Types of joints in welding

There are mainly five types of joints are used in welding for joining two parts of metal. 

• Butt Joint
• Corner Joint
• Lap Joint
• Tee Joint
• Edge Joint 

Now let we discuss joints in details :

• Butt joint :

A butt joint is a technique in which two metal parts lie in the same plane and are jointed at their edges without any special shaping.

• Corner joint :

A cornet joint is a technique in which two metal parts located at right angles to one another in the form of the shape of L are joined at the centre of the angle.

It is used to connect two parts together and forming a corner.

• Lap joint :

A lap joint is a technique in which two metal parts are overlapped that are joined.

• Tee joint :

A tea joint is a technique in which two metal parts those surfaces are located approximately 90⁰ to each other that can be welded from both sides. 

• Edge joint :

An edge joint is a technique in which two metal parts joined by two edges and making a corner.

All these types of joints used when the thickness of the two metal parts to be joined is small so that heat of welding penetrates the full depth of the joint.

However, when the thickness increases, it becomes necessary to prepare the edge in such a way that the heat is able to penetrate the entire depth.

For very thick metal plates, the welding needs to be done from both sides. To provide necessary access into the joint, it could be made as to the following joints :

• V - Joint 
• U - Joint 
• J - Joint
• Bevel Joint 

In single joint welding is to be carried out only one side while in double joints the edge preparations are used when welding is to be carried out both sides.

Heat transfer

In this article, we will discuss the heat, heat transfer and different modes of heat transfer. Now, first of all, we check it out what is the heat ?

Heat is the quality of being hot OR Intensity of high temperature. 

Heat is defined as the form of energy that is transferred across a boundary by virtue of a temperature difference.  

The temperature difference is the potential or force and the heat transfer is called the flux.

The transfer of heat normally from a high-temperature object to a lower temperature object.

Heat transfer :

The heat is transferred between two bodies which are in direct contact is called conduction.

Heat may be transferred between two bodies separated by empty space or gases by the mechanism of radiation through electromagnetic waves.

The transfer of heat between the wall and a fluid system in motion is called convection. 

All the above are the modes of heat transfer. The direction of heat transfer is taken from high-temperature system to the low-temperature system.

Heat flow into the system is taken to be positive and heat flow out of a system is taken as negative.

For denote, heat transfer symbol is used is Q.

There is no heat crosses the boundary of the system this process is called adiabatic process.
Thus, an adiabatic process is one in which there is only work interaction between the system and its surrounding.

A wall which is impermeable to the flow of heat is called an adiabatic wall.
A wall which permits the flow of heat is called a diathermic wall.

The unit of heat is Joule in S.I Unit system.

The unit of heat transfer is kW or W.

Work transfer and Heat transfer

In this article, we will discuss the work transfer and heat transfer properties and also some similarities between both of them then the difference between them.

Points to remember regarding heat transfer and work transfer :

• Work and heat transfer both are energy interactions.
• The same effect in a closed system is about either by heat transfer or by work transfer. 
• Both heat transfer and work transfer are boundary phenomena.
• Heat transfer is one type of energy interaction and it is due to temperature difference. All other energy interactions may be termed as a work transfer.
• Heat or work is not a property of the system. It cannot be stored by the system. Both heat and work are energy in transit.
• Both heat and work are path functions and inexact differentials. 
• The magnitude of heat transfer or work transfer depends upon the path of the system that follows during the change of state.

Difference between heat transfer and work transfer :

Heat transfer is an interaction of energy between a system and its immediate surrounding due to temperature difference. 

Work transfer is the interaction of energy between a system and its immediate surrounding due to property difference other than temperature.

Work transfer in thermodynamics

A close system and its surroundings can interact in two ways :

• By work transfer 
• By heat transfer 

Both are those are called interactions and these bring about changes in the properties of the system. 

In thermodynamics mainly studies these energy interactions and the associated property changes of the system.

Work Transfer :

Work is one of the basic modes of energy transfer. In mechanics, the action of a force on a moving body is called work. A force is a means of transmitting an effect from one body to another. An effect of that certain distance can be performed by a body. The product of force and distance is the same to accomplish the same effect. 

What is work?

The work is done by a force as it acts upon a body moving in the direction of the force.

The action of a force through a distance is called mechanical work. The product of the force and distance moved parallel to the force is the magnitude of mechanical work.

W = F * d

In thermodynamics, work transfer is considered as occurring between the system and the surroundings.

Work is said to be done by a system if the sole effect on things external to the system can be reduced to the raising of a weight.

When work is done by a system, it is arbitrarily taken to be positive.

When work is done on a system, it is taken to be negative. 

The symbol used for work transfer is W.

The unit of work is N.m or Joule. 1 N.m = 1 Joule 

The rate at which work is done is called power.

There are various types of work transfer which can get involved between them. 

