Lab 5(Report)
Name- Priyanshu Chand
Entry Number- 2020CHB1049
Date- 19 May 2021
GE102 (Workshop Practice) Lab Report
Name of the Experiment- Sand Mold Casting
Aim(A) Objective:
● To understand the sand mould casting process.
● To learn about the real life applications of Sand Mould Casting.
● To have an overview of some important fundamentals of Sand Mould casting.
● To understand Tools used in Sand mould Casting.
(B) MachinesMachine Tools/ Components-
● Pattern- Pattern can be made up of wood, polymer,etc. It is a replica of the
final object.
● Sand Casting Flask- It is made up of 2 parts- Cope and Drag. It is basically a
container that is filled by the molding sand.
● Mallet – It is used for rapping to separate the mold from the pattern.
● Hand Rammer – It is generally made from wood or metal and is available in
different types. It is used for ramming the sand mass in the molding box to
pack it uniformly around the pattern.
● Sprue Pin – It is used to produce a vertical hole in the sand called runner,
through which the molten metal is poured into the mould.
● Vent Pins – They are used to make small holes called vents in the sand mould
after ramming and striking off the excess sand. These vents allow the exit
of gases and steam during casting.
● Lifters – Lifters are tools used for cleaning, repairing and finishing the
bottom and sides of the deep and narrow opening in the mold.
● Draw Spike – It is a tool having screw heads on one end and is used for
drawing the embedded pattern from the molding sand.
● Strike of Bars – It is a flat bar used to remove excess sand from the top of
a box after ramming.
● Brush – Used to properly clean the surface after ramping.
● Safety Gloves – Protects us from heat while working with the molten metal.
● Crucible – It is a container in which the metal is melted inside the furnace.
● Crucible Handles – It is a handle which holds the Crucible.
● Trowels – Use to remove sand from where strikes of bars are not usable.
Experimental Procedure- Sand Cast Molding is the one widely used casting
Process. It is a process in which Molten metal flows into the sand mold where it
solidifies to form in the form of the Mold cavity. It is used to create Complex part
geometries. Sand Cast Molding is an Expendable Mold Process in which the Mold is
destroyed to remove the casting. In this process, a pattern is used to create each
Mold Cavity.
Procedure:
● We take 72 to 82 percent by weight of silica sand. To make the mold more
stronger, clay powder is taken around 8 percent, fire clay is taken around 6
percent by weight, then we add molasses around 5 to 8 percent by weight to
add moisture content in the mold. Then we mix the sand thoroughly.
● Then keep the pattern in the drag of the flask and then the drag is filled
with sand to make one part of the mold. The sand is rammed by the hand
rammers and then it is leveled by Strike of bars.
● Then drag is inverted and a parting plane is made. After that, two sprue pins
are kept on the drag, one at the pattern to make the riser and other at a
distance in order to make the sprue.
● Then the cope is joined and the sand is poured in the flask. Then the pores
are made in the flask with the help of vent pins.
● Then the sprue pins are removed and cope is removed. A pouring funnel is
made in cope’s upper face and runner on the drag’s upper surface. And the
pattern is also removed from the drag with the help of a draw spike.
● Then the cope is joined with the drag. And the molten part of the metal is
poured in the pouring funnel of the flask and the molten part flows through
the sprue and then through the runner to cast metal cavity.
● Then it is left to solidify. And after that cope is removed and the required
product is detached with the help of a mallet.
● And then the unwanted part such as the riser and the down sprue is removed
by cutting.
Schematic diagram of Casting Process
LAB Exercise:
(A) 5 product or components that are manufactured from sand cast molding are:
1. Valves
2. Cylindrical Block for Automobile Engine
3. Gears
4. Electrical Contact parts
5. Pulleys and Lever arms
(B)
Valves
Front View
Top View
Side View
Type of Casting Process- Green Sand Mold Casting
Materials- No Lead Brass
Equipment Required- Pattern, Sand Casting Flask, Mallet, Hand Rammer, Split
Levels, Vent Pins, Trowels, Safety Gloves, Brushes, Draw Spike
Steps● In the experiment, we take 72 to 82 percent by weight of silica sand. To
make the mold more stronger, clay powder, fire clay are added and then
molasses around 5 to 8 percent by weight is added to add moisture content
in the mold. Then we mix the sand thoroughly.
