Die casting and types

Bs-Mechanical Engineering & Technology Study Of Die-Casting Manufacturing Process
Umair Raza 19013386-002 MTL-121
Introduction:-
Metal Casting is one of the oldest materials shaping methods known.
Casting means pouring molten metal into a mold with a cavity of the
shape to be made, and allowing it to solidify. When solidified, the
desired metal object is taken out from the mold either by breaking the
mold or taking the mold apart. The solidified object is called the
casting. By this process, intricate parts can be given strength and
rigidity frequently not obtainable by any other manufacturing process.
Casting materials are usually metals or various cold setting materials
that cure after mixing two or more components together; examples are
epoxy, concrete, plaster and clay.
Foundry:- ” Foundry or casting is the process of producing metal/alloy by pouring the molten metal/alloy
into a prepared mould (of that shape) and then allowing the metal/alloy to cool and solidify. The solidified
piece of metal/alloy is known as a CASTING”.
Casting Terms:-
Flask: A metal or wood frame, without fixed top or bottom, in which the
mold is formed.
Drag - lower molding flask,
Cope - upper molding flask,
Cheek - intermediate molding flask used in three piece molding.
Pattern: It is the replica of the final object to be made. The mold cavity
is made with the help of pattern.
Parting line: This is the dividing line between the two molding flasks that makes up the mold.
Pouring basin: A small funnel shaped cavity at the top of the mold into
which the molten metal is poured.
Sprue: The passage through which the molten metal, from the pouring
basin, reaches the mold cavity. In many cases it controls the flow of metal
into the mold.
Runner: The channel through which the molten metal is carried from the
sprue to the gate.
Riser: A column of molten metal placed in the mold to feed the castings as it shrinks and solidifies. Also
known as feed head.
Gate: A channel through which the molten metal enters the mold cavity.
“Casting is a manufacturing process by which a liquid material is usually poured into a mold, which contains a hollow
cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a casting, which is
ejected or broken out of the mold to complete the process”.

Umair Raza 19013386-002 MTL-121
Core: A separate part of the mold, made of sand and generally
baked, which is used to create openings and various shaped
cavities in the castings.
Chaplets: Chaplets are used to support the cores inside the mold
cavity to take care of its own weight and overcome the
metallostatic force.
Vent: Small opening in the mold to facilitate escape of air and
gases.
Basic Features of Patternand Mould:-
 A pattern is made of wood or metal, is a replica of the final product and is used for preparing mould
cavity.
 Mould material should possess refractory characteristics and with stand the pouring temperature.
Pattern:-
 The pattern is the principal tool during the casting process.
 It is the replica of the object to be made by the casting process, with some modifications. The main
modifications are the addition of pattern allowances, and the provision of core prints.
 If the casting is to be hollow, additional patterns called cores are used to create these cavities in the
finished product.
 The quality of the casting produced depends upon the material of the pattern, its design, and
construction.
Function Of Pattern:-
 A pattern prepares a mold cavity for the purpose of making a casting.
 A pattern may contain projections known as core prints if the casting requires a core and need to be
made hollow.
 Runner, gates, and risers used for feeding molten metal in the mold cavity may form a part of the
pattern.
 Patterns properly made and having finished and smooth surfaces reduce casting defects.
 A properly constructed pattern minimizes the overall cost of the castings.
Steps involved in making a casting:-
 Make the pattern out of Wood, Metal or Plastic.
 Prepare the necessary sand mixtures for mould and core making.
 Prepare the Mould and necessary Cores.
 Melt the metal/alloy to be cast.
 Pour the molten metal/alloy into mould and remove the casting from the mould after the metal
solidifies.
 Clean and finish the casting.
 Test and inspect the casting.
 Remove the defects, if any. Relieve the casting stresses by Heat Treatment.
 Again inspect the casting.
 The casting is ready for shipping.

