape, and then allowed to solidify. The
solidified part is also known as a casting, which is
ejected or broken out of the mold to complete the
process.

4. - Can be used to create complex internal and external part
geometries
- Some casting processes can produce parts to net shape (no
further manufacturing operations are required)
- Can produce very large parts (cast parts weighing over 100
tons have been made like hydroelectric plants)
- Can be used with any metal that can be heated to its liquid
phase.
- Some types of casting are suited to mass production

6. C-clamps formed by casting.

7. Making of a bullet

10.  It is used to make large parts(typically Iron but
also Bronze, Brass, aluminum).
 There are basic steps in making sand castings.
 Pattern making
 Coremaking
 Moulding
 Melting and pouring
 Cleaning

11.  In pattern making, a physical model
of casting, i.e. a pattern is used to
make the mold. The mold is made by
packing some readily formed
aggregated materials, like molding
sand, around the pattern. After the
pattern is withdrawn, its replica
leaves the mould cavity that is
ultimately filled with metal to
become the casting.

12.  In core making, cores are formed,
(usually of sand) that are placed
into a mold cavity to form the
interior surface of the casting.
Moulding is a process that
consists of different operations
essential to develop a mold for
receiving molten metal.

13.  Melting is a process of
preparing the molten material
for casting.
 It is generally done in a
specifically designated part of
foundry, and the molten metal
is transported to the pouring
area where in the molds are
filled.

14. • The casting is separated from the
mold and transported to the
cleaning department.
• Excess metal is removed (Fins,
wires, parting line fins, and gates).
• Subsequently the casting can be
upgraded using welding or other
such as procedures.
• Final testing and inspection to
check for any defects

16. Advantages Disadvantages Recommended
Application
Least Expensive in small
quantities (less than 100)
Ferrous and non -
ferrous metals may be
cast
Possible to cast very
large parts.
Least expensive tooling
Dimensional accuracy
inferior to other
processes, requires
larger tolerances
Castings usually exceed
calculated weight
Surface finish of ferrous
castings usually exceeds
125 Root Mean Square.
Use when
strength/weight ratio
permits
Tolerances, surface
finish and low
machining cost does
not warrant a more
expensive process

17.  It may be defined as “a replica of the object to be
cast, used to prepare the cavity into which molten
material will be poured during the casting
process”. The making of patterns,
called patternmaking.

18.  Commonly used pattern materials are
 Wood
 Metals
 Plastics
 Plaster of paris
 Wax

19.  It is cheap and easily available.
 Can be shaped easily.
 Light in weight.
 Good surface finish.
 Can be preserved for long time by applying varnish to
it.

20. Strong and durable.
Have good surface finish.
Do not deform on storage.
Maintains dimensional tolerances.

21.  They have low weights.
 High strength.
 High resistance to wear.
 Smooth surfaces.
 Durable and cheaper.

22.  Plaster of paris is usually used in making master dies
and molds, as it gains hardness quickly, with a lot of
flexibility when in the setting stage.

23.  Variety of patterns are used in casting and the
choice depends on the configuration of casting
and number of casting required
 Single-piece pattern
 Split pattern
 Follow board pattern
 Cope and drag pattern
 Match plate pattern
 Loose-piece pattern
 Sweep pattern
 Skeleton pattern

24. (a)Split pattern
(b) Follow-board
(c) Match Plate
(d) Loose-piece
(e) Sweep
(f) Skeleton
pattern

29.  Moulding sand, also known as foundry sand,
is sand that when moistened or oiled tends to pack
well and hold its shape. It is used in the process
of sand casting.
 Types of moulding sand:-
 Natural sand i.e. contains sufficient amount of
binding clay.
 Synthetic sand i.e. they are clay free high silica sand,
suitable binders are added to make them usable.

30.  Green sand:-
 Mixture of silica, clay and water, it contains
moisture also.
 Moulds prepared by this sand does not require any
baking before pouring the molten metal.
 Dry sand:-
 it is moisture free.
 It possess greater strength than green sand.

31.  1. Strength:
 Strength of the
moulding sand depends
on:
 Grain size and shape
 Moisture content
 Density of sand after
ramming

32.  Thermal stability:
 The sand adjacent to the
metal is suddenly heated
and undergoes expansion.
 If the mould wall is not
stable under rapid heating,
cracks, buckling and
flacking off sand may
occur.

