This is very useful to engineering students and working peoples. Hence, updates your knowledge of Manufacturing Casting Product and their applications.

1. MANUFACTURING
TECHNOLOGY-I ME8351
By
PETER PRAKASH FRANCIS
Associate Professor,
VSB College of Engineering
Technical Campus, Coimbatore.

2. UNIT I METAL CASTING PROCESSES
Sand Casting : Sand Mould – Type of patterns - Pattern
Materials – Pattern allowances –Moulding sand Properties and
testing – Cores –Types and applications – Moulding machines–
Types and applications; Melting furnaces : Blast and Cupola
Furnaces; Principle of special casting processes : Shell -
investment – Ceramic mould – Pressure die casting -
Centrifugal Casting - CO2 process – Stir casting; Defects in
Sand casting.

3. INTRODUCTION TO METAL CASTING
• Metal casting is one of the oldest manufacturing process.
• In metal casting, metal is melted and poured into a cavity and after
solidification of the metal in the cavity, the metal takes the exact shape of
the cavity.
• The solidified object is then taken out from the cavity either by breaking
the cavity or taking the cavity apart.
• The solidified object is called the casting.
• The cavity is also known as Mould.

4. TERMS OF CASTING
Flask or moulding box : A frame made of metal or wood or plastic, in which
the mold is formed. Lower molding flask is known as drag, upper molding
flask as cope and intermediate molding flask, used in three piece molding, is
known as cheek.
Pattern: The replica of the object to be cast is known as pattern. The cavity
in the mould is created with the help of the pattern.
Parting line: The dividing line between the two molding boxes that makes up
the mold.
Moulding sand: Sand, which is used for making the mould is called as
molding sand. It is a mixture of silica sand, clay, and moisture in appropriate
proportions. The moulding sand must possess various properties such as
permeability, flow ability, cohesive strength, etc.

5. Facing sand: In order to give a better surface finish to the casting, a small
amount of fine carbonaceous material, known as facing sand, is usually
sprinkled on the paring surfaces of the molding boxes
Core: The part of mould, made of sand, used to create openings and various
shaped cavities in the castings.
Pouring basin: A funnel shaped cavity at the top of the mould into which the
molten metal is poured.
Sprue: The passage through which the molten metal flows from the pouring
basin, and reaches the mold cavity. It controls the flow of metal into the
mould.
Runner: The channel through which the molten metal is carried from the
sprue to the gate.

6. Gate: A passageway through which the molten metal enters the mold cavity.
Chaplets: Chaplets are used to support the cores inside the mold cavity. The
chaplets are used to prevent the core against buckling or metallostatic
pressure.
Riser: The Risers are like a sprue, which are placed at that part of the casting
which is solidified in the last. the risers takes care of the shrinkage of the
solidifying metal.
Vent: Small opening in the mold to facilitate escape of air and gases.
Drag: The bottom half of a horizontally parted mold.
Cope: The top half of a horizontally parted mold.
Draft: Slight taper given to a pattern to allow drawing from the sand.

7. SCHEMATIC DIAGRAM OF CASTING

8. STEPS IN MAKING SAND CASTINGS
There are five basic steps in producing a sand castings.
1. Pattern making
2. Core making
3. Mold preparation
4. Melting and pouring
5. Cleaning
6. Inspection

9. FLOW DIAGRAM OF MAKING SAND
CASTINGS

10. Pattern making
The pattern is a physical model of the casting used to make the mold. The
mold is made by packing some readily formed aggregate material, such as
molding sand, around the pattern. When the pattern is withdrawn, its imprint
provides the mold cavity, which is ultimately filled with metal to become the
casting. If the casting is to be hollow, as in the case of pipe fittings, additional
patterns, referred to as cores, are used to form these cavities.
Core making
Cores are forms, usually made of sand, which are placed into a mold cavity to
form the interior surfaces of castings. Thus the void space between the core
and mold-cavity surface is what eventually becomes the casting.
Molding
Molding consists of all operations necessary to prepare a mold for receiving
molten metal.

11. • Molding usually involves placing a molding aggregate around a pattern held with
a supporting frame, withdrawing the pattern to leave the mold cavity, setting the
cores in the mold cavity and finishing and closing the mold.
Melting and Pouring
• The preparation of molten metal for casting is referred to simply as melting.
Melting is usually done in a specifically designated area of the foundry, and the
molten metal is transferred to the pouring area where the molds are filled.
Cleaning
• Cleaning refers to all operations necessary to the removal of sand, scale, and
excess metal from the casting. Burned-on sand and scale are removed to improved
the surface appearance of the casting. Excess metal, in the form of fins, wires,
parting line fins, and gates, is removed. Inspection of the casting for defects and
general quality is performed.

12. Applications
• Transport like automobile, aerospace, railways and shipping.
• Heavy equipment construction , forming and mining.
• Machine tools application like machine, casting plastics moulding, forging
and forming .
• Plant machinery as paper textile, chemical steel and thermal plants.
• Electrical machine such as Motors, generators, pumps and compressor.
• Household kitchen and gardening equipment, furniture and fittings.
Advantages
• Suitable for small scale production.
• Suitable for all size and shape of casting.
• Cost is less.
• Suitable for low and high melting points metals.

13. Disadvantages
• Slow rate of production.
• Can be used for one casting only.
• Casting surface will not be smooth.
• Sand adheres with casting.

14. PATTERNSPattern is the model of the product. It is used to make mould cavity in sand.
This is slightly larger than the components.
Types of patterns
1. Solid pattern (or) single piece pattern (or) one piece pattern
2. Split pattern (or) two-piece pattern
3. Match plate pattern
4. Loose piece pattern
5. Sweep pattern
6. Skeleton pattern
7. Shell pattern
8. Segmental pattern
9. Cope and drag pattern
10. Follow board pattern
11.Gated pattern

15. SOLID PATTERN OR SINGLE PIECE
PATTERN Split pattern (or) two-piece pattern
Match plate pattern
 Two- piece pattern is also called as split piece pattern.
 These dowel pins are used to align the two halves of split piece
pattern. Holes in the drag half of the two- piece pattern match
exactly with dowel pins.
 It is used in AK-47 and widely used in steam valves.
 Single piece pattern is the cheapest
pattern among all other types of pattern.
This pattern generally used in simple
processes.
 Match plate pattern is a split pattern. Cope and drag areas are on
the opposite faces of metallic plate. This metallic plate is termed
as Match Plate.
 Used in piston rings of I.C. engines and Multi piece pattern has
wide scope in rotor hub.

