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1

LAB MANUAL

Metrology

&

Instrumentation

DIPLOMA SEM:-IV

MECHANICAL ENGINEERING DEPARTMENT

L.J. POLYTECHNIC, AHMEDABAD

Metrology & Instrumentation

Mechanical Engineering Department LJ POLYTECHNIC

L.J. POLYTECHNIC

CERTIFICATE

Enrollment No. : _________________

This is to certify that

Mr./Ms.____________________________________ of Diploma in

_______________ Semester __________ of class ___________ has

Performed Term Work of Subject _____________________________

Satisfactory and recorded in this journal of L J Polytechnic during the

Academic Year________.

_____________

Signature

Faculty In-Charge

_____________

Signature

Head of Department

Place: _________ Date: _________



LIST OF PRACTICALS

1. To measure external, internal and depth dimensions with the

help of vernier caliper.

2. To measure external dimensions with the help of outside

micrometer.

3. To measure inside diameter with the help of inside

micrometre.

4. To measure the height of object with the help of

height gauge.

5. To find the angle of the given specimen using bevel

protractor.

6. To find out the unknown angle of the given specimen-using

sine – bar and slip gauges.

7. To measure the tooth thickness of the given gear using

Gear tooth vernier caliper.

8. To measure roundness, cylindricity, concentricity,

Run out and ovality using dial indicator.

9. To Measure The Straightness With The Help Of Straight

Edge And Slip Gauges

10. To Measure The Flatness With The Help Of Flatness

Measurement Instrument

11. To measure surface roughness value of given

machined surface.

12. To study about limit gauge & measure dimension

with the help of it.

13. To study about Non destructive testing.

14. To study about different transducers and sensors.

15. To study about temperature pressure & flow

measurement

16. To study about different mechanical assmebly geometric

tolerances.



TO MEASURE EXTERNAL, INTERNAL AND DEPTH

DIMENSIONS WITH THE HELP OF VERNIER CALIPER.

Experiment No.: 1



AIM: TO MEASURE EXTERNAL, INTERNAL AND DEPTH DIMENSIONS

WITH THE HELP OF VERNIER CALIPER.

OBJECTIVES:

1. To know the working principles and applications of Vernier Caliper

2. To find the Least Count of the Vernier Caliper.

APPARATUS: Vernier Caliper

THEORY:

Vernier caliper works on the principle of minor difference in the two scales i.e.

main scale and the vernier scale. Vernier depth gauge measures the depth and the

Vernier height gauge measures the height of the component. Bore and telescopic

gauge measure the inner cavity. This is indirect measuring instruments. Vernier

caliper is the end standards.

FORMULA FOR FINDING LEAST COUNT:

(A) Measure the dimensions of a given cylinder with the help of a Vernier Caliper.

L.C.=

EXPERIMENT NO.:1 Date:

= _________mm



FIGURE:

Vernier Caliper

Line Diagram of Vernier Caliper



OBSERVATION TABLE:

A B C=A+B

Component-I Main scale reading(mm)

Vernier scale division Coincide

with main scale

(Vernier scale

division Coincide

with main scale) X

( Least Count)

Final Reading (mm)

Inner diameter

Outer diameter

Thickness

Depth

Total length

CONCLUSION:



TO MEASURE EXTERNAL DIMENSIONS WITH THE

HELP OF OUTSIDE MICROMETER

Experiment No.: 2



AIM: TO MEASURE EXTERNAL DIMENSIONS WITH THE HELP OF

OUTSIDE MICROMETER.

OBJECTIVES:

1. To know the working principle and application of outside micrometer.

2. To find the least count of the outside micrometer.

APPARATUS: Outside micrometer, Specimen.

THEORY:

Figure shows a 0-25 mm micrometer which is used for quick, accurate measurements

to the two-thousandths if a micrometer. It consists of the following parts:

Frame

Anvil

Spindle

Thimble

Ratchet

Locknut

The micrometer requires the use of an accurate screw thread as a means of obtaining a

measurement. The screw is attached to a spindle and is turned by movement of a

thimble or ratchet at the end. The barrel, which is attached to the frame, acts as a nut

to engage the screw threads, which are accurately made with a pitch of 0.05mm. Each

revolution of the thimble advances the screw 0.05mm. On the barrel a datum line is

graduated with two sets of division marks. The set below the datum line is graduated

with two sets of division marks. The half millimeters. The thimble scale is marked in

50 equal divisions, figured in fives, so that each small division on the thimble

represents 1/50 of 1/2mm which is 1/100mm on 0.01mm.

EXPERIMENT NO.: 2 Date:



FIGURE:

Line Diagram of Outside Micrometer

Outside Micrometer





L.C. =

= _________mm

OBSERVATION TABLE:

A B C=A+B

Sr.

No

Main scale

reading(MSR)

mm

Circular scale

division coincides

with main scale

Circular scale

reading(CSR)

=CSR X Least count in

mm

Total reading

(M.S.R+C.S.R) in

mm

Least Count of the Outside Micrometer: ___________

CONCLUSION:



TO MEASURE INSIDE DIAMETER WITH THE HELP OF

INSIDE MICROMETER

Experiment No.: 3



AIM: TO MEASURE INSIDE DIAMETER WITH THE HELP OF INSIDE

MICROMETER.