33.  Refractoriness:
 Refractoriness is the property of withstanding the high
temperature condition moulding sand with low
refractoriness may burn on to the casting.
 The refractoriness of the Silica sand is the highest.

34.  Flowability:
 Flowability or plasticity
is the property of the
sand to respond to the
moulding process so that
when rammed it will
flow all around the
pattern and take the
desired mould shape.

35.  Adhesiveness:
 It is the property of the
sand due to which it is
capable of
adhering(fixing) to the
surfaces of the other
materials.

36.  Various elements connected with a gating
system:-
 Pouring basin/cup.
 Spruce.
 Spruce base runner.
 Runner.
 Runner extension.
 Ingate.
 Riser.

38.  Pouring basin : This is otherwise called as bush or cup. It is
circular or rectangular in shape. It collects the molten
metal, which is poured, from the ladle.
Spruce : It is circular in cross section. It leads the molten
metal from the pouring basin to the spruce well.
Spruce Well : It changes the direction of flow of the molten
metal to right angle and passes it to the runner.
Runner : The runner takes the molten metal from spruce to
the casting. Ingate: This is the final stage where the molten
metal moves from the runner to the mold cavity.
Slag trap : It filters the slag when the molten metal moves
from the runner and ingate. It is also placed in the runner.

39.  Pure metals solidifies at a constant temp. equal to its
freezing point, which same as its melting point.
 The process of solidification starts with nucleation, the
formation of stable solid particles within the liquid metal.
Nuclei of solid phase, generally it start appearing at a
temperature below the freezing temperature. The temp.
around this goes down and is called super cooling or
undercooking.
 In pure metals super cooling is around 20% of the freezing
temp.
 In case of pure metals fine grains are formed near the wall
of the mould.

44.  Dendrite formation:-
 In alloys, such as Fe-C, freezing and solidification occurs over
a wide range of temp. There is no fine line of demarcation
exists between the solid and liquid metal.
 Here, ‘start of freezing’ implies that grain formation while
progressing towards the center does not solidify the metal
completely but leaves behind the islands of liquid metals in
between grains which freeze later and there is
multidirectional tree like growth.

45. Defects may occur due to one or more of the following
reasons:
 Fault in design of casting pattern
 Fault in design on mold and core
 Fault in design of gating system and riser
 Improper choice of moulding sand
 Improper metal composition
 Inadequate melting temperature and rate of pouring

46. Surface Defects:-

47.  These are due to poor design and quality of sand molds
and general cause is poor ramming.
 Blow is produced by gases which displace molten metal
from convex surface.
 Scar is shallow blow generally occurring on a flat surface.
 A scar covered with a thin layer of metal is called blister.
These are due to improper permeability or venting..
 Drop is an irregularly-shaped projection surface caused by
dropping of sand.
 A scab when an up heaved sand gets separated from the
mould surface and the molten metal flows between the
displaced sand and the mold.

48.  Penetration occurs when the molten metal flows
between the sand particles in the mould.
 Buckle is a V-shaped depression on the surface of a
flat casting caused by expansion of a thin layer of sand
at the mould face.

49. These defects also occur when excessive moisture or excessive gas forming
materials are used for mould making.
Blow holes are large spherical shaped gas bubbles.
Porosity indicates a large number of uniformly distributed tiny holes.
Pin holes are tiny blow holes appearing just below the casting surface.
Inclusions are the non-metallic particles in the metal matrix, Lighter impurities
appearing the casting surface are dross.

50.  Control of all casting stages is essential to maintaining
good quality
 Castings can be inspected visually or optically for surface
defects
 In destructive testing, specimens are determined for the
presence, location, and distribution of porosity and
defects
 Pressure tightness of cast components is determined by
sealing the openings in the casting and pressurizing it
with water, oil, or air.

51.  Cupola Furnaces:-
 A typical cupola furnace consists of a water-cooled vertical cylinder which is
lined with refractory material. The process is as follows:
 The charge, consisting of metal, alloying ingredients, limestone, and coal coke
for fuel and carbonization (8–16% of the metal charge), is fed in alternating
layers through an opening in the cylinder.
 Air enters the bottom through tuyeres extending a short distance into the
interior of the cylinder. The air inflow often contains enhanced oxygen levels.
 Coke is consumed. The hot exhaust gases rise up through the charge,
preheating it. This increases the energy efficiency of the furnace.
 Although air is fed into the furnace, the environment is a reducing one.
 Burning of coke under reducing conditions raises the carbon content of the
metal charge to the casting specifications.
 As the material is consumed, additional charges can be added to the furnace.
 A hole higher than the tap allows slag to be drawn off.

