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Surface finish measurement types and its Explanation

2021-01-23T00:02:00.017+05:30

Hey guys, welcome to MechGeni! In this post we are going to explain about different types of surface finish measurements and its detailed explanation.

Before going to start about verify whether you read our past article about

- surface finishing and its Terminologies

so that you may get more accuracy in understanding the types.

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Surface Finish Measurements

There are two methods which are used for measuring the finish of the machined part.

Surface inspection of the comparison method

Direct instrument measurements

Surface Inspection of Comparision Method

In comparison methods, the surface finish is assessed by observation of the surfaces. But these methods not reliable as they misleading if the comparison is not made with a surface made by the same techniques.

There are various methods under methods are:

Touch inspection
Visual inspection
Scratch inspection
Microscopic inspection
Surface photographs
Micro-interferometer
Wallace surface dynamometer
Reflected light intensity

Touch inspection

This method simply tells which surface is rougher. Fingertip is moved along the surface at a speed of 25 mm per second and the irregularities as small as 0,01mm can be easily detected.

We can use a tennis ball, which is rubbed over the surface, and vibration from the ball is transmitted to hand and surface roughness assessed thereby.

Visual inspection

In this type of comparison method, the surface is inspected by the naked human eye. Sometimes maginifiers(magnifying lenses) are also used by human to observe the surfaces.

In human eye visual inspection is often likely to have a error or misleading in measurements because the results may vary from one person to another since every person has a unique perspection of his own.

So, this type of inspection is not recommended for inspecting rougher surfaces and uneven surface measurements. surface finish particularly when surfaces having a high degree of finish are inspected.

Scratch Inspection

In this method, some of the softer materials like lead and plastics are rubbed over the surface which is to be measured. By doing the rubbing processes, the impression of this scratches is produced on the surface which can easily visualized for measuring the surface finishing.

Microscopic Inspection

It is one of the finest method for evaluation of surface finish. In this method, the surface which is to be inspected is compared to the master surface on the microscope for inspection. Sometimes a light beam is also used to check the finish by projecting it at 60° to the surface under inspection.

The main disadvantage of this method is, that this inspection can be done only in a small portion at a particular time.

For inspecting a larger surfaces this method consumes more time since many readings can be calculated for getting an average value.

Magnified Surface photographs

In this method of surface inspection, the magnified photographs of the surfaces are taken under different types of illumination.

In vertical illumination the defects like irregularities appear to be as dark spots and flat surfaces appears as bright area.

The photographs taken different types of illumination are compared with one another and then the results of the surfaces are assessed.

Micro-interferometer

In this method, an optical flat is placed on the surface to be inspected and illuminated by a monochromatic source of light. Interference bands are studied through a microscope.

Defects, i.e. scratches in the surface appear as interference lines extending from the dark bands into the bright bands. The depth of the defect is measured in terms of the fraction of the interference band.

Wallace surface dynamometer

This is a sort of friction meter and consists of a pendulum in which the testing shoes are clamped to a bearing surface and a predetermined spring pressure can be applied.

In this method the pendulum is lifted to its initial starting position and allowed to swing over the surface to be tested. If the surface is smooth, then there will be less friction and pendulum swings for a longer period.

Thus time of swing is a direct measure of surface finish.

Reflected light intensity

In this method a beam of light of known quantity is projected upon the surface. This light is reflected in several directions as beams of lesser intensity and the change in light intensity in different directions is measured by a photocell.

The measured intensity changes are already calibrated by means of reading taken from surface of known roughness by some other suitable method.

Direct instrument measurements

In this type of inspection the surfaces are directly inspected by the machines.

Some of the direct measurement instruments are

Stylus probe instruments.
Tomlinson surface meter.
Profilometer
Taylor-Hobson Talysurf

That's all for now, Hope that you understand about the types surface finishing measurements and its explanation.

If you have any queries or doubts put on the comment box. See you soon in the next topic. Please don't forget to share this with your friends and colleagues so that they can also learn the topics that you have learnt from here.

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Dial Indicators - Parts, Working, Types, and Advantages

2021-01-20T23:29:00.003+05:30

Hello mechons, welcome to MechGeni, now in this article we are going to explain you about the measuring device named Dial Indicators.

Here now we are going to explain about what are Dial indicators, principle of dial indicator, working of dial indicators, types of dial indicators and also the advantages, disadvantages and applications of dial indicators.

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First lets start with

What are Dial indicators?

A dial indicator is a very important compensator used in mechanical measurement applications.

Principle of Dial indicators

The dial indicator operates on the principle that a very slight upward pressure on the spindle or plunger at the contact point was multiplied through a system of gears and levers and it was indicated on the face of the dial by the pointer of the dial indicator.

The body of the dial indicator contains a round graduated scale and a contact point which is connected with the gear train. So that the pointer on the dial face magnifies and indicates the amount of plunger movement in the dial.

Construction of the dial indicator

The dial gauge consists of the following parts.

Circular dial body
Pointer or indicating hand
Graduated scale
Revolution counter
Bezel
Bezel clamp
Dust cap
Stem
Plunger

which is divided into

Spindle
Contact point

Parts of a Dial Indicator

In the side view we can see other Parts

Crystal
Back
Mounting lug

Side view of dial indicator

After opening the body of dial indicator, we can see internal parts and those are

Rack
Rack guide
Gear train
Hairspring
coil spring.

Working parts of the dial indicator

Working of dial indicator

Before we see the working of the dial indicator we must first understand how the magnification process is achieved with the help of Gears.

Let us Consider two gears A and B. These gears are meshing with each other. The number of teeths on gear A is less when compared to gear B. The smaller gear A is called Pinion, when we rotate the pinion by one revolution the gear B will rotate through a small angle. This change in angle of rotation on gear B depends on the gear ratio, now suppose if we rotated gear B by one full revolution then the number of revolution of pinion(Gear A) is more.

With this basic concept of the relation of gears now we can see how the magnification of the plunger is achieved in a dial indicator gauge.

The gear and pinion arrangement is used in this instrument to obtain the required high magnification ratio by arranging the gear train in a similar way to that of a clockwise movement.

A perfect sliding plunger is fitted in its own bearings. This plunger carries a rack, which was accurately meshed with pinion A, the rotation of the plunger about its own axis is prevented by a pin attached to it, which is located in a slot in Rack guide

In order to keep the plunger in an extended or normal position the light coil spring is employed. Now the small movement in the contact point causes the rack to rotate the pinion A with which it is being meshed.

The larger gear B is attached to the same spindle as pinion A. The gear B is further meshed with pinion C, which thus magnifies the movement of pinion A attached to the second pinion C.

Now the Gear D which is meshed with the third pinion E mounted on the same spindle.

This magnification is further enlarged at the tip of pointer by an amount depending upon its length

In order to take a backlash a light hair springage is always fitted to the dial gauge gear trains by meshing a gear F to pinion A and attaching spring with gear F is also to prevent gear backlash.

The gears which are used here are Precision cut. And the movement assembly resembles like a high-quality watch.

After final assembly each dial indicator gauge is thoroughly tested, checked and properly calibrated with the help of micrometer head or with the help of slip gauges.

If the pointer moves more than one revolution a revolution counter is also incorporated, which will correctly indicate the number of revolutions made by the main pointer and thus it enables a complete reading to be made when the gauge is used for direct measurement.

We can also rotate the round graduated scale to set the pointer to zero and in some dial indicators the bezel has two range pointers which are used to set the ranges.

( PleaseWatch the video for clear cut understanding )

Video by - ADTW youtube channel

Applications of dial indicator

Comparing two Heights or distance between narrow limits
Determining the errors in the geometrical forms such as ovality roundness and taper
For taking accurate measurements of deformation such in tension and compression
Positional errors of surfaces such as parallelism squareness and alignment are being determined with the help of dial indicators.
Alignment of Lathe centers is being checked with the dial gauge indicators.
To check the trueness of milling machine Arbors and to check the parallelism of shape or armed with table surface or vice.

Advantages of Dial Indicators

These are the most perfect tool for taking linear measurements
It is also used to measure several other measurements by combining with some other attachments to the dial gauge indicator.
Small in size and can be used in many production units.
The tool is very efficient to assume the quality of a workpiece

Disadvantages of dial gauge Indicator

Due to the vibrations of machines the Precision of this instrument is often poor.
Parallax Effect is also a main disadvantage while taking the measurements

Also read : Vernier Caliper - Parts, Types, Working & Applications

Conclusion

That’s all about Dial Indicators - Parts, Working, Advantages, Disadvantages and its Applications. Hope you understand the definitions and all about dial indicators so far.

If you have any queries or doubts or need improvements in this article don't hesitate to contact us. Also put your valuable comments on the comments section below.

And one more thing Don't forget to share this topic with your beloved friends and fellows of mechanical. See you soon in a new topic.

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Different types of engines used in Automobiles nowadays

2020-12-28T20:50:00.006+05:30

Different types of engines used in the cars

Hello guys, welcome to MechGeni, In this post we are going to see about the types of Engines used cars and many automobiles nowadays.

First let me explain

What is an Engine?

In simple words, An engine is a machine which is designed to convert one form of energy into mechanical energy.

The engines are broadly classified into Two main types

Among these, we are only using internal combustion engine nowadays in cars and in all automobiles , So based on the technological updates now we are going to see about the different types of engines used in Cars and also in many automobiles nowadays.

Types of engines used in Automobiles nowadays

Some of the types of Engines which are used in nowadays are

Inline engines
Straight engines
V engines
Boxer engine
Vo engines
W engines

Inline engines

Inline engines are the most common type of engines used in modern cars. In the type of inline engines the cylinders are arranged in a line that are facing upwards and are usually (normal) perpendicular angle to the car.

This type of engines are found more in family of hatchbacks and small of cars these engines are available in wide variety of configuration from a two cylinder engine to a six cylinder.

Video Attribution to - Engineering Explained

Straight engines

Straight engine is basically the same as an inline engine but the cylinders are positioned in parallel with the car from front to back as opposed to across the engine bay. This layout of engine is mostly using premium cars usually in rear-wheel drive cause these engines were present in wide variety of configuration from a four cylinder to six cylinders number.

V engines

The name itself of this type of engines are viewing that the engine from the front side the cylinders are arranged in a V-shape each bank of cylinders faces outwards and connects a common crankshaft at the base of the V. This strain is generally reserved for premium and performance, high cost because due to a snail. In this type we can place a higher displacement engine with more cylinders into smaller space. There are wide variety of configuration of V engines from six cylinder to 12-cylinder engines.

V - engine ( model)

Boxer engines

Boxer engines are also known as flat or a horizontally opposed engine. The cylinders are laid down on the side in two banks pointing away from each other. This type of engines helps to keep the centre of gravity usually low to benefit the handling. These engines are known for their distinctive sound. And there is only two car companies that are currently using boxer engines, they are Porsche and Subaru.

Vo engines

This type was developed by the Volkswagen Group it uses a similar principle 2v engines. But the distance between two cylinder rows are so narrow and it is squeezed together in one engine.

Many models blocked these engines and are rarely used now and are only used in some of the VW cars.

W engines

W engine is basically a two V engines which are joined together at the based performer with W configuration. These type of engines are only used in ultra luxury and in high performance cars like in some Bentley models and in Bugatti Veyron and the new sheriff.

W- engine ( model )

Conclusion

That's all guys for this now, I hope you guy found it interesting and tell me in the comment below that “which is your favourite type of engine” looking excited to see which is the most liked type of engine.

Always, Spark your Brain and Throttle your Knowledge

Micrometer - Parts, Types, Working and Applications

2020-11-11T17:00:00.000+05:30

Micrometer - Parts Working, Principle Types, Applications

Hello mechons, in this post we are going to see about the Measuring Device named "MICROMETER". Here, We will explain you about what is micrometer, types of micrometer , and the types of micrometer.

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First let's begin with a question

What is Micrometer?

The Micrometer is a device used for getting the exact measurement of objects. The other names micrometer are screw gauge, it is also called micrometer caliper since it is used for calibration purposes too. It is widely used by engineers to measure the exact dimensions of the objects which is to be measured.

In other words, the micrometer is a handy measuring device used mainly by engineers to measure the exact dimensions of the objects.

Now let's continue with

Parts of a Micrometer

What are the parts of Micrometer?

A basic Micrometer consists the following
parts

Frame
Anvil
Spindle
Lock Nut
Spindle
Sleeve
Thimble
Ratchet

(Micrometer-Parts labelled)

Frame

The frame of the micrometer will be in Shape of the English Alphabet 'C'. It is a rigid part that holds the object to be measured using the micrometer. The main purpose of the frame is to provide sufficient holding power between anvil and the spindle for holding the object. The anvil is stationary one, whereas the spindle is the movable one. The size of the frame depends on the measuring range.

Zero Adjusting screw:

The zero adjusting screw is a type of a screw which is located at the backside of the anvil. It is used to rectify the zero error of the micrometer before doing the measurement or calibration processes.

Anvil

The anvil is a small fixed stationary part of a micrometer positioned at one end of the frame. It is provided for holding the object between it and spindle in frame. Since it is a fixed part, it provides rigidity and gripness for the holding of objects.

Spindle

The spindle is the longest part of the micrometer. It is a movable part attached with the ratchet. We can rotate the spindle both in Clockwise and Counter-Clockwise. By using the ratchet we can adjust the position of the spindle to tightly hold the object which is to be measured.

Lock nut

The locknut acts as a stationary nut and control the rotation of the spindle. It is quater turn nut. Its purpose of providing is the spindle won't move after we locker the lock nut.

Sleeve

It is a cylindrical shaped part which placed on the micrometer spindle. It is the main scale of the micrometer. The rotation of the thimble takes place around the sleeve and the spindle. Since, the main scale is carved in the sleeve. The function of the sleeve is to indicate the reading of the micrometer.

Thimble

The thimble is mounted on the spindle of the micrometer. A fractional scale is craved on the surface of the thimble for the measurement of precision values. As mentioned as earlier, the rotation of the thimble takes place around the sleeve and the spindle.

Ratchet

The knurled grip surface used on the micrometer for rotating the spindle in the desired direction of the user is called as ratchet. It is provided to prevent the over tightening of the object to be measured and also to distribute the pressure equally to the surface of the object in each measurement process.

Also read:

Vernier Caliper with its types and parts

Principle of micrometer

Micrometer works based on the screw and nut principle. The screw is attached to the thimble. The circumference of the thimble is divided in to equal parts based on the graduations of the micrometer either in inches or in millimeter. The principle of screw and nut states that when a screw rotates a nut by a revolution, then the axial movement of the nut is equal to the pitch of the thread of a screw.

Let's Assume that, you are a pitch of screw in mm, then each rotation advances by the screw will be equal to the internal thread distance by you in mm. If the circumference of the cylinder is divided into n equal divisions, rotation of a cylinder through one division indicates 1/n rotation of the screw or 1/n mm axial advance.

In micrometer, the screw has a pitch of 0.5 mm and thimble has 50 divisions so that the least count of the micrometer is equal to 0.5/50 =mm. By reducing the pitch of the screw thread or by increasing the number of divisions on the thimble, the axial advance value per one circumferential division can be reduced and the accuracy of measurement can be increased.

How to use Micrometer?

The object is kept between the spindle face and the anvil face, and the ratchet is moved in a clockwise direction. This causes the anvil face and spindle face to fasten the object. When the object is securely tightened between the two, the ratchet makes a click noise indicating that the object is tightened and the measurement can be taken. The measurement can be read from the scale that is available on the sleeve.

Types of Micrometer

Based on the application, there are different types of Micrometers available. The following are the basic Micrometers:

Inside Micrometer
Outside Micrometer
Depth Micrometer

Inside Micrometer

While the outside micrometer is used for measuring the outer diameter of an object, the inside micrometer is used to measure the inside, or inside diameter (ID). These look more like a pen, but with a thimble in the middle that turns. As the thimble turns, the micrometer expands like a curtain rod would. This then extends until each end of the tool is touching the inside of the pipe. When this happens, you use the numbering system on the thimble to find your measurement.

(Inside Micrometer)

Outside Micrometer

This type of micrometer is designed for measuring the outside of objects—the outside diameter (OD). They look and move much like a C-clamp, which opens and closes by turning an internal screw. In a micrometer, the object you wish to measure is clamped between the anvil (the stationary end of the clamp) and the spindle (the moving part of the clamp). Once the object is secured in the clamp, you use the numbering system on the thimble (the handle portion) to find your measurement.

(Outside Micrometer)

Depth Micrometer

While inside and outside micrometers are both used to measure the diameter of an object or hole, a depth micrometer is for measuring the depth of a hole, recess or slot. Depth micrometers have a base that aligns with the top of the recess that needs to be measured. The thimble is on a shaft that sticks up from the base. As the thimble turns, a measurement rod comes down from the shaft. You continue to turn until the rod hits the bottom surface of the hole being measured. When this happens you use the numbering system on the thimble to find your measurement.

(Depth Micrometer)

Applications of Micrometer

A micrometer can be used to measure

Depth
Length
Thickness of all the object that are placed between the anvil and spindle.
It is commonly used in mechanical engineering and machining applications for measuring the length, width, depth, height.

Conclusion

That's all for now about Micrometer - Parts, types, Applications. I hope that you understand the principle of Micrometer, its types and its parts also with its applications.

If you have any queries or doubts or any suggestions put that in the comment box we will reply and rectify as fast as possible.

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Surface Finishing and its Terminologies

2020-11-05T21:06:00.003+05:30

SURFACE FINISHING AND ITS TERMINOLOGIES

Hello mechons, welcome to MechGeni!, in this post we are going to see about the simple topic titled "surface Finishing". Here We will explain you about what is surface finishing , definitions of surface finishing, and the basic terminologies used in surface finishing.

