sand casting, centrifugal casting, gating system, numerical, continuous casting, investment casting, inspection techniques, riser, sprue, aspiration effect

1. Sanjivani Rural Education Society’s
Sanjivani College of Engineering, Kopargaon-423 603
(An Autonomous Institute, Affiliated to Savitribai Phule Pune University, Pune)
NAAC ‘A’ Grade Accredited, ISO 9001:2015 Certified
Department of Mechanical Engineering
Gujrathi Sonam
Assistant Professor
Sanjivani College of Engineering, Kopargaon
E-mail : gujrathisonammech@sanjivani.org.in
Subject :- Manufacturing Process I (MP I)
S.Y. B.Tech. Mechanical
Unit 1- Casting Process

2. Contents
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
SAND CASTING – Pattern- types, material and allowances, Molding sand-
types, properties and testing
Molding – types, equipment’s, tools and machines, Core – types and
manufacturing, Gating system and Riser – types and design (Numerical),
Heating and pouring, cooling and solidification- process and time estimation
(Numerical), Defects and remedies, Inspection techniques.
Die casting, Investment casting, Centrifugal Casting, Continuous Casting.

3. Introduction
• Casting or founding is process of making metal or alloy parts
• The parts of desired shapes are produced by pouring the molten
metal or alloy into a prepared mould and then allowing the metal or
alloy to cool and solidify
• This solidified piece of metal or alloy is called as casting
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

4. Steps involved in casting
• Pattern making
• Sand mixing and preparation
• Core making
• Melting
• Pouring
• Finishing
• Testing
• Heat treatment
• Re-testing
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

5. Advantages of casting
• Versatile manufacturing process
• Freedom of design in terms of shape, size and quality
• Uniform directional properties and better vibration damping capacity
• Complex and uneconomical shapes which are difficult to produce by
other process
• A product obtained in one piece , so no further joining process is
needed
• Very heavy and bulky parts which are difficult to fabricate can be cast
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

6. Application
• Transportation vehicle
• Machine tool structure
• Turbine vanes and power generators
• Mill housing
• Pump filter and valve
• Agricultural parts and sanitary fittings etc.
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

7. Pattern making
• Model or replica of the object
• If one object to be cast, then also pattern is required
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

8. Materials for pattern making
• Wood
• Metal
• Plastic
• Plaster
• wax
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

9. Pattern allowances
• Shrinkage or contraction allowances
• Machining allowance
• Draft or taper allowances
• Distortion allowance
• Rapping or shaking allowance
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

10. Shrinkage allowance
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
There are two types of shrinkage allowance
a) Liquid shrinkage. (specified in % to volume)
b) Solid shrinkage. (specified in % over dimension)

11. Machining allowance
• The extra amount of material provided on the casting surface to be
machined is called machining finish allowance.
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
Excellent surface
finishing
Poor surface
finishing

12. Draft allowance
• Making vertical surface of pattern into inclined surface is called Draft
allowance. It is provided for easy removal of pattern from the mould
so that it will not damage the edges of mould while removing pattern
from sand.
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
Pattern without draft Pattern with draft

13. Distortion allowance
• It is not required on all casting but required on V and U shape components.
During solidification the legs are distorting outward making legs vertical,
the amount of bending legs outward is called distortion allowance. The
allowance depend upon L/T ratio
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

14. Patterns
• Split pattern,
• Follow-board,
• Match Plate,
• Loose-piece,
• Sweep,
• Skeleton pattern
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

15. Core
• It is a part of casting which is used to produce a hollow shape/cavity in
component
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
Properties
Refractoriness
Hot strength
Collapsibility
Permeability
Friability and Crumbling

16. Gating system
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
Define as a channel in the sand through which molten metal
travels from the pouring basin, sprue, runner, gate, cavity and
riser.

17. Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

18. Sprue (aspiration effect)
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

19. Riser Design
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

20. Chvorinovs Rule ( Defines the solidification time of casting.)
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
• Solidification time 𝑇𝑠 ∝
𝑉
𝑆𝐴
2
𝑇𝑠 = 𝐶
𝑉
𝑆𝐴
2
Ts = Solidification time
C = Mould constant (thermal/Physical property of the metal casting)
V = volume of metal
SA = Surface area of metal
It can be also written as-
𝑇𝑠 = 𝐶
1
𝑆𝐴
𝑉
2
It means if ratio, i.e. surface area to the volume of a metal is less then solidification time is more.

21. Why cylindrical shape riser is used??
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

22. Types of Riser Side Riser
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

23. Top Riser
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

24. In gate
• lies between Runner and cavity
Types- Top ingate, Bottom ingate, Side ingate, Parting line ingate
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
• Top gate
- Required minimum possible time for
feeding molten metal. (due to which
turbulence flow in molten metal increases
erosion and aspiration effect.)
- Good temperature gradient i.e. material
flow to the critical areas first and gives
directional solidification.

25. Bottom ingate
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
Liquid metal fills rapidly at the bottom
portion of the mould cavity and rises
steady and gently up the mould walls. (due
to which less turbulence and erosion in the
mould cavity).
Not used for deep and large casting as
metal cools gradually as it rises up.

26. Parting Gate
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
These ingate enter the mould cavity
along the parting line separating the
cope and drag portion of the mould.
Simplest in nature and construction
and have benefits of both ingate i.e. top
and bottom ingate.