53.  Various numbers of chemical reactions take place in different zones of
cupola.
 Well:-
 The space between the bottom of the tuyeres and the sand bed inside the
cylindrical shell of the cupola is called as well of the cupola
 Combustion zone :-
 The combustion zone of Cupola is also called as oxidizing zone. It is
located between the upper of the tuyeres and a theoretical level above it.
The total height of this zone is normally from 15 cm. to 30 cm.
 The heat generated in this zone is sufficient enough to meet the
requirements of other zones of cupola.
 A temperature of about 1540°C to 1870°C is achieved in this zone. Few
exothermic reactions takes place in this zone these are represented as:
 C + O2 → CO2 + Heat
 Si + O2 → SiO2 + Heat
 2Mn + O2 → 2MnO + Heat

54.  Reducing zone :-
 Reducing zone of Cupola is also known as the protective zone which is located
between the upper level of the combustion zone and the upper level of the
coke bed. In this zone, CO2 is changed to CO as a result of which the
temperature falls from combustion zone temperature to about 1200°C at the
top of this zone. The important chemical reaction takes place in this zone
which is given as under.
 CO2 + C (coke) → 2CO + Heat
 Melting zone:-
 The lower layer of metal charge above the lower layer of coke bed is termed as
melting zone of Cupola. The metal charge starts melting in this zone and gets
collected in the well.
 the chemical reaction given as under.
 3Fe + 2CO → Fe3C + CO2
 Preheating zone:-
 Preheating zone starts from the upper end of the melting zone and continues
up to the bottom level of the charging door. This zone contains a number of
alternate layers of coke bed, flux and metal charge.
 The main objective of this zone is to preheat the charges from room
temperature to about 1090°C before entering the metal charge to the melting
zone.

55.  It is simple and economical to operate
 It can refine the metal charge, removing impurities out of the
slag.
 It can be used to reuse foundry by-products and to destroy other
pollutants such as VOC from the core-making area.
 High melt rates
 Chemical composition control
 Efficiency of cupola varies from 30 to 50%.
 Less floor space requirements comparing with those furnaces
with same capacity.

56.  Since molten iron and coke are in contact with each
other, certain elements like Si, Mn are lost and others
like sulphur are picked up. This changes the final
analysis of molten metal.
 Close temperature control is difficult to maintain.

57.  Plaster-Mold Casting:-
 Mold is made of plaster
 Mixed with water and additives
and poured over a pattern
 After plaster sets, pattern is
removed and the mold is dried at
120 C
 Have low permeability – gases can
not escape
 Patterns are made of:
 Al alloys,
 Thermosetting plastics
 Brass or Zinc alloys
 Have fine details and good surface
finish
 Form of precision casting

58.  Developed in the 1940’s
 Produces close dimensional tolerances
 Good surface finish
 Low cost process
Common methods of making shell molds.
(a) Pattern rotated and clamped
(b) Pattern and dump box rotated
(c) Pattern dump box in position for the
investment
(d) Pattern and shell removed from dump box

59.  There is very high
dimensional accuracy and
surface finish.
 Process is suitable for
both ferrous and non-
ferrous precision pieces.
 Allows flexibility of
design.
 Cores are typically
eliminated.

60.  Can be used for
precision castings of
ferrous and non-ferrous
metals of any size.
 Coremaking is
eliminated.
 Binders or other
additives and related
mixing processes are
eliminated.
 Multiple castings can be
combined in one mould
to increase pouring
efficiency.

61.  Dies can sustain very high
production rates
 High design flexibility and
complexity allows products
to be manufactured from a
single casting instead of
from an assembly of cast
components.
 Good accuracy, consistency
and surface finish are
possible, with high metal
yields.
 Cleaning, machining,
finishing and fabrication
costs are low.

62.  Inertial forces due to spinning distribute the molten
metal into the mold cavity
 Dry-sand, graphite or metal mold can be rotated
horizontally or vertically
 Exterior profile of final product is normally round
 Gun barrels, pipes, tubes
 Interior of the casting is round or cylindrical
 If the mold is rotated vertically, the inner surfaces will
be parabolic
 Final product has a strong, dense exterior with all of the
lighter impurities on the inner surface.