16. Loose piece pattern
• In the production of axle
pin.
• Loose piece pattern is used
in the rotor hub.
Sweep pattern
• Circular discs, wheels, large
kettles are produces by making
use of sweep pattern.
Skeleton pattern
• Turbine manufacturing uses skeleton pattern.
• In daily applications such as water pipes are
mostly designed with the help of skeleton
pattern.

17. Shell pattern
Segmental pattern
• Shell pattern is specially used for
obtaining hollow shaped structure
• It is just a similar to that of a
sweep pattern.
• The segmental pattern is used
for constructing circular
structures like wheels, rims,
pulleys, etc.
Cope and Drag pattern
• Cope and drag patterns are a split pattern.
• This pattern is used in building flange pipe.
• Cope and drag pattern is used in water jacket
which is an important component of JCB.

18. Follow Board pattern
Gated pattern
• Low molding time
Molten metal is uniformly
distributed
• Implemented usually in small
castings such as corner bracket.
• When the use of solid or split patterns
becomes difficult.
• The exhaust shape of one half of the
pattern is made wooden board, which is
called as follow board pattern.

19. PATTERN MATERIALS
Types of patterns depend upon the following factors:
• The shape and size of casting
• No. of castings required
• Method of moulding employed
• Anticipated difficulty of moulding operation
SELECTION OF PATTERN MATERIALS (Requirements of a good pattern)
• Secure the desired shape and size of the casting.
• Resistance to wear and corrosion.
• Simple in design for ease of manufacture.
• Light in weight and convenient to handle.
• Have high strength and long life in order to make as many moulds as
required.

20. Generally, we use 5 different types of material to make the patter and
those are
•Wood
•Metals
•Plaster of Paris
•Plastics
•Wax
Wood
• As we all know woods are easily available, and the price is quite low.
• Generally, pines deodar, walnut, teak’s are used for making a pattern.
Advantages
• Wood is light in weight
• Easily Available in the market
• You can make any shape using wood
• Woods gives good surface finish

21. Disadvantages
• woods are very week in strength, and it wears out quickly due to its
low resistance to sand abrasion.
• It has poor wear resistance.
• It cannot withstand rough handling.
Metals:
In metals, cast iron, brass, aluminum are generally used in patterns. It gives
smooth surface finish, this is the only reason that metals are used in large
production casting.
a) Cast Iron
• It is cheaper, stronger, tough and durable and can produce a smooth
surface finish.

22. Advantages
• It is very cheap.
• It is easy to file and fit.
• It is strong.
Disadvantages
• It is heavy weight.
• It is brittle and hence it can be easily broken.
• It may rust.
b) Brass or Bronzes
• Heavier and expensive than Cast iron.
• It is suitable for small casting.
• It posses good strength, machinability and resistance to corrosion and wear.
Advantages
• Better surface finish than Cast iron.
• Very thin section can be easily casted.

23. Plaster :
• Plaster or gypsum cement is mixed with water and it is poured into a mould.
• Plaster can be easily made into difficult shapes easily worked.
• The main advantage of this pattern is it can easily cast into intricate shapes.
• However, it is not for repetitive usages as it is fragile.
Plastics:
• Different types of plastics are nowadays, used in pattern because of their lighter
weight, strength, and dimensionally stable and also for cheap in cost.
• Thermoplastics and polystyrene are commonly used for making patterns, and
Thermosetting plastics such as phenolics and epoxies are also used in a pattern.
Disadvantages
• It is costly
• It is heavier than cast iron

24. Wax:
• A wax pattern used in the investment casting process. By using this pattern we
get a high degree of accuracy and have an excellent surface finish.
• However it needs little care handling otherwise it can be broken, and it is used
in small casting.
Pattern allowance:
• Pattern allowance is a vital feature as it affects the dimensional characteristics of
the casting.
• Thus, when the pattern is produced, certain allowances must be given on the
sizes specified in the finished component drawing.
• The selection of correct allowances greatly helps to reduce machining costs and
avoid rejections.
1. Shrinkage or contraction allowance
2. Draft or taper allowance
3. Machining or finish allowance
4. Distortion or camber allowance
5. Rapping allowance

25. Shrinkage or contraction allowance:
• All most all cast metals shrink or contract volumetrically on cooling. The metal
shrinkage is of two types:
• Liquid Shrinkage: it refers to the reduction in volume when the metal changes
from liquid state to solid state at the solidus temperature. To account for this
shrinkage; riser, which feed the liquid metal to the casting, are provided in the
mold.
• Solid Shrinkage: it refers to the reduction in volume caused when metal loses
temperature in solid state. To account for this, shrinkage allowance is provided on
the patterns.
S.No Materials Shrinkage allowance mm/m
1 Brass 15.3
2 Steel 20.8
3 Zinc, Lead 25
4 Al 17
5 CI 10.4
Table 1 : Shrinkage
allowance

26. Draft Allowances:
• When the pattern is removed from the mold, the parallel surface to the direction
at which the pattern is withdrawn gets damaged slightly and gets converted into
slightly tapered surfaces.
• For compensation of these changes, these parallel surfaces on pattern are made
slightly tapered (nearly 1 -2 degrees). This allow easy removal of pattern from
the mold and does not effect the casting by anyway. These changes in pattern
surface to prevent it from damages are called draft allowances.
The magnitude of taper depends upon:
a) Molding Methods.
b) Mold materials.
c) Shape and size of pattern.

27. Machining allowances:
• To remove surface roughness, scale or oxidized portion and to bring the
product to the required size, the cast piece are machined.
• The amount of machining allowance depends on the following factors.
• Metal of casting
• Size and shape of casting
• Types of machining operation
• Moulding process employed
Shake or rapping allowances:
• When the pattern is to be removed from the sand of casting , the pattern will
have to be shaken slightly to remove it from the sand and this will cause a
slight increase in dimension of casting.
• To compensate this increase in dimension of casting, the patterns are made
slightly smaller from casting. This change in dimension of pattern is known
as shaking or rapping allowances.

28. Distortion or camber allowances:
• When the metal is in cooling process, stress is developed in the solid metal
due to uneven metal thickness in the casting process. This stress may cause
distortion or bending in the casting.
• To avoid this bending or distortion in
casting, camber is provided in the
opposite direction so that when bending
occurs due to uneven thickness of metal,
casting becomes straight. This change in
pattern shape to compensate bending
while casting is known as Bending
Allowances.

29. Molding Sand Composition
Base Sand:
• Silica sand is most commonly used base sand.
• Other base sands that are also used for making mold are zircon sand, Chromite
sand and olivine sand.
• Silica sand is cheapest among all types of base sand and it is easily available.
Binder.
• Binders are of many types such as, Clay binders, Organic binders and
Inorganic binders.
• Clay binders are most commonly used binding agents mixed with the molding
sands to provide the strength.
• The most popular clay types are: Kaolinite or fire clay (Al2O3 2SiO2 2H2O)
and Bentonite (Al2O3 4SiO2 nH2O).
• Bentonite can absorb more water than fire clay which increases its bonding
power.