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Ok, first let me start with

What is Surface Finishing

Normal people measure the surface of objects by touching the surface and sensing it. But we The Engineers not do that method. Here we will measure and the surface of an object by using some instruments. If we finish the surfaces there are some machines and tools to get smooth and fine finished surfaces. Examples : Grinding machine, CNC machine, etc.,

Definition of Surface finishing

The surface finish of an object is defined by the three basic characteristics namely waviness, surface roughness, and lay. It tells us the small, local deviations of a surface from the ideal surface(Perfectly flat).

We can define repetitive or random deviations from the normal surface which form the pattern of the surface.

If we machine the material, we won't get perfectly finished material due to some departures from ideal conditions.

Surface irregularities have a pattern and are oriented in a particular direction depending on the factors that cause these irregularities in the first place.

Surface irregularities arise due to the following factors

1. Feed marks of cutting tools

2. Chatter marks on the workpiece due to vibrations caused during the manufacturing process.

3. Irregular surface on the object due to the rupture of workpiece material during the metal cutting process.

4. Surface vibrations occur due to the deformation of the workpiece under the action of cutting forces.

5. Irregularities in the machine tool itself like lack of straightness of guideways.

Terminologies used in Surface Finishing

Some of the basic terminologies that must know about Surface finishing are as follows.

Real surface
Geometrical Surface
Effective Surface
Waviness
Surface texture
Surface roughness
Roughness height
Roughness width
Roundness width cut-off
Lay
Waviness height
Flaws

(Terminologies labelled)

Real surface

It is the surface limiting the body and separating it from the surrounding surface.

Geometrical Surface

It is the surface prescribed by the design or by the process of manufacture, neglecting the errors of form and surface roughness.

Effective surface

It is the representation of the real surface obtained by instrumental means.

Waviness

Waviness is an error in form due to incorrect geometry of the tool producing the surface. On the other hand, roughness may be caused by problems such as tool chatter or traverse feed marks in a supposedly geometrically perfect machine. The spacing of waviness is the width between successive wave peaks or valleys. Waviness height is the distance from a peak to a valley.

Surface Texture

Random deviations from the normal surface that form the pattern of the surface. The surface texture contains roughness, waviness, lay, and flaws.

Surface Roughness

Roundness consists of surface irregularities that result from the various machining process. These irregularities combine to form the surface texture.

Roughness height

It is the height of the irregularities with respect to a datum line. It is measured in mm or microns or microinches. It is also called the height of unevenness.

Roughness width

It is the distance parallel to the nominal surface between successive peaks or ridges which constitute the predominate pattern of roughness. It is measured mm.

Roundness Width Cut Off

Roughness width cut off is the greatest spacing of respective surface irregularities to be included in the measurement of the average roughness height. It should greater than the roughness width to obtain the total roughness height rating.

Lay

Lay represents the direction of the predominant surface pattern produced and it reflects the machining operation used to produce it.

Waviness Height

Waviness is defined as height the peak to valley distance of the surface profile, measured in mm.

Flaws

Irregularity which occurs at one place or widely varying intervals on the surface. It includes cracks, scratches, etc.

Conclusion

That's all for now about the surface finishing and its terminologies
I hope that you understand about surface finishing, its definition and its basic terminologies.

If you have any queries or doubts or any suggestions put that in the comment box we will reply and rectify as fast as possible.

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First Law of Thermodynamics

2020-10-30T23:12:00.004+05:30

The First Law of Thermodynamics

Hello mechons, in this post we are going to explain to you about a law of thermodynamics called First law of Thermodynamics with derivations, definitions and also the example of first of Thermodynamics.

Before going to learn about the First law of Thermodynamics, make sure that you know about Thermodynamic zeroth law.
If not read our Article titled "Zeroth law of Thermodynamics" to know about the thermodynamics zeroth law.

Ok first, let me start with

What is the First Law of Thermodynamics in a closed system?

When a system undergoes a thermodynamic cycle then the net heat supplied to the system from the surroundings is equal to a net work done by the system on its surroundings.

Q = W+∆E

If Q is the amount of heat transferred to the system and W is the amount of work transferred from the system during the process the net energy transfer (Q-W) will be stored in the system. The energy in storage is neither heat nor work and is names as internal energy or simply, the energy of the system.

We can write,

Q -W = ∆E

Here Q, W, and ∆E are units in joules. Energy stored in the system in different modes.

A differential form of The First Law of Thermodynamics is given by

δQ = δW + dE

δ- is Exact differential (Independent of Path)

E= K.E + P.E. + I.E

E = mV²/2 + mgz + U

δQ = δW + d( mV²/2) + d(mgz) + dU

Many thermodynamic process, changes K.E. and P.E. are negligible as compare to changes in I.E.

δQ = δW + dU

Different forms of stored energy

The energy in a storage called internal energy is a point or state function and hence a property of a system. The symbol E denotes the total energy stored in a system. Basically, there are two modes in which energy may store in a system,

1. Macroscopic energy mode

2. Microscopic energy mode

The macroscopic energy mode consists of the macroscopic kinetic energy and potential energy of a system.

E_k= mV²/2

For potential energy,

E_P= mgz

The microscopic energy mode refers to the energy stored in the molecular and atomic structure of the system, which is called the molecular internal energy. It is referred to as U.

One molecular energy contains the following energies:

Translation energy
Rotational energy
Vibrational energy
Nuclear binding energy
Electron energy

Enthalpy:

The enthalpy of a substance, h, is defined as

h = u+pv

Enthalpy is an intensive property of a system (kJ/kg).
Internal energy change is equal to the heat transferred in a constant volume process involving no work other than pdv work

δQ = pdv + du

At constant pressure,

pdv = d(pv)

δQp = du + d(pv)

δQp = d(u + pv)

δQp = dh

where h = u+pv is the enthalpy, a property of the system. Heat transferred at constant pressure increases the enthalpy of a system.

For an ideal gas, the enthalpy becomes,

h = u+RT

The Internal energy of an ideal gas depends only on the temperature, the enthalpy of an ideal gas also depends on the temperature only,

h= f(T)
H=mh

The Energy of an isolated System:

An isolated system is one in which there is no interaction of the system with the surroundings. For an isolated system δQ = 0, δW = 0
Then first law becomes,

dE = 0
E = Constant

Therefore, the energy of an isolated system is always constant.

Perpetual Motion Machine of the First Kind-PMM 1

The first law tells us the general principle of the conservation of energy. According to the law of conservation of energy tells us energy is neither created nor destroyed but it can be transformed from one form to another.

There is no machine that would continuously supply mechanical work without some other form of energy disappearing simultaneously. Such a fictitious machine is called a perpetual motion machine of the first kind, or in brief PMM1. PMM1 is impossible.

There can be no machine that would continuously consume work without some other form of energy appearing simultaneously.

Conclusion

That's all about the first law of Thermodynamics, definitions, derivations, and examples of the first law of Thermodynamics.
I hope that you understand the definitions and examples.

If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.

Always Remember to

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Vernier Caliper with its parts, types and applications

2020-10-30T22:58:00.002+05:30

Vernier caliper and its types

Hello mechons, in this post we are going to see about the simple measurement device named "vernier caliper". Here We will explain you about what is Vernier caliper, what are the types of vernier caliper, parts of the vernier caliper and applications of the vernier caliper.

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Ok, first let me start with

What is vernier caliper?

A vernier caliper is a device used to measure inner and outer diameters, length, depth, thickness of the object. In vernier caliper a vernier scale will be there which is the aid to increase accurate level of this device by taking readings between two graduation markings on a linear scale by mechanical interpolation. Also it reduces the uncertainty of the measurement and error of estimation.

Parts of Vernier Caliper

Now, moving to the next part,

What are the parts of a vernier caliper?

So, There are six major parts of the vernier caliper. They are

Lower jaws
Upper jaws
Depth rod
Main scale
Vernier scale
Thumb screw
Lock Screw

Image Source: Wikipedia(under Creative Commons Licence)

1➝Lower jaw, 2➝Upper jaw, 3➝Depth rod, 4&5➝Main scale, 6&7➝Vernier scale, 8➝Lock screw

Upper jaws

The upper jaws of the vernier are used for measuring the inner dimensions of objects such as pipes, tubes and cylinders. In upper jaws the one end is fixed with the main scale and the other end is free movable and attached with the vernier scale. To measure the inner dimensions it is placed inside the hole and expanded to measure.

Lower jaws

The most prominent part of the vernier caliper are the lower jaws. Like upper jaws in the lower jaws also one end is fixed with the main scale and the other jaw is free to move and it is attached with the vernier scale. The lower jaws of the vernier are used for measuring the outside dimensions such as height, length, width.

Depth rod

The depth rod is used to measure the depth of the holes or steps in the objects. It is very thin and located at the end of the main scale

The depth rod of a vernier is used for measuring the depth of holes.

Main scale

The main scale is the large stationary scale built along the body of the vernier caliper. Depending on the units used the main scale of the vernier is either nominated by centimeters and millimeters or by inches.

Vernier scale

The vernier scale is the smallest scale attached to the main scale of the caliper. It moves along the body of the main scale when the jaws are either opened or closed. This scale is used to increase the accuracy of the measurement because in the vernier scale the lowest level of the main scale is further divided into increments. The vernier scale is divided into 50 equal parts and each part representing 0.02 mm

Thumb screw

The thumb screw of the vernier is located at the bottom of the vernier scale. The main purpose of the thumbscrew is to provide grip for the user when moving the jaws. And it is also used in moving the jaws and depth rod while applying firm grip on the object

Lock screw

The lock screw is located in the upper position of the vernier. It is used for locking the object's position when it is placed properly. The purpose of providing the lock screw is after locking the object in a particular position the reader can take readings without any fear in the position of that object.

Types of vernier Caliper

Based on the standards the vernier calipers are classified into three types

Type A

In this type of caliper the jaws are present on both upper and lower ends for measuring internal and external measurements respectively. These types of calipers are generally made up of steels.

Type A

Type B

This type of vernier doesn't possess separate jaws for measuring internal and external measurements. It has only one set of jaws for both internal and external measurements.

Type B

Type C

This type is very similar to the type B, the main difference is the presence of the knife edge at the end. This type also doesn't possess separate jaws for measuring the internal and external measurements. The single set of jaw is used for measuring both the internal and external measurements.

Type C

Applications of vernier caliper:

It is used to measure internal and external diameters of the objects .
It is also used to measure length, breadth, thickness of the objects.
It is used to measure the depth of the holes and steps of the objects.

Conclusion

That's all for now about the vernier caliper, types of vernier caliper and applications of vernier caliper. I hope that you understand this topic.

If you have any queries or doubts regarding this topic don't hesitate put that in the below-mentioned comments section. We are here for you, we will reply as fast as possible.

And one more thing Always remember to

Spark your brain and Throttle your knowledge!.

Calibration of measuring instruments

2020-10-23T22:00:00.163+05:30

Calibration of measuring instruments

Hello mechons, in this post we are going to explain you about the simple topic in metrology called "Calibrations" in detailed. In calibration of measuring instruments we going to see about what is calibraition, need for calibration in measurements and basics of calibration of measuring instruments.

Ok, first let me start explaining with the question that arises in your mind after entering to this page.

What is calibration?

In simple words, the calibration is the traceability of measurement by applying the act of comparison with the known standards(Eg: ISO standards,

Before going to learn about calibration, check whether you know about accuracy, precision, and other static characteristics of Measurements. If not feel free to read our article about Engineering Metrology basics, where we explained all the static characteristics of Measurements such as accuracy, precision, sensitivity, drift and so on.

Why calibration is done in a instruments?

The calibration is done

To remove the errors that are produced in a process of measurement
To maintain the tolerance of error within the range of acceptance.
To improve the accuracy and Precision of Measurement and analysis results.

Need for calibration

To maintain quality control and quality assurance in the production
To obtain the requirements provided by ISO standards
To ensure the quality of goods in the global trade.

Basic requirements for calibrations

The basic requirements for calibrating are as follows

Reference standards
Certain environmental conditions
Traceability of calibration standards
Documentation of Calibration testing certificate.

Reference / Calibration standards:

Calibration or reference standards are instruments that are used to compared against the less accurate devices for verifying the performance of those less accurate instruments.

There are certain standards for calibration to check the accuracy.

SI, BIPM, NMI, Primary standards, Secondary standards, Working standards

What are the standards in Metrology?

Primary standards
Secondary standards
Laboratory standards
Working standards

Environmental conditions for Calibrations:

There are many environmental cases for errors to occur in the process of measuring or calibrating a device. To avoid certain environmental affects there some environmental condition that are required for calibrating a device in a laboratory.

The environmental affects includes factors like temperature, relative humidity, pressure, sound and vibrations. A laboratory for calibration must need to monitor these environmental situations while doing or before doing the calibrating process.

The temperature must be 68°F(20°C) acceptable range is ±4°F(±2°C)
The Relative humidity should be at 60%.
And at last the place where the testing happens must be free from sound, vibrations and dust.

Traceability / Uncertainty of Calibration

Traceability:

Traceability is defined as the property of result of a measurement or the value of a standard whereby it can be related with references like National or International standards.

Uncertainty:

Uncertainty is the way to estimate the amount error associated with the calibration measurement. The higher accuracy of calibration measurement is obtained from the smaller uncertainty value.

Documentation

The documentation is nothing but getting the documentary or filing the calibrated instruments or devices test report. There certain procedures for documentation of Calibration devices by following those rules laid by NMI's and ISO standards one have to document the calibrated report.

Conclusion

That's all about the Introduction to calibration of instruments, definition, need for calibration, requirements for calibrating an instruments. I hope that you understand this topic.

If you have any queries or doubts regarding this topic don't hesitate put that in the below-mentioned comments section. We are here for you, we will reply as fast as possible.

And one more thing Always remember to

Spark your brain and Throttle your knowledge!.

What are trusses and types of Trusses, frames

2020-10-20T20:00:00.804+05:30

TRUSSES or FRAMES:

Hello mechons, in this post we are going to explain to you about a little topic of the Engineering mechanics called Frames also called as Trusses.

Before going to learn about the types of frames and its uses first we need to know about,

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What are Trusses or Frames?

A structure with several bars riveted or welded together are called Trusses or Frames. They basically provide strength and support to a construction.

To find the support reactions at the end, same principles as in beams are used,

Analytical method
Graphical method.

Types of frames

End supports of frames are differentiated as,

Frames with simply supported ends.
Frames with one free end and one hinged end.
Frames with both end fixed.

Frames with simply supported ends:

In this case, it is same as simple support beam. Here, two simple supports are used at the ends. So, two vertical forces are considered at the two ends of the frame.

(Example for simple supported frame)

Free body diagram of Simple supported frame

(Free body diagram of simple supportrd frame)

Problem:

Example problem for Frames with simply Supported ends (Fig 1.1)

(Fig-1.1)

→ A truss of 12 m span is loaded as shown in

(Fig 1.1)

Given data:

Span AB = 12m

Let Ra be reaction at A

Rb be reaction at B

Now, equating Clockwise and Anticlockwise moments about the point A.

(Rb×12) = (2×3) + (3×6) + (2×9) + (2×4)+(6×8)

Rb × 12 = 98 K-Nm

Rb = 98 K-Nm /12m

Rb = 8.167 KN

Ra = ( 2+3+2+2+6) - 8.167

Ra = 6.833 KN

Frames with one end hinged (pin jointed) and other end freely supported on rollers

(Free body diagram)

When a frame carries horizontal or inclined load, a pin joint and a free end is needed to compensate the load. Types of load applied on frames with hinged and roller end,

Horizontal loading
Inclined loading

Problem

Example problem for frmae with one end hinged support and other end freely supported on rollers with horizontal loading (Fig 1.2)

(Fig 1.2)

Given data:

Span = 8m

Let Ra be Reaction at A and Re be Reaction at E

Solution :

As one end is supported as roller the reaction will be at vertical whereas At "A" it will be both horizontal and vertical.

Taking Moment about A,

- Re × 8 = (2W × 2) + (W×2)

= 6W

➝ Re = 6W/8

Re = 0.75 W

Vertical Component of Reaction Ra

Va = 2W - 0.75 W

Va = 1.25 W

Horizontal Component of Reaction Ra

Ha = W (←)

Reaction at A,

Ra = {w2 +(1.25)2}1/2

Ra = 1.6 W

tan ं = W/ 1.25 W

tanं = 0.8

ं = 38.6 °

Frames with Horizontal Loading:

(Frames with horizontal loading)

Resultant reaction's inclination with vertical is given by,

tan 𝚹 = ∑H / ∑V
Here, ∑H = Algebric sum of Horizontal reactions,
∑V = Algebric sum of vertical reactions.

Problem:

Example problem for frames with One end hinged and other end with roller support and horizontal load (fig 1.3).

(Fig 1.3)

Given data :

Span = 8m

Let Ra be Reaction at A and Re be Raction be Reaction at E.

Solution:

Taking moment about A,

Re × 8 = (2W × 2) + (W×2)

Re ×8 = 6W

➝ Re = 6W/8

Re = 0.75 W

Vertical Component of Reaction Ra

Va = 2W - 0.75 W

Va = 1.25 W

Horizontal Component of Reaction Ra

Ha = W (←)

Reaction at A,

Ra = {w2 +(1.25)2}1/2

Ra = 1.6 W

tan ं = W/ 1.25 W

tanं = 0.8

ं = 38.6 °

Frames with Inclined Loading:

(Free body diagram)

The support reactions are found by two methods:
1. Analytical method
2. Graphical method

Problem

Example problem for frames with one end hinged and other end with roller support and with inclined loads (Fig 1.4).

