MEP62 – Measurements and Metrology Laboratory Manual

ALPHA COLLEGE OF ENGINEERING AND TECHNOLOGY

Department of Mechanical Engineering

Kanniakoil to Bahour Main Road, Kanniakoil, Puducherry – 607402

Important Instructions to the Students

The purpose of this laboratory is to provide a more intuitive and physical understanding of the theory

of fluid machinery.

The main objective is to introduce a variety of classical experimental and the principles behind these

techniques.

This laboratory exercise also provides practice in making engineering judgments, estimates and

assessing the reliability of your measurements, skills which are very important in all engineering

disciplines.

Read the lab manual and any background material needed before you come to the lab.

You must be prepared for your experiments before coming to the lab. In many cases you may have to

go back to your fluid mechanics and machinery textbooks to review the principles dealt with in the

experiment.

To encourage you to be prepared and to read the lab manual before coming to the laboratory,

unannounced or viva questions may be asked at any time during the lab.

In performing the experiments, please proceed carefully to minimize any water spills, especially on

the electric circuits and wire. Make your workplace clean before leaving the laboratory. Maintain

silence, order and discipline inside the lab. Any injury no matter how small must be reported to the

instructor immediately.

Start writing your laboratory records early; don’t wait till the day before the lab records are due.

Most experiments require a significant amount of analysis, which cannot be done properly if you

start one or two days before the due date. Start early and give yourself time to get help in case you

run into problems, we can not help you if you wait till the last moment.

Tables of Contents

Sl.No: List of Experiments

1. Calibration of Micrometer.

2. Measurement of Taper using Sine Bar.

3. Measurement of Displacement by using LVDT and RVDT.

4. Measurement of Straightness and Squareness by Autocollimator.

5. Measurement of Temperature by Thermocouple.

6. Measurement of Strain using Strain Gauge.

7. Measurement of Gear tooth profile by Profile Projector.

Calibration of Micrometer.

AIM

To Determine the diameter of the given Job an to accuracy of 0.01mm by using micrometer

and checking the micrometer using Slip gauge.

APPARATUS REQUIRED

1. Micrometer

2. Specimen

3. Slip gauge

MICROMETER

The end of the screw forms one measuring tip and the other measuring tip is constituted by a

stationary anvil in the base of the frame. The screw is threaded for certain length and is plan afterwards. The

plain portion is called sleeve and its end is the measuring surface. The spindle is advanced by turning

thimble connected to the spindle.

The spindle is aside fit over the barrel and barrel is the fixed part attached with frame. The barrel is

graduated in unit of 0.05cm.i.e.20division per cm, which is the lead of the screw for one complete

revolution. The thimble has got 25 divisions around its periphery on circular portion. Thus it sub-divides

each revolution of the screw in 25 equal parts i.e. each division corresponds to 0.002cm.

PROCEDURE

1. The whole movable jaw assembly is adjusted so that the two measuring tip just touch

two parts to be measured.

2. Then lock nut is tightened.

3. Final adjustment depending upon the sense of correct feel is made by the adjusting Screw.

4. Measure the main scale readings i.e. the line coincide with o mark of vernier scale and noted

down the reading.

5. The measuring tip is so designed as to measure inside as well as outside dimension.

6. Calculate MSR, VSR and TSR.

TABULATION ( MICROMETER )

RESULT

Thus the Micrometer is made by a micrometer at an accuracy of 0.01mm.

S.NoMSR TSR VSR LC Mean

Value

Measurement of Taper using Sine Bar

AIM

To perform angular measurement by using Sine bar

APPARATUS REQUIRED

1. Sine bar

2. Slip gauge

3. Work piece

FORMULA USED

sin θ= Opposite sideHyp otenuse side

PROCEDURE

1. Clean the surface plate, Sine bar and Slip gauges using fine cotton cloth

2. Place the Job in the smooth flat surface

3. Place the sine bar in such a manner that the Lower surface of the Sine bar was uniformly touches the surface whose angle to be measured.