OBJECTIVES:

1. To know the working principles and applications of inside micrometer.

2. To find out least count of the inside micrometer.

APPARATUS: Inside Micrometer, Specimen.

THEORY:

Inside micrometer is used for measuring larger internal dimensions. It consist

of the following main parts;

1. Measuring Head (Micrometer Unit.)

2. Extension Rods.

3. Spacing Collars.

4. Handle.

The micrometer unit or measuring head consist of a barrel and a thimble

similar to the outside micrometer. It has no frame and spindle. A series of extension

rods are provided in order to obtain a wide measuring range. Using one range of

extension rods, distance between the contacting surfaces is varied by rotating the

thimble up to the extent of the screw length.

Spacing collars is used when those dimensions are needed which can‟t be

obtained by the use of extension rod and micrometer unit.

For using this instrument first the diameter of the bore is measured

approximately by a scale. Extension rod is then chosen to the nearest one and inserted

in the micrometer head. Then zero error is checked by taking the dimensions on

standard size specimen.




By suitable base arrangement inside micrometer can be converted into height

gauge. It is used for measuring the inside diameter of cylinders, rings etc. and also for

measuring parallel surfaces and for setting calipers etc.



L.C. =

= _________mm

FIGURE:

INSIDE MICROMETER & SPINDLE



OBSERVATION TABLE:

A

B C D=A+B+C

Component

Main

scale

reading

(MSR)

mm

Circular scale

division

coincides with

main scale

Circular scale

reading(CSR)

=CSR X Least

count in mm

Extension

rod size in

mm

Total reading

(M.S.R+C.S.R+

Extension rod

size) in mm

CONCLUSION:



Experiment No.: 4

TO MEASURE THE HEIGHT OF OBJECT WITH THE

HELP OF HEIGHT GAUGE.



AIM: TO MEASURE THE HEIGHT OF THE GIVEN SPECIMEN USING

HEIGHT GAUGE.

APPARATUS: Surface plate, Height gauge, and specimen whose height is to be

measured.

THEORY:

Vernier Height Gauge, This is just as vernier caliper, equipped with special base block

and other attachment which make the instrument suitable for height measurements.

Along with the sliding jaw assembly, arrangement is provided to carry a removable

clamp. The upper and lower surfaces of the measuring jaws are parallel to the base, so

that it can be used for measurements over or under surface.

The vernier height gauge is mainly used in the inspection of parts and work. With a

scribing attachment in place of measuring jow, this can be used to scribe lines at

certain distance above the surface. However dial indicator Can also be attached in the

clamp and many useful measurements made as it exactly gives indication when dial

tip just touching surface. For all these measurement, use of surface plate as datum

surface is very essential.

PROCEDURE:

1. Take the material (sample) for which the value must be measured.

2. Check the vernier and main scale must coincide at 0

3. After checking the 0 mark put the sample piece and slowly leaves the measuring

Jaw over the piece

4. Tight the screw and measure the main scale also vernier scale reading

5. The line coincide with the main scale that the VSR

6. By adding MSR with VSR*L




Figure:



VERNIER HEIGHT GAUGE



L.C. =

= _________mm



OBSERVATION TABLE FOR VERNIER HEIGHT GAUGE:

H1 (Job-1) in

mm

H2 (Job-2) in

mm

Reading 1 Reading 2 Reading 3 Reading 4

Average

CONCLUSION:



TO FIND THE ANGLE OF THE GIVEN SPECIMEN USING

BEVEL PROTECTOR

Experiment No.: 5



AIM: TO FIND THE ANGLE OF THE GIVEN SPECIMEN USING BEVEL

PROTECTOR.

APPARATUS: Surface plate, Bevel protractor, and specimen whose angle is to be

measured.

THEORY:

The bevel protractor is simplest instrument for measuring the angles between

two faces of a component. It consists of important parts such as stock, blade, body,

vernier, scale etc., Back of the instrument is flat and there are no projections beyond

its back. The blade has 150mm to 300mm long, 13mm wide and 2mm thick. Its ends

are beveled at angles of 45° and 60°. These are hardened and tempered to reduce

wear.

It is used for measuring and lying out of angles accurately and precisely within

5minutes. The protractor dial is slotted to hold a blade, which can be rotated with the

dial to the required angle and also independently adjusted to any desired length. The

blade can be locked in any position. It is capable of measuring any angle from 0° to

360°. This is widely used in workshops for angular measurement. The acute angle

attachment enables very small angles to be measured.

PROCEDURE:

1. The blade is clamped to the body of the bevel protractor.

2. Base plate is held against one of the plane surface which forms an angle.

3. The adjustable plate is survived with respect to the base plate and the angular

position is adjusted and locked.

4. The angle between the two surfaces is determined by referring the position of

the pointer.

