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. 
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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:


Types:

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:


Advantages:

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.

Disadvantages:

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. 

Application:

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.
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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.

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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.  

Refectoriness:

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.

Permeability:

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:

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.

Adhesiveness:

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

Collapsibility:

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.
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Wednesday, 31 August 2016

Difference between 2 Stroke vs 4 Stroke Engine

Today I am going to tell you about main difference between 2 strokes vs 4 stroke engines. We all heard about both of these engines but few of us know the basic differences between them. Before discussing on this topic first you should know about stroke. The stroke in an engine is the distance covered by the piston from top dead center to the bottom dead center. In simple words, stroke is the distance of cylinder between piston moves. If a piston moves 2 times in the cylinder, that means, engine is known as two stroke engine and if it moves 4 times in a four stroke engine. The crankshaft rotates one time between 2 strokes.

Difference between 2 Stroke and 4 Stroke Engine

The basic and main difference between two stroke and four stroke engine is that the crankshaft complete one revolution in one power stroke in 2 stroke engine and complete 2 revolution in one power stroke in four stroke engine. So the 2 stroke engine give high power compare to 4 stroke engine but the 4 stroke engine is more fuel efficient. There are many other differences which are given below.

Difference between 2 Stroke vs 4 Stroke Engine



S. No.


Two Stroke Engine

Four Stroke Engine

1.

It has one revolution of crankshaft within one power stroke.


It has two revolution of crankshaft between one power strokes.

2.

It can generate high torque compare to 4 strokes engine.


It generates less torque due to 2 revolution of crankshaft between one power strokes.


3.

It used port to inlet and outlet of fuel.


It used valve to inlet and outlet.

4.

2 stroke engines require lighter flywheel compare to other engines because it generates more balanced force due to one revolution for one power stroke.


It requires heavy flywheel because it generates unbalance force due to two revolutions for one power stroke.

5.
The charge is partially burn and mix with the burn gases during inlet. It is due to port mechanism.

In four stroke engine charge is fully burn and does not mix with burn charge in ideal condition.

6.

Easy lubrication due to lubrication oil mix with the fuel.


Comparatively complicated lubrication.

7.

More lubricating oil requires because some oil burns with fuel.

Comparatively less lubricating oil requires.


8.

These engines give less thermal efficiency.


These engines give more thermal efficiency.

9.

It has high power to weight ratio compare to others.


4 stroke engines have less power to weight ratio.

10.

It creates more noise.


It is less noisy.

11.

Two stroke engines are less efficient and generate more smoke.


Four stroke engines are more efficient and generate less smoke.

12.

These engines are comparatively cheaper.


These engines are expansive due to valve and lubrication mechanism.


13.

These engines are easy to manufacture.

These engines are comparatively hard to manufacture.


14.

These engines are generally lighter.

These engines are comparatively heavier than 2 strokes due to heavy flywheel and valve mechanism.


15.

These are mostly used in ships, scooters etc.


These engines mostly used in car, truck, and other automobiles.

16.

Due to poor lubrication more wear and tear occurs


Less wear and tear occurs.


These are all about between difference between 2 stroke and 4 stroke engine. If you have any query regarding this article, asks by commenting. 
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Diesel Cycle vs Otto Cycle

Today we will discuss about difference between Diesel cycle vs Otto Cycle. Both these cycle are air standard cycles of automobile engines. Otto cycle is used for petrol or spark ignition engine while diesel cycle is used for diesel or compression ignition engine.
Diesel Cycle vs Otto Cycle

The main difference between Otto cycle and Diesel cycle is that in Otto cycle heat addition takes place at constant volume and in diesel cycle heat addition takes places at constant pressure. This is the major difference between Otto cycle and diesel cycle. There are many other differences which are described below.

Diesel cycle vs Otto Cycle:



S.No.


Otto Cycle

Diesel Cycle

1.

Otto cycle is given by the Nicolas Otto in 1876.


It was given by Dr. Rudolph Diesel in 1897.

2.

It is ideal cycle for petrol engine.


It is ideal cycle for diesel engine.

3.

Otto cycle has higher thermal efficiency.


It has lower thermal efficiency.

4.

This cycle has comparatively low compression ratio. It compresses the mixture up to 11:1 ratio.


Diesel cycle has high compression ratio. It compresses the mixture up to 22.1 ratios.

5.

Otto cycle engine used spark plunge to ignite the air fuel mixture.


Fuel automatically ignites due to high temperature of compressed gas.

6.

Heat addition takes place at constant volume.


Heat addition takes place at constant pressure.

7.

Air fuel mixture drawn into the cylinder during intake stroke.

Once air is drawn into intake stroke. Fuel is injected after end or compression stroke by an injector.


These are all about Otto cycle and diesel cycle. If we have missed something, kindly let us know through commenting.  
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Monday, 15 August 2016

Types of Fluid Flow : Laminar and turbulence flow

Today we will learn about fluid flow. There are many types of fluids which are used in different conditions. The flow of fluid is also as much important as its types because it decide the appropriate application of it.

Types of Fluid Flow :  Laminar and turbulence flow

Types of Fluid Flow:


Fluid flow may be classified according to following ways.

1. Steady and Unsteady flow:

The flow in which characteristics of fluid like velocity, temperature, pressure, density etc. do not changes at a point with time is known as steady flow.

The flow in which characteristics of fluid changes with time at a same point is known as unsteady flow.


Types of Fluid Flow :  Laminar and turbulence flow

2. Uniform and Non Uniform flow

The fluid flow in which the properties of fluid like pressure, temperature, velocity etc. changes with respect time but does not changes with respect position is known as uniform flow.

The fluid flow, in which the properties of fluid like pressure, temperature, velocity etc. changes with respect time as well as with respect position, is known as non-uniform flow.


Types of Fluid Flow :  Laminar and turbulence flow

3. Laminar and turbulence flow

The fluid flow, in which the adjacent layers do not cross each other and move along we define path is known as laminar flow. In this flow, fluid flows along the straight line.

The flow in which adjacent layers cross each other and do not move along well defined path is known as turbulence flow.

Types of Fluid Flow :  Laminar and turbulence flow

4. Rotational and Ir-rotational flow

If the fluid particles flowing along stream lines also rotate about their own axes, then flow is known as rotational flow.

If fluid particles do not rotate about their own axes, then flow is known as irrotational flow.

5. Compressible and In-compressible flow

If the density of fluid varies from point to point in the flow, the flow is known as compressible flow.

If the density of fluid remains constant through the flow, the flow is known as incompressible flow.

We have discussed about types of fluid flow. If you have any doubt regarding this article, ask by commenting.
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