• pdV work
• Electrical work 
• Shaft work 
• Paddle-wheel work or Stirring work 
• Flow work 
• Work was done in stretching a wire
• Work was done in changing the area of a surface film
• The magnetization of a para-magnetic solid

TDI full form

What is the full form of TDI?

Answer :

• Turbocharged Direct Injection 

What does TDI mean?

It uses direct injection where a fuel injector sprays atomized fuel directly into the main combustion chamber of each cylinder and are also fitted with turbochargers to boost power output.

It is a very popular latest technology nowadays are used in many automobile companies like Tata Mahindra, Toyota, or Volkswagen.

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CRDI full form

What is the full form of CRDI?

Answer :

• Common Rail Direct Injection 

What does CRDI mean?

CRDI is the direct fuel injection system for petrol and diesel engine. 

Direct injection of the fuel into the cylinders of a diesel engine via a single or common line called common rail which is connected with all fuel injectors.

The common rail system accumulates high-pressure fuel in the common rail so that the fuel to be atomized and injects the fuel into the cylinder at a timing controlled by the Electronic Control Unit alloying high-pressure injection independent from the engine speed. 


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Emissions norms in India

Emission norms are statutory requirements that set specific limits to the amount of pollutants that can be released into the environment. Norms focus on regulating pollutants released by automobiles and from industries and power plants. The pollutants in general that are regulated are NO_x, sulfur oxides, CO or volatile hydrocarbons.

In USA, emission standards are managed by the Environmental Protection Agency ( EPA ).
The state of California has special dispensation to promulgate more stringent vehicle emissions standard.

The European Union has its own set of emissions standards that all new vehicles must meet. The European Union is to introduce Euro 4 effective from January 1, 2008. Euro 5 effective from January 1, 2010 and Euro 6 effective from January 1, 2014.

The first Indian emission regulations were ideal emission limits which became effective in 1989. Indian started adopting European Union norms and fuel regulations for four-wheeled light-duty and for heavy-duty vehicles. 

History of emissions norms in India :

• 1991 

Ideal CO Limits for Gasoline Vehicles and Free Acceleration Smoke for Diesel Vehicles, Mass Emission for Gasoline Vehicles.

• 1992 

Mass Emission Norms for Diesel Vehicles.

• 1996 

Revision of Mass Emission Norms for Gasoline and Diesel Vehicles, mandatory fitment of Catalytic Converter for Cars in Metros on Unleaded Gasoline.

• 2000

India 2000 ( equivalent to Euro I ) Norms, Modified IDC ( Indian Driving Cycle ), Bharat Stage II Norms for Delhi.

• 2001 

Bharat Stage II ( equivalent to Euro II ) Norms for All Metros, Emission Norms for CNG and LPG vehicles.

• 2003

Bharat Stage II ( equivalent to Euro II ) Norms for 11 major cities.

• 2005 

From 1st April Bharat Stage III ( equivalent to Euro III ) Norms for 11 major cities.

• 2010 

Bharat Stage III Emission Norms for 4-wheelers for entire country whereas Bharat Stage - IV ( equivalent to Euro IV ) for 11 major cities.

Disadvantages of liquid cooling system

The liquid cooling system takes away the excessive heat generated in the engine and saves it from overheating. It also keeps the engine at working temperature for efficient and economical working. Let us have a deep insight into the disadvantages provided by using this liquid cooling system. 

Disadvantages of a liquid cooling system :

• This is a dependent system in which water circulation in the jackets is to be ensured by additional means.
• Power absorbed by the pump is considered for water circulation and this affects the engine's power output.
• Cost of this system is considerably high.
• System requires considerable maintenance of its various parts.
• In the event of cooling system failure, serious damage to the engine may occur.

Advantages of liquid cooling system

The liquid cooling system takes away the excessive heat generated in the engine and saves it from overheating. It also keeps the engine at working temperature for efficient and economical working. Let us have a deep insight into the advantages provided by using this liquid cooling system. 

Advantages of the liquid cooling system :

• The compact design of engines with an appreciably smaller frontal area is possible.
• The fuel consumption of the high compression liquid-cooled engine is lower than that of the air-cooled engine.
• Because of even cooling of cylinder barrel and head due to jacketing makes it possible to reduce the cylinder head and valve seat temperature.
• Installation is not necessarily at the front of the mobile vehicles, aircraft as the cooling system can be conveniently located wherever required. This is not the case in the air-cooled engine.
• The size of engines does not involve serious problems as far as the design of a cooling system is concerned.
• In case of air-cooled engines particularly in high horsepower, range difficulty is encountered in the circulation of requisite quantity of air for cooling purposes.

Disadvantages of air cooling system

Air cooling system is carried out to the outer parts of the engine is radiated and driven away by the air stream obtained from the atmosphere. For efficient cooling fins are provided around the cylinder and cylinder head to increases the contact area. Air colling system mainly depends upon the following factors. 