5. Also the sides of the given components are measured suing vernier calipers.




Calculation of Least count of Bevel Protractor:

The main scale is graduated in degrees of arc, which are grouped into four

90°quadrants. The degrees are numbered to read either way: from zero to 90, then

back to zero which is opposite the zero you started at.

The vernier scale is divided into 24 spaces, 12 on each side of zero, numbered

60- 0-60. 12 divisions occupy the space of 23 degrees on the main scale.

Therefore, each division of the vernier =1/12 or 23° or 1

Since two divisions on the main scale equals 2 degrees of arc, the difference

between two divisions on the main scale equals 2° of arc, the difference between two

divisions on the main scale and on division on the vernier scale is

2° - 1

=

=

or 5 minutes

The reading of bevel protractor equals

a) The largest „whole‟ degree on the main scale indicated by the vernier zero

division, plus

b) The reading on the vernier scale in line with a main scale division.

Figure:

Universal Bevel Protector



Formula of Least Count:

L.C.=

=

=

or 5 minutes

OBSERVATION TABLE:

A B C=A+B

Component

no.

Main scale reading in

degree

Least count + Vernier

scale division coincides

with main scale

Final reading

CONCLUSION:



TO FIND OUT THE UNKNOWN ANGLE OF THE GIVEN

SPECIMEN-USING SINE – BAR AND SLIP GAUGES

Experiment No.: 6



AIM:TO FIND OUT THE UNKNOWN ANGLE OF THE GIVEN SPECIMEN-

USING SINE – BAR AND SLIP GAUGES.

APPARATUS:A surface plate, Sine Bar, Slip gauges, Specimen. Dial gauge.

THEORY:

Sine bar is common and most precise way of getting the angle or finding the

angle. The angle is found out by knowing the ratio of the length of two sides of a right

angle. The angle to be measured or determined by indirect method as a function of

sine, for this reason, the device is called a „Sine bar‟. Angles are measured accurately

by sine bars with the help of other auxiliary instruments such as slip gauges,

indicating devices etc.

The sine bar consists of a steel bar and two rollers. It is made from high carbon,

high chromium corrosion resistant steel, suitably hardened, precision ground and

stabilized .Rollers or cylinders are of accurate and equal diameters.

The sine principle uses the ratio of the length of two sides of a right triangle in

deriving a given angle. It may be noted that devices operating on sine principle are

capable of “self generation.” The measurement is usually limited to 450 from loss of

accuracy point of view.

PRECAUTIONS IN USE OF SINE BARS:

1. Sine bar not used for angle greater than 45°(impractical) fairly reliable for

angles less than 15°.

2. Longer sine bars should be used, since many errors are used by using longer

sine bar.




PROCEDURE:

1. Fix up the work specimen on the sine bar for which the angle is to be

measured.

2. One of the cylinders or rollers of sine bar is placed on the surface plate and

other roller is placed on the slip gauges of height „h‟.

3. The height „h‟ is to be adjusted by introducing the slip gauges in such a way

that the dial gauges show zero reading on both the ends. Now the top surface of

the work is parallel to the surface plate.

4. This height „h‟ is obtained by trial and error method. After obtaining zero

deflection on both ends, note down the slip gauge height „h‟.

5. Find out the angle using the formula,

Sin θ = h / l

Note: First calculate the approximate angle (θ1) of the given specimen using bevel

protractor, then calculate the approximate height of slip gauges for the length of sine

bar (h1).

FIGURE:



Details of slip gauges

RANGE IN MM STEP IN MM NO.OF PIECES

1.0005 - 1

1.001-1.009 0.001 9

1.01-1.049 0.01 49

0.5-24.5 0.5 49

25-100 25 4

TOTAL = 112



SPECIMEN CALCULATIONS:

1. L = Length of the sine bar = Distance between two centers of cylinders.

= --------------------- mm

2. h = Height of the slip gauge. = -------------------- mm

3. The angle „‟ of the given specimen,

=

=

RESULT: Angle using Sine Bar =

CONCLUSION:-



TO MEASURE THE TOOTH THICKNESS OF THE GIVEN

GEAR USING GEAR TOOTH VERNIER CALIPER

Experiment No.: 7



AIM: TO MEASURE THE TOOTH THICKNESS OF THE GIVEN GEAR USING

GEAR TOOTH VERNIER CALIPER.

APPARATUS: A gear tooth vernier caliper, gear specimen

THEORY:

The gear tooth vernier caliper can be conveniently used to measure the tooth

thickness at a specified position on the teeth. The tooth thickness is measured at the

pitch circle and is therefore referred to as the pitch line thickness of the tooth. This

caliper has two vernier scales and they are set for width („w‟) of the tooth and depth

( „d‟) from the top at which („w‟) is measured.

PROCEDURE:

(To measure the gear tooth thickness)

1. Find out the least count of the caliper and the number of teeth on the gear to be

tested.

2. Using vernier caliper find the blank diameter (i.e. Outer diameter) and

Dedendum circle diameter.