(Fig 1.4)

Given data:

Span = 10m

Let Ra be Reaction at A and Rb be reaction at B.

Solution:

1) Analytical method:

Perpendicular between support A and line of action of load at D.

5/ cos 30° = 5/ 0.866 = 5.8m

Perpendicular distance between support A and line of Action of load at C

= 5.8/2 = 2.9m

Equating clockwise moments and anticlockwise moments about A,

Rb x 10 = 2 x 2.9) + (1 x 5.8)

Rb x 10 = 11.6

Rb = 1.16 KN

Total wind load = 1+2+1 = 4KN

Horizontal component of wind load load = 4Cos60° = 4 x 0.5

= 2KN

Vertical component of Wind load

= 4Sin60° = 4x 0.866

= 3.464 KN

Balancing Vertical reaction at A=3.464-1.16

= 2.304 KN

Ra = (2^2 + 2.304 ^2)1/2

= 3.05 KN

tan ं = 2.0/2.304

tanं = 0.868

ं=41°

2) Graphical method:

(Graphical method)

First draw the free body diagram and name the forces and reactions according to BOCO's notations.
Add the forces together and assume them to act together at C.G (CENTRE OF GRAVITY) at C.
Draw the line of action of resultant force to meet at line of action of roller support.
Join OA, from O cut off OM equal to toatal componded load (i.e. 4KN) along the line of action of resultant force.
Complete parallelogram OLMN, with OM as diagonal.
Measure ON and OL. The length OL gives the magnitude and direction of Reaction Ra and also Reaction Rb magnitude.
By measuring, we get

Ra = 3KN

Rb = 1.2 KN

ं = 41°

Frames with Both End Fixed

The assumptions are,

1. Reactions are parallel to direction of loads.

2. In case of Inclined loads, Horizontal thrust is equally shared between reactions.

Problem:

Example Problem for Frames with both ends fixed (Fig 1.5).

(Fig 1.5)

Given data :

Span = 8m

Let Ra be Reaction at A and Rb be Reaction at B.

Solution

Assumption 1:

Reactions are parallel to the direction of loads

Equating moments at A,

Rb x 8sin60°= (2x2/Cos30°) + (1x4/Cos30°)

Rb x 8 x 0.866 = 9. 24

Rb = 9.24 / (8x0.866)

Rb = 1.33KN

Ra =(1+2+1) - 1.33

Ra = 2.67KN

Assumption 2 :

Horizontal thrust is equally shared by reactions.

Total horizontal component of load,

EH = 1cos60° + 2cos60° + 1cos60°

EH = 2KN

Horizontal thrust on each support,

Rah = Rbh = 2/2 KN = 1KN

Now, Equating clockwise and anticlockwise moments about A,

RBV x 8 = (2x2/cos30°) + (1x4/cos30°)

= 8/0.866

RBV = 9.24 /8

RBV = 1.15 KN

RAV = [ 1sin60° + 2sin60° + 1sin60°] - 1.15 KN

RAV = 2.31 KN

Ra = {(1)^2 + (2.31)^2}^1/2

Ra = 2.52KN

tan ंa = 2.31/ 1 =2.31

ं a = 66.6°

Similarly, Rb = ((1)^2 + (1.15)^2)^1/2

tan ं b =1.15/1 = 1.15

ं b =49°

Conclusion

That's all about the frames or trusses types, forumulae, and example problems in frames for now. I hope that you understand the definitions, formulae and types.

If you have any queries or doubts regarding this topic don't hesitate put that in the below-mentioned comments section. We are here for you we will reply as fast as possible.

And one more thing Always remember to

Spark your brain and Throttle your knowledge!.

Interferometry - Working of interferometers, types

2020-10-19T22:22:00.005+05:30

Interferometry

Hello mechons, in this post we are going to explain to you about the interferometry, Working of interferometers and the types of Interferometers with its applications.

Let me ask a question to you,

What is interferometry?

Interferometry is the branch of physics in which the electromagnetic waves are superimposed with each other and results in the interference of waves.

The interference of these waves are used to find the information of the properties. This Interferometry technique is almost used in many measuring and investigative fields such as astronomy, fiber optics, engineering metrology, seismology, oceanography, optical metrology, spectroscopy and so on.

Principle of Interferometry

Interferometers works on the basis principle of superposition. It combines the waves in such a way that is useful for diagnosis or some other purposes like understanding the nature of the properties based on the original state of waves. When two waves with same frequency interfere with each other, the resulting intensity pattern of these waves are determined by the phase difference between those interfering waves.

Basically two types of interfere will occur in combination of waves

1. Constructive Interference - If two waves are in the same phase, then it will undergo constructive interference.

2. Destructive interference - If two waves are in difference phase or out of phase then it will undergo destructive interference.

If two waves are neither in phase nor in out of phase, then those waves will have an intermediate pattern of intensity. In those cases the relative phase difference is used to determine the nature of the waves.(i.e. The difference between the phase angles).

Working of Interferometers

A beam of light single source is splitted up into two beams that will travel in two different paths. And those two beams of light is combined again to produce interference. These interfered waves gives us the information about the optical path and lengths of a component. In our Engineering Metrology these interference of waves are used to identify the shape and length of the objects, It gives results with high accuracy and high precision. The interferometers are the measurement instruments with highest precision in existence.

Types of Interferometers

What are the types of interferometers?

There are many types of interferometers in the world. But now we are going to see about just five main types of Interferometers in brief. They are

Michelson interferometer
Fabry-Perot interferometer
Mach - Zender Interferometer
Sagnac interferometer
Laser interferometer

(Schematic representation of Michelson interferometer)

Michelson interferometer

This is the famous type of interferometer among all the interfeeometrs. This type of interferometer was found in the early of 19th century. This type provide the souce of Einstein's theory of relativity.

Fabry- Perot interferometer

The Fabry-Perot interferometer also called as an etalon, is developed from the Michelson interferometer. This type of makes clearer and sharper interference fringes that are more easier to see and measure.

Mach-Zender interferometer

This type of interferometer uses two beams rather than splitting one and produces two output beams, and it analyzed the two beams of light separately. This types are widely used in fluid dynamics and aero dynamics.

Sagnac interferometers

This type of interferometers are also called as ring interferometer. This type of interferometers splits light into two beams. And these two beams are instructed to travel in opposite directions in a closed loop like ring structure. So, it is also called as ring interferometer.

Laser interferometers:

The most modern types of interferometers use laser light for the interference source. Since the laser light is more precise and produce coherent beams of light than ordinary light. The inventors of interferometry didn't have access to laser light in those days, so they had to use beams of light and passed it through the slits for splitting of ways and then for combining to produce interference. The laser interferometers are used to find the extreme accurate length of the objects. These have precise upto the range 0.1 μm to 100m.

Applications of interferometers

What are interferometers used in many fields such as

Measuring instruments for measuring and analysing flatness, length, and shape of the objects.
It is used in radar technologies and used in astronomy.
It is used in seismograph, fiber optics and optical metrology etc.,

Conclusion

That's all about the interferometry, types, working and applications of interferometers for now. I hope that you understand the definitions, working and types.

If you have any queries or doubts regarding this topic don't hesitate put that in the below-mentioned comments section. We are here for you we will reply as fast as possible.

And one more thing Always remember to

Spark your brain and Throttle your knowledge!.

Zeroth law of Thermodynamics definition and examples

2020-10-18T23:21:00.004+05:30

Zeroth law of Thermodynamics

Hello mechons, in this post we are going to explain to you about a little law of the thermodynamics called Thermodynamics Zeroth law and also the example of zeroth of Thermodynamics.

Ok first, let me start with

What is the Zeroth Law of Thermodynamics?

According to the statement of "Zeroth law of Thermodynamics",

When a body X is in thermal equilibrium with a body Y, and also with a body Z, then Y and Z will be in thermal equilibrium with each other.

All the temperature measuring types of equipments and instruments are working under the zeroth law of thermodynamics.

(Schematic representation)

Before we going to see the examples just read the basics of Thermodynamics article from us so, that you can get clear knowledge in the upcoming topic.

Examples of Zeroth law of Thermodynamics

Let us consider one example measuring of the temperature of the body. If we place the thermometer in the mouth that is body X and Thermometer class contact with the body that is body Y thermometer which consists of mercury that is known as a body Z at a certain time three bodies come in thermal equilibrium with each other.

Thermometer:

To obtain a quantitative measure of temperature, a reference body or datum is used, and a certain physical characteristic of this body which varies with temperature is selected. The changes in the selected characteristic may be taken as an indication of varies in temperature. The selected characteristic is called the thermometric property, and the reference or datum body which is used in the determination of temperature is called the thermometer. Most commonly thermometer consists of a small amount of mercury in an evacuated capillary tube.

(Thermometer)

Measurement of Temperature-The reference Points

If X is the thermometric property, we can arbitrarily choose for the temperature common to the thermometer and to all systems in thermal equilibrium with it the following linear function of :

⍬(X) = aX, where a is an arbitrary constant.

If X1 corresponds to ⍬(X1), then X2 will correspond to

[⍬(X1)/X2] X2

that is ⍬(X2)= [⍬(X1)/X2] X2

Two temperature on the linear X scale is to each other as the ratio of corresponding Xs.

Thermometer	Thermometric property	Symbol
1. Constant volume gas thermometer	Pressure	p
2. Constant gas thermometer	Volume	V
3. Electrical resistance thermometer	Resistance	R
4. Thermocouple	Thermal e.m.f	ɛ
5. Mercury-in-glass thermometer	Length	L

Electrical Resistance Thermometer

The resistance of the thermometer the change in resistance of a metal wire due to its temperature change. The wire, frequently platinum, may be incorporated in a Wheatstone bridge circuit.

The platinum resistance thermometer can measures temperature high degree of accuracy and sensitivity, this element is used for standard and calibration of other thermometers.

Restricted range

R = Ro (1+At+Bt²)

Ro - the resistance of the platinum wire. A & B are constants.

(Electrical Resistance Thermometer)

Thermocouple

A Thermocouple is a device that is used to measure temperature that instrument contains the joining of two dissimilar metals A and B. Seeback effect tells, a net e.m.f is generated in the circuit which depends on the difference in temperature between the hot and cold junctions. Microvoltmeter measures e.m.f. with a high degree of accuracy. The choice of metals varies depending upon their temperature range. Commonly copper-constantan, chromel-alumel, and platinum-platinum-rhodium are used.

At the 0-degree celsius reference junction, the thermocouple is calibrated by measuring e.m.f at various temperatures.

ɛ = a+bt+ct²+dt³

ɛ is thermal e.m.f. a,b,c, and d are constants it vary for different thermocouple.

Conclusion

That's all about the zeroth law of Thermodynamics and examples of the zeroth law of Thermodynamics.

I hope that you understand the definitions, and examples.

If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.

Spark your brain and Throttle your knowledge!.

Spark plug and its types, how to improve spark plug life

2020-10-07T22:30:00.351+05:30

SPARK PLUG

Hello guys, in this post we are going to explain to you about a little part of the engine called Spark plug. Now here we are going to see about What is Spark plug, types of spark plug, working of spark plug, and atlast why it is used only in petrol engine.

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Ok, first let's start with

What is a Spark plug?

(Spark plug)

A device which is used for producing electric current from the ignition system of the engine to the combustion chamber of a engine for igniting the air-fuel mixture with the help of the created electric spark, is called Spark plug. It is also called Sparking plug or Sparker. It is placed in the head of an internal combustion engine.

A Spark plug carries two electrodes separated by a small gap, between this small gap the current produced by the ignition system is passed to ignite the air-fuel mixture. The spark plug must have a resistance for withstanding that high temperature and voltage. If the gap between the electrodes are long, it may affect the energy produced by the spark, and also affects the shape of the insulator. Either it may cause deposition of carbon in the plug or preignition of the air-fuel mixture.

Parts of a Spark Plug

A spark plug is comprised with the following parts.

Plug terminal
Insulator
Metal Shell
Central Electrode
Ground electrode
Sealing Gasket
Insulator tip
Electode gap

(Labelled Spark plug parts)
Source: Marineengine digest

Plug Terminal

A terminal which is present in the top of the spark plug to get connected to the ignition system is called plug terminal. It is responsible for conducting high voltage to the central electrode of the spark plug. It is the portion which is attached to the high tension cable passing out from the cap of the distributor.

Insulator

It is the main part of the spark plug. This is made up of Aluminium Oxide(Al2O3) and ceramic material. It improves the temperature resistance of the spark plug. It posses high dielectric strength. Its main function is to provide mechanical support and insulation of central electrode. It can withstand upto 4000 volts.

Metal Shell

It is made up of steel shell. The metal shell withstands the torque of the spark plug, it is used to remove the heat from the insulator and it passes the heat to the cylinder head. It also acts as earth for the spark passing through the central electrode and helps the plug to get cooled.

Central Electrode

The central electrode of the spark plug is connected to the plug terminal through an wire and it connects to a resistance. The tip of the central electrode is made by the combination of nickel-iron, Chromium and copper. The voltage is supplied from the secondary winding to the central electrode through the distributor.

Ground Electrode

The ground electrode is made up of high nickel and steel alloys. It is welded to the metal shell. It also has some platinumaand iridium alloys to increase the lifetime of the spark plug.

Sealing Gasket

The spark plug also have a role in sealing the combustion chamber of the engine when it is fixed. It is necessary to ensure that there is no leakage form the combustion chamber. The sealing made with the cylinder head and it also plays a role in heat dissipation from the combustion chamber.

Insulator tip

The extended part of the insulator into the combustion chamber is called insulator tip. It has a major influence in thermal rating of the spark plug.

Electrode Gap

The gap between the Spark plugs are typically designed, by bending the ground electrode. The gap between the electrode may vary for each plug. But generally Spark plugs in automobiles have a gap between 0.6 and 1.8 mm. The electrodes play a vital role in producing the spark. If proper gap was not provided, the spark plug won't produce spark with suitable energy for igniting the air-fuel mixture and it may cause misfiring.

How Spark Plugs Work

At one end, it is connected to a high voltage source like ignition coil or the magneto, in the other end it is connected with two electrodes. When a high tension current passes through the plug terminal and ibto the central electrode, thus a potential difference is created between the electrodes. The fuel mixture ocvupies the gap between the electrodes so that the electric current doesn't flow beyond the tip of the central electrode.

If the voltage increases, the gap will be energised. As soon as the voltage energise the gap it will get ionised. After ionised they begin to act as conductor and allows the current to pass through this insulating gap. When it reaches a certain amount, the electrons begin to surge through the gap. This sudden movement of electrons increases the heat in that region due to the heat they began to expand fastly and causes the small explosion. This small explosion results in the formation of the spark from the spark plug and then it will cause the power stroke where the fuel moves the piston downwards because the ignition of the air-fuel mixture.

(Video source: Doe venna)

Types of Spark plug

The spark plugs are classified on the basis of temperature and the material used for production of the spark plug.

Based on the temperature it is classified into two types

1. Hot spark plug

2. Cold spark plug

Based on the material used it is classified into

Four types

1. Copper - Nickel type

2. Single Platinum type

3. Double platinum type

4. Iridium type

First we will discuss about temperature basis of classification,

Based on Temperatures

After the combustion of the fuel mixture, the heat which is produced needs to dissipate from the combustion chamber. The heat dissipate through the exhaust gases, between the gap of the spark plug surface and the cylinder wall of the engine. On the basis of temperature and heat dissipation, the spark plugs are classified into two types:

(Hot and cold spark plug)
Source: V-auto.org

Hot Spark Plug

The name itself will explain the function of this type of spark plug, that is the hot spark plug operates in a higher temperature range. To reduce the effect of heat it is made up less amount ceramic coat. This type of spark plug dissipates lesser combustion heat so that it makes the tip and electrode stay hotter. This hotness prevents the deposition of burnt fuel mixture and it won't allows to stay for long time.

Cold Spark Plug

In the case if high performable engines, it has heat production by default engine function. If we use hot spark plug in those kind of engine it will cause pre-ignition of the engine. In some extreme cases, it may lead to the melting of electrode tip. So, to avoid melting cold spark plugs are used. In these cold spark plug the ceramic coat insulation is large in amount, so that the dissipation of heat is high. These kind of spark plugs are used for high performable engines.

(Melting of spark plug)

Based on Material Used

Based on the types of materials used the spark plugs are classified into four types

Copper- Nickel Type

This type of spark plug is the most basic type. In this type the central electrode is made up of copper- nickel alloys. This type is not suited for high performance engine because copper is a weak metal, nickel is added to provide strength to the copper. Even after the addition of nickel, this types are very weak for withstanding the high heat and temperature. It also has a larger diameter and requires high voltage to perform. So, it will surely melt off when plugged in a high performance engine.

Single Platinum Type

In this type, the spark plug have a small size of platinum disc at the end of the central electrode. This platinum end strengthens the plug more than the copper-nickel alloy coating. It also reduce the accumulation of burnt slags.

Double Platinum Type

In this type the platinum tips are provided on both the central electrode as well as the ground electrode. These spark plug will spark twice ina combustion cycle. One at the compression stroke and the next at the beginning exhaust stroke. There won't be any ignition in the second spark. It is just wasted. It is used in the ignition system having waste spark distributor. The advantage of this waste spark is that, it is not affected by rain season or any dampness and it also reduces the accumulation of waste between the gap.

