Mild Steel Specification, Properties And Uses

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Steel is the most used material in many industry. types of steel depends on the percentage of different elements in the steel. these elements decides the properties of the steel. changing the composition of steel will also cause the change in properties of steel. here we will discuss a special type of steel i.e. "Mild Steel".
mild steel rods


What Is Mild Steel

Mild steel is an industrial material.It is Commonly used type of Steel. It is used for many purposes and man industries because of its properties and advantages. It is most economical form of steel and that is why it is most used Steel for many purposes.

Mild Steel is basic type of carbon Steel. The Carbon Steel has the carbon percentage range 0.08% to 1%. 

Mild steel is a low carbon steel and it has the percentage of carbon 0.15% to 0.3%.

Mild steel properties

Mild steel is a type of low Carbon Steel because it has very low amount of carbon. The hardness of the Steel depends on the amount of carbon in it. If the amount of carbon is higher, the ductility of the material will be low. This theory makes the mild steel a ductile material as it contains less amount of carbon in it.

Mild steel contains 0.15 % to 0.30% of carbon. Below this percentage the Steel is called dead Steel. And above this percentage of carbon steel is called high Carbon Steel.

As mild steel is not an alloy Steel so it will not contain other elements prominently. Other contents like chromium, molybdenum, silicon, Manganese etc will be in very few percentage which will not affect much to its properties.

Due to great ductility and malleability, mild steel can be used for many purposes like wiring, pipe drawing, thin sheet making, kitchen utensil manufacturing etc.

The low amount of carbon causes the less brittleness in the material but the amount of carbon is sufficient enough to make the Steel hard. So where ever the combination of less brittleness and good hardness is required mild steel can be a better choice for the manufacturers.

mild steel material has the property of conduction of electricity. So it can be used for many electrical purpose is like wiring, welding etc.

Mild steel has the ferromagnetic properties. So it can be used for magnetocaloric purposes and for other magnetic are electric devices.

Mild steel is widely used in manufacturing industry because of it's great machinability. This important property makes the mild steel to be used in big industries like construction, automobile and pumps etc.

Mild steel is the cheapest of carbon Steel and it is the most used steel in the world.

The environment can cause the corrosion or rust on the mild steel. It causes in the mild steel because of absence of alloying elements because alloying elements have very low percentage in the mild steel. So this should be taken care of during assessment of the material selection. One should use stainless steel if he wants rust free products.


Mild Steel Grades

According to Indian Standard 2062, there are nine mild
steel grades specified.
  1. Fe250 or E250
  2. Fe275 or E275
  3. Fe300 or E300
  4. Fe350 or E350
  5. Fe410 or E410
  6. Fe450 or E450
  7. Fe550 or E550
  8. Fe600 or E600
  9. Fe650 or E650
Where number denotes the value of tensile strength in MPa.

Mild steel uses

It is widely used in automobiles.

That is very suitable for structural purpose like Truss.

It can be used in furniture to provide the strength.

The wires of mild steel can be drawn.

The nails and fencing are commonly made of mild steel.

Conclusion

The properties of the mild steel is the main reason of its use worldwide. this material offers great ductility, malleability, Machinability, Weldability in the operation in the cheapest price. which makes mild steel a special material.

Scissors mechanism

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A scissors mechanism uses linked, folding supports in a criss-cross 'X' pattern.






Working of Scissors Mechanism

Extension is achieved by applying pressure to the outside of a set of supports located at one end of the mechanism, elongating the crossing pattern. This can be achieved through hydraulic, pneumatic, mechanical or simply muscular means.
It may require no power to return to its original position, but simply a release of the original pressure.also used in kinematic of mechanisms

Uses
This mechanism is used in devices such as lift tables and scissor lifts. Modern low-profile computer keyboards make an extensive use of it as well, installing each key on a scissor support to ensure their smooth vertical movement, allowing the use of a cheap and reliable rubber dome contact set, instead of expensive and colmplex array of mechanical switches.

Magnetic Refrigeation or Magnetic Cooling System, Refrigeation Principle And Working

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Magnetic refrigeration is a new technology which seem to brought the revolution in the refrigeration industry because of its advantages over general electric refrigerator.