4. Calculate the angle using the Formula

sin θ=hl

Where h is the Vertical height of the slip gauge

L is the Length of the sine bar (200 mm )

ANGULAR MEASUREMENT USING SINE BAR

TABULATION

RESULT

Thus the angle in the work pieces were Determined using Sine bar

Angle measured in worpiece = --------- º

Test specimen

H1 H2 H2-H1 sin

SPECIMEN CALCULATION

θ = Sin-1 ( h / l ) = Sin-1 ( 26 / 200 )

= 7.47 º

Measurement of Displacement by using LVDT and RVDT

Workpiece Height h (mm) Length (mm) θ = Sin-1 ( h / l ) 1. 26 200 7.47 º2. 21.33 200 6.12 º3. 19.44 200 5.58 º4. 25.5 200 7.33 º

AIM:

To measure the scale by using Linear variable differential transformer

APPARATUS REQUIRED :

LVDT setup

Connecting rods

Theory:

Linear variable differential transformer is the most popular electro mechanical displacement

Into electrical signal in effect is a transformer consisting of three symmetrical spaced coils carefully

Wounded on insulation. It works on mutual inductance principle and consists of a primary coils

Wound .AC carried excitation is applied to the primary and two secondary are connected externally in a

Series opposition to it. A cylindrical shield of ferromagnetic material is spun over the washers.

The devices also becomes extremely rugged and reliable. There is a non contacting magnetic core,

Carefully annealed to improve the stability which moves in the centre of the core varies the mutual

Inductance of each secondary to the primary,which determines the voltage inducted from the primary

To the secondary.If the core is centered in the middle of the two secondary windings

If the core is moved off middle position then the mutual inductance of the primary with secondary

Will be greater than the other and a differential voltage will appear across the secondary in series

For off center displacement within linear range of operation the output is essential a linear

Function of core displacement

Procedure

1.Check the connection made and switch on the instrument by rocker switch at the front panel

the display glows to indicate is ON.

2. Allow the instrument in ON position for 10 minutes.

3. Rotate the micrometer till it reads 20

4. Adjust the CAL potentiometer at the front panel so the display reads the 10.

5. Rotate the core of the micrometer till it reaches the 10 and adjust the zero potentiometer

6. Rotate back the micrometer core upto 20

7.As the core of the LVDT moves the display reads the displacement

8. Rotate the core of micrometer in steps of 2mm and tabulate the readings

9. Plot the graphs between actual reading Vs indicator reading, Actual reading

Vs error and Display the results.

RESULT :

Thus the Performace test on LVDT was conducted

Measurement of Straightness and Squareness by Autocollimator.

Aim- Measurement of the Straightness and Square ness Using AutocollimatorApparatus- AutocollimatorTheory-Definition of straightness-a plane is to be said straight over a given length. If thevariation or distance of its point from two planes perpendicular to each other and parallel

to the generation direction at of the line remain within specified tolerance limits .thereference planes being so chosen that there intersection is parallel to the straight linejoining two points suitably located on the line to be tested and two points being closeends of the length to be measured.Principal of Autocollimator: - it works on the principal that if the light source is placedin the focus of a collimating lens then the light is projected as parallel beam. If this beamis made to strike a plane reflector normal (perpendicular ) to the optical axis then it isreflected back along its own path brought to the same focus.But if reflector is titled through a small angle the parallel beam is reflectorthrough twice that angle and is brought to focus in same plane as a light source but to oneside at a distance x=2F – Focal length of collimating lensConstruction: - A line diagram of injected reticule autocollimator consists of three partsas micrometer, lighting unit and collimating lens.Working: - when lamp is illuminated then ray from lamp passes through convener, targetreticule and stills on 45 transparent beam splitter. Beam splitter then reflector is placednormal to optical axis which reflects the ray along its own path and an image istransparent beam splitter and the image is seen through eye piece of microscopic onexternal reflector. Now we tilt the plane reflector by a small angel the ray will reflectback but twice the angle and in this condition we couldn’t fine the image on microscopeeye piece. Therefore in order to obtain an image operate micrometer microscope till theimage is seen or collected on an external reflector. Stop rotating micrometer, note downthe reading. The reading are directly in angular value that is in minutes 1, 2, 3 and 10 on.Hence the difference in two reading of micrometer gives the value of ‘x’Therefore we can calculate from equation x= 20Where f is focal length of collimating lens.Auto collimator is quite accurate and read unto 0.1 sec and used for distance.Procedure:-(1) Make the distance of 50mm internal on the w/p(2) Set the cross wire so that two cross will coincide.(3) Set the mirror so that the cross wire will be visible(4) Move the reflector on next 50mm mark and adjust it to see reflection of crosswire.(5) Take the reading of reflected crosswire deviated or moved up or down. Measurethe distance between two crosswireResult: - The mean deviation of surface is found out to be 0.024 mm upward anddownward

Measurement of Temperature by Thermocouple.