(Platinum spark plug)
Source: Marine Engine digest

Iridium Type

It is the best type of spark plug among all the types. In this type the central electrode tip is made up of metal called iridium. The iridium is one of the strongest metal. It is more stronger than all the other metal type spark plugs like copper, nickel and platinum. It has a small diameter therefore it requires only small amount of voltage for performance of spark. It has the capacity for withstanding the high heat. The only disadvantage in this type is that the cost of the spark plug. Since it is the strongest it is much more expensive when compared all the other types of spark plug available in the market.

(Iridium spark plug)
Source: Marine engine digest

Why spark plug are used only in petrol engines?

In the case of a diesel engine, the fuel is burned when the fuel is injected at high pressure to the hot compressed air in the cylinder. This hot compressed air reaches the engine cylinder with the help of a turbocharger or natural respiration. And with the help of the Fuel pump, the fuel reaches the combustion chamber. And hence both fuel and air enter the combustion chamber separately. Thus with the help of that hot compressed air, the combustion process takes place in a diesel engine.

But in the case of a petrol engine, the combustion will occur only when the air-fuel mixture gets ignited by the spark from spark plug which is present inside the engine cylinder. So in petrol engines, we are using spark plug to ignite the air-fuel mixture in yhe combustion chamber of the engine.

Symptoms of spark plug deterioration

After some times the span of the spark plug reduces and it will begin to Over time your car spark plug’s health will begin worsed. Generally, the span of a spark will be mentioned by the manufacturers. Ideally you have to change it after a runtime of 15,000 km. There are some symptoms that will indicate you about the deterioration of your spark plug. Some of the symptoms of deterioration of your spark plugs are

Rough idle condition when you start vehicle. once you turn on your vehicle
False firing of engine
High consumption of fuel
Low throttle power
Sudden rise in power

These are the some indications that your spark plug is losing its value.

(Spark plug deterioration)

How to improve your spark plug life?

Choose the right type of plug according to the performance of your engine.
Clean the tip of Electrodes regularly because sometimes there will be a chance for deposition of burnt gas. It may reduce the effectiveness of the spark plug.
Regularly monitor the spark plug gap. It should be between 0.6 to 1.8mm as I mentioned earlier.
Clean the mounting area of spark plug periodically.

Conclusion

That's all about the spark plug and types, construction and working of spark plug. Also, I had given some symptoms for deterioration of spark plug and ways to improve the spark plug.

I hope that you understand the definitions, types, construction, working, symptoms of deterioration of spark plug.

If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.

Spark your brain and Throttle your knowledge!

Errors in measurement

2020-10-03T17:43:00.017+05:30

Errors in Measurement

Hello mechons, in this post we are going to explain to you about the errors in measurement and errors types with details

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(Erros in measurement)

So, first let's start with

What are Errors in Measurement?

An error is defined as the dissimilarity between the calculated measurement and the exact measurement.

For example, if two persons are using a same instrument for measuring it is not sure that both are getting the same outcomes. There will be a slight differences between the measured output of those two persons. Those slight differences are called as errors.

In general, the error is the difference between the true value and measured value of the measurement.

In order to reduce the errors the instrument must be calibrated in a right way.

Calibration is the act of comparison of Measurements to maintain the accuracy of certain measurements. It is the process used for configuration of instruments to provide results within the acceptable range of tolerance. To know more about calibration process, read our article titled, "Calibration of measuring instruments" in that we are clearly deatiled about calibration process.

Terminology of Measurement

Before we are going to know about the errors types we must know some of the main terminology and basics of engineering Metrology.

The quality of the measurement can be described by using the following terms such as Precision, accuracy, sensitivity, repeatability.

Errors Types

The errors in measurement are caused by various factors and the errors are classified in the following types.

1. Systematic Errors

2. Gross Errors

3. Random Errors

Systematic Errors

The systematic errors are further classified into three types. They are

1. Observational Errors

2. Environmental Errors

3. Instrumental Errors

Observational Errors

The observational error occurs because the false study of instrument reading. There are many sources for this kind of errors to occur.

The main source of this error is Parallax effect. Parallax meaning 'alternation'. The parallax is defined as the displacement or the difference in the appropriate position of an object viewed in two different sides of views.

For example, if you took reading by using an ammeter, the indicator of the ammeter will have very small oscillation over the surface of the scale. As a result of this a fault happens above the indicator except the original value.

In order to reduce this parallax error extremely precise meters along with reflected scales are being used.

(Observational error)

Environmental Errors

Environmental errors occurs due to the outside environmental situation of the measuring instruments. These errors mostly occurs due to change in certain atmospheric conditions like temperature, moisture, humidity etc.,

There are some efforts to reduce these environmental errors. They are as follows

The evaluation should be finished within the stable environmental situation.
Always prefer to use the instrument which is not affected by the environmental issues such as temperature, pressure, humidity, etc.,

With these remedial steps we can avoid the environmental errors.

Instrumental Errors

Instrumental errors will happen due to some of the imitation of Devices wgich are being used for measuring. These errrors may occur due to the operation taken while measuring using the instrument or may be at the calculation. These errors will have impact in the value all the way from low level to high level.

Improper observer of the instrument

The errors on the instrument may happens because of the mistakes made the operator of the instrument. If an operator operates an advanced instrument without proper knowledge about that instrument will have a drastic effect. The improper observation may not cause harm to the instrument but it will cause all the other possible issues.

Gross Errors

This kind of errors are defined as the physical analysis error. This error can be occur due to the occurrence of mistake in calculating or recording the output values made by the observer. This error will occur in allover the experiment, wherever the observer records aor calculate with the different value other than the real ones. With proper knowledge these kinds of error can be predictable and also it can be easily corrected.

To avoid these error careful recording and calculations must be done throughout the experiment or work. It is also suggested to take two or more readings by different and accumulate it together to eliminate these gross errors.

Random Errors

The random error will occur due to the oscillations or vibrations in the apparatus which is being measured. This kind of error will be in the instrument at most of the times.

These errors are cleared by taking careful recording throughout the experiment . It is also suggested to take two or more readings by different and accumulate it together to eliminate these gross errors.

The Measurement Errors Calculation

The errors in measurement doesn't stands that the taken measurement were wrong instead it stands for that the device is not accurate enough for measuring. The errors are eliminated in three types of calculations namely

Absolute error
Relative error
Percentage error

Absolute error

The absolute error is defined as the variation between actual value and measured value of the measurement.

Absolute error = Actual Value - Exact Value

Percentage error

The percentage error is defined as the percentage ratio of absolute error and the exact value.

Percentage error (%) =
[(Actual value-Exact value) / Exact value] x 100

Relative error

The relative error is defined as the ratio of the absolute error and the actual value of the measurement.

Relative Error = Absolute error/actual value

Additional Resources

What are errors?
An error is defined as the dissimilarity between the calculated measurement and the exact measurement.
How many types of errors are there?The errors in measurement are caused by various factors and the errors are classified in the following types.
1. Systematic Errors
2. Gross Errors
3. Random Errors
what are gross errors
This kind of errors are defined as the physical analysis error. This error can be occur due to the occurrence of mistake in calculating or recording the output values made by the observer
what are the types of systematic errors
Observational errors, environmental errors, instrumental errors

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Conclusion

That's all about the errors in measurement and errors types, I hope you understand the definitions, types of errors in measurement.

If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.

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Basics of Thermodynamics

2020-09-28T20:47:00.003+05:30

Introduction to Thermodynamics

Hello guys, in this post we are going to explain to you about the basic concepts and terminologies of Thermodynamics.

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So, first let's start with the basics of Thermodynamics

What is Thermodynamics?

Thermodynamics is the branch of science which deals with the relations among heat, work, and properties of the system which are in equilibrium. It describes state and changes in the state of physical systems. The word Thermodynamics is got from the Greek words. Thermos means Heat and Dynamics meaning flow. Thermodynamics deals with heat and work.
It is based upon observations of common knowledge that have been formulated into thermodynamic law.
The applications of the thermodynamics law :

Energy Technology
Notably in steam
Nuclear power plants
Internal Combustion engines
Compressor
Chemical process plants
Direct energy conversions

Terminologies used in Thermodynamics

System:

A system is a finite quantity of matter under consideration that is separated from the rest of the universe by real or imaginary boundaries.

(Thermodynamic terminologies)

Surroundings:

Everything in the universe that is not part of the system and can interact with it is called as surroundings. That is outside of the system.

Boundary:

Boundary defined as it is (fixed or movable) separate the system from the surroundings. The boundary is sometimes real sometimes imaginary.

For example, take the cricket stadium here cricket ground is a system, outside the cricket stadium is surroundings and the wall or place which the audience sat is a separate system from the surroundings is called Boundary.

Types of Systems

Closed system
Open system
Isolated System

Closed System

A system that permits the exchange of energy but not masses, across the boundary with its surroundings is called a closed system.
An example of this system is a mass of gas contained in an engine, a closed beaker, and a Pressure cooker.

Open System

A system that permits the exchange of energy and mass, across the boundary with its surroundings is called an Open system. Most of the engineering systems are always open.
An example of this system is the turbine, boiler, steam engine, and open beaker.

Isolated System

An isolated system is defined as a system that can exchange neither mass nor energy with its surroundings.
Eg. Universe
Till now we didn't find anything is around the universe so it is called an Isolated system.

(TYPES OF SYSTEMS)

Homogeneous system

A quality of matter homogeneous throughout in chemical composition and physical structure is called a phase. A system containing a single-phase is called a homogeneous system.
Eg. A Mixture of Nitrogen and Oxygen.

Heterogeneous systems

A system containing more than one phase is known as a heterogeneous system.
Eg. Ice floats in water.

Macroscopic view vs Microscopic view

Macroscopic View	Microscopic View
In this approach to thermodynamics is concerned with gross or overall behavior.	In this approach, a certain amount of matter is considered the events occurring at the molecular level.
Simple Mathematical formulae required	Advanced Mathematical and statistical formulae are required.
To Describe the few properties required	To Describe a large number of variables are needed
The properties are easily measured by instruments.	The properties cannot be easily measured by instruments
It is also called as Classical Thermodynamics	It is also called as Statistical Thermodynamics

(Macro and microscopic studies)

Properties of Systems

A property of a system is a characteristic of the system which depends upon its state, but independent of how the state is reached.

Intensive properties

These properties are free from the mass of the system.
Eg. Pressure and Temperature.

Extensive properties

These properties free from the mass of the system.
Eg. Volume
If we divide Extensive properties by mass associated with them to obtain the intensive properties.
If Specific Volume is called intensive property.

State

The state defined as the condition of the system at an instant of time as described or measured by its properties also state is defined as each unique condition of a system.

Thermodynamic Equilibrium

A system that satisfies the conditions of thermal, mechanical, and chemical equilibria and contains the macroscopic properties which are independent of time is said to be in thermodynamic equilibrium.

Thermal Equilibrium

The temperature of the system does not vary concerning time and temperature the same at all points.

Mechanical Equilibrium

The pressure in the system is constant at all points and does not change concerning time. The unbalanced force, not in the system.

Chemical Equilibrium

Chemical composition which is the same through the system does not vary with time and No chemical reaction takes place in the system.

Thermodynamic Process

If the system undergoes a change in state or an energy transfer at a steady-state the process has occurred.

Non-flow process

A process may non-flow in which a fixed mass within the defined boundary is undergoing a change of state. The closed system undergoes non-flow processes.
Eg. Heating the substance within the cylinder.

Flow process

A process may a flow process in which mass is entering and leaving through the boundary of an open system.

Quasi-static process

Quasi means almost. A quasi-static process is also named a reversible process. This process is a succession of equilibrium states and unbounded slowness is its characteristic feature. A process which is but a locus of all equilibrium points passed by the system.
Different types of processes that are commonly used in the study of thermodynamics.

Isothermal Process

The isothermal process is defined as one in which the temperature of the system remains constant during the change from its initial to final states. During the isothermal process, the system allows to exchange of heat with its surroundings and the temperature of the system remains constant.

Adiabatic Process

An adiabatic process is defined as that one that does not exchange heat with its surroundings during the change from initial to final states of the system. A thermally and completely insulated system with its surroundings can have changes in temperature during the transformation from initial to final states in an adiabatic process.

Isobaric or Constant Pressure Process

The isobaric process is that process in which the pressure of the system remains constant during its change from the initial to the final state.

Isochoric or Constant Volume process

The isochoric process shows no change in the volume of the system during its change from the initial to the final stage of the process.

Reversible process

In a reversible process, the series of changes carried out on the system during its transformation from initial to the final state may be possibly reversed exactly. This is possible when the changes are carried out very slowly in many smaller steps on the system during its change from initial to the final state. By doing so, each of its intermediate states will be in equilibrium with its surroundings.
For example, when the ice melts a certain amount of heat is absorbed. If we remove the same amount of heat to form water, we will get ice.

Irreversible Process

An irreversible process is one that cannot be retained to the initial state without making a permanent change in the surroundings. Spontaneous processes are always irreversible in nature.

(Reversible and irreversible)

Reversible Process	Irreversible Process
This process is slow when it is going through a series of smaller stages with each stage maintaining equilibrium between the system and surroundings.	In this process, the system reaches the final state from the initial state with an observable speed. During the conversion, there is no equilibrium maintained between the system and surroundings.
The reversible process occurs in the forward and backward direction	The irreversible process occurs only one direction
Work done is high compare to the irreversible process	Work done is small compare to the irreversible process
If we brought back the reversible process, we need not change anything in the surrounding. Eg.Exapansion and compression of elastic material like spring, rubber, etc. Electrolysis	If we brought back the reversible process, we need to change anything in the surrounding. Eg. Relative motion with friction Diffusion Throttling

Cycle

A cycle is defined as the series of processes the end states are the same.

For example, we are going to college or school every day. First, we will go to the school from the house and after school time finished we will come to our home. This scenario is called a cycle.

Point Function

Point function is defined as two properties that are located a point on the graph (co-ordinate axes) then those properties are called point function.
Eg. Pressure, Volume, Temperature.

Path Function

The path function is defined as two properties that are not located a point on the graph then those properties are called path function.
Eg. Heat and Work.

Temperature

The temperature is a thermal state of a body that differentiates a hot body from a cold body.
The temperature is directly proportional to the molecular energy stored in the body.
There are various types of instruments are available to measure the temperature of the body.

For ordinary temperature we can use a thermometer and to measure high temperature we will use Pyrometers.
The SI unit of temperature is Kelvin(K). We can also measure temperature in °C( Degree Celsius) 1°C =273.15 K.

Pressure

Force per unit area is called pressure. The pressure may be caused by gases, vapors, and liquids. The instrument that is measuring the only gauge pressure that means how much amount of pressure caused by gases, vapors, and liquids. That instrument didn't take the atmospheric pressure (Pressured exerted by the atmosphere ).

When gauge pressure is greater than atmospheric pressure is known as positive pressure.

When gauge pressure is less than atmospheric pressure is known as vacuum pressure.
Absolute pressure means the sum of gauge pressure and atmospheric pressure.

Mathematically:

Absolute pressure= Atmospheric pressure + Gague pressure
Vacuum pressure = Atmospheric pressure - Absolute pressure.

Atmospheric pressure is measured by the barometer.
Unit of pressure: SI unit is N/m² or we can call pascal (Pa). Another term is bar, 1 bar = 10⁵N/m².
Standard atmospheric pressure is = 1.01325 bar that is equal to 760 mm of Hg (Hg means Mercury).

Work

Work is defined as force moves through a system. Also, we can say the product of the pressure and area. Typically it is defined as it is a transient quantity that only appears at the boundary while the displacement of the state is taking place within a system.

Sign convention:

Work done by the system is termed as positive work. Eg. When a gas expands pushing a piston outwards.
Work done on the system is termed as negative work. Eg. Force applied to a rotating handle.

SI unit of work is Joule(N-m).

Heat

The form of energy that is transferred across a boundary by virtue of a temperature difference is known as heat.

Sign Convention:

Heat received by the system is Positive heat (+Q).
Heat rejected by the system is Negative heat (-Q).

SI unit of heat is Joule(N-m).

Heat	Work
To heat transfer temperature difference is required	The temperature difference is not required
Stable system attain the heat transfer	Work is cannot be transferred by a stable system
The external effect is calculated in heat transfer	The external effect is not calculated in work transfer
*Similarities:*
Heat and work are path functions inexact differentials.
Heat and work are correlated with a process, not a state
The system possesses energy but not in the form of work or heat.

Sensible Heat

The amount of heat is required to raise the temperature of the substance is known as sensible heat.
If we applying heat is sensible, the temperature of the system varies.

Latent Heat

The amount of heat is required to change the phase of the substance is known as latent heat.
The temperature of the system doesn't vary while phase changing.

For example,
If we heat the water, the temperature of the heat increasing until the water vaporization takes place this heat is known as sensible heat and if we add heat during the vaporization, phase change occurs then the temperature of the water is constant that means latent heat.

Specific heat

It is defined as the amount of heat required to raise a unit mass of the substance through a unit rise in temperature. the symbol is used to mention specific heat C.
SI unit of the specific heat is J/kg K.

(Graphical representation)

Conclusion

That's all about the Basics of Engineering Thermodynamics, I hope you understand the definitions, types, terminologies of Thermodynamics.

If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.

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Generalised Measuring Systems

2020-09-23T13:48:00.000+05:30

GENERALIZED MEASUREMENT SYSTEMS:

Hello mechons, in this post we are going to explain to you about what is a generalized measurement system, the basic requirements for measurements, measuring instruments, and elements of the general measurement system

Ok, first let's begin with

What is an instrument?

An Instrument may be defined as a device that is used to provide a functional relationship between properties of physical variables(heat, mass, pressure, etc.,) which are used and must include ways for communication to a human observer.

