Casting is a process where molten metal is poured into a mold and allowed to solidify. There are several casting methods, including sand casting where a mold is made of sand and discarded after use, investment casting where a wax pattern is used to make a ceramic mold, and die casting where molds called dies are used to produce parts by injecting molten metal under high pressure. Each method has advantages like complexity of parts possible but also disadvantages like costs or surface finish.

3. •
Casting is the process of
producing metal/alloy component
parts of desired shapes by pouring
the molten metal/alloy into a
prepared mold (of that shape) and
then allowing the metal/alloy to
cool and solidify. The solidified
piece of metal/alloy is known as a
CASTING or FOUNDRY”.

4. EXAMPLES OF CAST PARTS
Crank handle formed by casting; some areas
were machined and assembled after casting

5. EXAMPLES OF CAST PARTS
Complex part formed by casting

6. CASTING TERMINOLOGY
Flask
The box containing the mold
Cope
The top half of any part of a 2-part mold
Drag
The bottom half of any part of a 2-part mold
Core
A shape inserted into the mold to form internal cavities
Mold Cavity
Hollow mold area in which metal solidifies
Riser
Extra cavity to store additional metal to prevent shrinkage

7. Gating System
Channels used to deliver metal into the mold cavity
Pouring Cup
The part of the gating system that receives poured metal
Sprue
Vertical channel
Runners
Horizontal channels
Parting Line / Parting Surface
Separate the cope and drag of a 2-part mold
Draft
Taper on a pattern that allows removal from the mold
Casting
The process and product of solidifying metal in a mold

8. CATEGORIES OF METAL CASTING PROCESSES
1.
Expendable mold processes - mold is sacrificed to remove part
TYPES: Sand Casting, Shell mold Casting,, Mold Casting,
Investment Casting
•
•
2.
Advantage: more complex shapes possible
Disadvantage: production rates often limited by time to make
mold rather than casting itself
Permanent mold processes - mold is made of metal and can be
used to make many castings
TYPES:Die Casting, Permanent Mold Casting, Centrifugal Casting
•
Advantage: higher production rates
•
Disadvantage: geometries limited by need to open mold

9. Process
Advantages
Sand
Wide range of metals, poor
finish,
sizes, shapes, low cost tolerance
Shell mold
better accuracy, finish, limited part size
higher production rate
Expendable
pattern
Plaster mold
Wide range of metals,
sizes, shapes
complex shapes, good
surface finish
complex shapes, high
accuracy, good finish
complex
shapes,
excellent finish
good finish, low porosity,
high production rate
Ceramic mold
Investment
Permanent mold
Die
Centrifugal
Disadvantages
Examples
wide engine blocks, cylinder
heads
connecting
housings
rods,
gear
patterns
have
low cylinder heads, brake
strength
components
non-ferrous metals, low prototypes of mechanical
production rate
parts
small sizes
impellers, injection mold
tooling
small parts, expensive
jewellery
Costly mold,
shapes only
simpler gears, gear housings
Excellent
dimensional costly dies, small parts, precision gears, camera
accuracy, high production non-ferrous metals
bodies, car wheels
rate
Large cylindrical parts, Expensive, limited shapes pipes, boilers, flywheels
good quality

10. IMPORTANT METAL CASTING METHODS
• Sand Casting
• Investment Casting
High Temperature Alloy,
Complex Geometry, Rough
Surface Finish
High Temperature Alloy, Complex
Geometry, Moderately Smooth
Surface Finish
• Die Casting
High Temperature Alloy,
Moderate Geometry, Smooth
Surface

11. SAND CASTING
• The most ancient , useful casting process
• Nearly all alloys can be sand casted ,
e.g. steel, nickel, titanium
• Mold can be used only one time
• Parts ranging in size from small to very large
• Production quantities from one to millions

12. • Sand casting typically has a low production rate.
• Use of a furnace, metal, pattern, and sand mold in this process