30. Water (Moisture):
• Clay acquires its bonding action only in the presence of the required amount
of moisture.
• When water is added to clay, it penetrates the mixture and forms a
microfilm, which coats the surface of each flake of the clay.
• The amount of water used should be properly controlled.
• This is because a part of the water, which coats the surface of the clay flakes,
helps in bonding, while the remainder helps in improving the plasticity.
S.NO Moulding Sand Constituents Weight Percent
(%)
1 Silica Sand 92
2 Clay 8
3 Water 4
Typical Composition of Molding Sand

31. Types of Moulding Sand:
According to the use, moulding sand may be classified as below:
1. Green Sand:
The green sand is the natural sand containing sufficient moisture in it. It is mixture of
silica and 15 to 30% clay with about 8% water. Clay and water act as a bonding
material to give strength. Molds made from this sand are known as green sand mould.
The green sand is used only for simple and rough casting products. It is used for both
ferrous and non-ferrous metals.
2. Dry Sand:
When the moisture is removed from green sand, it is known as dry sand. The mould
produced by dry sand has greater strength, rigidity and thermal stability. This sand is
used for large and heavy castings.
3. Loam Sand:
Loam sand is a mixture of 50 percent sand and 50 percent clay. Water is added in
sufficient amount. It is used for large and heavy moulds e.g., turbine parts, hoppers
etc.

32. 4. Facing Sand:
A sand used for facing of the mould is known as facing sand. It consists of silica
sand and clay, without addition of used sand. It is used directly next to the surface
of the pattern. Facing sand comes in direct contact with the hot molten metal;
therefore it must have high refractoriness and strength. It has very fine grains.
5. Parting Sand:
A pure silica sand employed on the faces of the pattern before moulding is known
as parting sand. When the pattern is withdrawn from the mould, the moulding
sand sticks to it.
To avoid sticking, parting sand is sprinkled on the pattern before it is embedded in
the moulding sand. Parting sand is also sprinkled on the contact surface of cope,
drag and cheek.
6. Backing or Floor Sand:
The backing sand is old and repeatedly used sand of black colour. It is used to
back up the facing sand and to fill the whole volume of the box. This sand is
accumulated on the floor after casting and hence also known as floor sand.

33. Properties of Molding Sand
• Permeability
• Flowability
• Green Strength
• Collapsibility
• Dry Strength
• Hot Strength
• Refractoriness
• Adhesiveness
• cohesiveness

34. Permeability
• During pouring and subsequent solidification of a casting, a large amount of
gases and steam is generated. These gases are those that have been absorbed by
the metal during melting, air absorbed from the atmosphere and the steam
generated by the molding and core sand.
• If these gases are not allowed to escape from the mold, they would be entrapped
inside the casting and cause casting defects.
• To overcome this problem the molding material must be porous or permeable to
provide path for the escape of gases. Proper venting of the mold also helps in
escaping the gases that are generated inside the mold cavity.
Flowability (or) Plasticity
• It is ability of molding sand to get compacted to a uniform density. Flowability
assists molding sand to flow and pack all around the pattern and take up the
required shape.
• The sand mold should response to different molding processes.
• Flowability increases as the clay and water content increases.

35. Green Strength
• The molding sand that contains moisture is termed as green sand. The strength
of the sand in green or moist state is termed as green strength.
• A mold with adequate green strength will be able to retain its shape and will
not distort or collapse.
• The green sand particles have the ability to cling to each other to impart
sufficient strength to the mold.
Collapsibility
• It is property due to which the sand mold automatically gets collapsed after
casting solidifies.
• The molding sand should also have collapsibility so that during the
contraction of the casting it does not provide any resistance, which may result
in the cracks in the casting.
Dry Strength
• It is the strength of the molding sand in dry conditions.

36. • When the molten metal is poured in the mold, the sand around the mold cavity
is quickly converted into dry sand as the moisture in the sand evaporates due
to the heat of the molten metal.
• At this stage the molding sand must posses the sufficient strength to retain the
exact shape of the mold cavity and at the same time it must be able to
withstand the metallostatic pressure of the liquid material.
• Dry sand strength is related to grain size, binder and water content.
Hot Strength
• It is strength of the sand above 212°F.
• As soon as, the moisture is eliminated, the sand would reach at a high
temperature when the metal in the mold is still in liquid state.
• The strength of the sand that is required to hold the shape of the cavity is
called hot strength.
• In absence of hot strength the mold may enlarge, break, erode or get
cracked.

37. Refractoriness
• It is the ability of the molding material to withstand the temperature of the
liquid metal to be poured so that it does not get cracked, fused with the metal
or experience any major physical change.
• Refractoriness is essential while casting high melting point materials.
• The refractoriness of the silica sand is highest.
Moulding Sand Testing Methods
• The moulding sand after, it is prepared should be properly tested to see
that require properties are achieved.
• Tests are conducted on a sample of the standard sand.
• The moulding sand should be prepared exactly as it is done in the shop
on the standard equipment and then carefully enclosed in a container to
safeguard its moisture content.
• Sand tests indicate the moulding sand performance and help the foundry
men in controlling the properties of moulding sands.

38. • Sand testing controls the moulding sand properties through the control of its
composition.
The following are the various types of sand control tests:
1. Moisture content test
2. Clay content test
3. Grain fitness test
4. Permeability test
5. Strength test
6. Refractoriness test
7. Mould hardness test
Moisture content test:
• Moisture is the property of the moulding sand it is defined as the amount of
water present in the moulding sand. Low moisture content in the moulding
sand does not develop strength properties.
• High moisture content decreases permeability.

39. Procedures are:
1. 20 to 50 gms of prepared sand is placed in the pan and is heated by an infrared
heater bulb for 2 to 3 minutes.
2. The moisture in the moulding sand is thus evaporated.
3. Moulding sand is taken out of the pan and reweighed.
4. The percentage of moisture can be calculated from the difference in the weights,
of the original moist and the consequently dried sand samples.
Percentage of moisture content = (W1-W2)/(W1) %
Where, W1-Weight of the sand before drying,
W2-Weight of the sand after drying.
Clay content test:
Clay influences strength, permeability and other moulding properties. It is
responsible for bonding sand particles together.