(Vernier caliper)

BASIC REQUIREMENTS OF MEASUREMENT:

The standard instruments which are used for comparison purposes must be accurate & must be accepted worldwide.
The apparatus that is used for measuring and the method which is followed for measuring must be acceptable worldwide.

MEASURING INSTRUMENT:

A measuring instrument is defined as a device for determining the magnitude of any quantity or variable that is to be measured.

ELEMENTS OF A GENERALIZED MEASUREMENT SYSTEM:

The main functional elements of a measuring system are listed as below

Primary Sensing Element.
Variable Conversion Element
Variable Manipulation Element
Data Transmission Element
Data Presentation Element

Primary sensing element:

The primary sensing element makes the contact first with the quantity which is to be measured.

It means that the unknown quantity which is to be measured is first detected by a primary sensor and that primary sensor provides the output in an analog form(like voltage). Then this analog output is converted into an electrical signal by using a transducer.

(Transducer is a device that converts the physical form of signals into electrical form.)

The primary sensing element transfers the measurand to the variable conversion element for further processing.

(Pressure sensor)

Variable conversion element:

The output which is provided by the primary sensing element may be at any form of an electrical signal, it

maybe a voltage signal, a frequency signal, or other electrical Parameters.

To perform the desired function by the instrument, it is necessary to convert that output into some other suitable forms. And these conversions of information must be done without any loss in the original data provided by the measurand. This conversion of information is performed by a variable conversion element and it is also named as an intermediate transducer of measurement system.

Variable manipulation element:

The variable manipulation element is used for modification of the direct signals provided variable conversion element. In the modification, the processes like amplification, attenuation, filtering of the signal may be carried out. So that the desired output is produced without any change in the physical nature of the variable to be measured. The variable manipulation system is the middle stage of the measurement system.

(Elements of general measurement system)

Data Transmission Element:

The functional element of the measuring system must be separated in some situations, then it is necessary to transfer data from one element to another. The function of separating data element is carried by the Data transmission element.

Data Presentation Element:

The information about the quantity to be measured must be able to communicate with the human observer for monitoring and controlling purposes. Therefore the information of the measurand must be presented in the way that a human observer can easily understand and manipulate it. This function of presenting the information suited for observation is done by using data presentation element.

(Presentation element)

Conclusion

That's all about the elements of general measurement system, I hope that you understand the definitions, elements of measurements.

If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.

Spark your brain and Throttle your knowledge.

Basics of Engineering Metrology

2020-09-22T23:56:00.007+05:30

Introduction to Engineering Metrology :

Hello mechons, in this post we are going to explain to you the basics of Engineering Metrology(i.e. Introduction to Metrology) in which we talk about Metrology with its definition also with its type along with we will also explain what is measurement and types of Measurements.

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What is Metrology?

Metrology is defined as the Science of Measurement. Concerned knowledge in measurement and includes both theoretical and practical problems related to measurement. It is used to enforce, validation, and verification to predefined standards. Metrology is a term which is derived from the Greek word "Metrologia" which means measure.

(Speedometer)

Types of Metrology

Metrology is into three types based on the purpose of using. They are

Scientific Metrology

Industrial Metrology

Legal Metrology

Scientific Metrology

It deals with the organization and development of measurement standards and with their maintenance at the highest level. They are creating some standard to measure the object and that is taken as reference.

Industrial Metrology

It deals with the to validate enough function of measuring instruments which used in the Industry and Production and Testing Process. It is vital to work with quality in Industrial activities. Already we had a reference by using that reference we try to check whether it is the correct one or not.

Legal Metrology

It is related to the accuracy of measurement where these have an influence on the transparency of economical transaction, safety, and Health. We are using this measurement in daily life but it is not taken into account. Its parameter is to regulate, advise, supervise, and control the manufacturing and calibration of measuring instruments.

Measurement

Let's continue with, What is measurement?

Measurement is a Process or act of obtaining a quantitative comparison between a predefined standard and an unknown magnitude. For example, we have a one-liter vessel. We want to know how much water containing another vessel. For that, we have to compare with a known quantity with the unknown quantity, that process known as Measurement.

(Manometer)

Methods of Measurements

Basically, the measurements are classified into two types

Direct method
Indirect method

Direct Method of Measurement

The value of quality is obtained directly by comparing the known standard.

There are no mathematical calculations to get a result.

Eg. Measuring Height by using scale or tape. This method is not accurate since it has human interactions.

Indirect Method of Measurement

In this method, parameters are measured directly by direct measurement, and the value is determined by some mathematical relationship.

Eg. Measurement of Velocity by measuring distance traveled and time is taken to travel that distance.

Levels of Measurement

Primary Measurement
Secondary Measurement
Tertiary Measurement

Primary Measurement:

In this measurement, we need not do any conversion (translation) to get the required quantity. It is get by direct observation.

Eg. Matching of two heights, it means determining the height of two objects with a centimeter or meter rod.

Secondary Measurement:

A secondary measurement we need only one conversion (translation) to get the required quantity.

Eg. Measure the Pressure of gas may not be observable.

Frist the Pressure is converted into length. A length scale or a standard that is calibrated in length units equivalent to known changes in pressure.

Tertiary Measurement

A Tertiary measurement involves two translations.

The measurement of the temperature of an object by Thermocouple.

(levels of measurement)

If you to know about the standards of measuring instruments, read our article about "Calibration of measuring instruments", where you will get all details about Calibration process, standards of measuring instruments and so on.

Metrological Terminologies

Accuracy

The measuring instrument gives a value close to the true value of the measured quantity.

Accuracy is determined as the maximum amount by which the result differs from the true value.

Precision

Precision is the capacity of a measuring instrument to give the same reading when repetitively measuring the same quantity under prescribed conditions.

Precision is not close to the true value.

ACCURACY	PRECISION
Accuracy is a measure of correctness.	Precision is a measure of how much-defined information is given.
The value is correct and free from error.	Exactness is applied
Accuracy can be improved	Precision cannot be improved
Depends on the person measuring	Depends on the tool measuring
Accuracy = Mean value - True Value	Precision = Individual value - Arithmetic value
If Accuracy means the following results may be obtained 1.172 Kg 1.284 Kg 0.918 Kg 0.893 Kg	If Precision means the following results may be obtained 1.513 Kg 1.526 Kg 1.578 Kg 1.569 Kg

(High accuracy & low precision)

(High accuracy & high precision)

(Low accuracy & high precision)

(Low accuracy & low precision)

Sensitivity

The ratio of the magnitude of the output signal to the input signal or If we change the smallest value in the measured value, the instrument will respond that is known as Sensitivity.

It is represented by the slope of the calibration curve if the coordinates are expressed in actual units.

Repeatability

Repeatability is the precision of a set of measurements taken over a short tie interval.

Condition:

Where test results are obtained independently using the same methods, items, place, operators equipment with a short interval of time.

Reproducibility

Reproducibility is the precision of a set of measurements.

Condition:

Where test results obtained using the same method and items but in different places, operators, and equipment.

Readability

It refers to the ease with which readings of a measuring instrument can be read.

The measuring device can give value in the number form. Readability improved by magnified glass fine and widely spaced graduation.

Response time

The time elapses after a sudden change of the measured quantity until the Instrument gives an indication.

Resolution

The smallest variation of a measured quantity which changes the indication of the measuring instrument.

Stability

The ability of the measuring instrument that constantly maintains the metrological characteristics with time.

Calibration

The set of operations that create the relationship between values indicated by instruments and corresponding values given by standards under specified conditions.

Confirmation

The set of operations required to validate an object of measuring equipment is in a state of compliance with requirements for its intended use.

Correction

It is defined by systematic error. Systematic error cannot find exactly sp correction is subjected to uncertainty.

Range

The difference between the largest and smallest readings of the instrument able to measure is called the range of Instrument. It is represented as lower and upper values.

Span

Span is the algebraic difference between the upper and lower range values of the instrument.

If the highest point of calibration is Smax units and Lowest is Smin units then the range can be calculated as follows

Span= (Smax -Smin ) units

Drift

A slow change of metrological characteristics of measuring instruments.

Drift occurs very slowly and can be checked by periodic inspection and maintenance.

Causes of Drift:

Temperature Variation.
Wear and tear.
Stray electric and Magnetic fields
High mechanical stress created in some parts of instruments and systems
Mechanical vibrations

Classification of drift

Zero drift
Span drift
Zonal drift

Zero drift:

If the whole of instrument calibration gradually shifts over by the same amount.

It may be a permanent set or slippage and can be corrected by shifting the pointer position.

( Fig. Zero drift)

Span drift:

If the calibration from zero upward changes proportionally, it is called span or Sensitivity drift.

It may be due to change in spring gradient etc.

(Fig: Span drift)

Zonal drift:

When the drift occurs only over a portion of the span of the instrument it is called zonal drift.

(Fig: Combined drift)

Error:

The difference between the instrument measured value and the true value of that object.

Types of Errors

Systematic Errors
Random errors
Gross errors

Systematic errors:

Systematic errors are reproducible inaccuracies that are consistently in the same direction.

Random errors:

Random errors occur due to random and unpredictable variations in experimental conditions like temperature, Pressure, etc.,

Gross errors:

Gross errors occur due to the carelessness of an observer is known as gross errors.

Hysteresis

Hysteresis is the phenomenon defined as the difference outputs while loading and unloading.
Hysteresis takes place due to the fact that all the energy put into the stressed part when loading is not recoverable while unloading.
The output at particular input while increasing and decreasing varies because of internal friction or hysteresis damping.

Linearity

Linearity is defined as the ability of an instrument to produce its input linearly.
The closeness of the calibration curve to a specified straight line.

Conclusion

That's all about the Introduction to Metrology, I hope you understand the definitions, types, and levels of Measurement and Metrology.

If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.

Spark your brain and Throttle your knowledge.

Principles of Engineering Mechanics

2020-09-22T19:24:00.003+05:30

BASIC PRINCIPLES OF ENGINEERING MECHANICS:

Hello mechons, in this post we are going to explain to you all the basic principles of engineering mechanics.

1. TWO FORCE SYSTEM:

If a body is acted upon by two forces, then the two forces must be equal, collinear, and opposite to each other.

2. THREE FORCE SYSTEM:

If a body is acted upon by three forces, then the resultant of any two forces must be equal, collinear, and opposite to the third force.

3. FOUR FORCE SYSTEM:

If a body is acted upon by four forces, then the resultant of any two forces must be equal, opposite, and collinear to the resultant of the other two forces.

Methods For Equilibrium:

Analytical.
Graphical

ANALYTICAL:

LAMI'S THEOREM:

STATEMENT OF LAMI'S THEOREM:

If three coplanar forces acting at a point that is in equilibrium, then each force acting at the point is proportional to the sine of the angle between the other two forces.

(Representation of Lami's theorem)

Let P, Q, R be three coplanar forces,𝝰, 𝛃, 𝜸 be the angles between them

Then, P/sin 𝞪= Q/sin 𝜷 = R/sin 𝜸

GRAPHICAL:

CONVERSE LAW OF TRIANGLE OF FORCES:

If three forces at a point can be represented as three sides of a triangle, then they are in equilibrium.

(Triangle law of forces)

CONVERSE LAW OF POLYGON OF FORCES:

If any number of forces can be represented as sides of a polygon, then they shall be in equilibrium.

(Polygon Law of forces)

CONDITIONS OF EQUILIBRIUM:

1. Body may move in one direction.

2. Body may rotate itself but there should not be any movement.

3. Body may move and also rotate itself in one direction.

4. Body may be completely at rest.

By the above conditions, we get,

1. If a body moves in one direction, a resultant force acts on it. If it is considered to be in Equilibrium, then it's horizontal (𝚺H) and vertical(𝚺V) forces are zero.

𝚺H~0, 𝚺V~0

2. If a body rotates itself without moving, then it has a resultant couple acting on it. If it is said to be in equilibrium, then the resultant moment(𝚺 M) is zero.

𝚺M~0

3. If a body rotates and also moves in one direction, then it has a resultant force and a resultant couple acting on it. If it is said to be in equilibrium, then the resultant force(𝚺H, 𝚺V) and moment(𝚺M) are zero.

𝚺H~0, 𝚺V~0, 𝚺M~0

4. If a body is in rest, no resultant force or couple acts on it.

𝚺H~0, 𝚺V~0, 𝚺M~0

TYPES OF EQUILIBRIUM:

1. Stable equilibrium:

If a body returns to its original position after applying a force, then it is said to be in stable equilibrium.

Ex: A smooth cylinder in a curved plain, after a displacement, comes back to its original position to bring the weight back to the horizontal axis.

(Stable equilibrium)

2. Unstable equilibrium:

If a body does not return to its original position, then it is said to be in unstable equilibrium.

Ex: A smooth cylinder in a convex plane, tends to move away from the initial position.

(Unstable equilibrium)

3. Neutral equilibrium:

If a body occupies a new position after displacement, then it is said to be in neutral equilibrium.

Ex: A smooth cylinder in a horizontal plane.

(Neutral equilibrium)

Conclusion:

That's all about engineering mechanics principles, for now, we hope that we covered almost all the principles of Engineering mechanics, also we hope that you understand the definitions.

If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.

Spark your brain and Throttle your knowledge.

Carburetors with types and working

2020-09-12T16:38:00.030+05:30

CARBURETOR

Hello mechons, in this sparking day we are going to explain to you about what are Carburetors, parts of a simple carburetor, what are the types of carburetors, how the carburetors work also the advantages and disadvantages of carburetors with its applications.

What are Carburetors?

(carburetor)

The carburetor is a device that is used for mixing the air and fuel in the correct and proper ratio of air-fuel mixture for an internal combustion engine for combustion. In general for burning the fuel inside the combustion chamber of an engine cylinder in all conditions we need a rich air-fuel mixture, to get such a rich air-fuel mixture we are using a device called Carburetor.

The main purpose of the carburetor is to regulate the air-fuel mixture ratio and by regulating that, it controls the speed of the engine since the speed of the engine depends upon the amount of air-fuel mixture passing inside the engine cylinder.
And also the main thing is that we are using the carburetors only in Petrol engines(SI engines) and not in diesel engines(CI engines). (Here SI stands for - Spark Ignition & CI stands for Compressed Ignition). Just read our post about the difference between Spark and compressed ignition engine for more clarification in differences between these ignition system.

Do you know, Why carburetors are used in petrol engines, not in diesel engines?
The carburetors are used only in Petrol engines i.e. Spark ignition because of the difference in the mode of combustion between Petrol and diesel engines.

In the case of a diesel engine, the fuel is burned when the fuel is injected at high pressure to the hot compressed air in the cylinder. This hot compressed air reaches the engine cylinder with the help of a turbocharger or natural respiration. And with the help of the Fuel pump, the fuel reaches the combustion chamber. And hence both fuel and air enter the combustion chamber separately. Thus with the help of that hot compressed air, the combustion process takes place in a diesel engine.

But in the case of a petrol engine, the combustion will occur only when the air-fuel mixture gets ignited by the spark from spark plug which is present inside the engine cylinder. This flow of air-fuel mixture is regulated and monitored by the carburetors.

So in petrol engines, we are using the mixture of fuel and air for the combustion process than a direct injection of fuel into the combustion chamber.
Thus to get that air-fuel mixture we are using Carburetors in Spark ignition(SI) or Petrol engines.

Parts of a Carburetor:
Ok, let's talk about the parts of the carburetors
So now, what are the parts of a Carburetor?
A simple carburetor is comprised of the following parts which are listed below:
Throttle Valve
Choke Valve
Mixing Chamber
Metering system
Idling system
Float Chamber
Idle and Transfer port
Venturi
Strainer

Throttle Valve:
The throttle Valve is one of the most important parts of a Carburetor. It regulates the air-fuel mixture which is supplied to the engine cylinder. The throttle valve is opened when the driver throttled the accelerator.

Choke valve:
A valve that controls the air-fuel mixture is called a Choke valve. The primary function of the Choke valve is controlling the amount of air that is present inside the mixing chamber. The valve is remains opened partly, in the case when we are in need of a rich air-fuel mixture we can operate the valve and this valve remains very close to the inlet of the air passage, so we are able to get rich air-fuel mixture when we use this valve. We use this valve more in the rainy season because in those times is the engine will not get enough air to get started, so by using this valve we get rich air-fuel mixture to start the engine.

Mixing Chamber:
The mixing process of air and fuel takes place in this chamber and then supplied to the cylinder of the engine. Hence it is called a mixing chamber.

Metering system:
The flow of fuel into the nozzle is controlled by the metering system. The metering system is responsible for forming the correct air-fuel mixture.
It contains two important parts:
1. Metering orifice
2. Fuel discharge nozzle
When the air gets passes through the venturi, it creates a low-pressure field in the throat. Due to the difference in pressure, the fuel is discharged. The amount of fuel entering is controlled by the metering orifice and discharge hole at the exit of the fuel discharge nozzle.

What is the function of the nozzle tip in a carburetor?
The difference of level between the upper end of the main nozzle and float chamber fuel level is called nozzle lip.
The function of the nozzle tip is to reduce the overflow of fuel from the nozzle, the main nozzle end is usually kept at a higher level than the float chamber fuel level.

Idling system:
The idling system contains a passage directly from the float chamber to the Venturi tube. It creates a rich air-fuel mixture during the process of idling or throttling the accelerator up to 15%.

Float Chamber:
It acts as a storage tank of fuel for a continuous supply of fuel to the engine cylinder. It has a float valve that regulates the level of fuel in the float chamber. When the level of fuel decreases the float will move downwards so that the fuel supply valve opens and the flow of fuel takes place. If the fuel level increases, the float will move upwards and the fuel valves close so that the supply of fuel flow can be stopped.