As you all know the sole purpose of refrigeration is to remove the heat from an enclosed area and place That heat somewhere else. 
It's a cooling Technology and In this process the magnetocaloric effect principle is used.

in the system a controlled magnetic field in introduced. this system will be able to create a series of magnetization and demagnetization pattern. these patterns will create a temperature gradient in the material.. this series of magnetization and demagnetization will set a system to provide hot or cold temperature as per the requirement. 

 This technology is developed to replace the conventional vapour compression refrigeration system because that system is very harmful for the environment as it emits many  harmful gases like CFC, HFCS etc. 

Although magnetic refrigerators used for Industrial and research purpose. This technology is very efficient as compared to Vapour compression refrigeration system. This technology still hard to use for house purpose is because of its high cost intense magnetic field. Researches assured that in future devil make this technology to used for commercial purposes.

In this Technology very low temperature can be achieved. And the temperature can also be manipulated as per requirements

Magnetocaloric Effect

Magnetocaloric Effect

This effect is found on a material kept in a varying magnetic field. If an object is placed on a varying magnetic field the temperature change will takes place. if the material is brought towards the magnetic field the temperature of the material will increase and when the material will move away from the magnetic field the temperature of the material will decrease.
the maximum or minimum temperature according to this effect also depends on the properties of material.

Thermodynamic cycle

The Refrigeration cycle of magnetic refrigeration is analogous to carnot Refrigeration cycle. But the process the magnetic field varies so the strength of the system also increases and decreases.


Magnetic refrigeration working cycle


The thermodynamic cycle of magnetic refrigeration is described as following

1. Adiabatic Magnetization

In this process of the cycle nature of the substance will increase. The dipoles of the magnetochloric material will get aligned if they are placed in an insulated environment. In this Process and entropy of the material will decrease and so as the heat capacity.

2. Isomagnetic Enthalpy Transfer

The heat added in the previous process will be removed through a fluid. To avoid the heat reabsorbing by the dipoles the magnetic field will kept constant. The external fluid is introduced for this process. Once the process is completed i.e. The substance is sufficiently cool, the coolant will be separated from the system.

3. Adiabatic Demagnetization

In this stage the magnetic field surrounding to the material will be reduced. Will remain constant in this process. Because of the thermal energy the magnetic Moment will overcome the magnetic field. It will cost the material to cool. 

4. Isomagnetic entropic transfer

By keeping the magnetic field constant material will be prepared prevented from reheating.
The material is kept in contact with the environment that is to be refriderated as the sample is cooler rough related environment, heat energy transfer into the working material. 

Magnetocaloric materials of refrigerant

Refrigerant which has the quality of high entropy change at the working temperature this type of refrigerator type of refrigerator under the magnetic field is desirable.

The paramagnetic salt is proposed as the refrigerant  But the temperature above 40K paramagnetic material cannot be used as the temperature variation is very small in the magnetization process. In the magnetic refrigeration we need low temperature because the heat capacity of material increases with the temperature and the entropy change produced by magnetic field is not enough to get the required temperature variation in the paramagnetic material. 

The ferromagnetic material have property of changing the temperature very rapidly and it can produce magnetic field variation in this temperatures. So for the high temperatures ferromagnetic material as refrigerant is preferred while for the low temperatures paramagnetic material can be used
 Paramagnetic salt can become a diamagnetic or ferromagnetic so the lowest temperature required can be achieved by this method.

Advantages of Magnetic Refrigeration

Following are the advantages that Magnetic Refrigeration offers-

Reduce noise and vibration

The system has the ability to reduce the noise and vibration during its operation.

Safety

The magnetic refrigeration system has better safety for its users because it's a low pressure system. As the system do not use gaseous refrigerant so the danger of hazardous leakage of the gas can be eliminated. The magnetic emissions in this system is very low so this is also a safety feature.

Energy saving

The system can save the energy up to 50%. In the world changing so fast it is a need for our future to adopt a environmental friendly technology.