3. Find the module of the gear and the addendum.

4. Set the slide on the vernier caliper to a height equal to the addendum.

5. Measure the Chordal tooth thickness and Chordal pitch.

6. To find the base pitch, find the distance between X and X + Y number of teeth.

7. By using above measured values calculate all the other elements of gear tooth.




FIGURE:

Gear Tooth Vernier Caliper



OBSERVATIONS AND CALCULATIONS:



L.C. =

= _________mm

1. Least count of the gear tooth vernier caliper L.C = mm

2. Number of teeth on the gear, N =

3. Diameter of the gear blank ( i.e. Outside dia), Do = mm

4. Module of the gear, m =

= mm

5. Vertical scale set at reading „d‟ =

6. Chordal thickness tc =

OBSERVATION TABLE:

A B C=A+B

Sr. No. Main scale reading(mm)

Horizontal

Vernier scale division Coincide with horizontal

main scale

Horizontal

Vernier scale

division

Coincide with

horizontal main

scale X

( Least Count)

Chordal

thickness( t)

mm

Component-I

Component-II



TO MEASURE ROUNDNESS, CYLINDRICITY,

CONCENTRICITY, RUN OUT AND OVALITY USING

DIAL INDICATOR

Experiment No.: 8



AIM: TO MEASURE ROUNDNESS, CYLINDRICITY,

CONCENTRICITY, RUN OUT AND OVALITY USING DIAL

INDICATOR.

APPARATUS: Dial Indicator, Stand, V-block, Circular work piece.

THEORY:

There are various reasons, when machining parts can be out of roundness.

These are clamping distortion, presence of dirt and chips on clamping surfaces, heat

and vibration etc. Roundness can be defined as a condition of a surface of revolution,

like cylinder or cone, where all points of the surface intersected by any plane

perpendicular to a common axis. Roundness expresses a particular geometric form

of a body of revolution in all three dimension, the circular contour is the

characteristic form of the entire periphery of a plane Figure. For measuring

roundness the circularity of the contour is to be determined improper roundness of

machined parts could be due to poor bearings in the spindle or due to the deflections

of the work piece as the tool is brought to bear on it. Due to poor alignment of the

center or deflection of the shaft, the shaft ground between centers can be out of round.

CIRCULARITY: Circularity is only in one plane, where as roundness even includes three

dimensions such as in balls of ball bearings.

ROUNDNESS: Roundness is a condition of surface of revolution such as cylinder, cone or

sphere where all points on surface intersected by any plane perpendicular to common

axis or passing through a common center are equidistant from the axis.

OVALITY: This error occurs when there is a difference between the diameters.




Error = Maximum diameter - Minimum diameter =Major axis-Minor axis

PROCEDURE:

1. In this method the dial indicator is placed above the work piece, as shown in

Fig. (a).

2. The work piece whose roundness is to be measured is divided into 12 equal

parts. The work piece is then held in the V-block.

3. The work piece is kept in such a way that the dial indicator touches the work

piece at position 1. The work piece is then rotated to position 2 to position 12

successively and the variation in the surface profile is noted by the dial

indicator.

4. The procedure is repeated at least three times to get the higher accuracy

and the average value of the reading is taken.

5. Then a circle of diameter equal to 4 times the maximum value of the reading is

drawn and then the circle is again divided into 12 equal parts.

6. Inside the circle a small concentric circle of suitable diameter (say 0.5 times of

work piece diameter) is drawn as shown in Figure (b).

7. The values of readings at various positions are plotted between as small

concentric circle and maximum diameter circle. The points at various positions

are joined by straight lines to get the actual profile of the work piece.

8. The error is then obtained by measuring the radial distance between minimum

circumscribing circle and maximum inscribing circle.



FIGURE:

Experimental Setup



Polar Diagram

OBSERVATION TABLE:

Component

No.

Dial Indicator Reading

1 2 3 4 5 6 7 8

CONCLUSION:



Experiment No.: 9

TO MEASURE THE STRAIGHTNESS WITH THE HELP OF

STRAIGHT EDGE AND SLIP GAUGES



AIM: TO MEASURE THE STRAIGHTNESS WITH THE HELP OF

STRAIGHT EDGE AND SLIP GAUGES

OBJECTIVES : After compliting this expriment this expriments, you will able to:

(A) Mesuare the Straightness of a given job by wedge method.

(B) Develop the skill of wrringing process.

EQUIPMENT:

- Straight edge.

- slip gauge set

- surface plate

- job

RATIONALE:

Guide way of a lathe,spindle of a machine,surface of a measuring table and many

others similer situations where if referance surace is not straight or uniformally linier

if produce defective marking or products hence a straightness is reqired to be check.

Naturally the straightness of a straight edge and surface plate should be very high

,beacause they are consider as standard compare to other instruments in laboratory and

workshop .

To carry out straightness measurements, position the straightness interferometer in the

path between the laser head and the straightness reflector. The outgoing beam from

the laser passes through the straightness interferometer which splits it into two beams

which diverge at a small angle and are directed to the straightness reflector. The

beams are then reflected from the straightness reflector and return along a new path to

the straightness interferometer as shown in Figure. At the straightness interferometer

the two beams are converged and a single beam is returned to the entry port in the

laser head.

