Tuesday, 10 January 2017

What is Cast Iron and it Types

Today we will discuss about what is cast iron and types of cast iron. Cast iron is ferrous carbon alloys which contain 1.7 to 4.5 percent carbon in either free or combine form. Cast iron is a brittle and less ductile material which has high compressive strength. Due to its high compressive strength it is used to make base or body of most machines. Cast iron also have low melting point which is around 1200 degree centigrade which make it suitable for casting. Due to its casting properties it is named as cast iron. It has low cost of manufacturing and has excellent machining property.  

Cast iron also contain small quantity of impurities such as silicon, sulphur, manganese and phosphorus, copper, nickel, chromium, which effect its properties small or large level. The effect of these properties is as follow.

Silicon:  It is present in cast iron up to 4 percent. It promotes graphite formation which make it soft and easily machinable.

Sulphur:  It is present up to 0.1 present. It makes cast iron hard and brittle.

Manganese: It promote carbide formation of cast iron which make it ehite and hard. It is present up to 0.75 percent.

Chromium: It also promote carbide formation which make it hard and difficult to machine.

According to the carbon percentage, cooling condition, alloying element, heat treatment etc. cast iron may be divided into following types.

What is Cast Iron and it Types

Cast Iron and its Types:

1. Gray Cast Iron:

Cast iron which contain carbon in free form, known as Gray cast iron. It is also known as commercial cast iron due to mostly used in commercial purpose. It contains 3 to 3.5 percentile carbon and rest iron. This cast iron has low tensile strength, high compressive strength and no ductility. It has excellence machining property. This metal is designate by FG followed by the digit show maximum tensile stress.

2. White Cast Iron:

Cast iron in which carbon is present in combined form or in carbide form known as white cast iron. White colour is due to carbide formation. It contain up to 2.3 percent carbon. It is hard and not suitable for machining. This iron has high tensile strength and a low compressive strength.

3. Malleable Cast Iron:

This cast iron is obtained from white cast iron by heat treatment process. It is mostly obtain by annealing of white cast iron. It has improved strength and ductility like steel but can be cast easily.  It is often used for small castings requiring good tensile strength and the ability to flex without breaking (ductility). Uses include electrical fittings, hand tools, pipe fittings, washers, brackets, fence fittings etc.

4. Nodular Cast Iron:

It is also known as ductile or high strength cast iron. It has high strength. It is obtained from Gray cast iron by adding small amount of magnesium to the molten stage. It is designate by SG followed by the numbers which indicate tensile strength and percentage elongation.

5. Mottled Cast Iron:

Cast iron which have equal amount of free carbon and carbide known as mottled cast iron. It has intermediate property and colour of Gray cast iron and white cast iron.

6. Chilled Cast Iron:

If the white cast iron quick cooled from molten stage, the iron produced is known as chilled cast iron.

7. Alloy Cast Iron:

Alloy cast iron produced by adding some alloying element in cast iron like nickel, chromium, copper etc. It has increase properties according to the alloying element. This cast iron is produce to get desire properties of cast iron.

This is all about what is cast iron and types of cast iron. If you have any query regarding this article ask by commenting.

Sunday, 23 October 2016

Difference between Orthogonal and Oblique Cutting

Today we will discuss about difference between orthogonal and oblique cutting. What is Orthogonal Cutting? What is Oblique Cutting? Metal cutting or commonly known as machining, is the most common phenomenon used in manufacturing industries. Every product, big or small, undergoes a machining process to get final product. So the knowledge of basic types of metal cutting are most important. If we talk about metal cutting two terms comes in our mind orthogonal and oblique. These both are the metal cutting mechanism which is purely depending on the feed angle and cutting direction of tool. 
Orthogonal cutting is a type of metal cutting in which the cutting edge of wedge shape cutting tool is perpendicular to the direction of tool motion. In this cutting the cutting edge is wider than width of cut. This cutting is also known as 2D cutting because the force develop during cutting can be plot on a plane or can be represent by 2D coordinate.
Difference between Orthogonal and Oblique Cutting
Orthogonal Cutting
Oblique cutting is another type of cutting in which the cutting edge of wedge shape cutting tool make a angle except right angle to the direction of tool motion. This will affect the cutting conditions. It is also known as 3D cutting because the cutting force develop during cutting cannot be represent by 2D coordinate or used 3D coordinate to represent.
Difference between Orthogonal and Oblique Cutting
Oblique Cutting
The basic and main difference between orthogonal cutting and oblique cutting is that in orthogonal cutting, cutting edge of the tool is perpendicular to the direction of motion but in oblique cutting the cutting edge make an angle with the direction of motion. There are many other differences which are describe below.