13. Sand Casting process cycle
• Mold-making A sand mold is formed by packing sand into each half of the mold.
• Clamping Binding of the both halves of molds
• Pouring Molten metal ladled and poured into the mold.
• Cooling The solidification and cooling of molten metal for a predetermined
solidification time
• Removal/Shakeout After predetermined time has passed, breaking the mold
• Trimming Removing the extra parts called flash by cutting from casting

14. Factors effecting the quality of sand cast :
 Strength - Ability of the sand to maintain its shape.
 Permeability - Ability to allow venting of trapped gases through the sand
.Permeability is determined by the size and shape of the sand grains.
 Thermal stability - Ability to resist damage, such as cracking, from the heat of
the molten metal.
 Collapsibility - Ability of the sand to collapse, or more accurately compress, .
 Reusability - Ability of the sand to be reused for future sand molds.

15. • Advantages :
 Can produce very large parts.
 Many material options.
 Low tooling and equipment cost.
 Scrap can be recycled.
 Short lead time possible.
• Disadvantages:
 Poor material strength.
 Poor surface finish and tolerance.
 Secondary machining often required.
 Low production rate.
Aluminum piston for an internal
combustion engine: as-cast and after
machining.
 High labor cost.
• Applications: Engine blocks and manifolds, machine bases, gears, pulleys

16. INVESTMENT CASTING
• Investment casting is one of the oldest manufacturing processes
• molten metal is poured into an expendable ceramic mold
• The mold is formed by using a wax pattern
• Using ceramic slurry that hardens into the mold
• Investment casting also called "lost-wax casting"
• Lost -wax processes increases production time and cost

17. Investment Casting Process Cycle
• Pattern creation (a) Wax pattern
(pattern creation)
• Mold creation (b) Multiple patterns
assembled to wax sprue
• Immersing -
(c) Shell built 
immerse into ceramic slurry
 immerse into fine sand
(few layers)

18. • Wax removal (d) dry ceramic
melt out the wax
fire ceramic (burn wax)
• Pouring (e) Pour molten metal (gravity)
 cool, solidify
[Hollow casting:
pouring excess metal before solidification
• Casting removal (f) Break ceramic shell
(vibration or water blasting)

19. • Advantages:
 Can form complex shapes
 Many material options
 High strength parts
 Excellent surface finish and accuracy
 Little need for secondary machining
• Disadvantages:
 Time Consuming process
 High labor cost
 High tooling cost
 Long lead time possible
• Applications: Turbine blades, pipe fittings, lock parts, hand tools, jewelry.

20. DIE CASTING
• Produces geometrically complex metal parts
• Reusable molds used, called dies.
• A furnace, metal, die casting machine, and die is used
• The metal, typically a non-ferrous alloy such as aluminum or zinc, .
• After the molten metal is injected into the dies,
it rapidly cools and solidifies into the final part, called the casting.

21. Die casting process cycle
• Clamping -
Preparation, binding and clamping of mold
• Injection Molten metal is transferred to the die
• Cooling Solidification and cooling of molten metal
• Ejection The removing of cast by hydraulic mechanism
• Trimming -.
Cutting the extra metal by sawing

22. DIE CASTING PROCESS

23. DIE CASTING EQUIPMENT
• Two types of die casting machines are :• Hot chamber die casting machine
• Cold chamber die casting machine
•
PARTS FORMED BY DIE CASTING

24. HOT-CHAMBER DIE CASTING
• Used for metal/alloys with low melting temperatures, such as zinc, tin,
and lead.
• Clamping of the die
• Molten metal poured in a chamber
• Injecting the metal by forcing plunger
• Metal flows through a goose neck
• Low pressure required around 1000 - 5000 psi
• After the solidification , ejection of cast part by hydraulic system .

26. Hot chamber die casting process
1)Clamping.
2)Injection
3) Cooling
4) Ejection

27. Cold Chamber Die Casting
• Used for alloys with high melting temperatures e.g. aluminum
• Clamping the die
• Horizontally injection..
• High Pressure is required around 2000 - 20000 psi.
• Solidification for predetermined time
• After solidification, the part can be ejected by the clamping unit.

29. Cold chamber die casting process