● Create a mold by packing sand in each half of the mold. The sand is packed
around the pattern which is a replica of the external shape of the Valve.
● The Mold halves are closed by clamping them together.
● The mold cavity is filled with molten metal through the gating system.
● Then Metal is left to cool down and solidify.
● The Sand Mold is broken away and the product is removed with the help of
Mallet.
● The unwanted part is removed and the final product is produced.
Limitations of the Process1. Poor dimensional accuracy and surface finish for some processes.
2. Safety Hazards
3. Environmental Hazards
4. Since Sand Mould Casting is an Expendable process, Mold is destroyed every
time to remove the casting which results in higher production costs for the
producing Molds.
5. There are many defects involved in Sand Mould Casting as well including:
●
Sand blow- Balloon shaped gas cavity caused by release of Mold gases during
pouring. It occurs at or below the casting surface near the top of the casting. Main
causes are Low Permeability, poor venting and high moisture content of the Sand
Molds.
●
Pin Holes- It consists of many small gas cavities formed at or slightly below the
surface of casting. These are caused by the release of gases during Pouring.
●
Sand Wash- An irregularity in the surface of casting that results from the
erosion of sand Mold during Pouring, and the counter of erosion is formed in the
surface of the final cast part.
●
Scabs- Scabs are rough areas on the surface of the casting due to encrustations
of sand and the metal. It is caused by a portion of mold surface flaking off during
solidification and becoming embedded in the casting surface.
●
Penetration- When fluidity of liquid metal is high, it may penetrate into sand mold
or sand core, causing the casting surface to consist of a mixture of sand grains and
metal. Harder packing of the sand mold helps to alleviate this condition.
●
Mold Shift- A step in cast product at parting line caused by sidewise relative
displacement of cope and drag.
●
Core Shift- It is usually similar to Mold Shift, but it is the core that is displaced,
and the displacement is usually vertical.
●
Mold Crack- It occurs when mold strength is insufficient, and a crack develops,
into which liquid metal can seep to form a “fin” on the metal casting.
Use of this Lab in My field of Specialization● Pipes Junction and Meter valves are used in the chemical plants in the pipes
used to transport various chemicals and water
● Pumps and Motor has a very big use in Chemical Plants to transport
Controlled volumes of liquid from a storage tank to Chemical additives. Pump
and Motor Housings are made from Sand Mold Casting.
● Gas Cylindrical Nozzles are made through the Sand Cast Molding Process.
Gas Cylinders are used to store Various gases in the Chemical Plants.
● Wood Burning stoves, pipes, Pulley, etc. are other objects made from Sand
Cast Molding used in Chemical Plants.
Conclusions- The things that I learned from the experiment are:
● It is one of the most widely used and the oldest processes to form Complex
shapes of the Metals.
● Sand Mould Casting is an Expendable Mold Process. So more and more
Complex Shapes are possible.
● Nearly all alloys can be sand casted including metals with high melting
Temperatures, such as steel, nickel and Titanium alloys.
● Parts ranging from a small size to a very large can be made using sand mold
Casting.
● Versatility- The objects of different size,weight and shape can be made
from Sand Mold Casting.
● Poor dimensional accuracy and surface finish for some processes, Safety
Hazards, Environmental Hazards are some disadvantages of Sand Mold
Casting.
● There are many defects also that we have to deal with when it comes to
Sand Mold Casting like Mold Crack, Core Shift, Mold Shift, Penetration,
Scabs, Pin Holes, Sand Blows, Sand Wash,etc.