4 U ONLY

2.  STEPS INVOLVED IN MAKING CASTING
 making pattern and core box
 Making mould
 Melting and pouring the metal
 Cleaning
 Inspection and testing
 Reclaiming sand
 CASTING PROCESS :
 Casting is the process of pouring molten metal into
the previously made cavity to the desired
shape and allow it to solidify.

3.  Pattern is the solid form that used to make the
mould.
 Types of pattern
1. Loose pattern
2. Gated pattern
3. Match plate pattern
4. Cope and drag pattern
5. Pattern devices
6. Shell pattern
7. Built up pattern
8. Lagged up pattern

4.  LOOSE PATTERN
 Not connected to other patterned or mounted
on a plate.
 Classified in to
1. Solid piece pattern
2. Self core pattern
3. Split pattern
4. Loose piece pattern

5.  GATED PATTERN
 They are number of loose pattern connected with gatting
system.
 Reduce moulding time.
 Extra cost for operation of separating individual casting.
 COPE AND DRAG PATTERN
 Used for medium and large size casting.
 Separate pattern plates are made for cope and drag
halves.

6.  PATTERN DEVICES
 When the size of casting is too large and
number casting to produce is only two or one
then full pattern prove uneconomical.
 In such case sweeps, segments, skeletons
and follow boards are used.

7.  SHELL PATTERN
 U-used mostly for piping work
 C -consist of a thin cylindrical or
 curved metal piece
 BUILT UP PATTERN
 Intricate patterns are built op by
joining segments of wooden strips.
 These segments are cutting strip of
wood to the curvature required and
gluied together to form the desired
size of the pattern.

8.  MATCH PLATE PATTERN
 Designed to work with match
plate moulding machine for high
production rate.
 They are expensive.
 Accuracy is more than those
made by hand moulding.
 LAGGED UP PATTERN
 Used for cylinders, pipes
and columns.

9.  Following material can be used for pattern
making
1. Wood
2. Metal
3. Plastic
4. Plaster

10.  Most commonly used
 Readily available
 Worked easily
 Can join by glue
 Can preserved with shellac
 Repaired easily
 Hard , strong and less likely to wrap

11.  Used in mass production
 Can hold dimension and don’t wrap
 Are not effected by moisture
 More wear resistance
 Can get good surface finish
 Used: aluminium, white metal,cast iron,
brass , mild steel
 Are expensive as compare to wooden
 Heavier

12.  Good wear resistance
 Are not effected by moisture
 Give good surface finish
 Light in weight
 Because of glossy surface pattern withdrawn is easy
 Can’t withstand shock
PLASTER
• Easy to cast
• It is brittle
• It expands on solidifications

13.  PATTERN DRAFT
• Taper provided to
facilitate its withdrawal
• It may be positive or
negative according to
shape of cavity.

14.  MACHINING ALLOWANCE
 Provided to take care of the
surface finish and
dimensional requirement of
casting.
 Depends on material of the
casting ,size, and surface of
casting, the method of
casting and moulding.

15.  SHAKE ALLOWANCE
 Cause : rapping of pattern before they are
withdrawn.
 A negative allowance is applied to the
dimension which are parallel to the parting
plane.

16.  Certain casting like large flat plates and V
OR U shape castings have tendency to wrap
or distort on cooling
 Cause: uneven metal thickness

17.  Liquid shrinkage
 Solidification shrinkage
 can make good by gating and
risering system
 Solid shrinkage
 Can’t remove easily
 Can compensated by making
the pattern larger than the
requires

18.  Green sand
 Contain : 15-25 % clay , 6-8%water
 Used to produce small to medium size mould
 Dry sand
 It is the green sand that has been dried after
preparing the mould
 Give strength to mould
 Used for large casting

19.  Loam sand
 Contain 50% clay
 Used for heavy casting with the help of
sweep and skeleton pattern
 Parting sand
 Stickness
 Contain :clay free dry silica sand, sea sand ,
parting compound

20.  Facing sand
 Made of silica sand and clay without addition of
any used sand
 Thickness: 20 to 30mm
 Backing sand
 Consist of old repeatedly used mould sand
 Reduce cost
 System sand
 More strength , permeability ,refractiness
 Used: for filling whole flask in mechanized
foundries

21.  Core sand(oil sand)
 Silica sand mixed with core oil
 Used: for making larger cores
 System sand
 Used in mechanized foundries.
 Due to absence of fresh sand system sand
must have more strength ,permeability and
refractiness compared to backing sand.