40. Procedures are:
1. Small quantity of prepared moulding sand was dried.
2. Separate 50 gms of dry moulding sand and transfer wash bottle.
3. Add 475cc of distilled water + 25cc of a 3% NaOH.
4. Agitate this mixture about 10 minutes with the help of sand stirrer.
5. Fill the wash bottle with water up to the marker.
6. After the sand etc., has settled for about 10 minutes, Siphon out the water
from the wash bottle.
7. Dry the settled down sand.
8. The clay content can be determined from the difference in weights of the
initial and final sand samples.
Percentage of clay content = (W1-W2)/(W1) * 100
Where, W1-Weight of the sand before drying,
W2-Weight of the sand after drying.

41. Grain fitness test:
• The grain size, distribution, grain fitness are determined with the help of the
fitness testing of moulding sands. The apparatus consists of a number of
standard sieves mounted one above the other, on a power driven shaker.
• The shaker vibrates the sieves and the sand placed on the top sieve gets
screened and collects on different sieves depending upon the various sizes of
grains present in the moulding sand.
• The top sieve is coarsest and the bottom-most sieve is the finest of all the
sieves. In between sieve are placed in order of fineness from top to bottom.
Procedures are:
1. Sample of dry sand (clay removed sand) placed in the upper sieve
2. Sand is vibrated for definite period
3. The amount of same retained on each sieve is weighted.
4. Percentage distribution of grain is computed.

42. Permeability test:
The quantity of air that will pass through a standard specimen of the sand at a
particular pressure condition is called the permeability of the sand.
Following are the major parts of the permeability test equipment:
1. An inverted bell jar, which floats in a water.
2. Specimen tube, for the purpose of hold the equipment
3. A manometer (measure the air pressure)
Steps involved are:
1. The air (2000cc volume) held in the bell jar is forced to pass through
the sand specimen.
2. At this time air entering the specimen equal to the air escaped through
the specimen
3. Take the pressure reading in the manometer.
4. Note the time required for 2000cc of air to pass the sand

43. Calculate the permeability number
6. Permeability number (N) = ((V x H) / (A x P x T))
Where,
V-Volume of air (cc)
H-Height of the specimen (mm)
A-Area of the specimen (mm2)
P-Air pressure (gm / cm2)
T-Time taken by the air to pass through the sand (seconds)
Strength test:
• Measurements of strength of moulding sands can be carried out on the
universal sand strength testing machine. The strength can be measured in
compression, shear and tension.
• The sands that could be tested are green sand, dry sand or core sand. The
compression and shear test involve the standard cylindrical specimen that was
used for the permeability test.

44. a. Green compression strength:
Green compression strength or simply green strength generally refers to the
stress required to rupture the sand specimen under compressive loading.
The sand specimen is taken out of the specimen tube and is immediately
(any delay causes the drying of the sample which increases the strength) put
on the strength testing machine and the force required to cause the
compression failure is determined. The green strength of sands is generally
in the range of 30 to 160 KPa.
b. Green shear strength:
With a sand sample similar to the above test, a different adapter is fitted in
the universal machine so that the loading now be made for the shearing of
the sand sample. The stress required to shear the specimen along the axis
is then represented as the green shear strength. It may vary from 10 to 50
KPa.

45. c. Dry strength:
This test uses the standard specimens dried between 105 and 1100°C for 2 hours.
Since the strength increases with drying, it may be necessary to apply larger stresses
than the previous tests. The range of dry compression strengths found in moulding
sands is from 140 to 1800 KPa, depending on the sand sample. Steps involved are:
1. Specimen is held between the grips
2. Apply the hydraulic pressure by rotating the hand wheel
3. Taking the deformation use of the indicators.
Refractoriness test:
The refractoriness is used to measure the ability of the sand to withstand the higher
temperature. Steps involved are:
1. Prepare a cylindrical specimen of sand
2. Heating the specimen at 1500 °C for 2 hours
3. Observe the changes in dimension and appearance
4. If the sand is good, it retains specimen share and shows very little expansion. If the
sand is poor, specimen will shrink and distort.

46. The spherical indenter is penetrates into the mould surface at the time of testing.
The depth of penetration w.r.t. the flat reference surface of the tester.
Mould hardness number = ((P) / (D – (D2-d2))
Where,
P- Applied Force (N)
D- Diameter of the indenter (mm)
d- Diameter of the indentation (mm)

47. Meaning of Cores:
• Core is a pre-prepared shape of the mould. It is used to provide internal
cavities, recesses, or projections in the casting. It is usually positioned into a
mould after the removal of the pattern.
• A core is usually made of the best quality sand and is placed into desired
position in the mould cavity. Core prints are added to both sides of the pattern
to create impressions that allow the core to be supported and held at both ends.

48. Types of Cores:
Generally, cores are of two types:
1. Green Sand Core:
A core formed by the pattern itself, in the same
sand used for the mould is known as green sand
core. The pattern is so designed that it provides the
core of green sand. The hallow part in the pattern
produces the green sand core.
2. Dry Sand Core:
A core is prepared separately in core boxes and
dried, is known as dry sand core. The dry sand
cores are also known as process cores. They are
available in different sizes, shapes and designs as
per till requirement.
Some common types of dry-sand cores are:

49. (i) Horizontal Core:
The horizontal core is the most common type of core and is positioned horizontally
at the parting surface of the mould. The ends of the core rest in the seats provided
by the core prints on the pattern. This type of core can withstand the turbulence
effect of the molten metal poured. A horizontal core for gear blank mould.
(ii) Vertical Core:
The vertical core is placed vertically with some of their portion lies in the sand.
Usually, top and bottom of the core is kept tapered but taper on the top id greater
them at bottom.

50. (iii) Balance Core:
The balance core extends only one side of
the mould. Only one core print is available
on the pattern for balance core. This is best
suitable for the casting has only one side
opening. This is used for producing blind
holes or recesses in the casting.
(iv) Hanging Core:
The hanging core is suspended vertically in
the mould. This is achieved either by
hanging wires or the core collar rests in the
collar cavity created in the upper part of the
mould. This type of core does not have
bottom support.

51. (v) Drop Core:
The drop core is used when the core has to
be placed either above or below the parting
line. A drop core is shown in Fig. 3.11 (J).
This core is also known as wing core, tail
core, chair core, etc.
Core Materials:
The compositions of core material are the mixture of sand, binders and additives.
Core sands are silica, zircon, Olivine etc. and core binders are core oils, resins,
molasses, dextrin etc., are generally used for preparation of core materials.
Sand contains more than 5% clay reduces not only permeability but also collapsibility
and hence not suitable for core making.