27. Side gate
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
Molten metal enter into the cavity from
sides.
Used for large casting.
Large cavity gets fill in minimum possible
time

28. Classification of gating system
1) Non pressurised
2) Pressurised
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

29. Pressurised gating system
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
• The pressure of molten metal is greater then the atmospheric pressure.
(External forced is applied to increased the pressure)
• Air aspiration effect is minimum.
• Velocity is high. Severe turbulence may occur at corner of mould walls
• Optimum gating ratio for pressurised gating system is 1:2:1 or 3:2:1
(it is the ratio of cross sectional area of sprue:runner:ingate)

30. Casting Defects
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
Sr
No
Visible Defects Internal
Defects
Surface Defects
1 Shift or Mismatch Blow Hole Scar
2 Shrinkage cavity Porosity Blister
3 Mis run Inclusions Swell
4 Hot tear Dross
5 Fins/Flash

31. Visible Defects
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
• Shift or Mismatch
•The dislocation of upper and bottom portion of the
casting across a plane is called mismatch
• Cause: mismatch of the cope and drag or mismatch of
split patterns during the mould making.
• Remedy: Can be eliminated by providing dovetail / lug
pins so that the cope and drag can be properly located
Flash / Fin
• The additional material get attached to the casting across
the parting plane is called flash
• Cause: Improper closure of the cope and drag will leave
space across the parting plane which will be occupied by
molten metal and results in flash.
• Remedy: Can be eliminated by providing dovetail pins/
lugs so that the cope and drag can be properly located

32. Shrinkage cavity
• The open space produced in the casting due to non availability of molten
metal for compensating the liquid shrinkages taking place during
solidification is called shrinkage cavity.
• Cause: non uniform heat transfer from the casting.
• Remedy: eliminated by using chills
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

33. Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
• Misrun
• Non availability of molten metal at a farthest point from the pouring point is called
Misrun
• Cause: when the solidification starts before complete filling of casting cavity.
• •Pouring temperature is too low
• •Pouring is done too slowly
• Remedy: By increasing the Degree of Super heat.
• By Minimizing the Pouring time.
Hot Crack
Cause: Crack formed during cooling after solidification because of internal
stresses developed in the casting
Remedy: maintain the optimum cooling rate or slow cooling will relieve
stresses without crack formation

34. Internal defects
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
• Blow Hole: presence of air or gas bubbles
inside the casting is called Blow Hole.
• Cause : Low porosity of molding sand
• •Because of aspiration effect.
• Remedy:
• Increase the porosity property by decreasing the
ramming force
• Increase the grain size of the sand particles
• Decrease the moisture content

35. Porosity
• Presence of very small sized air/gas particles inside the casting is
called Porosity
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

36. Inclusion/ sand Inclusion
• The presence of sand particles inside the
casting is called inclusion.
• Causes: Due to sand erosion. (Sand
erosion will takes place due to turbulent
flow of molten metal.)
• Remedy: Ensure a laminar flow by
designing a proper gating system.
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

37. Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
• •Dross: Presence of foreign particles or impurities inside the casting is
called dross.
• Remedy: the dross can be eliminated by skim bob and strainer.
• •Making runner above or below the ingate.
Scar: is shallow blow generally occurring on a flat surface
and is open to atm.
Blister: a scar covered with a thin layer of metal is called
blister.
These are due to improper permeability or venting.
Sometimes excessive gas forming constituents in
moulding sand.

38. Numerical
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon
• Compare the solidification times for castings of 3 different shapes of
same volume i.e. cubic, cylindrical and spherical (with height equal to
its diamter)

39. Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

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44. Inspection techniques
• Destructive testing
• Non destructive testing
• Visual inspection
• Inspection for dimensional accuracy
• Sound test
• Impact test
• Pressure test
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

45. Metals for casting
• Ferrous casting alloys
• Cast iron
• Steel
• Non ferrous casting alloys
• Aluminum alloys
• Magnesium alloys
• Copper alloys
• Tin based alloys
• Zinc alloys
• Nickel alloys
• Titanium alloys
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

46. assignment
• Solidification of casting
• Pure metal
• alloys
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

47. Hand moulding equipment
• Hand riddle
• Rammers
• Slicks
• Lifters or cleaners
• Draw spike
• Bellow
• Sprue cutter
• Swab
• Vent wire
• Trowels
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

48. Hand moulding equipment
• Draw screws and rapping plate
• Smoothers and corner slicks
• Mallet
• Sprue pin
• Gate cutter
• Brush and duct bag
• Clamps, cotters and wedges
• Nails and wire pieces
• Spray gun and spirit level
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

49. Hand moulding equipment
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

50. Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

51. Moulding machines - assignment
• Squeeze moulding machines
• Jolt moulding machines
• Jolt squeezing machines
• Sand slinger
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

52. Casting process
• Pressure die casting
• Centrifugal casting
• Investment casting
• Continuous casting
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

53. Pressure die casting
• Hot chamber die casting
• Cold chamber die casting
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

54. Cold chamber die casting
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

55. Centrifugal die casting
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

56. Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

57. Investment casting
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

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63. Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

64. Continuous casting
• conceived in the 1860s
• major improvements in efficiency and productivity and significant reductions in
cost
• the molten metal in the ladle is cleaned and equalized in temperature by blowing
nitrogen gas through it for 5 to 10 min. The metal is then poured into a refractory
lined intermediate pouring vessel (tundish) where impurities are skimmed off.
The molten metal travels through water cooled copper molds and begins to
solidify as it travels downward along a path supported by rollers (pinch rolls)
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

65. Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

66. Advantages continuous casting
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

67. Disadvantages continuous casting
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon

68. Thank
you
Gujrathi S.M. Department Of Mechanical Engineering, Sanjivani COE, Kopargaon