The straightness is measured by detecting the optical path change from a

relative lateral displacement between the interferometer and the reflector. The

straightness measurement can be in a horizontal or vertical plane depending on the

orientation of both the straightness interferometer and reflector. Figure shows the set-

up for a horizontal straightness measurement.

EXPERIMENT NO.:9

Date:



PROCEDURE:

(1) clean the surface plate.

(2) Put the job on the surface plate.

(3) Marks two point A & B at 0.554 L distance on the straight edge and devide

them in to two equal part as shown in fig 1remaining length of the straight edge

should be kept approximately equal on both the side.

(4) Put the straight edge on the slip gauge ,keep 10 mm slip gauge below (A) and

20 mm slip gauge below (B).

(5) Insert the required slip gauge below point no 1 of a straight edge and note the

reading in table 1.

(6) Repeat the step 5 for point no 2 to 9.

(7) Make the necessary calculation

(8) Write the conclusion.

Calculations:

Conclusion:



TO MEASURE THE FLATNESS WITH THE HELP OF

FLATNESS MEASUREMENT INSTRUMENT

Experiment No.: 10



AIM:TO MEASURE THE FLATNESS WITH THE HELP OF

FLATNESS MEASURMENT INSTRUMENT.

THEORY:

The flatness measurement kit is used to measure flatness. The angular interferometer

is attached to the turning mirror and the angular reflector is attached on top of the

selected flatness base. The angular interferometer is placed in the path between the

laser head and the angular reflector. Figure 1 - Principle of measurement The laser

beam is split into two by the beam-splitter inside the angular interferometer. One part

of the beam (the measurement beam A1) passes straight through the interferometer

and is reflected by one of the twin reflectors of the angular reflector back through the

interferometer and into the laser head. The other beam (measurement beam A2) passes

through the periscope part of the angular interferometer to the second reflector from

where it returns through the interferometer and into the laser head.

FLATNESS MEASUREMENT

An angular measurement is produced by comparing the path difference

between the beams A1 and A2, (i.e. the measurement is independent of the distance

between the laser and the interferometer). The 'flatness reading' displayed by the

software is the incremental height between the 'front' and 'back' feet of the flatness

base plate on which the angular reflector is fitted. This incremental height is

calculated from the angular measurement and knowledge of the distance between the

centers of the front and back feet of the flatness base plate. This distance, termed 'the

foot-spacing', must be entered into the calibration software before measurement starts.




TO MEASURE SURFACE ROUGHNESS VALUE OF GIVEN

MACHINED SURFACE

Experiment No.: 11



AIM:TO MEASURE SURFACE ROUGHNESS VALUE OF

GIVEN MACHINED SURFACE.

THEORY:

Engineering components are manufactured by Casting, forging, welding etc… these

components are then subjected to various machining operations for getting required

geometrical surfaces it is not practically possible to produce a component having a

geometrically ideal surface. The surface finish after machining depends upon the

material, vibration, deflection, speed, feed and other working conditions the surface

finish requirements depend upon the functional requirements of the components to be

assembled For high class of accuracy, surface finish requirements are high and hence

it is more expensive Surface quality or surface texture or surface finish is the amount

of geometric irregularity produced on the surface. Surface texture notes on a drawing

refer the required finish that must be machined on any particular surface.

Surface of a body is its boundary which separates it from another body.

Surface may be (i) Normal surface (ii) Rough surface (iii) Wavy surface and (iv)

Wavy surface roughness superimposed.

TYPE OF SURFACE ROUGHNESS




SURFACE ROUGHNESS INDICATION: The value or values defining

the principal criterion of roughness are added to the symbol as shown in figure.

a = Roughness value, Ra

in micrometers

= grade numbers N1to

N12

b = Production method

c = Sampling length

d = Direction of lay

e = Machining allowance

and

f = other roughness values

DIRECTION OF LAY:

The direction of lay is the direction of the predominant

surface pattern ordinarily determined by the production method and is shown in

table.



ROUGHNESS GRADES & SYMBOLS: The principal criterion of surface

roughness, Ra may be indicated by the corresponding roughness grade number, as

shown in Table.

SURFACE ROUGHNESS FOR VARIOUS MACHINING

PROCESSES:



CONCLUSION:



TO STUDY ABOUT LIMIT GAUGE & MEASURE

DIMENSION WITH THE HELP OF IT

Experiment No.: 12



AIM: TO STUDY ABOUT LIMIT GAUGE & MEASURE

DIMENSION WITH THE HELP OF IT.

THEORY:

These are also called „go‟ and „no go‟ gauges. These are made

to the limit sizes of the work to be measured. One of the sides or ends of

the gauge is made to correspond to maximum and the other end to the

minimum permissible size. The function of limit gauges is to determine

whether the actual dimensions of the work are within or outside the

specified limits. A limit gauge may be either double end or progressive.