Difference between Orthogonal and Oblique Cutting

Difference between Orthogonal cutting and Oblique cutting:

S. No.

Orthogonal Cutting

Oblique Cutting


The cutting angle of tool make right angle to the direction of motion.

The cutting angle of tool foes not make right angle to the direction of motion.


The chip flow in the direction normal to the cutting edge.

The chips make an angle with the normal to the cutting edge.


In orthogonal cutting only two components of force considered cutting force and thrust force which can be represent by 2D coordinate system.

In oblique cutting three component of force are considered, cutting force, thrust force and radial force which cannot represent by 2D coordinate. It used 3D coordinate to represent the forces acting during cutting, so it is known as 3D cutting.


This tool has lesser cutting life compare to oblique cutting.

This tool has higher cutting life.


The shear force act per unit area is high which increase the heat developed per unit area.

The shear force per unit area is low, which decreases heat develop per unit area hence increases tool life.


The chips flow over the tool.

The chips flow along the sideways.

Today we have learned about orthogonal cutting and oblique cutting. If you have any query regarding this article, ask by commenting.

Saturday, 8 October 2016

Hydraulic Turbine: Working, Types, Advantages and Disadvantages

Today we will learn about hydraulic turbine and its types, working, advantages and disadvantages and. Hydraulic turbine which are generally known as water turbine used to convert hydraulic energy or we can say that energy of water (kinetic and pressure energy of water)  into mechanical energy. This mechanical energy is further used to drive a generator which converts it into electrical energy. The basic concept of this type of turbine is that water flowing from a dam generates a pressure force while passing through the turbine. This pressure force use to rotate the turbine which further rotate the generator and convert hydraulic energy into electrical energy.

Hydraulic Turbine: Working, Types, Advantages and Disadvantages

Working Principle:

According to Newton's law a force is directly proportional to the change in momentum. So if there is any change in momentum of fluid a force is generated. In the hydraulic turbine blades or bucket (in case of Pelton wheel) are provided against the flow of water which change the momentum of it.  As the momentum is change a resulting pressure force generated which rotate the rotor or turbine. The most important phenomenon is the amount of change in momentum of water which is directly proportional to force. As the change in momentum high the force generated is high which increase the energy conversion. So the blade or buckets are designed so it can change maximum momentum of water. This is the basic principle of turbine. These turbines are used as hydro electric power plant.

Hydraulic Turbine: Working, Types, Advantages and Disadvantages


The hydraulic turbine can be classified according to the energy available at inlet, direction of flow of water, Specific speed, head available at inlet etc. These all types are described as below.

According to Type of Energy Available at Inlet:

Impulse Turbine:
Impulse turbine is those turbines which are use impulse energy or we can say kinetic energy of water to rotate the turbine. In this type of hydraulic turbine all pressure head or pressure energy is converted into velocity head or kinetic energy at the inlet of turbine by using nozzle. This high speed water jet strikes the blade or bucket of turbine which develop a force which rotate it. Only kinetic energy changes at the inlet and outlet of turbine and the pressure of water remain same. This kind of turbine is known as impulse turbine. There are various design available of impulse turbine but the Pelton wheel most suited for it. These are generally high head and low discharge hydraulic turbine.

Reaction Turbine:
As the name implies these turbines is used pressure energy of water to rotate the turbine. In practically no turbine can purely used pressure energy. So it used both its pressure energy and kinetic energy. These turbines rotate partially due to impulse action and partially due to pressure change over the runner blades. The water flow over blades covert both its kinetic energy as well as pressure energy into force and rotate the turbine. The change in pressure energy of water known as degree of reaction of the turbine. So it is known as reaction turbine. They are generally low head, high discharge turbine.