Idle and Transfer port:
There are other two ports or nozzles present along with the main nozzle in the venturi for the supply of fuel to the engine cylinder called Idle and transfer ports or nozzles.

Venturi:
A hollow tube which helps to decrease the air pressure of the chamber for which the fuel comes out from the fuel pipe.

Strainer:
A component that is used for filtering the fuel before it gets enters the float chamber is called Strainer. It posses fine filters that remove the dust and other unwanted materials from the fuel. If these dust are not removed then, these specks of dust will block the nozzle.

Working of a simple carburetor
The Float and valves system maintains a constant level of fuel in the float chamber. The float chamber remains open in the atmosphere. The fuel from the fuel tank is supplied to the float chamber by using the fuel pump. The strainer now filters the fuel and removes the dust and unwanted materials from the fuel. Then this fuel is supplied to the main nozzle. The suction of air from the atmosphere takes place. This air passes through the venturi and it reduces the area of cross-section at the throat of the venturi.

Now the fuel is passed from the float chamber to a discharge jet tube which is at the tip of the throat of the venturi. Because of this, the pressure at the main nozzle and the velocity of the airflow increases. Due to the difference in pressure at the nozzle and the float chamber causes the formation of a mixture of atmospheric air and the fuel occurs. This difference in pressure at the float chamber and venturi is known as carburetor depression.

If we open the throttle valve more airflow will occur at the venturi tube and a large quantity of air and fuel mixture is supplied to the engine so that the engine can produce more power and also possess high speed, when close the throttle valve these actions takes place in the reverse way i.e. The quantity of air-fuel mixture reduces at venturi tube, so the power and speed of the engine get reduced.

Types of carburetors
So, let's start with the types of carburetors
what are the types of carburetors?
Based on the flow directions of the air-fuel mixture, the carburetors are classified into three basic types as follows:

1. Updraft carburetors
2. Horizontal or side-draft carburetors
3. Downdraft carburetors

Updraft carburetor
If the air supply is from the bottom side of the mixing chamber then it is called an updraft carburetor. The name itself will explain the working of this type, in updraft carburetors the air enters from the bottom side of the carburetor and moves towards the upside against the gravitational force, the fuel enters from the float chamber. Due to the difference in pressure between these two, chambers the venturi will mix the fuel that comes out from the float chamber with the inlet air and make the air-fuel mixture.

And then this air-fuel mixture is passed to the throttle valve which is directly connected to the accelerator, now this air-fuel mixture is passed to the engine cylinder where the combustion will occur when we rise the accelerator. The main disadvantage of this type is this type of carburetors has to lift the fuel droplets against gravitational force by air friction, and also the jet tube cross-section is small, because of these disadvantages these type of carburetors cannot supply the air-fuel mixture at high-speed.

Horizontal or side draft carburetor
If the air supply from the side of the carburetor then it is called horizontal draft or side draft carburetor. In horizontal or side-draft carburetors, the jet tube is placed in the horizontal direction. The air is coming in through one end of the carburetor and gets mixed with the fuel to form an air-fuel mixture. Then this air-fuel mixture is passed to the engine cylinder. Here also the throttle valve controls the quantity of air-fuel mixture passing through the engine cylinder. This resembles downdraft carburetor, when you rotate the downdraft carburetor in a horizontal direction then it is a horizontal draft or side draft carburetor. The advantage of this type is there is no airflow of resistance.

Downdraft carburetor
If the air is supply is from the upper side of the mixing chamber then it is called down-draft carburetor. In a downdraft carburetor, the air-fuel mixture enters the carburetor from the upside and moves towards the downside of the carburetor with the help of gravity. This type of carburetors is also works under the same principle due to the pressure differences between the two venturi the fuel comes out from the chamber mixed with the air. The air-fuel mixture is controlled by the choke valve. The throttle valve controls the quantity of air-fuel mixture passing through the engine cylinder. These type of carburetors allows the proper flow of air-fuel mixture to the engine cylinder. These carburetors help to operate engines at both high and low speed.

Which type of carburetors are widely used and why?
In most of the cases down-draft carburetors are generally used, because of the advantages as follows :

1. The flow of the air-fuel mixture is assisted by gravity, so the engine function is better at lower speeds under load.
2. We are able to achieve higher Volumetric efficiency when we use this type of carburetors.

Functions of a carburetor
The functions of a carburetor are :

1. The primary function of carburetors to produce an air-fuel mixture for combustion.
2. The speed of the engine is controlled by carburetors.
3. It maintains the ratio of air and fuel in the air-fuel mixture.
4. Maintaining a certain amount of fuel in the float chamber at all times.
5. To supply the correct amount of air-fuel mixture at the correct strength under all conditions of load and speed of the engine.

Advantages of the carburetor
1. Carburetor parts are cheap when compared to fuel injectors.
2. By using this, we can get more air-fuel mixture.
3. In the case of road tests, carburetors produce more power and precision.

Disadvantages of the carburetor
1. At low speed, the air-fuel mixture supplied by the carburetor is so weak and it will not
ignite properly.
2. The carburetor working may be affected by changes in atmospheric pressure.
3. Fuel consumption and air emissions are more when compared to fuel injectors.
4. Cost of maintenance is higher than the fuel injection system.

Applications of Carburetor
1. Used in Spark-Ignition Engine.
2. Used in controlling the speed of the vehicles.
3. Used to convert the main fuel(petrol) into fine droplets and it mixes the fuel with air for burning the fuel smooth and proper without any problem.

Conclusion:
That's all about carburetors, I hope you understand the definition, parts,
types, working, functions, advantages, and disadvantages of the carburetor.
If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.

Spark your brain and Throttle your knowledge.

External combustion engine

2020-09-08T19:50:00.013+05:30

EXTERNAL COMBUSTION ENGINE:

Hello guys, in this sparking day we are going to expalin about the category of external combustion engine and Classification with examples.

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External Combustion engine

So now,

What is an External Combustion engine?

(Steam engine invented by James Watt)

Like Internal combustion engine(IC engine) the external combustion engine is an category of heat engine. It is also shortly known as EC engine. In this type of heat engine the working fluid or fuel or gas present inside the cylinder is heated by an external heat supplying source through which the heat is passed to the engine wall or heat exchanging element. Then the fuel or fluid is expanded by the heat which is applied at engine wall or at heat exchanging element to carry out the mechanism of engine by producing motion and other usable work. After this process the working fluid is cooled and compressed and reused incase closed cycle engine or dumped outside incase of open cycle engine.

Types of external combustion engine:

There are two basic kinds of External combustion engine

1. Steam engine

2. Stirling engine

Steam engines:

Steam engines were the oldest type of engine used to produce power for vehicles in the olden days, The best example for the use of steam engine is steam train. These steam trains get power by using steam engine for motion of the train. It is the exact place where the steam engines were used in large scales, but due to the invention of diesel engine the steam engine became out of usage. This is because the loss of energy in steam engine is much greater when compared to that of diesel engines. Especially the amoubt of heat loss on the way from the boiler to the piston is more. Also these engines are bulk in size and produce low work to power ratio so because of these reasons the usage of the steam engine was reduced nowadays. However still these steam engines are used in power stations.

(Schematic diagram of a STEAM ENGINE)

Stirling engines:

Stirling engines are also one the categories of external combustion engines. Like steam engines these engines also have a low power-to-weight ratio as well, but theoretically, these engines are capable of reaching high levels of efficiency. A lot of research is being in process for how the actual efficiency of these engines could be improved, these engines may also have a great potential in future when we use more renewable energy sources.

(Schematic diagram of a STIRLING ENGINE)

Differences between Internal and External Combustion Engines:

The main difference between the internal and external combustion engine occurs in place where the Combustion occurs.

In internal combustion(IC) engines the combustion takes place inside the cylinder where the working fluid or fuel is present.
But in case of an external combustion(EC) engines, the combustion takes place outside the cylinder. The heat will be transferred into the working fluid with the help of an heat exchanger or throughthe engine wall.

Conclusion:

Here is all EXTERNAL COMBUSTION ENGINE.

if you have any doubts about this or anything that you want to include here Comment your thoughts in the comments section below. We will rectify and reply for that as fast as possible.

Spark your brain and Throttle your knowledge.

Internal combustion engine types and working

2020-08-30T17:47:00.029+05:30

INTERNAL COMBUSTION ENGINE

Hello guys, in this post we are going to see about the Internal combustion engine with its classifications, parts of internal combustion (ic) engine and working of an Internal combustion engine.

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Ok, first lets start with

What is an Internal Combustion (IC) engine?

The type of engine in which the combustion of fuel taking places inside the cylinder of a engine is known as Internal combustion(IC) engine.

Principle of Internal Combustion engine

There are two principles which have been used in reciprocating internal combustion engines are:

Otto Cycle:

The otto cycle was named after The German scientist known as Nikolous Otto for Otto cycle engine

Diesel Cycle:

The Diesel engine was named after the French-born German engineer known as Rudolf Christian Karl Diesel for diesel cycle engine.

Both the otto and Diesel-cycles were used in Two-stroke engine and Four-stroke engine categories.

Classification of Internal Combustion Engines

The IC engines are classified under the basis of following types. They are:

Based on the type of fuel used:

Gas engine
Petrol engine
Light oil engine (kerosene)
Heavy oil engine (diesel)

Based on the working cycle:

Otto cycle engine
Diesel cycle engine
Dual combustion engine

Based on the speed of the engine:

Low-speed engine
Medium speed engine
High-speed engine

Based on the category of ignition:

Spark ignition engine
Compression ignition engine

Based on type of cooling system:

Air-cooling engine
Water-cooling engine

Parts of Internal Combustion(IC) Engines

Cylinder:

The cylinders of IC engines are generally made of nickel and cast iron. The body of the cylinder body comprises with the passage of both inlet and outlet of fuel. It is also referred to as the heart of engine. The piston of the engine reciprocates within the cylinder. The cylinder is made up of nickel and cast iron. The cylinder head block contains spark plug and it is fitted along with the atomiser.

Spark plug:

It is the small part in a Petrol engine or SI engine which is used to produce spark to burn the fuel.

Fuel injector:

The part which is only used in a Diesel engine or CI engine for spraying the fuel inside the engine cylinder is called fuel injector.

Pistons:

The Pistons which are generally used in internal combustion(IC) engines moves to the end inside the cylinder. So it is known as trunk pistons.The reciprocating member of the engine which moves with in the cylinder is called Piston. The piston rings are fitted at the top of the piston to prevent the leaking of fuel which passes through the piston. So these rings are known as "compression ring".

Connecting rod:

The part of the engine which converts the reciprocating motion of piston into rotary motion of crankshaft is called connecting rod.The rod which links between the piston and the crank is called as connecting rod. The end which is connected with piston is called wrist pin or piston pin and the end whichis connected with the crank is called as crank pin. With the help of the connecting rod, the pressure of the working gases is transferred to the Crank.

Crank and crankshaft:

The rotating member of the engine which makes circular motion inside the crankcase is known as crank. It is made up of steel forging. The body of the crank is rectangular in cross section. The rotating member of the that connects the crank and connecting rod is known as crankshaft. It is placed inside the crank case.

Flywheel:

For controlling the fluctuation of speed which is being produced by the fluctuation of energy produced per a cycle of operation, a heavy weight element in the form of a wheel will be mounted on the crankshaft is known as flywheel. It is made of up of cast iron. It is also responsible for storing energy in the form of inertia and also for converting it into mechanical work.

Governors:

For controlling the speed of the engine due to fluctuation in external load, a controller mechanism is used known as governor. It also connects with the engine crankshaft.

Intake manifold:

The passage pipe which carries the fresh fuel or air-fuel mixture into the cylinder is known as intake manifold.

It is used because for providing equal amount of fuel to every cylinder in the engine.

Exhaust manifold :

The passage pipe which is carries out the exhaust gas from the engine cylinder is known as exhaust manifold.

Piston rings:

The piston is accommodated with some ring like structures on it outer surface. It is called Piston rings. The Piston rings fits the fuel tightly between the Piston and the cylinder so that it prevents the leakage of high pressure gas. These rings are made up of special category of cast iron,so it retains elasticity even at very high temperature.

And these rings sealed between the gap cylinder lines and the piston. It is also responsible for carrying the lubricants between those parts, i.e. Piston and Cylinder. The rings which are held nearer to cylinder head are known as “compression rings” and those are held away from the compression rings are known as “oil rings”.

Camshaft:

The main part of the valve gear mechanism is called as cam. It is provided for operating the function of opening and closing of both Inlet and Exhaust valves and it also operates the fuel injection pump incase of Diesel engine.The camshaft is driven by the crankshaft at a speed which is the half speed of the crankshaft.

Push Road and Rocker arm:

The cam motion is transferred to the valve by means of the pushrod and rocker arm that rotates in a vertical plane about the lever due to rotation produced by the cam.

It is provided for monitoring the motion of the cam.

Crankcase:

It is one of the part of the engine which provides shelter for the crank and other engine parts. It also acts as the sump for storing lubricants in it.

Inlet valve:

The valve which controls the entry of fuel or air-fuel mixture into the cylinder of engine is is called Inlet valve.

Exhaust valve:

The function of this valve is to control the exhaust of the burnt gases from the engine cylinder into the atmosphere.The valve whivh controls the process of removing burnt gas after combustionis known as exhaust valve.

Valve spring:

The spring which operates the closing function of valve is known as valve spring.

Top dead center(TDC) :

It is the uppermost end position of the piston at the head of the cylinder.

At TDC the angle of the crank is supposed to be at 0'.

Bottom dead center:

The lower end position of the piston at the end of the crankis called bottom dead center. At BDC, the angle of the crank is supposed to be at 180'.

Stroke or stroke length:

The distance through which piston moves within the cylinder of the engine during one stroke is known as stroke length. Approximately it is equal to twice the length of the crank. In other words it is said that stroke length is the total distance between the top and bottom dead centers.

Cylinder bore:

The inner diameter of the cylinder of an engine is called cylinder bore.

Stroke volume:

The volume of the piston at covered in one stoke within the cylinder is known as stroke volume.

Clearance volume:

The volume which is left between the head of the cylinder and piston at the time when the piston is at either end i.e.,TDC or BDC.

Cycles of IC engines

The internal combustion engine has three basic cycle for operation. They are

1. Otto cycle

2. Diesel cycle

3. Dual combustion cycle

Otto cycle

It consists of two reversible adiabatic, two constant volume process. Heat is supplied during process 2-3 at constant volume and heat is rejected during the process 4-1 at constant volume. During adiabatic process 1- 2 and 3- 4, no heat is supplied rejected.

Diesel cycle

It consists of constant pressure and a constant volume, and two adiabatic processes. Heat is supplied during constant pressure process 2-3 and is rejected during constant volume process 4-1. During adiabatic process 1-2 and 3-4, no heat is supplied or rejected.

Dual combustion cycle

It consists of two constant volume process, two adiabatic processes, and one constant pressure process. Heat is supplied partly at constant volume process 2-3 and partly at constant pressure process 3-4. Heat is rejected at constant volume process 5-1. No heat is added during adiabatic process 1-2 & 4-3.

What is four-Stroke Engine?

If the four events of operation i.e. suction, compression, expansion, and exhaust are completed in 4 strokes of piston i.e. by two revolutions of the crankshaft, the engine is called four stroke engine.

working principle of 4-Stroke Petrol engine

(Four stroke engine)

It based on Otto cycle. Inlet valve, exhaust valve, and spark plugs are mounted over the cylinder head. It runs in the following sequence of operation

Suction stroke:

In this stroke, the Piston moves outward. The pressure within the cylinder falls and the mixture of oil and fuel enters into the cylinder through the inlet valve till the end of the stroke. In this stroke, the exhaust valve will remain closed and no Spark will give by the spark plug.

Compression stroke:

In the stroke, the Piston moves inward and inlet and exhaust valve are in closed condition. So the charge within the cylinder is compressed adiabatically. At the end of the stroke, the spark plug supplies the spark and burning of charge starts.

Expansion stroke:

As the charge burnt, the high pressure is built up above the piston and for which Piston moves outward and expansion of burnt gas take place adiabatically. So power is produced in this stroke. At the end of the stroke, the exhaust valve open and some of the burnt gases escape into the atmosphere and pressure Falls.

Exhaust stroke:

In the stroke, the inlet valve is in the closed condition and the exhaust valve is in open condition and Piston moves inward. So, burn gases are driven out from the cylinder. At the end of the stroke and exhaust valve will close and inlet valve will open to start the next cycle.

Just read our article about Four-Stroke engine with its classifications, to know more.

What is two-Stroke Engine?

(Two stroke engine- Yamaha RX100)

If the basic four events of operation i.e. suction, compression, expansion and exhaust stroke are completed in two-stroke of piston i.e. one revolution of the crankshaft, the engine is called two-stroke engine.

working principle of two-Stroke Petrol engine

It consists of three parts namely inlet, exhaust, and transport instead of the valve.It worked in the following ways:

Upstroke:

The Piston moves upward and first cover the inlet port. So the charge enters into the casing through the inlet port, for the movement of the piston, It covers transfer port and then exhausts port. So the charge above the piston compressed adiabatically. Thus in this stroke suction and compression are completed in single Piston movement. After compression ignition of charge starts by means of the spark plug.

Down stroke:

The Piston moves downward due to a force exerted by the burnt gases. So, expansion burnt gases take place. After expansion, it fast uncovers the exhaust port and then transfer port. So, scavenging of burnt gases takes place. For further movement of the piston, it covers the inlet port. Thus, the cycle is repeated.

Just read our article about Two-Stroke engine for more clarifications.

Scavenging and Turbocharging

What is Scavenging in IC Engine?