A double end gauge has the „go‟ member at one end and „no go‟

member at the other end. The „go‟ member must pass into or over an

acceptable piece but the „no go‟ member should not. The progressive

gauge has „no go‟ members next to each other and is applied to a work

piece with one movement. Some gauges are fixed for only one set of

limits and are said to be solid gauges. Others are adjustable for various

ranges.

PLUG GAUGES:

Plug gauges are the limit gauges

used for checking holes and consist of two

cylindrical wear resistant plugs. The plug

made to the lower limit of the hole is known

as „GO‟ end and this will enter any hole

which is not smaller than the lower limit

allowed. The plug made to the upper limit of

the hole is known as „NO GO‟ end and this

will not enter any hole which is smaller

than the upper limit allowed. The plugs are

arranged on either ends of a common handle. Plug gauges are normally

double ended for sizes up to 63 mm and for sizes above 63 mm they are

single ended type.




RING GAUGES:

Ring gauges are used for gauging shafts. They are used in a similar

manner to that of GO & NO GO plug gauges. A ring gauge consists of a

piece of metal in which a hole of required size is bored.



SNAP (or) GAP GAUGES:

A snap gauge usually consists of a plate

or frame with a parallel faced gap of the

required dimension. Snap gauges can be

used for both cylindrical as well as non

cylindrical work as compared to ring

gauges which are conveniently used only

for cylindrical work. Double ended snap

gauges can be used for sizes ranging

from 3 to 100 mm. For sizes above 100

mm up to 250 mm a single ended

progressive gauge may be used.

CONCLUSION:



TO STUDY ABOUT NON DESTRUTIVE TESTING

Experiment No.: 13



AIM: To study about Non-destructive testing.

THORY:

In manufacturing, welds are commonly used to join two or more metal parts. Because

these connections may encounter loads and fatigue during product lifetime, there is a

chance that they may fail if not created to proper specification. For example, the base

metal must reach a certain temperature during the welding process, must cool at a

specific rate, and must be welded with compatible materials or the joint may not be

strong enough to hold the parts together, or cracks may form in the weld causing it to

fail. The typical welding defects (lack of fusion of the weld to the base metal, cracks

or porosity inside the weld, and variations in weld density) could cause a structure to

break or a pipeline to rupture.

Welds may be tested using NDT techniques such as industrial radiography or

industrial CT scanning using X-rays, ultrasonic testing, liquid penetrate

testing, magnetic particle inspection or via eddy current. In a proper weld, these tests

would indicate a lack of cracks in the radiograph, show clear passage of sound

through the weld and back, or indicate a clear surface without penetrate captured in

cracks.

ULTRASONIC TESTING:

Ultrasonic non-destructive testing (UT) is commonly used for flaw detection in

materials. Ultrasound uses the transmission of high-frequency sound waves in a

material to detect a discontinuity or to locate changes in material properties.


http://en.wikipedia.org/wiki/Welding

http://en.wikipedia.org/wiki/Fatigue_(material)

http://en.wikipedia.org/wiki/Specification

http://en.wikipedia.org/wiki/Industrial_radiography

http://en.wikipedia.org/wiki/Industrial_CT_scanning

http://en.wikipedia.org/wiki/Ultrasonic_testing

http://en.wikipedia.org/wiki/Liquid_penetrant_testing

http://en.wikipedia.org/wiki/Liquid_penetrant_testing

http://en.wikipedia.org/wiki/Magnetic_particle_inspection

http://en.wikipedia.org/wiki/Eddy_current



A typical pulse-echo UT inspection system consists of several functional units, such

as the pulse/receiver, transducer, and a display device. A pulse/receiver is an

electronic device that can produce high voltage electrical pulses. Driven by the pulse,

the transducer generates high frequency ultrasonic energy. The sound energy is

introduced and propagates through the materials in the form of waves. When there is a

discontinuity (such as a crack) in the wave path, part of the energy will be reflected

back from the flaw surface. The reflected wave signal is transformed into an electrical

signal by the transducer and is displayed on a screen. Knowing the velocity of the

waves, travel time can be directly related to the distance that the signal traveled. From

the signal, information about the reflector location, size, orientation and other features

can sometimes be gained.

Dye Penetration Test

Dye penetrant inspection (DPI), also called liquid penetrate inspection (LPI) or

penetrant testing (PT), is a widely applied and low-cost inspection method used to

locate surface-breaking defects in all non-porous materials (metals, plastics, or

ceramics). The penetrant may be applied to all non-ferrous materials and ferrous

materials, although for ferrous components magnetic-particle inspection is often used

instead for its subsurface detection capability. LPI is used to detect casting, forging

and welding surface defects such as hairline cracks, surface porosity, leaks in new

products, and fatigue cracks on in-service components.



Inspection steps

1. Pre-cleaning:

The test surface is cleaned to remove any dirt, paint, oil, grease or any loose scale that

could either keep penetrant out of a defect, or cause irrelevant or false indications.

Cleaning methods may include solvents, alkaline cleaning steps, vapor degreasing, or

media blasting. The end goal of this step is a clean surface where any defects present

are open to the surface, dry, and free of contamination. Note that if media blasting is

used, it may "work over" small discontinuities in the part, and an etching bath is

recommended as a post-blasting treatment.