According to Direction of Flow:

Tangential Flow Turbine:
In this hydraulic turbine the water flow through tangent of runner. The water jet strikes the runner tangentially and rotates the turbine. Example Pelton wheel turbine

Hydraulic Turbine: Working, Types, Advantages and Disadvantages
Pelton Turbine

Radial Flow Turbine:
In this type of turbine the water flows in radial direction. This is subdivided into two types. The first one is known as inward radial flow in which the water flows from periphery to the center. Example Francis turbine.
Second one is known as outward flow radial turbine in which water flow towards periphery from center.

Hydraulic Turbine: Working, Types, Advantages and Disadvantages
Francis Turbine
Axial Flow Turbine:
In this hydraulic turbine, the water flow from the axis of turbine. Example Kaplan turbine

Hydraulic Turbine: Working, Types, Advantages and Disadvantages
Kaplan Turbine

Mixed Flow Turbine:
When the water enters the turbine radically and exit axially or vice versa, it is known as mixed flow turbine.

According to Head of Water Available at Inlet:

High Head Turbine:
 If the water level or water reservoir is above 150 - 2000 m from the axis of turbine, it is known as high head turbine. It is best suited for impulse turbine.

Medium Head Turbine:
If the water level varies from 30 -130 m from the axis of the turbine, it is known as medium head turbine. Example Francis Turbine

Low Head Turbine:
If the water level is below 30 meter from the axis of turbine, it is known as low head turbine. These hydraulic turbine required high discharge rate to work efficiently. Example Kaplan turbine.

According to Specific Speed of Turbine:

Low Specific Speed Turbine:
If the specific speed is less than 50 the turbine is considered as low specific speed turbine. Example Pelton wheel

Medium Specific Speed Turbine:
If the specific speed is between 50 - 150, it is considered as medium specific speed turbine. Example Francis Turbine

High Specific Speed Turbine:
If the specific speed of turbine is above 250 it is known as high specific speed turbine. Example Kaplan Turbine

Advantages and Disadvantages:

Hydro power plant or we can say that hydraulic turbines are widely used form the last decades. It is an efficient renewable energy source. There are many up and downs in every project so there are also have many advantages and disadvantages which are describe below.


  • It is a renewable energy source. Water energy can be used again and again.
  • The running cost of turbine is less compare to other.
  • It has high efficiency.
  • It can be control fully. The gate of dam is closed when we does not need electricity and can be open when we needed.
  • Dams are used from very long time so it can be used for power generation.
  • It does not pollute environment.
  • It is easy to maintain.
  • The dam constructed for hydraulic turbine can become a tourist place.


  • Initial cost is very high. It takes several decades to become profitable.
  • It can destroy the natural environment at site. Large dam cause big geological damages.
  • It can develop at only few sites where proper amount of water is available.

This is all about Hydraulic turbine working, types and advantages and disadvantages. If you have any query regarding this article, ask by commenting. 

Saturday, 1 October 2016

Casting Defects : Types , Causes and Remedies

In this article we will learn about casting defects its causes and remedies. Defects are common phenomenon in any engineering process. There is such limitation of any process, which causes defects. The proper designing and moulding can give a defect free cast but due to some control limitation and human interference, defects are generally occur. By the proper assistance on work we can minimize the casting defects. Generally a proper casting product also has some defects so a research is going in foundry industry to minimize these defects. These casting defects can be found out by the non destructive testing methods which includes ultrasonic testing, radiography testing, magnetic particle testing, die penetration testing etc. Today I will point out some common casting defects, its causes and remedies of it.

The basic conditions which spark the defects in casting or the favorable conditions of casting defects are

1. Defecting design of pattern
2. Improper melting of metal
3. Defects in mould
4. Due to moulding material
5. Improper cooling of mould
6. Defecting gating system
7. Improper venting in mould

Types of casting defects:

These defects can be classified into three major categories.

