manufacturing technology I - unit 1 PPT Metal casting process

1. Metal Casting Processes
G.GOPINATH
By
AP/Mech/RVSTCC

2. METAL CASTING PROCESSES
Sand casting – Sand moulds - Type of patterns – Pattern
materials – Pattern allowances – Types of Moulding
sand – Properties – Core making – Methods of Sand
testing – Moulding machines – Types of moulding
machines - Melting furnaces – Working principle of
Special casting processes – Shell, investment casting –
Ceramic mould – Lost Wax process – Pressure die
casting – Centrifugal casting – CO2 process– Sand
Casting defects – Inspection methods

3.  1.Manufacturing
 Manufacturing in its broadest sense is the process of converting raw
materials into useful products.
 • IT Includes
 i) Design of the product
 ii) Selection of raw materials and
 iii) The sequence of processes through which the product will be
manufactured. Casting.
Any Product in the engineering industry will be manufactured in the below
methods
 1. By totally deforming the metal to the required shape. (Casting
/Forming)
 1. By joining two metals. (Welding)
 2. By removing the excess material from the raw stock.(Machining)

4.  Casting.
 Casting is the process of producing metal parts by
pouring molten metal into the mould cavity of the
required shape and allowing the metal to solidify. The
solidified metal piece is called as "casting".
 Sand Casting /Sand Moulding.
 Sand Casting is simply melting the metal and pouring it
into a preformed cavity, called mold, allowing (the metal
to solidify and then breaking up the mold to remove
casting.
 In sand casting expandable molds are used. So for each
casting operation you have to form a new mold.

5. Types of sand
 a) Green-sand - mixture of sand, clay, and water,Binders
(Molases, Linseed oil); "Green” means mold contains
moisture at time of pouring.
 b) Dry-sand - organic binders rather than clay and mold
is baked to improve strength
 c) Skin-dried - drying mold cavity surface of a green-sand
 - mold to a depth of u p t o 25 mm, using torches or
heating
 d)Core Sand
 e)Baking sand
 f)Loam Sand
 g)Parting sand, Etc

6. Patterns
 Patterns are the replica or physical models of the final
required shape of the casting, made by wood
(teak,magony,pine), plastics, Metals, Plaster of paris etc.,
Types of patterns.
 1.Solid pattern
 2.Split piece pattern
 3.Three piece pattern
 4.Loose piece pattern
 5.Match plate pattern
 6.Segmental pattern
 7.Sweep patten
 8.skeleton Pattern
 9.shell Pattern.

7.  Pattern Allowance.
 Allowance are the extra dimensional compensation
give to the pattern in order to attain the correct shape
and size of the final solidified metal casting.Five types
of allowances were taken into consideration for various
reasons.
 Allowance types – refer PDF pg.no 8

8. Steps in Sand Casting
 The cavity in the sand mold is formed by packing sand
around a pattern, separating themold into two halves •
The mold must also contain gating and riser system For
internal cavity, a core must be included in mold A new
sand mold must be made for each part.
 1. Pour molten metal into sand mold
 2. Allow metal to solidify
 3. Break up the mold to remove casting
 4. Clean and inspect casting
 5. Heat treatment of casting is sometimes required to
 improve metallurgical properties.

9. Sand Moulding

10. Sand Moulding Preparation

11. Sand Moulding

12. Sand Moulding

13. Types of Pattern
 Single Piece Pattern Split piece pattern

14. Types of Pattern
Match Plate Pattern Cope and Drag pattern

15. Types of Pattern
Gated Pattern

16. Types of Pattern
Loose Piece Pattern

17. Types of Pattern
Sweep Pattern

18. Types of Pattern
Skeleton Pattern Segmental Pattern

19. Types of Pattern
Shell Pattern

20. Pattern Allowances
 Shrinkage Allowances

21. Pattern Allowances
Draft allowances

22. Pattern Allowances
 Distortion Allowances

23. Pattern Allowances
 Machining Allowances

24. Pattern Allowances
Rapping Allowances or Shake Allowances
 Negative Allowance
 To rap the pattern from the sand
 It creates some space around the pattern

25. Moulding Sand
Constituents of Moulding Sand
 Silica sand grains
 80-90% Silicon dioxide
 Quartz rock
 Imparts refractoriness, chemical resistivity, permeability.
 Clay
 5-20%
 Bonding Strength
 Moisture
 2-8%
 Miscellaneous materials
 Limestone, magnesia, soda and potash.

26. Types of Moulding Sand
 Green Sand
 18-30% Silica
 6-8% water
 Soft, light and porous
 Dry Sand
 Green sand dried and baked
 Large castings
 Loam Sand
 50% of clay
 Large Castings

27. Types of Moulding Sand
 Facing Sand
 Face of mould
 Surface of pattern
 20-30 mm
 Backing Sand
 Back up facing sand
 System Sand
 No facing sand
 Reactivated sands
 Parting Sand
 Avoids sticking of pattern to mould sand
 Avoids sticking of cope and drag
 Core Sand
 Silica and core oil, to prepare core

28. Properties of Moulding Sand
 Porosity or Permeability (gas holes and pores)
 Flowability
 Collapsibility
 Adhesiveness (should cling or stick to sides of box)
 Cohesiveness or strength
 Refractoriness (withstand high temp.)

29. Moulding Sand Preparation
 Mixing of sand (Sand ,binders and additives)
 Sand Tempering (adding moisture)
 Sand Conditioning
 Muller Machine
 Riddles (screening sand)
 Magnetic Separators
 Aerators(sand grains)

30. Moulding Tools
 Showel
 Riddle
 Rammer
 Trowel
 Slick
 Lifter
 Strike-off bar
 Sprue pin
•Bellow
•Swab
•Gate cutter
•Mallet
•Vent Rod
•Draw spike
•Clamps
•Moulding boxes

34. Core
A core is a device used in casting process to
produce internal cavities and reentrant angles. The
core is normally a disposable item that is destroyed to
get it out of the piece. They are most commonly used
in sand casting.

35. Core Requirements
 Strong
 Permeable
 Refractory
 Low residual gas forming
 Stable
 Ease collapsable

36. Core

37. Core Sand
 Sand and Binder
 Silica, zircon, olivine, carbon, chamotte
 Not have more than 5% of clay.

38. Core Making
 Core Sand Preparation
 Roller Mills
 Core mixers
 Core Moulding
 Core Blowing Machines
 Core Ramming
 Core Baking
 Core ovens
 Batch type
 Continuous type
 Dielectric Bakers
 Core Finishing
 Core dressing
 Core coating

39. Core Ovens
 Batch type Continuous Type

40. Types of Core
 Horizontal Core
 Vertical Core
 Balanced Core
 Hanging Core
 Wing Core
 Ram-up Core
 Kiss Core

41. Types of Core
 Horizontal Core

42. Types of core
 Vertical Core

43. Types of Core
 Ram up core