Cost reduction

The technology is in development phase for domestic use. As It requires low level of maintenance, it can reduce the cost of operation for the users.


Gear Materials ( Gear Manufacturing)

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Material to manufacture a gear is selected as per the strength needed. the material that can sustain a wear and noise etc. Based on the requirement, the metal or nonmetal material can be choosen for gear manufacturing.

Metals like Steel, cast iron, bronze and a non metal like wood, compressed paper, synthetic resins etc can be choosen as the material for gear manufacturing. Non metallic gear material is preferred when there is a need to reduce the noise in the gear operation.

Gear material properties
To select an appropriate material for gear, it should have following properties
1. Good machinability
2. High tensile Strength to bear the load and prevent failure
3. Coefficient of friction should be low.
4. High endurance to wear dynamic loads.

Factors to select gear material
There are many factors on the basis of which a gear material should be selected.
Strength, durability, machinability, endurance, cost are some factors under which a material can be selected.

Gear Terminology ( Terms Used In Gear )

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The following are the terms used in Gears. During the design and calculation of the gears these terms are considered.
Gear Terminology

Pitch Circle

Pitch Circle Is an imaginary circle where two gears will meet as two cylinders with Zero friction.

Pitch circle diameter

It is an important parameter because pitch Circle diameter is used to define the size of the gears. It is simply the diameter of the Pitch Circle.

Pitch point

The point where to Pitch Circle meets is referred as pitch point.

Pitch surface

The surface at the pitch point of the Rolling cylinder replaced by meshing gears.

Pressure angle or obliquity

Angle between the common normal to the point of contact of two gears and the common tangent in the Pitch Circle. It is also called obliquity.
The standard obliquity are 14½° and 20°.

Addendum

The radial distance of a tooth from the Pitch Circle to the top of the tooth is called addendum

Dedendum

The radial distance of a tooth from the Pitch Circle to bottom of the tooth is called dedendum.

Addendum circle

The circle from the top of the tooth which is corecentric to the Pitch Circle

Dedendum circle

A circle from the bottom of the tooth which is Cocentric to the Pitch Circle.

Circular pitch

In the pitch circle distance between two identical points of two consecutive teeth or distance between a point in a tooth and some point on the nearby gear is called circular pitch
Pc=πD/T

Diametral pitch

The ratio between number of teeth and pitch circle diameter

Module

The ratio between pitch circle diameter and number of teeth. It is inverse of diametral pitch

Clearance

The radial Distance from the top of the tooth to the bottom of the tooth in a mating gear is called clearance.

Full depth

Distance between addendum circle and dedendum circle or the sum of addendum and dedendum is called full depth.

Working depth

Distance between addendum Circle to the clearance circle is called working depth.

Tooth thickness

The thickness of tooth along the Pitch Circle is called tooth thickness.

Tooth Space

The space between two consecutive teeth along the Pitch Circle is called tooth space.

Backlash

The difference of toothpaste and tooth thickness is called backless, or in a meeting gear the space between two teeth is called backlash.

Face of tooth

The surface of tooth above the Pitch Circle called face of tooth.

Flank of teeth

The surface below the Pitch Circle is called flank.

Topland

The top surface of a gear is called topland.

Face width

Width of the tooth parallel to the gear rotation axis is called face width.

Gear profile

A Curve formed by the face and the flank of the tooth

Fillet radius

In The root of a gear teeth a fillet is provided. And the radius That connect the root circle and profile of the tooth is called fillet radius.

Path of contact

It is path of point of contact of two mating gears from beginning to the end of the gear meshing.

Arc of contact

In the mating gear the path of a point on the pitch circle is called arc of contact.

Arc of approach

It is a path of a point on pitch Circle of mating gear from the point of engagement to the pitch.

Arc of recess

Path of point on Pitch Circle of two mating gears from the point of disengagement.

Mechanical Governor (Device), Working Principle, Types and Function of Governer

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A mechanical governor is a device used to control the speed of machine such as vehicle engine. It governs the speed of engine. It is used in small engine to large engine. It also used in car engines.