1. Blow Hole:

It is a gas hole or gas cavity which is occurs at the surface or the internal part of casting. It is due to gas interrupted into the casting due to poor ventilation. Mostly it is occur at surface which makes a circular of oval shape gas hole. These defects can be seen after machining of surface.
These defect cause due to improper venting system, excessive gas or moisture contain and due to low permeability of sand and high temperature of sand. It is also due to low pouring temperature of metal.

Casting Defects : Types , Causes and Remedies

2. Scar:

Scar is generally occur at flat surface and it is due to improper venting or permeability of sand. The blow is covered by the thin layer of metal.
Casting Defects : Types , Causes and Remedies

3. Scab:

This is also known as slag inclusion of sand inclusion. This is look like as slag inside the cast and very difficult to remedy because generally it does not occur at single point. This defect generally occurs due to defective mould or core, low binding strength of moulding material or sand. It is also due to low permeability of sand.
Casting Defects : Types , Causes and Remedies

4. Penetration:

This defect occurs when fluidity of molten metal is high. When mould is porous and does not enough stronger to resist molten metal, this defect occur. The liquid metal penetrates the mould and mix with sand. This gives uneven casting surface.
Casting Defects : Types , Causes and Remedies

5. Cold shut:

It is the basic defect which generally occurs. It is occur when the molten metal flow through two different paths. When the two stream of molten metal comes in contact and solidify before they mix completely, some bubbles form between them. This phenomenon is known as cold shut. It is also known as cold lap.

Casting Defects : Types , Causes and Remedies

6. Mismatch:

It is defect due to mismatch of cope and drag. It is also known as shift. When the cope shift relative to drag known as mold shift and when drag shift known as cope shift. It is due to the bouncy of the molten metal, loose box pins etc.
Casting Defects : Types , Causes and Remedies

7. Misruns:

Misruns is a phenomenon when the cast materials solidify before the proper filling of mould. This result presence of incomplete cavity filling. It is due to too thin wall thickness, improper gating system, slow pouring, damaged pattern and poor fluidity of molten metal.
Casting Defects : Types , Causes and Remedies

8. Hot tear:

 A hot tear or crack is generally not visible because the casting has not separated into fragments. This is occurring due to uneven cooling and improper position of chills. This is generally occur where abrupt section change. This is occur during solidification of casting when the solid portion have not sufficient strength to resist tensile force.

Casting Defects : Types , Causes and Remedies

9. Shrinkage:

This defect generally arises during volume contraction during solidification. It is occur when the liquid metal does not sufficient to compensate the volume shrinkage. This is due to insufficient size of riser, improper direction solidification of casting, improper location of chills or in gates.

Casting Defects : Types , Causes and Remedies

10. Buckle:

The formation of uneven line on the cast surface is known as buckle. It generate due failure of sand surface or expansion of sand surface due to heat of molten metal.

11. Pin hole:

Pin holes are similarly to blow holes but smaller into size. These are generally present at surface or sub surface and in large numbers. This is due to improper ventilation for gas and low permeability of moulding material.

12. Warpage:

It is the defect or deformation in a casting that occur during or after solidification due to different rates of solidification of different sections of casting, so stresses are set up in adjoining walls resulting in warpage these area.

13. Swell:

This defect generated due to insufficient strength of mould when metal flow to the mould due to liquid metal pressure, the wall of the mould cavity damage. It is also due to rigidity of the pattern is insufficient then it cannot withstand with the ramming pressure and the wall of cavity damage.

Today we have learnt about major casting defects and its causes. These defects can be remove by proper casting techniques. If you have any query regarding this article ask by commenting. 

Sunday, 25 September 2016

Types of Casting

In this article we will learn about types of casting used in manufacturing industries. Casting is a major manufacturing process which is mostly used in heavy industries. Most of the components like outer casing of turbine, lathe bed, valve casing, hydro turbine blades, Pelton wheel, Francis runner and many other parts of major machinery are made by the casting. The cast product has low strength compare to forging but any difficult parts can be cast by this technology.

Types of Casting:

Casting is widely used any many different shapes and material can be cast by it. There are various method of casting available which are used for different shapes and material. Casting has following types.

Sand Casting:

It is widely used for casting different process. Sand is easily available and has high refectory property so it is used in casting. It is done by following steps.