22.  GRAIN TEXTURE :
 Permeability decrease from left to right.
 Compounded grains are least desirable at high
temp. bec. They tends to disintegrate.
 Uniform grain size => more permeability

23.  As the amount of clay increases , strength of
mould will increase.
 Amount of water &
max. strength available = f ( type of clay )
MOISTURE CONTENT :
 Active the bonding action
MEATHOD OF PREPARING THE MOULD :
 Intensity of ramming (high degree of ramming
increase the bulk density & reduce permeability
)

24.  Strength
 Should have adequate strength in its green ,
dry and hop state
 Depends: grain size and shape
: moisture content
: density of sand
 Thermal stability
 Dimensional stability under rapid heating
,cracks, buckling, and flaking off of sand.

25.  Permeability
 Natural porosity of sand which will permit steam
and other mould gases to escape.
 Higher if clay content is less and grain size is
large.
 Refractoriness
 Ability to withstand the temperature of liquid
metal.
 Measured by sinter point.
 Reusability
 Important to reuse of sand otherwise apart from
cost it will create disposal problem.

26.  Flowability
 Ability to flow all around the pattern and take
desired mould shape.
 Increase as clay and water content are
increased.
 Collapsibility
 Sand should collapse after the casting is
solidified .
 The property is very important for core sand
which forms interior detail of casting.
 Conductivity
 Sand should have enough conductivity to permit
removal of heat from the casting.

27.  Clay content test
 For testing purpose clay content is defined
as all substance which settle at a rate less
than 25 mm per minute when suspended in
water.

28.  Moisture content test
 Determined by drying 50
gm of moist sand to
constant weight between
105 to 110 c in a
uniformly heated oven
,cooling to room
temperature and
weighing dry sample.
 The difference in weights
gives the moisture
content.

29.  Permeability test
 For purpose of comparison permeability is
quantified as a permeability number
 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)

31.  Core
 To produce inside detail, recess , cavity in a
casting a suitable solid mass should be placed in
the mould to prevent the metal from pouring in
these place resulting in a cavity.
 This solid mass in a mould is called core.
 Core material
 Sand
: green sand
: Dry sand
 metal

32.  Method of core making
1. Preparation of core sand mix
2. Core making
3. Core drying or backing
4. Core finishing

33.  Green sand moulding
 They are moulds by using conventional clay
sands and poured with the moulds in wet
sand.
 Composition : 60% floor sand, 30% new
sand, 10% coal dust.
 Least expensive method of moulding.
 Lack of permeability and strength due to
moisture.

35.  Dry sand moulds
 They are completely dried in ovens before
pouring.
 Composition: 53% floor sand, 42% new sand,
5% horse manure or saw dust and blinders
like flour, resin, molasses or clay.
 Used for large casting requiring strong mould
.
 More dimensional accuracy compared to
green sand moulding.
 They are more susceptible to distortion and
hot tears , longer production cycle.

37.  Loam sand moulds
 They are built up with unburnt bricks or large cast
iron parts and plasters with loam mortar.
 Chopped straw may be added for strength and cow
dung added to enhance workability.
 Large cylinders , heavy bells, chemical plant pans
are cast using loam sand moulds.
 It is time consuming.

38.  Carbon dioxide moulds
 The mould is prepared by
ramming clean sand mixed
with sodium silicates
around the pattern .
 The carbon dioxide is
added to harden the
mould.
 It has high accuracy and
good surface
finish.
 Reduce the manual work
and cost.

39.  Floor moulding
 The moulding is done on the foundry floor ,
is known as floor moulding.
 It is used for medium and large size casting .
 Metal flask is used for holding the sand.

40.  Pit moulding
 Very large moulds are made in pits below the
foundry floor, is known as pit moulding.
 The pit acts as the drag part of the mould
while a separate cope is used above it.
 The sides of pit are lined with bricks while its
bottom is covered with a thick layer of
cinders.
 Reduces the efforts and cost of casting.

41. PREPARE A
MOULD
POUR A
MOLTEN
METAL

42. PICS
REFERENCE
REFERENCES
FOR VIDEO
 MOULDING :
 Westpointfoundry.org
 Metalworkingnews.info
 SAND TESTING :
 Slideshare.net
 Hnsa.org
 PATTERNS :
 Mechanicalinventions.blogs
pot.com
 Chinasavvy ( casting
process )
 YOUTUBE :
UNIVERSITY OF
ARKANSAS
(permeability test )