Scavenging is process in which the removal and cleaning out of burnt gases takes places by the intake of fresh air or fuel mixture in the engine cylinder. This process is known as scavenging.

Supercharging

The process of allowing fresh air or air-fuel mixture in large quantity in the engine cylinder during normal suction is known as supercharging or boosting. The instrument used for the supercharging process is called as supercharger.

The objective of supercharging:

To increase the output efficiency of the engine.
To reduce the effect of high altitude.
To decrease the weight of engine for Per KW power developed.
Improving the engines to take overloads.

Turbocharger

By using a turbocharger, a large amount of energy within the exhaust gas is used for some other purposes. The released exhaust gas is allowed to expand in a nozzle and a huge quantity of kinetic energy is obtained which is used to drive the exhaust gas turbine.

The exhaust gas turbine is connected to the supercharger. The Combination of a supercharger and exhaust gas turbine is known as turbocharger.

Detonation

Very rapid combustion of the last portion of the Unburnt charge will generate high-pressure waves and unusual sound in the cylinder.

If the ignition temperature is reached and the delay period is shorter then the time is taken by the flame front to reach the last portion of the Unburnt charge, detonation will take place.

Effect of detonation:

Reverberating shock produced in the combustion chamber.
Breaking of engine parts due to high-pressure waves.
Power losses.
Overheating of spark plug and cause of Pre-ignition.
Increases heat loss and reduce total thermal efficiency of the engine.

Pre-ignition

The automatic ignition of charge before normal ignition given by spark plug. It occurs in Spark ignition engine.

The overheat carbon deposit on the combustion chamber, exhaust valve, spark plug supply to spark to ignite the fresh charge before the spark plug.

Effects of pre-ignition

Produces detonation
Reduce thr output power of the engine.
Poor engine operation
Create damages in engine parts due to high temperature.

Firing Order in I.C. Engine

The sequence in which the firing takes place in the different cylinder in a multi-cylinder engine. The Proper firing order can reduce the vibration and ensure the balancing of the engine also provide proper flow of power from different cylinder to the common crankshaft.

Firing order in multi-cylinder engine:

3-cylinder engine: 1-3-2
4-cylinder engine:1-3-4-2 or 1-2-4-3
6-cylinder engine:1-5-3-6-2-4 or 1-2-4-6-5-3
8-cylinder engine:1-6-2-5-8-3-7-4 or 1-4-7-3-8-5-2-6

Lubrication of Internal Combustion Engine

The function of Lubrication system

The primary objectives of lubrication are:

To reduce friction between moving the parts to the minimum extent so that power loss is less.
To reduce wear and tear of moving parts.
To cool the system when it is overheated.
It also provides cleaning processes of removal waste from inside the system.
To remove excess heat from the engine.
To improve the efficiency and life span of the engine.

Parts to be lubricated

The following parts of I.C. Engine are to be lubricated:

Main bearing of the crankshaft.
Big end bearing of the connecting rod,
Cylinder wall.
Small end bearing.
Valves guides.
Camshaft bearing.
Camshaft driving gears.

Methods of lubrication system

Splash Method

In this system, a dipper on the lower part of the connecting rod bearing cap enters into the oil through containing lubrication oil with each revolution the crankshaft. The dipper flashes the oil to the upper part of the engine as a fine oil spray which lubricates the cylinder wall, piston ring, big end bearing and small end bearing of the connecting rod.

Forced feed system method

In this system, the oil is pumped to the all lubricating point. The lubricating oil is supplied under pressure by means of a pump operated by the camshaft of the engine.

Cooling system of the Internal Combustion engine

The necessity of cooling:

Cooling of I.C. Engine is necessary because of following ways-

To prevent damage of engine parts due to high temperature.
To prevent the breakdown of the lubricating system.
To prevent overheating valves, its guide/ seats to prevent wear of valves.
To prevent loss of strength of piston and other parts.
The purpose of the cooling system is to keep the engine at is efficient temperature (700– 900) at all engine speed and operating condition.

Method of cooling system

It is classified as follows-

1. Air cooled engine

2. Water cooled engine

Air cooling

In this system, the engine cylinder is cast with a no. of extended surface known as fines provided around the surface of the cylinder. Atmospheric air flows through this fine and carried away the heat generated from the cylinder into the atmospheric. This type of cooling is used in the scooter/motorcycle etc.

Liquid Cooling

Water is used for cooling media. In this system cylinder and cylinder head are surrounded by water jackets and which cold water is circulated.

Also read :

Difference between spark and compressed ignition engine for further classification.

Conclusion:

Here is all INTERNAL COMBUSTION ENGINE.

if you have any doubts about this or anything that you want to include here.. Comment your thoughts in the comments section below. Thanks for reading mechons.

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What is Two stroke engine and how it works

2020-08-03T22:44:00.016+05:30

TWO-STROKE ENGINE

Hello guys, in this post we are going to see about the two-stroke engines with its classifications, parts of a two-stroke engine, working and applications of two-stroke engines.

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Okay, let us start with a question :

What is a Two-stroke engine?

It is also one of the categories of internal combustion(IC) engines which completes the combustion process with just two-strokes i.e.,

1. Up-stroke

2. Down-stroke

at one revolution of the crankshaft.

(Two-stroke engine - Yamaha RX100 model)

Types of Two-stroke engine

The two-stroke engine is also categorized into two types. They are

1. Two-stroke Petrol engine

2. Two-stroke Diesel engine

Two-stroke- petrol engine

It is the type of two-stroke engine which operates with the principle of OTTO CYCLE.

Two-stroke- diesel engine

The type of two-stroke engine which operates with the principle of diesel cycle.

The practical applications of this two-stroke diesel engine are very low because it doesn't have enough compression ratio or pressure required to burn the fuel. So under these circumstances and drawbacks these types of engines are neither available in the market nor in use.

Also, there are some more limitations that are there for these engines those criteria sets were mentioned below as limitations of the two-stroke engine.

(cross-sectional view)

Basic Terminologies

There are some basic terminologies that one must learn before knowing about the two-stroke engine they are

Top dead center (TDC):

It is the uppermost end position of the piston at the head of the cylinder.

At TDC the angle of the crank is supposed to be at 0'.

Bottom dead center (BDC):

The lower end position of the piston at the end of the crank is called the bottom dead center. At BDC, the angle of the crank is supposed to be at 180'

Cylinder bore:

The inner diameter of the cylinder is called the cylinder bore.

Stroke length:

The distance through which the piston moves within the cylinder of the engine during one stroke is known as stroke length.

Parts of a Two-stroke engine

The two-stroke is comprised of the following parts. They are:

Cylinder
Cylinder head
Piston
Connecting rod
Crank
Crankcase
Crankshaft
Ports
Spark plug (For Petrol engine)
Fuel Injector (For Diesel engine)

1. Cylinder:

It is also referred to as the heart of the engine. The piston of the engine moves within the cylinder.

2. Cylinder head:

It is the topmost portion of the cylinder nearer to Top dead center(TDC), and it is called as cylinder head.

3. Piston:

The reciprocating member of the engine which moves within the cylinder is called the Piston.

4. Piston rings:

The piston is provided with some ring-like structures in it. So, it is called Piston rings. And it is sealed between the gap cylinder lines and the piston. It is responsible for carrying the lubricants between those parts, i.e. Piston and Cylinder.

5. Crank:

The rotating member of the engine which makes circular motion inside the crankcase is known as a crank.

6.Crankcase:

It is one of the parts of the engine which provides shelter for the crank and other engine parts. It also acts as the sump for storing lubricants in it.

7. Connecting rod:

The part of the engine which converts the reciprocating motion of the piston into rotary motion of the crankshaft is called the connecting rod.

8. Crankshaft:

The rotating member of the that connects the crank and connecting rod is known as the crankshaft.

9. Cam and Camshaft:

It is provided for operating the function of opening and closing of both Inlet and Exhaust valves and it also operates the fuel injection pump in case of a Diesel engine.

10. Ports:

In two engine valves are replaced by ports. They were generally used in Two-stroke engines like two-stroke petrol engines. These are the openings for inlet charge and exhaust gases. There are 3 ports are present in a two-stroke engine:

Inlet port
Transfer port
Exhaust port

11. Spark plug:

It is the small part of a Petrol engine or SI engine which is used to produce a spark to burn the fuel.

12. Fuel injector:

The part which is only used in a Diesel engine or CI engine for spraying the fuel inside the engine cylinder is called the fuel injector.

13. Flywheel:

It is a part that mounted over the crankshaft and made up of cast iron. It is responsible for storing energy in the form of inertia and also for converting it into mechanical work.

Two-stroke engine working animation

Source: Wikimedia commons
Creative commons file Attribution-Share Alike-3.0

Working Principle of Two-Stroke engine

As we said earlier, In a two-stroke engine, there will be one power stroke for every single revolution of the flywheel. The two-stroke engine is comprised of the following two strokes.

First stroke ( Suction and Compression stroke)
Second stroke (Power and Exhaust stroke)

Suction and Compression stroke

During the suction and compression stroke, the piston starts reciprocating from the BDC to the TDC.
At the same time, it will close all ports such as the inlet port, transfer port, and exhaust port. Then the fuel filled above the piston is adiabatically compressed.
At the same, while the spark plug produces the spark, and the fuel gets ignited and the power stroke will follow after it.
The power from the crankshaft is transferred by means of a connecting rod. During this stroke, the piston reciprocates downward as it uncovers the inlet port.
Due to the production of partial pressure in the crankcase, the inlet port opens and the air-fuel mixture enters the crankcase.

Second stroke or Power and Exhaust stroke

During the second stroke, the piston reciprocates down from TDC and at that time the inlet port is kept closed.
Due to the downward motion of the piston air-fuel mixture is pushed by the bottom end of the piston so that the fuel from the crankcase passes out through the transfer port.
Since the exhaust port opens, the output exhaust gas leaves the cylinder through the exhaust port but after this stroke also there are some exhaust gas remains inside the cylinder.
The unique shape of the two-stroke piston head deflects the fresh charge inside the cylinder.
So, the air-fuel mixture moves downward and pushes the exhaust gas out by means of the exhaust port.
The process at which the exhaust burnt gas is pushed out by the fresh air-fuel mixture is called SCAVENGING.
After the completion of one revolution by the crankshaft.
This cyclic process is repeated once again for the next cycle.
Just read Four-Stroke engine article from us for more clarifications in internal combustion engines.

(Video Attribution: Mechanic tips)

The difference of Two-stroke engine

Generally, both the two-stroke petrol and diesel engine functions under the same principle but the only difference is the usage of the spark plug in the case of a petrol engine whereas the fuel injectors in the case of diesel engines.

Lubrication system in the Two-stroke engine

In a two-stroke petrol engine,

A petrol lubrication system was used.

In this kind of lubrication, a small quantity of lubricant is mixed with petrol itself. The normal mixing ratio is of this type is near equals to 3% that of the oil. If it less than it creates damage to the engine or if it added more there will be excess deposition of carbon elements in the cylinder head and the engine will also produce grey smoke.

When the air-fuel mixture enters the cylinder due to the production of the high temperature it evolves and passes out through a thin film of lubricant over the cylinder wall, crankcase, and shaft.

Two-stroke engine Port timings

Two-stroke- petrol engine

The Inlet port opens at an angle of - 40' before TDC.
The Inlet port closes at an angle of - 40' after TDC.
The exhaust port opens at an angle of - 60' before BDC.
The exhaust port closes at an angle of - 60' after BDC.
The transfer port opens at an angle of - 50' before BDC.
The Transfer port closes at an angle of - 50' after BDC.
Ignition takes place between 15 and 20' before TDC.

Benefits and limitations of Two-stroke engine

Benefits

More power production.
Simple in design and less weight when compared to a Four-stroke engine in which the design is complex and also carries more weight.
The two-stroke engine has a low weight compared to a four-stroke engine because of its small flywheel size.
Only less friction is produced when compared to a Four-stroke engine. So mechanical efficiency is a little bit high in the case of a two-stroke engine.
Low maintenance cost.

Limitations

Consumption of lubricants is more than that of a four-stroke engine.
The power stroke is created at every stroke, so more amount of heat will be produced, therefore we have to lubricate the engine often and cool it properly.
In the two-stroke engine, some quantity of fresh fuel mixes with the exhaust gas and passes out from the cylinder. Therefore, the engine has less output efficiency.
The absence of a well developed lubricating system is the main limitation. It lacks the Lubrication system which is present in the four-stroke engine.
It produces more air and noise pollution than the four-stroke engine.

Two-stroke Engine's applications

There many olden motorcycle models that operate with two-stroke engines but those are not available nowadays.
In the early stages, two-stroke engines are also used in Racing cars. But now almost all the countries banned two-stroke racing cars.
Two-stroke engines are used in boats.

Why we are not using Two-Stroke engines nowadays?

The reason behind why we are not using the two-stroke engine is because :

The two-stroke engine is not in use nowadays because it creates more air pollution and noise pollution. This is the main reason behind the prohibition of using two-stroke engines in many countries. Not all countries banned these types of engines but almost many countries banned.

This type of engine for keeping an idea of making pollution a free atmosphere in the future.

Conclusion

That's all about TWO-STROKE ENGINE.

I hope that you understand the Two-Stroke engine types, working, principle, lubrication and etc...

If you have any doubts or any queries about this or anything that you want to include here.

Put that in the comments section. Also, Comment your thoughts in the comments section below.

We will reply and rectify as fast as possible.

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Difference between Spark ignition(SI) engine & Compressed ignition(CI) engine

2020-08-01T18:50:00.025+05:30

Difference between spark and compressed ignition engine

Hello guys, In this post we are going to see about some difference between spark and compressed ignition engine

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let’s start with the basic overview of SI and CI Engine.

First let us start with the question:

What is Spark Ignition(SI) Engine?

Spark Ignition engine are those types of the engine where the burning of the fuel or gasoline takes place with the aid of a small part of engine called Spark Plug, where a spark is produced to ingite the fuel.

In this variety of engine, the rich Air-fuel mixture comes from the part of carburetor and enters into the engine's cylinder through the valves and then the compression stroke takes place and finally, a spark is given by the spark plug to ignite the air-fuel mixture and we get power stroke.

And now the 2nd question:

What is Compression Ignition (CI) Engine?

The engine which the rise in temperature and pressure during compression stroke is far sufficient to produce spontaneous ignition of the fuel.

In this category of engine, only the air is get compressed in the cylinder of the engine after the compression takes place the pressure and temperature of the air are rised heavily and it is far enough for burning the fuel which is being sprayed by the fuel injectors.

Difference Between SI and CI Engine:

Now Let’s See the difference

(Difference Between SI and CI engine)

Conclusion

These are the difference between SI Engine and CI Engine. If you have any doubts or questions or need of improvement about this topic please comment it in the comments section, we will reply and rectify as fast as possible.

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Four-stroke engine with classifications

2020-08-01T18:12:00.030+05:30

FOUR-STROKE ENGINE

Hello mechons, in this sparking day we are going to explain to you about what is Four-stroke engine, the parts of a four-stroke engine, what are the types of a four-stroke engine, the working of the four-stroke engine also the advantages and disadvantages of Four-Stroke engine with its applications.

(Four-Stroke engine)

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What is the Four-Stroke Engine?

A four-stroke engine is one of the categories of Internal combustion(IC)engine, where four strokes take place successively. They are the
Suction stroke
Compression stroke
Power stroke or expansion stroke
Exhaust stroke

which will be completed on two revolutions of the crankshaft. So, these categories of engines are so-called Four-stroke engine.

Nowadays, almost all the automobiles in the world function on the basis of four-stroke engines only.

There are some basic terminologies that one must learn before knowing about the four-stroke engine they are:

1. Top dead center (TDC):
It is the uppermost end position of the piston at the head of the cylinder.
At TDC the angle of the crank is supposed to be at 0'. 

2.  Bottom dead center (BDC):
The lower end position of the piston at the end of the crank is called the bottom dead center. At BDC, the angle of the crank is supposed to be at 180'.

3.  Cylinder bore:
The inner diameter of the cylinder is called the cylinder bore. 

4.  Stroke length:
The distance through which the piston moves within the cylinder of the engine during one stroke is known as stroke length. 

Parts(Components) of a Four-Stroke engine:

The Four-stroke is comprised of the following parts. They are:

1. Cylinder:

It is also referred to as the heart of the engine. The piston of the engine moves within the cylinder.

2. Cylinder head: 
It is the topmost position of the cylinder nearer to Top dead center(TDC), and it is called a cylinder head.

3. Piston: 
The reciprocating member of the engine which moves within the cylinder is called Piston. 

4. Piston rings: 
The piston is provided with some ring-like structures in it. So, it is called Piston rings. And it is sealed between the gap cylinder lines and the piston. It is responsible for carrying the lubricants between those parts, i.e. Piston and Cylinder. 

5. Crank: 
The rotating member of the engine which makes circular motion inside the crankcase is known as a crank. 

6. Crankcase:
It is one of the parts of the engine which provides shelter for the crank and other engine parts. It also acts as the sump for storing lubricants in it. 

7. Connecting rod:
The part of the engine which converts the reciprocating motion of the piston into rotary motion of the crankshaft is called the connecting rod. 

8. Crankshaft: 
The rotating member of the that connects the crank and connecting rod is known as the crankshaft. 

9. Cooling fins or Water jackets:
The purpose of this part is to provide cooling for the engine.

10. Cam and Camshaft: 
It is provided for operating the function of opening and closing of both Inlet and Exhaust valves and it also operates the fuel injection pump in case of a Diesel engine.

11. Inlet valve: 
The valve which controls the entry of fuel or air-fuel mixture into the cylinder of the engine is called the Inlet valve. 