  • Design is made by using software or manually.
  • A wooden pattern is created in pattern shop. Generally patterns are made into two half and can be increased accordingly to complexity.
  • The pattern is placed into the flask and mixture of sand and clay with water pour into it. The runner, riser, core, gating system is also fit into it.
  • When the mould gets hard the pattern is removed from mould and molten metal pour into it.
  • The metal is allowed to get solidify into the casting.
  • After solidification cast is removed from casting and send to machine shop for machining.
The sand casting is used for all metal and at low cost. An another advantage is  that it can be used for very complex shape. It gives poor surface finish.

Types of Casting

Shell Casting:

It is an another method of casting and used to cast thin section like turbine blade etc. This casting is different from sand casting. A metallic pattern is used in this type of casting. It consist following steps.
  • First a metallic pattern is cast. The metal is used for casting is generally aluminum or cast iron
  • The patterns is heated up to 250 degree and put into flask.
  • The flask is filled with sand resin mixture. The resin gets solidify immediately after gating contact with heated pattern.
  • After the sand solidify the pattern and the extra sand taken out. Now a shell of cavity is created. This shell is further heated into burner which allow proper bond.
  • The metal is poured into the shell and allows to solidify.
  • After solidification cast is removed from shell and send for machining.
Types of Casting

Investment Casting:

In this type of process, wax pattern is used. The pattern is first created by wax dipped into refectory material. This refectory material make a shall outside the wax pattern. After it mould is heated which allow waxing out from mould. Now the molten metal poured into cavity formed by it and allows solidifying. The cast is taken out after proper solidification of cast and send for machining.
The main advantage of this process is that a very high accuracy and surface finish can obtain by it. It is used for complex shape and batch production.

Types of Casting

Plaster Mould Casting:

These method uses plaster mould for casting. First plaster mould is created using patterns. After removal of pattern, the plaster mould allows to dry into an oven. After dried, molten metal is poured into it and allow solidifying. After complete solidification cast is sand to the machine shop. Mostly zinc and aluminum is used as molten metal. This casting is used to create prototype.

Types of Casting

Ceramic Mold Casting

Ceramic mold casting is same as investment casting but it does not use wax pattern. The slurry of ceramic and liquid binder is pour on pattern which is easily solidify. There is no wax pattern is used so there is no limitation of size of casting. This type of casting is mainly used to cast heavy component like valve bodies, military equipment etc.

Types of Casting

Pressure Dies Casting:

This casting is mostly used to cast aluminum, lead etc. In this casting a liquid metal is pumped at high pressure into a metallic die and allow to solidify. The metal is allowed to solidify there and take out after solidification .The die is again used for next cast. It is well suitable for batch production of casting low melting point metal. It is not suitable for high melting temperature metals. The tooling cost is also high.

Types of Casting

Centrifugal Casting:

It is one of the most suitable casting processes of casting symmetrical cylindrical component. In this process a liquid metal is poured at the center of a rotating die. The die rotate and a centrifugal force act on the molten metal which forces it to towards circumference. It is used to create hollow shape. The light impurities crowed near center which is removed by machine. This process eliminates the use for core and gating system.  This type of casting is used to make pipes etc.

Types of Casting

Continuous Casting:

It is a different casting process which is used to create continuous cast. In this process we do not use mould or cope and drag. It is different in principle. In this process the molten metal poured into a trash which is connected to a copper pipe. The copper pipe is surrounded by water cooling. The metal is directly or immediately cooled after when running through pipe. The casting product takes out from other side. This process continuously run and molten metal continuously pour into it. It is used to create square or other shape simple block which further used for rolling or other process. 

Types of Casting

These all are main types of casting. If you have any doubt regarding this article, ask by commenting. 

Sunday, 11 September 2016

Gas Turbine : Types, Advantages, Disadvantages, working and Application

Today we will learn about types, advantages and disadvantages, application and working of gas turbine. There are different gas turbines which used in different conditions. Gas turbine is mainly used air as the working fluid. The air is taken from atmosphere and compressed into a compressor. The compressed air is passed through combustion chamber where it is heated. Due to continuously heating in combustion chamber, pressure and temperature of air increases. This high pressure hot air allow to flow over the moving blades of turbine, which rotate the turbine. Finally the air is exhausted into the atmosphere. This is the main process of gas turbine. The power developed by the gas turbine is used for rotate the compressor and for doing some external work.

