Familiarization with metal casting Coursework

1. Familiarization with metal casting I
Semester – 04
Manufacturing Engineering - II
ME 2170
Index No Name Mark
160595G Siriwardhana H.H.A.D
Workshop Name Foundry shop
Course B. Sc Engineering
Department Mechanical Engineering
Group M2.5
Date of Performance 21.11.2018
Date of Submission 05.12.2018
Due date of submission 03.12.2018
Department of Mechanical Engineering
University of Moratuwa
Sri Lanka
Ashika

2. INTRODUCTION
Casting is one of the oldest manufacturing process. It is the industry of pouring liquid
metal is usually poured into a mould, which contain a hollow cavity of desired shape, and then
allowed to solidify. Solidified part is also known as casting, which is ejected or broken out of
the mold to complete the process. As a result, in just one step, complex or simple design can be
created from any metal that can be dissolved.
One of the most important factor in choosing a casting method. It is depend on
dimensional tolerance, the metal used, size of the run and shape, symmetry and complexity.
Some of casting processes are sand casting, investment casting, pressure die casting,
centrifugal casting, continuous casting and thin roll casting. We use different metal for casting.
Such as cast iron, steel, bronze, brass, aluminum alloy, pot metal alloy and lead, tin & zinc.
There are many physics using for metal casting. Some of they are gravity, viscosity,
density, solubility, diffusion rate, high latent heat etc...

3. PROCEDURE
Preparation of sand Pattern making Melting raw metal
Mold & core making
Pouring into mold
Solidification & cooling
Removal of sand mold
Cleaning & inspection

4. DISCUSSION
 Purposes of following functions.
1. Core Print
Definition of core print is the part of a foundry pattern which makes an opening in a
mold to receive a core and to support it while the metal is being poured. It is an added
projection on the pattern and it forms a seat in the mold on which the sand core rest during
poured on the mold. And also core print must be adequate size and shape so that it can support
the weight of the core during the casting operation.
Core print should be made to afford the east ailment in the molding. It should exactly fit
the seat of plenty of bearing surface and won’t be crushed out of shape by the weight of the
core or by the molten metal.
2. Riser
It is normally known as feeder head. And also it is sort of passage in the mould sand,
shrinkage takes place during cooling and solidification of casting. The riser must be kept open
to the atmosphere and place in such a location that it maintains a positive pressure of liquid
metal on all portions of the casting it is intended to feed.
The cylindrical shaped riser are generally recommended compared to spherical shaped
riser which although consider as the best. Once the casting process has been completed, the
risers can be sawn off. The metal can then be recycled to make further sand casting.

5. 3. Vent hole
Vent holes as the name suggest are vents for the routing of air or gases from the cavity
of the die to the outside environment. In casting process during the start of the shot there is
rapid expansion of cold air inside the cavity when it comes in contact with the molten metal.
This rapid expansion is volume is vented out through vent in turn is connected to a vacuum
system.
Since the process is slow there is no requirement of any vacuum system vent holes can
serve the purpose. But many vent hole have to be provide because the gases produced due to
the burning of the resin in the sand core, has to be removed out of the cavity in addition to the
expanding air.
If we fail to remove the gases, they cause serious porosity or blowholes in the casting.
Further, expanding air can cause serious force in the die resulting in the increase in parting line
gap which may cause flashes and other problem.
4. Gating system
It is nothing but the basic design, which is needed to construct a smooth and proper
filling of the mold cavity of the casting without any discontinuity, voids or solid inclusions. A
proper method of gating system is that it leads the pure molten metal to flow through a ladle to
the casting cavity, which ensures proper and smooth filling of the cavity. This depend on the
layout of the gating channels too, such as the direction and the position of the runner, sprue and
ingates. And also efficient way of gating system is that is shows the way to the pure molten
metal to flow through the casting cavity which ensure proper and smoother filling of the cavity.

6.  Different type of tool used by the mould maker.
1. Drag and cope
Upper part of the casting flask known is known as cope, when the lower part of it is
known as drag.
2. Rammer
It has heavy flat bottom surface which is made of iron. In casting process, this tool is
used to pack the green sand tightly by applying forceful impact.
3. Shovel
Use to handle and board scoop or blade for digging and mounting material from the
storage to the place where casting is doing.
4. Lifters
This devices use to lift or put green sand carefully in to the mould cavity. These are
considerably small as it carries a little amount of material from or to the cavity.
5. Strike off bar
It is normally wooden bar which has a flat thick bottom. This is used to remove the
additional sand from the mould and flatten it after ramming.
6. Went wires/stick
This is used to create the vent hole. It is having a smaller round cross sectional area.
7. Trowel
It is a flat bladed hand tool for levelling spreading or shaping green sand in the mould.
It is used when creating pouring basin.
8. Dust bag
This is containing powder which is use to sprinkle dust in the middle of the surface
which separate the cope and drag this prevents cope adhesion with drag.
9. Sprue pin
This is wooden piece which is having descending cross section and conic shape. This
can use to produce the sprue well in moud.
10. Riddle
A tool which consist of a wooden handle and a bucker which is made of a steel net. It is
used to separate smaller sand from large sand particles. Smaller sand particle are
essential for a smooth mould surface.

7.  Gating system of sand mould is horizontal gating system.
Many complex component are easily produced by sand casting process, because of its
advantages over other manufacturing process. The quality product with minimum
manufacturing cost can be achieved by well-designed gating system. A gating system is a basic
design, which is needed to construct,
 A smooth & proper filling of the mold cavity of the casting without any
discontinuity.
 Riser ensures the smooth, uniformed and complete filling of clean molten metal.
 Clean metal implies preventing the entry of slag and inclusion into the mould
cavity which minimizes the surface turbulence.
 Complete filling of the casting cavity
The main elements needed for the gating system are as follows,
 Pouring basin or bush.
 Sprue or down sprue.
 Runner
 Ingate.
 Ladle.
 Slag trap or filter.
Pouring basin
This is otherwise called as bush or cup. It is circular or rectangular in shape. It collects
the molten metal, which is poured, from the ladle.
Sprue
It is circular in cross section. It leads the molten metal from the pouring basin to the
sprue well.
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8. REFERENCESS
 http://www.engineeringarticles.org/metal-casting-definition-types-and-processes
 https://weldguru.com/metal-casting
 https://nptel.ac.in/courses/112107144/metalcasting/lecture4.htm
 https://www.merriam-webster.com/dictionary/core
 http://www.themetalcasting.com/gating-system-types.html
 https://www.quora.com/What-is-the-use-of-vent-holes-in-casting-process
 http://www.themetalcasting.com/gating-system-types.html