52. The commonly used core sand is a mixture of following items:
(i) Core Sand:
The sand may be green sand for smaller castings and mixture of fire clay, green
sand and betonies for heavier casting. The cores are oven backed to dry away its
moisture. The dry sand cores are strong than green and cores. Also, the sand with
rounded grains is best suitable for core making as they have better permeability
than the angular grains sand.
(ii) Oil Sand:
Oil sand can be used for almost any sand casting application.
A typical composition of oil sand is:
Sand 95 — 96%
Cereal flour 1 — 1.05%
Core oil 1 — 1.5%
Water 1 — 2%
Bentonite 0.1—0.3%

53. Oil sand is very popular in core making because:
(a) They get good strength.
(b) They provide excellent surface finish.
(c) They have better collapsibility after baking.
(c) The backed oil sand cores are very hard and not easily damaged in handling of
mould.
(iii) Resin Sand:
These are thermosetting or thermoplastic binders such as rosin, phenol, urea,
furan, formaldehyde etc. are used to obtain good bonds to sand. They are
becoming common in use due to their high strength, low gas formation, excellent
collapsibility, resistance to moisture absorption, better dimensional accuracy to
casting, etc.
(iv) CO2 – Sodium Silicate Sand:
Silica sand and sodium silicate (3-4%) is rammed in the core and then CO2 gas is
passed through sand to make the core hard. Such types of cores are used for very
large castings. They do not need to drying and hence is very fast method of core
making,

54. There are two types of binders used are:
a. Inorganic Binders:
They include fire clay, bentonite, limonite, silica powder, iron oxide, aluminum
oxide, etc. They are very fine powder and popularly used.
b. Organic Binders:
They include core oils like petroleum oil, vegetable oil, linseed oil, corn oil,
malasses and dextrin. Organic binders get harder rapidly and provide good strength.
(vi) Core Additives:
In addition to core sand and core binder, some additives are used to improve the
special properties of the core.
(v) Core Binders:
Natural sand has not sufficient binding properties and hence some binders are used
to improve the binding strength of core sand. The functions of binders are to hold
the sand grains together and to provide better strength to the core.

55. Core Box
Any kind of hollowness in form of holes and recesses in castings is obtained by
the use of cores. Cores are made by means of core boxes comprising of either
single or in two parts. Core boxes are generally made of wood or metal and are of
several types. The main types of core box are half core box, dump core box, split
core box, strickle core box, right and left hand core box and loose piece core box.
Half core box
This is the most common type of core box. The two
identical halves of a symmetrical core prepared in the
half core box. Two halves of cores are pasted
or cemented together after baking to form a complete
core.

56. Dump core box
Dump core box is similar in construction to half core box as
shown in Fig. 10.18. The cores produced do not require
pasting, rather they are complete by themselves. If the
core produced is in the shape of a slab, then it is called as a
slab box or a rectangular box. A dump core-box is used to
prepare complete core in it. Generally cylindrical and
rectangular cores are prepared in these boxes.
Split core box
Split core boxes are made in two parts as shown in Fig.
10.19. They form the complete core by only one ramming.
The two parts of core boxes are held in position by means of
clamps and their alignment is maintained by means of
dowel pins and thus core is produced.

57. Strickle core box
This type of core box is used when a core with an irregular shape is desired.
The required shape is achieved by striking oft the core sand from the top of
the core box with a wooden piece, called as strickle board. The strickle board
has the same contour as that of the required core.
Loose piece core box
Loose piece core boxes are highly suitable for making cores where provision
for bosses, hubs etc. is required. In such cases, the loose pieces may be
located by dowels, nails and dovetails etc. In certain cases, with the help of
loose pieces, a single core box can be made to generate both halves of the
right-left core.

58. Mould
A mould is a hollowed-out block that is filled with a liquid like plastic, glass, metal, or
ceramic raw materials .The liquid hardens or sets inside the mold, adopting its shape.
A mold is the counterpart to a cast.
Moulding method 1) Floor moulding 2) Bench moulding 3) Pit moulding 4) Machine
moulding.
This method of moulding is commonly used for preparing the mould of heavy and
large size of jobs.
Floor moulding
• In floor moulding , the floor itself acts as a drag.
• It is preferred for such rough type of casting where the upper surface finish has
no importance.
Bench moulding
• Bench moulding is done on a work bench of a height convenient to the mould.
• It is best suited to the mould of small and light items which are to be casted by
non- ferrous metals.

59. Pit Moulding
• Large sizes of jobs which cannot be accommodated in moulding boxes
are frequently moulded in pits.
• Here, the pit acts as a drag. Generally, one box, i.e. cope is sufficient
to complete the mould.
• Runner and riser , gates and pouring basin are cut in it.
Machine moulding
• Machine moulding method is preferred for mass production of
identical casting as most of the moulding operations such as ramming
of sand, rolling over the mould, and gate cutting etc. are performed by
moulding machine.
• Therefore, this method of moulding is more efficient and economical
in comparison to hand moulding.

60. Classification of moulding Process:
1) Green sand moulding 2) Dry sand moulding 3) Loam sand moulding 4)
Shell mould 5) plaster mould 6) C02 Moulding
Green sand moulds
• Suitable proportions of silica sand (85 - 92 %), bentonite binder (6-12 %), water
(3-5 %) and additives are mixed together to prepare the green sand mixture.
• The pattern is placed on a flat surface with the drag box enclosing Parting sand
is sprinkled on the pattern surface to avoid green sand mixture sticking to the
pattern.
• The drag box is filled with green sand mixture and rammed manually till its top
surface.
Advantages
• Green sand molding is adaptable to machine molding.
• No mold baking or drying is required.
• There is less mold distortion than in dry sand molding.
• Time and cost associated with mold baking or drying is eliminated.
• Green sand molding provides good dimensional accuracy across the parting line.

61. Disadvantages
• Green sand molds possess lower strengths.
• They are less permeable.
• There are more chances of defects (like blow holes etc.) occurring in castings
made by green sand molding.
• Surface finish deteriorates as the weight of the casting increases.
• Dimensional accuracy of the castings decreases as their weight increases.

62. Loam sand moulding:
• Loam sand moulding are prepared with coarse grained silica sand, clay,
coke, horse manure and water.
• This process of moulding is performed in different way.
• First, a rough structure of desired shape is made by hand by using bricks
and loam sand.
• The surface of structure are blackened and dried before being casted.
Classification of Moulding Machines:
There are three main types of moulding machines. The types are: 1. Squeezers 2.
Jolt Machines 3. Sand Slingers.
Advantages
• Faster production rate
• Less production cost
• Less defect in casting
• More accuracy

63. 1. Squeezers:
The working principle of a squeezer type moulding
machine. The pattern plate is clamped on the machine
table, and a flask is put into position. A sand frame is
placed on the flask, and both are then filled with sand
from a hopper.
Next, the machine table travels upward to squeeze the
sand between the pattern plate and a stationary squeeze
head. The squeeze head enters into the sand frame and
compacts the sand so that it is level with the edge of the
flask. These machines rammed the sand harder at the
back of the mould and softer on the pattern face.
Squeezer machines are very useful for shallow patterns.