Gas Turbine : Types, Advantages, Disadvantages, working and Application

Gas Turbines:


The gas turbine may be classified as follow.

According to the path of the working substance:

1. Closed cycle gas turbine

It is the simplest form of gas turbine, which consist a compressor, combustion chamber, gas turbine and a cooling chamber. This turbine is worked on Brayton cycle. First the air is compressed into a compressor. This compressed air is send into the combustion chamber where the fuel is burn where air is heated at constant pressure. Than this heated air is passed over the turbine, which rotate it. This expansion of air takes place issentropically. Now the air is cooled into the condenser at constant pressure and again sends to compressor. This process is run continuously which generate power. The air is again used into this system and does not exhaust into atmosphere, so it is known as the closed cycle gas turbine.
Gas Turbine : Types, Advantages, Disadvantages, working and Application

2. Open Cycle Gas Turbine:

An open cycle gas turbine consist same parts as closed cycle gas turbine except cooling chamber. It consist a compressor, a combustion chamber and a gas turbine. The compressor sucked the fresh air from atmosphere and compresses it. This compress air sends to combustion chamber where heat is added into it. Finally this high temperature air sends to gas turbine where it expands issentropically and rotates the turbine. At the end after air is fully expanded into combustion chamber it is exhausted into the atmosphere and new air sucked by the compressor. This process runs continuously to develop the power. The air does not complete the full cycle and every time new air drawn from atmosphere, so it is known as open cycle gas turbine.
Gas Turbine : Types, Advantages, Disadvantages, working and Application

According to the process of heat absorption:

According to heat absorption the gas turbine can be divided into two types.

1. Constant pressure heat absorption

This is an ideal cycle of gas turbine. The air is compressed issentropically and heat is added at constant pressure. This turbine works on Brayton cycle.

2. Constant volume heat absorption
In this turbine the gas is heated at constant volume in combustion chamber while heat is rejected into the condenser at constant pressure. This turbine works on Atkinson cycle.

Advantages and Disadvantages:


1. It requires less space for installation.
2. The installation and running cost of gas turbines are less compare to others.
3. It has very high power to weight ratio.
4. It generates less vibration compare to reciprocating engine.
5. It starts easily and quickly.
6. It can work in changing load condition easily.
7. Its efficiency is higher than IC engines.
8. It can develop uniform torque, which is not possible in IC engines.


1. Starting problem. It cannot start easily because compressor is driven by the turning itself. So an external unit is required to rotate the compressor to start the turbine.
2. Most of power is used to drive the compressor so it gives less output.
3. Overall efficiency of turbine is low because exhaust gases contain most of heat. 


The gas turbine is used where high power and speed are main consideration. Gas turbine is used in jet population unit in air craft, in ships as population unit, in supercharging system in automobile and also in electric generating station and in locomotives. The open cycle turbine is mainly used in airplanes.

Today we have discussed about gas turbine types, advantages and disadvantages, working and application. If you have doubt regarding gas turbine, ask by commenting.

Sunday, 4 September 2016

Types of Sand used in Moulding Process

In this article we will learn about types of sands used in moulding process. Sand is mostly used nonmetallic material used in moulding. Silica Sand has good refectoriness and porosity which is desirable for mould manufacturing. It has also high strength at high temperature which make it most useful material in mould manufacturing.  Basically moulding sand is the mixture of silica with water, clay and some binding agent. Different process used different types of sands.

Types of Sand used in Moulding Process:

According to their uses moulding sand can be divided into following types. 

Types of Sand used in Moulding Process

1. Green sand:

Green sand which is also known as natural sand is the mostly used sand in moulding. It is basically the mixture of sand, clay and water. The clay contain of green send is about 30% and water contain is about 8%. Clay and water used to increase binding strength of sand. This sand is mostly used to casting both ferrous and nonferrous material. It is fine, soft and has good porosity. This sand is easily available at low cost.