Umair Raza 19013386-002 MTL-121
Procedure:-
The basic steps of the investment casting process are:-
 Production of heat-disposable wax, plastic, or polystyrene patterns.
 Assembly of these patterns onto a gating system.
 “Investing,” or covering the pattern assembly with refractory slurry.
 Melting the pattern assembly to remove the pattern material.
 Firing the mold to remove the last traces of the pattern material Pouring, Knockout, cutoff and
finishing.
Applications of Casting:-
 Transportation.
 Turbine vehicles vanes.
 Power generators.
 Railway crossings.
 Agricultural parts.
 Aircraft jet engine parts.
 Sanitary fittings.
 Communication, Construction and Atomic Energy applications, etc..
Six basic steps in this process:-
 Place a pattern in sand to create a mold.
 Incorporate the pattern and sand in a gating system.
 Remove the pattern.
 Fill the mold cavity with molten metal.
 Allow the metal to cool.
 Break away the sand mold and remove the casting.
Raw Materials for Foundry:-
Metals and alloys Fuels (For melting metals) Fluxes
Types of Casting:-
Following are the basic types of casting:-
 Sand casting
 Die casting
 Shell mold casting
 Permanent mold casting
 Investment casting (lost wax casting)
 Lost-foam casting
 Centrifugal casting
Explanation of Casting Types:-

Umair Raza 19013386-002 MTL-121
Sand Casting:-
Sand casting, also known as sand molded casting, is a
metal casting process characterized by using sand as the
mold material. The term "sand casting" can also refer to
an object produced via the sand casting process. Sand
castings are produced in specialized factories called
foundries. Over 70% of all metal castings are produced
via a sand casting process.
Sand casting is relatively cheap and sufficiently
refractory even for steel foundry use. In addition to the
sand, a suitable bonding agent (usually clay) is mixed or occurs with the sand. The mixture is moistened,
typically with water, but sometimes with other substances, to develop strength and plasticity of the clay and
to make the aggregate suitable for molding. The sand is typically contained in a system of frames or mold
boxes known as a flask. The mold cavities and gate system are created by compacting the sand around
models, or patterns, or carved directly into the sand.
Sand Casting Steps:-
Basic materials & equipment for sand-casting:-
Container of molten metal (filled from furnace) Top and bottom mold forms (made of metal, open at top
and bottom) Rammer (tool to compact the sand; often a pressing machine is used).
Basic Summary of Sand Casting Process:-
1. First of all, mix the sand.
2. Sand placed into bottom mold from the compacted.
Molding
Pouring
into Mold
Melting
Of Metal
MoldSand
Heat
TreatmentCasting
Inspectio
n
Cleaning &
Finishing
Solidificatio
n
Furnaces Shakeou
t
Defects
Dimension
Additional
Heat
Treatment

Umair Raza 19013386-002 MTL-121
3. Pattern placed into mold.
4. Add the top mold form.
5. A tube or pipe provides a path to pour the metal in Pattern is still inside!
6. Fill top form with compacted sand.
7. Take the top mold off and remove pattern & pipe or post 5 6/
8. Replace the top mold and fasten securely! Pouring hole In the middle of the sand is a cavity shaped
like the pattern!
9. Pour the metal (container is filled from furnace immediately before you are ready to pour).
10. Wait for the metal to cool (minutes to days, depending on the size of the casting).
11. 8 SHAKE OUT: Break apart the two halves of the mold & take out the part—usually requires
vibrating or striking the mold to break apart the sand.
12. CLEANING. Sand is cleaned off the part, the “tab” where metal flowed in must be removed.
13. Mold forms are reused.
14. Sand is broken up, screened to remove debris and clumps, and sent for remixing.
Sand Casting Applications:-
Sand casting is extensively used, for cast iron and steel parts of medium and large size where surface
smoothness and dimensional precision are the main concerns. Sand casting is also used to make large parts
in material like bronze, brass, aluminum, etc. Also used for casting sculptures which can have a certain
amount of rough surface finish.
Die Casting:-
Die casting Die casting is a metal casting process that is characterized
by forcing molten metal under high pressure into a mold cavity. The
mold cavity is created using two hardened tool steel dies which have
been machined into shape and work similarly to an injection mold
during the process. Most die castings are made from non-ferrous metals,
specifically zinc, copper, aluminium, magnesium, lead, pewter and tin
based alloys Depending on the type of metal being cast, a hot- or coldchamber machine is used. The casting
equipment and the metal dies represent large capital costs and this tends to limit the process to high volume
production. Manufacture of parts using die casting is relatively simple, involving only four main steps,
which keeps the incremental cost per item low. It is especially suited for a large quantity of small to medium
sized castings, which is why die casting produces more castings than any other casting process. Die castings
are characterized by a very good surface finish (by casting standards) and dimensional consistency
Shell mold casting:-
Shell molding, also known as shell-mold casting, is an expendable mold
casting process that uses a resin covered sand to form the mold.  As
compared to sand casting, this process has better dimensional accuracy,a
higher productivity rate,and lower labor requirements. It is used for small
to medium parts that require high precision. Shell mold casting is a metal
casting process similar to sand casting, in that molten metal is poured into
an expendable mold. However,in shell mold casting, the mold is a thin-
walled shell created from applying a sand-resin mixture around a pattern. The pattern, a metal piece in the shape of the
desired part, is reused to form multiple shell molds. A reusable pattern allows for higher production rates,while the
disposable molds enable complex geometries to be cast. Shell mold casting requires the use of a metal pattern, oven,