12. Exhaust valve: 
The valve which controls the process of removing burnt gas after combustion is known as the exhaust valve.

13. Intake manifold: 
The passage which carrying the fresh fuel or air-fuel mixture is known as the intake manifold. 

14. Exhaust manifold:
The passage which is carrying out the exhaust gas from the engine cylinder is known as exhaust manifold. 

15. Spark plug:
It is the small part of a Petrol engine or SI engine which is used to produce a spark to burn the fuel.

16. Fuel injector: 
The part which is only used in a Diesel engine or CI engine for spraying the fuel inside the engine cylinder is called the fuel injector. 

17. Carburetor: 
It is a part that is used in a Petrol engine to pass the air-fuel mixture into the cylinder and also for maintaining the mixture incorrect ratio.

18. Flywheel: 
It is a part that mounted over the crankshaft and made up of cast iron. It is responsible for storing energy in the form of inertia and also for converting it into mechanical work.

(Parts of an IC engine) 

Classification of Four-stroke engine:
The Four-stroke engine is basically classified into two types:
Four-stroke - Petrol engine
Four-stroke - Diesel engine

Four-Stroke Petrol engine:
( Source : Wikipedia 
under creative commons license Attribution -share Alike 3.0 ) 

In this picture the numbers 1,2,3, 4 denote the Suction stroke, compression stroke, power or expansion stroke, and exhaust stroke respectively. 
This category of the engine based on the principle Otto cycle.

Construction of a Four stroke - petrol engine:

A four-stroke petrol engine consists of:

Cylinder
Spark plug
Piston with piston rings
Connecting rod
Crank
Crankshaft
Valves etc., 

In four-stroke engines, ports are replaced by means of using valves. 
There are two valves:
Suction valve
Exhaust valve
And those valves are operated with the help of a Camshaft which is rotated at speed of half the speed of a crankshaft.

Working of Four stroke - petrol engine:

The piston moves from the top dead center to the bottom dead center is called  the piston stroke and it consists of four strokes:
Suction Stroke
Compression Stroke
Power or Expansion Stroke
Exhaust Stroke

Suction stroke:
In the Suction stroke, the suction valve opens, exhaust valves remain under closed condition. The piston starts moving from TDC to BDC and the air-fuel mixture enters into the engine cylinder due to the partial vacuum pressure produced inside the cylinder.
At once, the piston reaches the BDC, the inlet valve closes and a half revolution takes place at the flywheel. 

Compression Stroke:
In the compression stroke, the piston starts moving from BDC to TDC, at that time both the suction and exhaust valves are in the closed condition.
The air-fuel mixture, which was entered into the cylinder during the suction stroke, is now compressed into the combustion chamber where the heat which is produced during the compression stroke and vapourises the mixture.
 As the piston approaches the TDC, the compression stroke ends with a spark created from the spark plug. 

Power Stroke or Expansion stroke:
Once again both the inlet and exhaust valves are kept at the closed conditions in this stroke.
The compressed fuel gets ignited by the spark which has high intensity and expands adiabatically, 
Therefore, the piston starts moving downward i.e. towards BDC then the stroke is completed.

Exhaust Stroke:
During the exhaust stroke, the inlet valve is kept in the closed condition and the exhaust valve is kept open. The piston starts moving up from BDC to TDC.
The stroke is completed at once the piston reaches the TDC. 
And again these strokes are repeated to carry the next cycle. 
In the exhaust stroke at a particular time and angle, both the valves are in an open condition for some time period. This time period is called valve overlap and the angle is known as the Angle of overlap. It takes because at this time and angle the fresh air-fuel mixture or fuel is entered to the engine cylinder and pushes out the burnt gases from the engine cylinder. And this process is called Scavenging.
These are the working process of the Four-stroke Petrol engine.


Valve timings of Four stroke petrol engine
Theoretical valve timings:
The Inlet valve will open when the piston is at Top Dead Center(TDC).
The Inlet valve will close when the piston reaches Bottom Dead Center(BDC) 
Spark produces when the piston reaches Top Dead Center. 
The exhaust valve will open when the piston at Bottom Dead Center. 
The exhaust valve will close when the piston reaches the Top Dead Center. 

Actual valve-timings:
The Inlet valve opens at an angle of  10'-20' before TDC
The Inlet valve closes at an angle of 30'-40' after BDC. 
Spark produces at an angle of occurs 20'-35' before TDC. 
The exhaust valve opens at an angle between 30' and 50' before BDC
The exhaust valve closes at an angle of  10'-20' after TDC. 


Four-stroke petrol engine's application :
It has various types of usages like:
In automobiles generally on two-wheelers, also in cars, trucks, etc., 
Small pump sets
Electrical generator and so on. 


Four-Stroke Diesel engine:

Construction of Four-stroke Diesel engine

A Four-stroke - Diesel engine contains the following parts. They are:
Cam
Camshaft
Crankshaft
Cylinder
Connecting rods
Fuel injector
Fuel pump
Inlet and exhaust valves
Piston etc., 


Working of Four-stroke- Diesel engine:
     (Attributions to- Automotivebasics channel) 

The Four-stroke diesel engine functions as similar to that of the Petrol engine. Here also the four strokes take place successively. They are :
Suction Stroke
Compression Stroke
Power or Expansion Stroke
Exhaust Stroke

1. Suction Stroke:

In a suction stroke, the inlet valve is in the open and the exhaust valve remains in closed condition. 
The air is sucked into the cylinder as the piston moves from TDC to the BDC due to the development of the partial vacuum air is entered inside the cylinder.
At once, the piston reaches the BDC, the inlet valve closes and a half revolution takes place at the flywheel. 

2. Compression Stroke:

In this stroke Piston reciprocates from the bottom dead center to the top dead center as a result of this the air which is present inside the engine cylinder is compressed at high pressure and heated.
In compression stroke, both the inlet and exhaust valves are in the closed condition. A very high temperature is produced during this stroke. 
At the last stage of this compression stroke,  the fuel injector injects the fuel at high pressure into the compressed hot air, thus the ignition carried out inside the cylinder.

3. Power or Expansion Stroke:

During the power stroke, both the inlet and exhaust valves are kept in the closed conditions. 
The piston at TDC is pushed downward by the expansion of burnt gas. Therefore a Power stroke is produced.

4. Exhaust stroke:
In exhaust stroke, the exhaust valve is opened and the inlet valve is in a closed condition. The piston moves from BDC to TDC and it pushes the burnt gas out of the cylinder. 
And here also the scavenging process happened for the removal of the burnt gas and admittance of fresh fuel. 


valve timings of Four stroke Diesel engine
Actual valve-timing:
The Inlet valve opens at an angle of 10'-30' before TDC
The Inlet valve closes at an angle of  20'-50' after BDC
The exhaust valve opens nearly at an angle of 40' before BDC
The exhaust valve closes at an angle of 15' after TDC
Fuel injection starts at an angle of 5' - 15' before TDC
Fuel injection stops at an angle of  15' -24' after TDC.


Four-Stroke Diesel engine Applications :
The four-stroke Diesel engine is one of the most popular varieties of engines over a long time. It has various types of applications like:
Small pumping sets
In the automobile industries 
Air compressors
Drillers
Boats & Ships
Power saw
JCB's
Tanks
Diesel-electric locomotives and so on.

Advantages of Four -Stroke engine:

High torque
High fuel economy than a two-stroke engine
Consumption of lubricants is low
Pollution caused is less due to the proper burning of fuel
Durability is more
Proper cooling system, so that the life of the engine is longer.
The Thermal efficiency and HP of this type of engine is relatively high.

Disadvantages of Four-stroke engine:

Many moving parts, so there is more friction and hence the engine has less mechanical efficiency.
The complicated design of the engine.
The weight of the engine is more because of the heavy construction of flywheel.
Due to the presence of more parts the maintenance of the engine often required.

Fuel Supply System in Four-Stroke engine:

Fuel supply system in Four-stroke petrol engine:

The petrol engine fuel supply system consists of:

Fuel feed system
Fuel injection system
Fuel tank
Fuel lines
Fuel filter
Fuel pump
Carburetor

At first, an electric petrol pump or mechanical petrol pump sucks the fuel from the fuel tank via a filter then the fuel through fuel lines passes to the carburetor where the air-fuel mixed with proper ratio and enters into the engine cylinder for combustion.

Fuel supply system in Four-stroke Diesel engine:

Diesel engines fuel supply system consists of:

Diesel tank
Feed pump
Filter
Injection pump
Injector
Connecting lines

There are two categories of the fuel injection system of the Diesel engines. They are:

Air injection system or Indirect injection
Solid injection system or Direct injection

Four-stroke engine Lubrication system:

The supply of lubricating oil between two moving parts of the vehicle is called lubrication.

Needs for lubrication in the engine :

The primary objectives of lubrication are:

To reduce friction between moving the parts to the minimum extent so that power loss is less.
To reduce wear and tear of moving parts.
To cool the system when it is overheated.
It also provides cleaning processes of removing waste from inside the system.

Parts that are needed to be lubricated in an engine :

The following parts in the engine required to lubricated. They are

Crankshaft bearings
Both ends of connecting rod bearings
The inner wall of the cylinder
Valve openings
Timing gears
Camshaft bearings

Cooling system of Four-Stroke engine:

All the heat that is produced by the combustion of the fuel is not completely or totally converted into power at the crankshaft. Its only nearly about 20% of the heat is used as the power for the crankshaft. And nearly 35% of heat is transferred to the cylinder wall that causes pre-ignition of the fuel or air-fuel mixture and also the lubricants were burnt away due to that heat, If the engine was not cooled properly it maybe lead to the seizing of the engine. There are two types of cooling processes available for the engines. They are

1. AIR COOLING SYSTEM

2. LIQUID COOLING SYSTEM

Ways to improve the efficiency of Four-stroke engines

Still, there are many methods that have been implemented to extract the vast amount of waste heat which is expelled at the exhaust of the engine and convert it into some useful work, that decreases the exhaust pollutants in the mean time.

Some of those ways are

1. Usage of Rankine Cycle,

2. Supercharging

3. Turbocharging and thermoelectric generation can be very useful as a waste heat recovery system.

Also read:

1) Internal combustion engine

2) Two-Stroke engine with its types and working principles

Download as pdf
{getButton} $text={Download pdf} $icon={download} $color={#006080}
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Conclusion :

That's for now, 

I think that almost everything related to this category was covered. If you have any doubts regarding this comment that in the comment section provided below or if you have suggestions for improving this please comment that too. So, that we may able to satisfy your need. 

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Mechanical Engineering as your career

2020-07-29T21:35:00.002+05:30

Mechanical engineering as your career:

Mechanical engineering is one of the oldest branches of engineering. It is also referred to as the ‘Father’ of engineering. Another appealing feature of mechanical engineering is that the application base of this field of study is extremely very broad and diverse. Almost all inventions during the ancient period and a vast majority in the modern era are direct contributions of one or the other application of mechanics.

Traditionally, the mechanical engineers have to deal with concepts such as mechanics, thermodynamics, robotics, kinematics, structural analysis, fluid mechanics and many others. These concepts are applied in the process of designing manufacturing units, different types of automobiles, aircraft parts and aerospace parts and a vast assortment of industrial machinery. Mechanical engineers also contribute in the development of various engines, power station equipments, heating and cooling systems and other simple and complex machineries.

Mechanical engineers not only design new mechanical systems but they are also responsive for the testing, maintaining and manufacturing them. However, the pasts have changed. Nowadays the scope of mechanical engineer is expanding beyond its traditional boundaries.

Mechanical engineers are now focussing their attention towards new areas of research such as nanotech, development of composite metals, biomedical equipments,etc. The increasing scope of this particular job profile now requires professionals to get into financial and marketing aspects of product development and even into people and resource management. All in all mechanical engineering offers a wide variety of job options to students who are looking for a stable and pursuing mechanical engineering as their career.

Eligibility for begin your career as mechanical engineer:

Passing your middle school level is the basic eligibility for a mechanical engineering course to become a professional mechanical engineer.

To be eligible for a mechanical engineering graduate programme (BE/BTech) in a college, you must have scored at least 50 percent of marks and 60 percent for eligible for IITs (Indian Institute of Technology) in with physics, chemistry, maths subjects.

After passing in your middle school exams, you can also pursue your ways cracking entrance examinations such as:

The Joint Entrance Examination(JEE) for IITs, also various NITs, IIITs, and other regional government and private colleges.
Another option is state level entrance tests conducted by the state level authorities like WBJEE, JKCET, UPCET, JCET, APCET so on.
Another option is private colleges entrance exam like BITSAT, VITEEE & so on.
Also there are some decent institutions which can also accommodate you for pursuing your courses with your high school marks.
Apart from these, there are numerous of engineering colleges across the length and breadth of our country where you can get into a graduate programme in mechanical engineering.
You can also opt for a diploma in engineering from a polytechnic. For obtaining a diploma, the basic eligibility is completion of Class 10 with 50 percent marks. The duration of these diploma courses is three-years for regular and four- years for part-time. You can also go for an associate membership qualification from the Institute of Mechanical Engineers, which is considered at equal with the diploma earned from a state run polytechnic or a university degree.
Another option is to earn a similar qualification offered by the Institution of Engineering (India). Diploma holders can also get direct entry into the second year of a graduate program (lateral entry programme).

After your UG course:

After successful completion of the graduate program, you can go for the two-year masters program in mechanical engineering or ME/MTech. If you are interested in pursuing a PG programme in mechanical engineering from any of the IITs, then you must appear for the Graduate Aptitude Test for Engineers (GATE).

Is this a correct Career for Me?

Like other career paths, the entry into this particular branch of engineering also requires you to possess certain basic skills.

First and foremost, you must have a knowledge about some basic mechanical components and machineries and how those machineries work.
You must be good at physics, chemistry and mathematics.
You must also have skills such as an analytical bent of mind, logical reasoning and problem solving capabilites
You must have patience, physical strength, and ability to work for more hours and an creative spirit that are important ingredients for becoming a professional mechanical engineer.

Job Prospect:

Since mechanical engineering is the broadest among the all engineering fields, the job prospects on offer for skilled mechanical engineers are a plenty and unending one. Mechanical engineers are required for designing, testing, manufacturing, installing , operating and maintaining a large stream of machines and mechanical systems that are used in numerous industries. Those professionals can find employment in both government and private sector.

Pay Package: Mechanical engineering offers a large variety of career opportunities to job aspirants. The average monthly salary of mechanical engineers who are new to this profession is approximately in the range between Rs.10,000 and Rs.25,000. Good campus placements can fetch even better packages for deserving students. Mechanical engineers who hold a post-graduate degree from a reputed academic institute tend to get better offers than diploma and degree holders. From here on the annual pay package depends on a number of factors such as the skills, set possessed, experience, expertise, nature of roles and responsibilities, etc. Highly skilled mechanical engineers can easily command pay packets as high as Rs 40-45 lacs per annum.

Demand and Supply:

There is great demand for skilled mechanical engineers in different segments of the industry. Their expertise is required in traditional manufacturing industries such as automobiles, aviation, shipping, aerospace, power plants and machinery manufacturing. In recent times, the services of expert mechanical engineers have even been sought in fields such as nanotechnology, biomedical engineering, energy conservation and environmental engineering.

There is also great requirement for mechanical engineer consultants who have management skills along with technical proficiency. The primary role of such professionals is to manage both technology and people and firms that provide engineering consultancy require them. Various engineering colleges and polytechnics across the country are doing their best to meet the burgeoning demand of skilled mechanical engineering professionals.

The job market for mechanical engineers is perennial. Even the vagaries of the global economic crisis could not knock out the demand for these professionals in the Indian job market. Although some branches of mechanical engineering went out of focus during the meltdown period, the overall situation was much better as compared with other careers. On the brighter side, things are getting ackward to normal and this evergreen career path is again gaining coin amongst career aspirants as it did during the pre- meltdown years. In fact, this is a period of resurgence for mechanical engineers. They not only have countless options in the industrial sector but they can also make foray into new realms of technology and even get into management and technical consultancy.

According to a survey, mechanical engineering is amongst the most sought after branches of engineering preferred by students seeking admission to various technical institutes across India in the recent years.

International Focus:

Highly qualified professionals from this field, such as post- graduates from various IITs, often seek suitable employment in foreign countries. It is not that only highly qualified mechanical engineers get opportunity to work abroad. If you are employed in a multinational company, you may also get the chance to work on offshore projects.

Classifications of jobs in mechanical stream:

In broad terms, the job profile of mechanical engineers can be classified into the following functional segments:

Research and Development (R&D): Engineers whose role is to do research and then plan for new machines and their constituent parts.
Design: Professionals whose responsibility is to draft technical drawings, manually or with the aid of computers.
Production: Engineers who supervise the manufacturing of mechanical components and machines.
Analysis and testing: Engineers who analyse and test different types of machines and their parts to ensure that they function flawlessly.
Installation: Professionals who install machines and mechanical parts at the client location.
Maintenance: Engineers whose primary role is to ensure that machinery is working as per specifications.

Top recruiting sectors for Mechanical Engineers:

1. Automobile and auto part manufacturers

2. Aerospace industry

3. Various Government sector undertakings

4. Aviation companies

5. Steel plants

6. Thermal plants and gas turbine manufacturers

7. Air conditioning and refrigeration industry

8. Shipping industry

9. Engineering consultancies

10. Armed forces

Tips for Getting Hired:

1. It is advisable to earn a post-graduate degree in this field.

2. Computer proficiency is a must these days.

3. You must have excellent. communication and interpersonal skills.

4. A management degree further brightens your career prospects.

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