 It makes the engine to run at the speed you want it to run. even with varying loads controlling speed of engine. In the modern vehicle there is always a need of  varying the load. This device helps to control the speed with varying loads and make compliance with requirements.
fig mechanical governer ( image source )


When there is increase in load, it causes the speed of engine to decrease and when there is decrease in load, it causes the speed of engine to increase. Increase in load needs more fuel to maintain the speed and when load decreases engine need less fuel to supply. Governor performs the task to maintain the proper supply of fuel according to the need of the engine.

How mechanical Governor works

Mechanical Governor has two balls of equal weights attached to the arms of the Governor. These balls called Governor balls. These balls revolve when spindle of governor rotates.

The upper end of the arms is attached with the spindle. This makes the ball to move up and down while rotating with respect to vertical axis. The lower side arms are linked to the sleeve which revolves along with the spindle. This also makes the sleeve to move up and down while revolving.

When speed increases the sleeve goes upward and tends to go down wards with the decrease in speed. Stopper in the spindle controls the movement of sleeve and a lever will connect the sleeve to throttle valve. This mechanism controls the fuel supply appropriately.


Types of governor

 Governors mainly divided into two types, although they are further subdivided into several parts. Two main types of governor are following
1. Centrifugal governor
2. Inertia governor


Centrifugal governor

Centrifugal Governor detects change in speed with the help of gear and flyweight. This Governor balance the centrifugal force of the rotating Ball by equal and opposite radial for controlling force. Flyweight helps the Governor change in speed. The rotating balls will be opposite to each other and have the same weight.

If we operate a small, lightweight engine which beer is light load, then the carburetor will supply the amount of air fuel mixture to combustion chamber.
Then the crankshaft will start spinning and the centrifugal force cause the flyweight to open. the pressure is applied on governor and crank. The Crank is Linked with throttle valve and the action will cause the fly weights to pull the throttle valve to the closed position.

If the load Of the crankshaft is increased then it will cause the flyweight to spin slowly, and the centrifugal force will decrease and it will not completely pull the throttle valve to the closed position and therefore the air fuel supply will be increased


Inertia governor

Inertia Governor are quit different from centrifugal governor because it works on different principle. The Governor balls are arranged such that the inertia force generated from the angular acceleration of the Governor shaft tend to change their positions. The displacement of the balls is controlled by Spring and mechanism of governor. Through this the supply of air fuel mixture can be controlled.

In this governor the positions of the balls depends on the rate of change of speed of the Governor shaft. Because of this the quick response will be obtained as we change the load. This type of governor takes action due to acceleration and not due to finite change in speed.

 Centrifugal governor is preferred over inertia governor because inertia Governor have practical difficulty of arrangements expected balance of revolving parts.



Press working terminology

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Press is very important machine of manufacturing industry. The sheet metal industries fully dependent on press machines. Press provides Metal cutting operation in just one blow.

In the Press machines die is used.It is designed according to the design of the product that you want to manufacture. Press can perform many operations. To read these operations please click here.

The figure of a Press die is shown below


The main components of press machine are described below.


Bed

The lower part of press machine is called bed. It is like a table which bears all the load of press. It is stationery portion. Boister plate is mounted on this part.

Boister plate

The part which is used to Mount the die assembly is called boister plate. It support the die block and locate it at right place.

Die set 

It is an assembly which has two or more parts. It is Design according to the final product required. It is usually have one upper part and one lower part.

Die block

This part has the cavity of required part.

Lower Shoe

Die block is mounted on the lower Shoe and lower shoe is mounted on the boister plate. So basically it is the lower part of the shoe.

Punch

This part is fastened with the moving part Ram in the press. This is male part of die set which produce required shape in the component with the use of pressure.

Upper shoe

The upper part of die set is called upper shoe.

Punch plate 

The punch plate is one which uphold the punch. It is also called panch retainer.

Backup plate

This place is used tu prevent the excessive pressure that damages the die. This place distributes the pressure in a wide area of plate to decrease the intensity of pressure. Therefore it prevents the punch holder from crushing.

Stripper

This is a plate used to hold the specimen on the die. It strip out the metal strip off the punches.