64. 2. Jolt Machines:
• The working principle of jolt type of
moulding machine. As can be seen,
compressed air admitted through the
hose to a pressure cylinder to lift the
plunger and the flask, which is full of
sand, up to a certain height, where the
side hole is uncovered to exhaust the
compressed air.
• The plunger then falls down and strikes
the stationary guiding cylinder.
• The shock waves generating from each
of successive impacts contributes to
packing or ramming the moulding sand
in the flask.

65. • There are also some machines, such as jolt-squeeze machines, that
employ a combination of the working principles of two of the main
types. No matter what type of moulding machine is used, special
machines are used to draw the pattern out of the mould.
• Basically, these machines achieve this by turning the flask (together with
the pattern) upside, down and then lifting the pattern out of the mould.
Roll-over moulding machines and rock-over pattern-draw machines, are
some examples of this category.

66. Sand Slingers:
• The working principle of a sand slinger
machine. As can be seen, moulding sand is
fed into a housing containing an impeller
that rotates rapidly around a horizontal axis.
• Sand particles are picked up by the rotating
blades and thrown at a high speed through
an opening onto the pattern, which is
positioned in the flask. This type of machine
is employed in moulding sand in flasks of
any size, whether for mass production of
moulds or individual mould.
• The rate of discharging sand is about 300 to
2000Kg/min.

67. Melting Furnaces
Melting is an equally important parameter for obtaining a quality of casting.
Furnaces can also be classified according to the molten metal
1. Gray Cast Iron
• Cupola
• Air furnace
• Rotary furnace
• Electric arc furnace
2. Steel
• Open hearth furnace.
• Electric furnace.
• Arc furnace
• High frequency induction furnace
• Converter

68. 3. Non-ferrous metals
Crucible furnaces (Al ,Cu)
• Pit type
• Tilting type
• Non-tilting or bale out type
• Electric resistance type (CU)
Pot furnaces (fuel fired) (Mg & Al)
• Stationary
• Tilting
Reverberatory furnaces (fuel fired ) (Al & Cu)
• Stationary
• Tilting
Rotary furnaces
• Fuel fired
• Electrically heated
Induction furnaces (Al & Cu)
• Low frequency
• High frequency
Electric Arc furnaces (Cu)

69. CUPOLA FURNACE
• For many years, the cupola was the primary method of melting used in iron
foundries. The cupola furnace has several unique characteristics which are
responsible for its wide spread use as a melting unit for cast iron.
• Cupola furnace is employed for melting scrap metal or pig iron for production
of various cast irons.
• It is also used for production of nodular and malleable cast iron. It is available
in good varying sizes. The main considerations in selection of cupolas are
melting capacity, diameter of shell without lining or with lining, spark arrester.
Shape
A typical cupola melting furnace consists of a water-cooled vertical cylinder which is
lined with refractory material.

70. Construction
The construction of a conventional cupola consists of a vertical steel shell
which is lined with a refractory brick.
• The charge is introduced into the furnace body by means of an opening
approximately half way up the vertical shaft.
• The charge consists of alternate layers of the metal to be melted, coke fuel and
limestone flux.
• The fuel is burnt in air which is introduced through tuyeres positioned above
the hearth. The hot gases generated in the lower part of the shaft ascend and
preheat the descending charge.

72. Blast Furnace:
• A blast furnace is a type of metallurgical furnace used
for smelting to produce industrial metals, generally pig
iron, but also others such as lead or copper. Blast refers
to the combustion air being "forced" or supplied above
atmospheric pressure.
• In a blast furnace, fuel (coke), ores, and flux (limestone) are
continuously supplied through the top of the furnace, while
a hot blast of air (sometimes with oxygen enrichment) is
blown into the lower section of the furnace through a series
of pipes called tuyeres, so that the chemical reactions take
place throughout the furnace as the material falls downward.
The end products are usually molten metal and slag phases
tapped from the bottom, and waste gases (flue gas) exiting
from the top of the furnace. The downward flow of the ore
along with the flux in contact with an up flow of hot, carbon
monoxide-rich combustion gases is a countercurrent
exchange and chemical reaction process.
Fe3O3 +3CO =2Fe+3CO2

73. Special Casting Process:
• Special Casting process are being extensively used in the industrial process
as they have been developed to effect a saving time and expense to produce
a better quality casts.
• Unlike Sand Casting, in these special casting process, we do not require
drying or Baking of moulds or cores or rapid hardening action takes place
due to chemical reactions in them.
Need for special casting process:
• Sand mould casting process gives satisfactory results at low cost.
• All metals may be cast in sand moulds and there is no limitations as regards the
size of the casting which can be made.
• Sand casting enjoys wide applications and a very large quantity of castings even
today is produced through sand casting only.
• However, sand moulds are single purpose moulds as they are completely
destroyed after the casting has been removed from the moulding box.
• It becomes therefore obvious that the use of a permanent mould do a considerable
saving in labour cost of mould making.

74. Shell Casting:
• Shell casting is a classification of Expendable mould casting and also called as
Croning process /c- process.
• This process is preferred for rapid, automated, repetitive, mass production and
smooth finish of the product, mostly for steel, iron, non-ferrous alloys.

75. Casting Process
• The mould is formed from a mixture of fine sand (100-150 mesh) and
thermosetting resin binder placed against a heated metal pattern – Grey cast
iron.
• A metal pattern is heated about 200 to 300°C, the melting point of the resin.
• A silicon-based agent added in acetone sprayed on the pattern for easy
removal.
• A resin soaked layer of about 4 to 12 mm in thickness of the shell.
• The shell is stripped mechanically and once more heated for 3 to 5 minutes in
a special oven to cure the plastic material up to 420°C.
• Both sections are matched and joined by guides to obtain the casting mould.
• This process may range weight 200gms to 200 kg in both ferrous and
• This process may range weight 200gms to 200 kg in both ferrous and non-
ferrous metals.
• In Shell Moulding,
If Fine sand is used, we get lower strength, good surface finish of casting
If Coarse sand is used we get , higher strength, lower surface finish of casting

76. Advantages of Shell Moulding
• High suitable for thin sections like petrol engine cylinder.
• Excellent surface finish.
• Good dimensional accuracy of order of 0.002 to 0.003 mm.
• Negligible machining and cleaning cost.
• Occupies less floor space.
Disadvantages of Shell Moulding
• Higher pattern cost.
• Higher resin cost.
• Not economical for small runs.
• Dust-extraction problem.
• Complicated jobs and jobs of various sizes cannot be easily shell
molded.
Applications
• Cams, cam shaft, piston and pistion rings can be made.
• It is used for making brake drums, bushings, air compressor, crank
cases and cylinders, conveyor and rollers etc..