• The total area of fin surface
• The velocity and amount of the cooling air
• The temperature of fins and of the cooling air 

Let us have a deep insight into the disadvantages provided by the air cooling system. 

Disadvantages of air cooling system : 

• It can be applied only to small and medium engines.
• Cooling is not uniform.
• In places where ambient temperatures are lower.
• Higher working temperatures compared to water-cooling.

Advantages of air cooling system

Air cooling system is carried out to the outer parts of the engine is radiated and driven away by the air stream obtained from the atmosphere. For efficient cooling fins are provided around the cylinder and cylinder head to increases the contact area. Air colling system mainly depends upon the following factors. 

• The total area of fin surface
• The velocity and amount of the cooling air
• The temperature of fins and of the cooling air 

Let us have a deep insight into the advantages provided by the air cooling system. 

Advantages of air cooling system : 

• The design of engines becomes simpler because no water jackets are required in this system.
• The cylinder can have identical dimensions and be individually detachable and therefore cheaper to renew in case of an accident.
• No danger of coolant leakage.
• Minimum maintenance problem because of the absence of cooling pipes and radiator.
• The engine is not subject to freezing trouble.
• The weight of the air-cooled engine is less than that of the water-cooled engine.
• Power to weight ratio is improved in this system.
• An engine is rather a self-contained unit as it requires no external components like radiator, header, tank etc.
• Installation of air-cooled engines is very easy.

Difference between annealing and normalizing

What is annealing?

The heat treatment process that alters the physical and sometimes chemical properties of a material to increase its ductility and reduce its hardness and making it more reliable and workable is called annealing.

What is normalizing?

Normalizing is also heat treatment process that mainly considered for thermal and microstructure properties used to relieve internal stresses, refine the grain size and improve mechanical properties. 

Let us have a deep insight into the comparison between annealing vs normalizing. 

Basic Difference :

Annealing: It is the process of heating metal in a furnace above its. recrystallization temperature and allows it to cool inside the furnace. 

Normalizing: The process is similar to that of annealing, but after soaking stage the material is taken out from the furnace and allowed to cool in the atmosphere.

Definition :

  

Annealing: It is a method of heat treatment used to make metals ductile and less hard.

Normalizing: It is a type of annealing process which is only specific to ferrous alloys.

Cooling process :

Annealing: The metals can be cooled down after heating either by cooling them in the air or quenching them in water.

Normalizing: It is important that the cooling process takes place slowly in this process so that it is always cooled in air and not quenched in water.

Grain Size : 

Annealing: It is not crucial to achieving a uniform grain size during the process.

Normalizing: Obtaining a uniform grain size is important for the process.

The hardness of the final product : 

Annealing: The metals are made to be less hard and ductile after annealing.

Normalizing: The alloys remain harder after normalizing when compared to a full annealing process.

Purpose :

Annealing: To increase some of the properties like ductility, softness, toughness, fine grain size and machineability so this reduces the hardness. 

Normalizing: To increase machinability, hardness to attain fine grain size than attained during annealing less softness and ductility.

Process :

Annealing: Heating the steel to a defined temperature and cooling it in a conditioned atmosphere like in furnace. 

Normalizing: Heating the steel to the above austenitic range and cooling in air.

Internal Stresses : 

Annealing: Internal stresses are least.

Normalizing: Internal stresses are slightly more.

Pearlite design : 

Annealing: Pearlite is coarse.

Normalizing: Pearlite is fine.

Cost :

Annealing: More expensive as it uses ovens.

Normalizing: Less expensive than annealing.

SFC full form

What is the full form of SFC?

Answer :

• Specific fuel consumption

What does SFC mean?

It is an automobile term that is used to describe the fuel efficiency of an engine. 

It describes the efficiency of an engine also an important parameter to decide how good engine performance is?

SFC is inversely proportional to the thermal efficiency of the engine.


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What is SFC

In this article we will discuss about the SFC and their full form and some basic introduction about SFC with the use of example. Let we first know the full form.

Full form of SFC is specific fuel consumption.

Specific fuel consumption is describe efficiency of an engine design with respect to thrust output it expressed in terms of kilograms of fuel per kilowatt-hour.

It is important parameter that reflects how good the engine performance is.

It is inversely proportional to the thermal efficiency of the engine.

Specific fuel consumption of air-breathing jet engines at their maximum efficiency varies more or less inversely with speed.

which means that the fuel consumption per or per km can be a more appropriate comparison for aircraft that travel at very different speeds.

SFC = Fuel consumption per unit time / Power 

It also called as thrust specific fuel consumption (TSFC)

SFC is dependent on engine design, but differences in the SFC between different engines using the same underlying technology tend to be quite small. 

SFC varies with throttle setting, altitude and climate.

What is creep

What is creep ?

Answer :

Creep is defined as slow and progressive deformation of the material with time under a constant stress.