Umair Raza 19013386-002 MTL-121
sand-resin mixture, dump box, and molten metal. Shell mold casting allows the use of both ferrous and non-ferrous
metals, most commonly using cast iron, carbon steel, alloy steel, stainless steel, aluminum alloys, & copper alloys.
Typical parts are small-to-medium in size and require high accuracy,such as gear housings, cylinder heads,
connecting rods, & lever arms.
Permanent mold casting:-
Permanent  mold casting: Permanent mold casting is metal casting
process that employs reusable molds ("permanent molds"), usually
made from metal. The most common process uses gravity to fill the
mold, however gas pressure or a vacuum are also used. A variation
on the typical gravity casting process, called slush casting, produces
hollow castings. Common casting metals are aluminum, magnesium, and copper alloys. Other materials
include tin, zinc, and lead alloys and iron and steel are also cast in graphite molds
Investment casting (lostwax casting:-
Investment casting is an industrial process based on and also called lost-wax casting, one of the oldest
known metal-forming techniques .From 5,000 years ago, when bees wax formed the pattern, to today’s high-
technology waxes, refractory materials and specialist alloys, the castings allow the production of
components with accuracy, repeatability, versatility and integrity in a variety of metals and high-
performance alloys.  The process is generally used for small castings, but has been used to produce
complete aircraft door frames, steel castings of up to 300 kg (660 lbs) and aluminium castings of up to 30 kg
(66 lbs). It is generally more expensive per unit than die casting or sand casting, but has lower equipment
costs. It can produce complicated shapes that would be difficult or impossible with die casting, yet like that
process, it requires little surface finishing and only minor machining..
Lost-foam casting:-
Lost-foam casting Lost-foam casting (LFC) is a type of evaporative pattern casting process that is similar to
investment casting except foam is used for the pattern instead of wax. This process takes advantage of the
low boiling point of foam to simplify the investment casting process by removing the need to melt the wax
out of the mold.
Centrifugal casting:-
Centrifugal casting or roto-casting is a casting technique that is typically
used to cast thin walled cylinders. It is noted for the high quality of the
results attainable, particularly for precise control of their metallurgy and
crystal structure. Unlike most other casting techniques, centrifugal
casting is chiefly used to manufacture stock materials in standard sizes
for further machining.
Conclusion:-
An unsuccessful casting results in considerable trouble & loss of time, in almost all instances, defects in
casting can be avoided by strict observance of procedures governed by certain fundamental rules &
principle. Seldom is a defect in a casting attributable to factors others than the carelessness or ignorance of
the operator. With present techniques, casting failures should be the exception not the rule..

Umair Raza 19013386-002 MTL-121
References:-
https://en.wikipedia.org/wiki/Casting#:~:text=Casting%20is%20a%20manufacturing%20process,mold%20t
o%20complete%20the%20process.
https://www.thomasnet.com/articles/custom-manufacturing-fabricating/types-of-casting-processes/
https://en.wikipedia.org/wiki/Sand_casting
https://en.wikipedia.org/wiki/Plaster_mold_casting
https://www.custompartnet.com/wu/shell-mold-castinghttps://en.wikipedia.org/wiki/Die_casting
https://www.custompartnet.com/wu/die-casting
https://www.custompartnet.com/wu/SandCasting
https://www.afwfoundry.com/sand-casting-applications/
https://www.slideshare.net/HAWAMAHAL/casting-70563248

Die casting and types

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Die casting and types