Application of the penetrant to a part in a ventilated test area.

2. Application of Penetrant:

The penetrant is then applied to the surface of the item being tested. The penetrant is

usually a Brilliant colour mobile fluid with very low surface tension and capillary

action. The penetrant is allowed "dwell time" to soak into any flaws (generally 5 to 30

minutes). The dwell time mainly depends upon the penetrant being used, material

being tested and the size of flaws sought. As expected, smaller flaws require a longer

penetration time. Due to their incompatible nature one must be careful not to apply

solvent-based penetrant to a surface which is to be inspected with a water-washable

penetrant.

https://en.wikipedia.org/wiki/Solvent

https://en.wikipedia.org/wiki/Vapor_degreasing



Steps of Dye Penetration Test

3. Excess Penetrant Removal:

The excess penetrant is then removed from the surface. The removal method is

controlled by the type of penetrant used. Water-washable, solvent-removable are the

common choices. When using solvent remover and lint-free cloth it is important to not

spray the solvent on the test surface directly, because this can remove the penetrant

from the flaws. If excess penetrant is not properly removed, once the developer is

applied, it may leave a background in the developed area that can mask indications or

defects. In addition, this may also produce false indications severely hindering the

ability to do a proper inspection. Also, the removal of excessive penetrant is done

towards one direction either vertically or horizontally as the case may be.

4. Application of Developer:

After excess penetrant has been removed, a white developer is applied to the sample.

Several developer types are available, including: non-aqueous wet developer, dry

powder, water-suspendable, and water-soluble. Choice of developer is governed by

penetrant compatibility (one can't use water-soluble or -suspendable developer with

water-washable penetrant), and by inspection conditions. When using non-aqueous

wet developer (NAWD) or dry powder, the sample must be dried prior to application,

while soluble and suspendable developers are applied with the part still wet from the

previous step. NAWD is commercially available in aerosol spray cans, and may

https://en.wikipedia.org/w/index.php?title=Non-aqueous_wet_developer&action=edit&redlink=1



employ acetone, isopropyl alcohol, or a propellant that is a combination of the two.

Developer should form a semi-transparent, even coating on the surface.

The developer draws penetrant from defects out onto the surface to form a visible

indication, commonly known as bleed-out. Any areas that bleed out can indicate the

location, orientation and possible types of defects on the surface. Interpreting the

results and characterizing defects from the indications found may require some

training and/or experience [the indication size is not the actual size of the defect].

5. Inspection:

The inspector will use visible light with adequate intensity (100 foot-candles or

1100 lux is typical) for visible dye penetrant. Ultraviolet (UV-A) radiation of adequate

intensity (1,000 micro-watts per centimeter squared is common), along with low

ambient light levels (less than 2 foot-candles) for fluorescent penetrant examinations.

Inspection of the test surface should take place after 10- to 30-minute development

time, and is dependent on the penetrant and developer used. This time delay allows the

blotting action to occur. The inspector may observe the sample for indication

formation when using visible dye. It is also good practice to observe indications as

they form because the characteristics of the bleed out are a significant part of

interpretation characterization of flaws.

6. Post Cleaning:

The test surface is often cleaned after inspection and recording of defects, especially if

post-inspection coating processes are scheduled.

https://en.wikipedia.org/wiki/Acetone

https://en.wikipedia.org/wiki/Isopropyl_alcohol

https://en.wikipedia.org/wiki/Foot-candles

https://en.wikipedia.org/wiki/Lux



TO STUDY ABOUT TRANSDUCERS

AND SENSORS

Experiment No.: 14



AIM: TO STUDY ABOUT DIFFERENT TRANSDUCERS AND

SENSORS.

THORY:

1] LVDT:

The LVDT (Linear Variable Differential Transformer), is an absolute

position/displacement transducer that converts a position or linear displacement from

a mechanical reference (zero, or null position) into aproportional electrical signal

containing phase (for direction) and amplitude (for distance) information. The LVDT

operation does not require an electrical contact between the moving part (probe or

core assembly) and the coil assembly, but instead relies on electromagnetic coupling;

this and the fact that LVDTs can operate without any built-in electronic circuitry are

the primary reasons why they have been widely used in applications where long life

and high reliability under very severe environments are a required, such as in

Military/Aerospace, process controls, automation, robotics, nuclear, chemical plants,

hydraulics, power turbines, and many others.

The LVDT consists of a primary coil (of magnet wire) wound over the whole length

of a non-ferromagnetic bore liner (or spool tube) or a cylindrical, non-conductive

material (usually a plastic or ceramic) form. Two secondary coils are wound

symmetrically on top of the primary coil for “long stroke” LVDTs (i.e. for actuator

rod position) or each side of the primary coil for “Short stroke” LVDTs (i.e. for

electro-hydraulic servo-valve or EHSV). The two secondary windings are typically

connected in “series opposing” (Differential). A ferromagnetic core, which length is a

fraction of the coil assembly length, magnetically couples the primary to the

secondary winding turns that are located over the length of the core. Even though the

secondary windings of the long stroke LVDT are shown on top of each other in the

above cross-section illustration, nowadays MEAS winds them both at the same time




using custom designed, dual carriage computerized machines. This method saves

manufacturing time and also creates secondary windings with the same exact

resistance and symmetrical capacitance distribution, therefore allows better

performance (linearity, phase symmetry, lower null voltage, etc.).