2. Dry Sand:

If the green sand mould is baked or dried in an oven, the moisture of this mould will be evaporate. This sand is known as dry sand. It has high strength so it can be used in large casting. The mould prepared by it, is known as dry mould.

3. Loam sand:

Loam sand is the mixture of sand and clay with water. It contains up to 50% clay and 18% water. This sand is used for big size casting. This sand does not use pattern and the mould made by sweep or skeleton pattern.

4. Facing sand:

It is main sand which is in direct contact with molten metal. It is used for making faces of mould. This sand is with direct contact with pattern. This sand dose not used in other casting or the facing sand is the fresh sand and don’t reuse. It is mainly the mixture of silica sand and clay. It has high strength and refectoriness.

5. Backing sand:

This sand is used to back up the facing sand. The total flask in poured by backing sand after pouring facing sand. It is mainly the used sand so it has blackish in color. It is used to support facing sand.

6. Parting sand:

This sand is free from the moisture and clay content. It is used to separate cope and drag. This sand does not stick with pattern.

7. Core Sand:

This sand is used to making core. This is the mixture of normal silica sand with oil. It is also known as oil sand. The oil used in silica sand is linseed oil or light mineral oil with binders. For large casting water is also add into the mixture of silica and oil.

Today we have learned about types of sand used in moulding process. If you have any doubt about this article, ask by commenting.


Properties of Moulding Sand

In this article we will learn about properties of sand which are desirable in moulding process.  A material which has high refectories can be used as mold manufacturing. There are many metallic and non metallic material used to mold manufacturing but sand is the mostly used non metallic material for moulding. It has high refectories properties and has high chemical stability at high temperature. It is easily available, cheap and can be shaped easily. These are the basic properties of sand due to which it is used in moulding.  

Properties of Moulding Sand

Sand Properties:


The basic and main sand properties for moulding are given below.  


It is the basic and most desirable properties of moulding material. It is define as the property of a material to withstand with high temperature without any crack or braking of mold, which can provide good casting. This property of sand can be extending to some extent by mixing some adhesive. The poor refectories give poor surface finish and poor casting. The degree of refectoriness depend on the SiO2 contain and grain size of the sand. The higher the SiO2 contain give higher refectoriness.


It is the property which allow to escape any gas, air and moisture contain from the mold. It is also known as porosity of sand. This property is desirable for making cast without any defect. All of these gases and air particles generated during pouring and solidification of molten metal into the mold. These particles should be removed from the mold before casting, otherwise it will generate many defects in the casting product and decrease its strength. Permeability is function of grain size, moisture and clay contain.


Cohesiveness is the property due to which the sand particle attracts each other within the mold. It is the property which increases the binding capacity of moulding sand which make good mold.

Green strength:

It is known as the strength of sand mold mixed with water. The sand mixed with water should have sufficient strength and toughness to handle the mold. Green strength of sand is mostly depends on the adhesive and cohesive property of sand. Adhesive is property by virtue of which the sand particles attract other particles which makes strong bond between sand, clay and moisture particle. It is desirable for strong mold. The cohesiveness of particle is desirable to taking out the pattern from the mold without breaking it. The green strength is depends the grain size, clay contain and moisture contain in the sand.

Dry strength:

When the molten metal gets contact with the mold, the moisture of adjacent layer evaporates which makes it dry. So the dry strength of sand should be sufficient enough so it can be withstand with molten metal.
Flow ability and plasticity
It is the ability of sand which allows it to flow like fluid into the mold. This property of sand is required to make uniform mold. It allows the sand particle to flow all over the mold during ramming process. It increases with decreasing in green strength. It is also depends on the grain size, clay and moisture content.


It is the property of sand due to which sand particles attract other particles. It is desirable for the making strong mold.


This property of sand is required to avoid cracks in casting after solidification. After the molten metal get solidified into the mold, the mold should be collapsible which allow free contraction of metal which avoid tearing and cracking of casting product.

These all are desirable properties of sand which allow the sand to use in moulding process. It you have any doubt about this article, ask by commenting.