77. Investment Casting Process
• It is produce investment
castings from both ferrous and
non-ferrous metals.
• It is required specifications
for medical, aerospace, and
other critical industry
applications at foundry.

78. Casting Process
• The master pattern is made of wood and metal around the mould is formed.
• The master mould is filled with liquid wax, with a thermoplastic material
liquefied by heating or mercury.
• The heated material becomes solid when they are cooled to normal
temperature.
• The process referred as “Investment” of the pattern takes place when the
expandable wax pattern is coated with a slurry consisting of silica flour, a
small amount of kaolin and graphite mixed with water.
• The finished mould is dried in air for 2 to 3 hours and then baked in an oven
for about 2 hours to melt out the wax.
• At a temperature of 100 to 120°C the wax melts and run through the hole in
the bottom.
• After the mould is sintered at about 1000°C to improve the resistivity, finally it
is cooled down to a temperature between 900 and 700°C for casting.
• The molten metal is poured into the mold and is taken out after solidification
by breaking the mold.

79. Applications
• It is produce complex investment cast parts with superior surface finishes
in the industries fastest lead-times for the following markets:
• Aerospace
• Defense
• Medical
• Electronics
• Automotive
• Oil and Gas
• Agriculture
• Commercial
Advantages of Investment Casting
• Very high melting temperature material can be cast.
• Very high dimensional accuracy, tolerance close to -/+ 0.1
mm and surface finish can be achieved.
• Suitable for mass production of small-sized casting.
Disadvantages of Investment Casting
• Unsuitable for the casting of more than 5 kg weight.
• Precise control is required in all stages of casting.
• Expensive in all respects.

80. Pressures die casting
• The pressure die casting process is the most common for low melting point castings
(Al, Zn and Mg).
Casting Process
• The liquid metal is injected into the mould under high pressure and allowed to solidify
at the high pressure.
• The solidified cast is then taken out of the mold or the die which is ready for the next
cast.
• Two types of pressure die casting are generally common in the industry –
• High pressure die casting
• Low pressure die casting
• The process is not suitable for casting of high melting temperature materials as the die
material has to withstand the melting (or superheated) temperature of the casting.
• Pressure die castings also contain porosity due to the entrapped air. Also, the dies in the
pressure die casting process are usually very costly.
• In the hot-chamber die casting process, the furnace to melt material is part of the die
itself and hence, this process is suitable primarily for low-melting point temperature
materials such as aluminum, magnesium etc.

81. Applications of Pressure Die Casting are:
• The pressure Die Casting process is majorly used in the manufacturing of
• Carburetor bodies
• Hydraulic brake cylinders
• Refrigeration castings
• Connecting rods and automotive pistons
Centrifugal Casting
• In the centrifugal casting process, the molten metal poured at the centre of a
rotating mould or die. Because of the centrifugal force, the lighter impurities
are crowded towards the center of the case.
• For producing a hollow part, the axis of rotation is placed at the centre of the
desired casting. The speed of rotation is maintained high so as to produce a
centripetal acceleration of the order of 60g to 75g.
• For producing a hollow part, the axis of rotation is placed at the centre of the
desired casting.

82. • No cores are therefore required in the casting of hollow parts although solid
parts can also be cast by this process.
• The centrifugal casting is very suitable for axisymmetric parts.
• Very high strength of the casting can be obtained. Since the molten metal is fed
by the centrifugal action, the need for complex metal feeding system is
eliminated. Both horizontal and vertical centrifugal castings are widely used in
the industry.

83. Advantages of the Special Casting process
• Greater dimensional accuracy.
• Higher metallurgical quality.
• Lower production cost (in certain cases).
• Ability to cast extremely thin sections.
• High production rates.
• Better surface finishes on the castings; therefore low labour and finishing costs.
• Minimum need for further machining of castings.
• Castings may possess a denser and finer grain structure.
• Castings are slightly stronger and more ductile than solid mould castings.
Applications
• Good mechanical properties due to the grain structure formed by centrifugal action.
Typically cylindrical shapes are produced:
• In sizes of up to 6 m (20 ft) diameter and 15 m (49 ft) length.
• With a wall thickness range from 2.5 to 125 mm (0.098 to 4.921 in).
• In tolerance limits of the outer diameter of 2.5 mm (0.098 in) an die inner diameter of
3.8 mm (0.15 in).
• In a surface finish from 2.5 to 12.5 mm (0.098 to 0.492 in) rms.

84. CASTING DEFECTS and types of casting defects
• Pinholes
• Subsurface blowhole
• Open holes
• Open shrinkage
• Closed shrinkage
• Cuts and washes
• Fusion
• Run out
• Swells
• Drops
• Rat tails, veins and buckles
• Metal penetration
• Hot tear/crack
• Hot/Hard spots
• Cold shut/lap
• Misruns
• Cold shots
• Slag inclusion (scab)
• Shift/mismatch
• Flash, fin and burrs
• Warping

85. Pinholes
Pinholes, also sometimes referred to as porosities,
are very tiny holes (about 2 mm) usually found in
the cope (upper) part of the mold, in poorly vented
pockets. They usually appear in large numbers
together, either at the surface or just below the
surface of the casting. They are always visible to
the naked eye and don’t require equipment to
identify.
Subsurface blowhole
Blowholes, or simply blows, are larger cavities than pin holes. A subsurface blowhole
appears on the inside of a cast and usually isn’t visible until after machining.
Remedies
Subsurface blowholes can be difficult to detect before machining, requiring harmonic,
ultrasonic, magnetic or x-ray analysis.

86. Open holes
These blowholes appear on the surface of the cast and are easier to detect than
subsurface blowholes.
Causes and prevention of gas porosity
There are several causes of cavity defects.
• Poor venting of mold and cores.
• Insufficient drying of mold and cores.
How can you prevent gas porosity?
Remedies
• Incorporate good fluxing and melting practices: melt metal in a vacuum, in an
environment of low-solubility gases or under a flux that prevents contact with the
air.
• Increase gas permeability of sand: coarser sands have a higher permeability
• Increase permeability of mold and cores. Allow air and gas to escape from the mold
cavity
• Dry out molds and cores before use and store dry
• Increase rate of solidification by reducing metal temperature during casting.