2] CAPACITENCE TRANSDUCER:

The capacitor can be used to measure the fluid level in a storage tank. In a basic

capacitive level sensing system, capacitive sensors have two conducting terminals that

establish a capacitor. If the Capacitive Sensor Applications gap between the two rods

is fixed, the fluid level can be determined by measuring the capacitance between the

conductors immersed in the liquid. Since the capacitance is proportional to the

dielectric constant, fluids rising between the two parallel rods will increase the net

capacitance of the measuring cell as a function of fluid height. To measure the liquid

level, an excitation voltage is applied with a drive electrode and detected with a sense

electrode. Figure illustrates a basic set-up of a liquid level measurement system.



3] PIEZO ELECTRIC TRANSDUCER:

The piezoelectric effect is understood as the linear electromechanical interaction

between the mechanical and the electrical state in crystalline materials with no

inversion symmetry. The piezoelectric effect is a reversible process in that materials

exhibiting the direct piezoelectric effect (the internal generation of electrical charge

resulting from an applied mechanical force) also exhibit the reverse piezoelectric

effect (the internal generation of a mechanical strain resulting from an applied

electrical field). For example, lead crystals will generate measurable piezoelectricity

when their static structure is deformed by about 0.1% of the original dimension.

Conversely, those same crystals will change about 0.1% of their static dimension

when an external electric field is applied to the material. The inverse piezoelectric

effect is used in production of ultrasonic sound waves.

http://en.wikipedia.org/wiki/Poling_(piezoelectricity)

http://en.wikipedia.org/wiki/Centrosymmetry

http://en.wikipedia.org/wiki/Reversible_process

http://en.wikipedia.org/wiki/Force



TO STUDY ABOUT TEMPERATURE PRESSURE & FLOW

MEASUREMENT

Experiment No.: 15



AIM: TO STUDY ABOUT TEMPERATURE PRESSURE &

FLOW MEASUREMENT

THORY:

1] TEMPERATURE MEASUREMENT:

THERMOCOUPLE

A thermocouple, shown in Figure consists of two wires of dissimilar metals joined

together at one end, called the measurement(“hot”)junction. The other end, where the

wires are not joined, is connected to the signal conditioning circuitry traces, typically

made of copper. This junction between the thermocouple metals and the copper traces

is called the reference (“cold”) junction.

The temperature of the thermocouple‟s reference junction must be known to get an

accurate absolute-temperature reading. When thermocouples were first used, this was

done by keeping the reference junction in an ice bath. Figure 2 depicts a thermocouple

circuit with one end at an unknown temperature and the other end in an ice bath (0°C).

This method was used to exhaustively characterize the various thermocouple types,

thus almost all thermocouple tables use 0°C as the reference temperature.




2] PRESURE MEASUREMENT:

BOURDON TUBE PRESSURE GAUGE

Basic Bourdon tubes are made from metal alloys such as stainless steel or

brass. They consist of a tube of elliptical or oval cross-section, sealed at one end.

There are various shapes of Bourdon tube, including helical, spiral and twisted. A

common design is the C-shape, as shown to the right. Here the tube is at atmospheric

pressure. When increased pressure is applied to the open end, it deflects outwards

(tries to straighten) in proportion to the pressure inside the tube (the outside of the

tube remains at atmospheric pressure). As the pressure is decreased, the tube starts to

return to its atmospheric pressure position. The amount by which the tube moves in

relation to the pressure applied to it depends on factors including its material, shape,

thickness, and length. Compared to other elastic pressure sensors the deflection

produced by Bourdon tubes is large. The Bourdon tube pressure gauge, shown here,

consists of a Bourdon tube connected to a pointer. The pointer moves over a calibrated

scale. When pressure is applied, the movement of the tube is fairly small, so to

increase the movement of the pointer it is mechanically amplified. This is usually by a

connecting mechanism consisting of a lever, quadrant and pinion arrangement.



OBSERVATION TABLE:

Sr.

No.

Reading

1 2 3 4 5 6 7 8 9 10 11 12

3] FLOW MEASUREMENT:

VENTURIMETER

In the venturimeter figure the fluid is accelerated through a converging cone of angle

15-20° and the pressure difference between the upstream side of the cone and the

throat is measured and provides the signal for the rate of flow. The fluid slows down

in a cone with smaller angle (5-7°) where most of the kinetic energy is converted back

to pressure energy. Because of the cone and the gradual reduction in the area there is

no "vena contracta". The flow area is at minimum at the throat. High pressure and

energy recovery makes the venturimeter suitable where only small pressure heads are

available. A discharge coefficient Cv- of 0.975 may be taken as standard, but the

value varies noticeably at low values of the Reynolds' number.

CONCLUSION:

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