87. SHRINKAGE CASTING DEFECTS AND CAUSES
• Shrinkage occurs because metals are less dense as a liquid than a solid.
• A shrinkage cavity is a depression in a casting which occurs during the
solidification process. Shrinkage porosity appears with angular edges,
compared to the round surfaces of gas porosity. Cavities might also be paired
with dendritic fractures or cracks.
• Large shrinkage cavities can undermine the integrity of the casting and may
cause it to eventually break under stress.
• Shrinkage can result in two types of casting defects.
Open shrinkage defects
• These are open to the atmosphere. Air compensated as the shrinkage cavity
forms.
• Pipes are open shrinkage defects that form at the surface and burrow into the
casting. Caved surfaces are shallow, open shrinkage defects that form across
the surface of the casting.

88. Closed shrinkage defects
• Also known as shrinkage porosity, closed shrinkage defects form within the
casting. Macro shrinkage can be viewed with the naked eye, but micro
shrinkage cannot.
• Closed shrinkage defects usually appear at the top of hot spots, or isolated
pools of hot liquid.
• Prevent shrinkage cavities by improving casting structure.
• Alloys always shrink when changing from molten to solid. This is because
the density of a casting alloy in the molten state is lower than that in the solid
state.
• You should expect some shrinkage during solidification. Factor a shrinkage
allowance into the pattern design before casting.

89. Remedies
• Design a running (gate) system
with risers that ensure a continuous flow of
molten metal.
• Increase local heat dissipation by inserting
internal chills, cooling ribs or cooling coils.
• Reduce casting temperature to limit the
total volume deficit.
Cuts and washes
• Cuts and washes are areas of excess metal. These appear when the molten metal
erodes the molding sand.
• A cut appears as a low projection along the surface of the drag face, decreasing in
height as it extends from one side of the casting to the other.
• Causes and prevention of cuts and washes.

90. • Cuts and washes can be caused by molten
metal flowing at a high velocity, causing
too much metal to flow through the gate.
Remedies
You can prevent cuts and washes easiest by
• Designing the gating system properly
• Improving mold and core strength
• Adding more binders to the facing and core
sand
Fusion
• Fusion occurs when sand grains fuse
with molten metal.
• It appears as a thin crust with a brittle,
glassy appearance firmly adhered to the
casting.

91. Remedies
• Low refractoriness of clay or sand.
• Too high pouring temperature of molten metal Refractoriness is the ability of
the molding material to resist the temperature of the liquid so it doesn’t fuse
with the metal.
• Silica sand has the highest refractoriness.
• Improving the refractoriness of the molding material and/or reducing the
pouring temperature of the molten metal will help prevent fusion.
Run out
Run out is when liquid metal leaks out of the
mold, leading to an incomplete or missing casting.
A faulty mold or flask is responsible for run out.
Remedies
• To prevent this casting defect, design the casting mold with precision. Inspect and
replace any defective molds before casting.
• High temperatures can lead to excess wear and tear of the mold. Use quality raw
materials for your mold that can resist high temperatures.

92. Swells
• Swells are an enlargement of the casting. Swells typically take on the shape of
a slight, smooth bulge on the vertical face of castings.
Remedies
• Swell is usually caused by improper or soft
ramming of the mold or a low strength mold.
• Molds should be built to withstand liquid metal
pressure. Otherwise, the mold wall may give
way or move back, causing swelling.
• Using a strong, properly rammed mold
prevents swells.

93. Drops
• Drops occur when pieces of sand fall
into metal casting when it’s still liquid.
• Drops appear as an irregularly shaped
projection on the cope (top) surface of a
casting.
Remedies
• Low sand strength: Use sand of a higher strength if this your culprit.
• Soft ramming: Provide harder ramming.
• Insufficient fluxing of molten metal: Properly fluxing molten metal removes
impurities.
• Insufficient reinforcement of sand projections in the cope: Reinforce sand
projections using nails or gaggers to fix this issue.

94. Rat tails, veins and buckles
Rat tails, or veins, appear as an irregular line
or crack on the casting, when the surface of
the molding sand buckles up. Rat tails
usually occur on the surface of the mold
bottom, an area covered with molten
material.
Buckles are a more severe form of rat tails.
Remedies
Rat tails and buckles occur when excessive heat of the metal causes the sand to
expand. This may be caused by
• Poor expansion properties of the sand add combustible additives to sand.
• A hot pouring temperature Reduce pouring temperature of metal.
• Poor mold design Large and flat sections are more prone to rat tails. The mold
also should not be too hard, as it must allow for proper expansion.

95. Metal penetration
• Metal penetration occurs when liquid
metal penetrates gaps in the molding
sand.
• The penetration is visible to the naked
eye as a rough and uneven surface finish
of the casting.
Remedies
• Use of sand with low strength and high permeability.
• Use of large or coarse sand grain: the coarser the sand grains, the more
severe the metal penetration.
• Lack of mold wash.
• Soft ramming of sand.

96. HAND MOULDING EQUIPMENT
In hand moulding process, all the moulding operations, such as ramming
the sand, placing and drawing the pattern, turning over the moulding boxes,
etc., are performed by hand.
Showel: It consists of iron pan with a
wooden handle. It can be used for mixing
and conditioning the sand.
Trowels: These are used for finishing flat
surfaces and comers inside a mould.
Common shapes of trowels are shown as
under. They are made of iron with a wooden
handle.

97. Lifter: A lifter is a finishing tool used for repairing the
mould and finishing the mould sand. Lifter is also used
for removing loose sand from mould.
Hand riddle: It is used for ridding of sand to remove
foreign material from it. It consists of a wooden frame
fitted with a screen of standard wire mesh at the bottom.
Strike off bar: It is a flat bar, made of wood or iron to
strike off the excess sand from the top of a box after
ramming. Its one edge made beveled and the surface
perfectly smooth and plane.
Vent wire: It is a thin steel rod or wire carrying a pointed
edge at one end and a wooden handle or a bent loop at the
other. After ramming and striking off the excess sand it is
used to make small holes, called vents, in the sand mould
to allow the exit of gases and steam during casting.

98. Rammers: Rammers are used for striking
the sand mass in the moulding box to pack it
closely around one pattern. Common types
of rammers are shown as under.
Swab: It is a hemp fiber brush used for
moistening the edges of sand mould, which
are in contact with the pattern surface,
before withdrawing the pattern. It is also
used for coating the liquid blacking on the
mould faces in dry sand moulds.
Sprue pin: It is a tapered rod of wood or
iron, which is embedded in the sand and
later withdrawn to produce a hole, called
runner, through which the molten metal is
poured into the mould.

99. Sprue cutter: It is also used for the same
purpose as a sprue pin, but there is a marked
difference between their use in that the
cutter is used to produce the hole after
ramming the mould. It is in the form of a
tapered hollow tube, which is inserted in the
sand to produce the hole.

100. THANK YOU