AIM:

To measure temperature using thermometer and 3 type thermocouple apparatus and

Compare the results

APPARATUS REQUIRED:

Temperature indicator

Temperature source

Thermocouple

Thermometer

FORMULA USED :

Error = Va – Vi

% Error = Error

-------------- x 100

Va

Where Va is the actual temperature

Vi is the thermocouple indiacted temperature

THEORY :

The basic principle of thermocouple is when two dissimilar metals are joined together

An e.m.f will exist between the two points A and B,which is primarily a function of the junction

Temperature. The above principle is called see back effect

The thermocouple consists of one hot junction and one cold junction. The hot junction will

Be introduced into the place where temperature is to be measured.The other cold junction is

Maintained at constant reference temperature.Also one voltage measuring instrument is connected

To the free ends of the thermocouple.

In thermocouple the known temperature is called reference temperature.The temperature

Which is to be measured is introduced in the thermocouple hot junction

A common arrangementfor establishing the reference temperature is ice bath.The reference

Temperature is controlled to be at a constant temperature is at 0º C

The temperature difference between the Ice bath and the Hot junction temperaturewill create

An e.m.f.This e.m.f production is measured in the mill voltmeter.So this change in e.m.f

Rate will give the measure of temperature.

PROCEDURE

1. Clean the instrument and its accessories by finecooton cloth.

2. Check connection made and switch on the instrumentby rocker switch.

3. The display glows to indicate is on.

4. Allow the instruments in on position for 10 minutes for initial warm up.

5. Fill around 3/4th full of water to the kettleand place the thermometer and and thermocouple

Inside the kettle

6.Note down the initial water temperature from the thermometer.Adjustthe initial set potentiometer

in the front panel till the display reads initial water temperature

7.Switch on the kettle and wait till the water boils notedown the thermometer reading and set

Potentiometer till the display reads boiling water temperature.

8. Remove the thermometer and temperature sensor from the Kettle and change the water and replace

The thermometer reading and set final set potentiometer till the display reads boiling water

Temperature

9. Switch on the kettle and note down the reading for every 10 º intervaland tabulate the readings

10. Plot the graphs between actual reading Vs indicator reading.

RESULT:

Thus the performance test on Thermocouple trainer has been Performed.

TABULATION

S. Actual Thermoc Erro

NO temperature ( Va )

ouple Indicated

temperature (Vi )

Vi

Vi

Vi Vi

r % Error

1.2.3.4.

Measurement of Strain using Strain Gauge.

Measurement of Gear tooth profile by Profile Projector.

AIM

To measure the thread parameter of given screw thread using Profile projector

APPARATUS REQUIRED

1. Profile projector2. work holding Center

PARAMETER TO BE MEASURED

1. Major and Minor diameter2. Depth and Pitch of thread3. Addendum and dedendum.

THEORY

Minor diameter

It is the diameter of an Imaginary co-axial cylinder which would touch the root of external

Or internal thread.

Major Diameter

It is the diameter of an imaginary co-axial cylinder which would touchthe crest of external

Or internal thread.

Depth

The distance between the crest and root of the thread is called Depth of Thread

Pitch of Thread

The distance measured parallel to the axis from a point on a thread to the

Corresponding next point

Addendum

For external thread it is the radial distance between major and pitch cylinders.

Dedendum

For external thread it is the radial distance between the Pitch and Minor cylinders

For internal thread it is the radial distance between major and Pitch cylinders

Helix angle

The helix angle is made by the thread at the pitch line with axis.

PROCEDURE

1. Clean the instrument and its accessories by fine cotton cloth2. Clamp the specimen in between the jaws present in the profile Projector3. Switch on the power and adjust the degree of magnification in profile projector

4. The magnification depends upon the distance between the Local plane of the lens andThe screen

5. Bring the specimen image to the screens axis by adjusting the micrometer and rotationOf screen

6. Now the parameter of threads are measured and tabulatethe readings.

RESULT:

Thus the thread parameters of given screw thread was found using profile projector

Major diameter of the screw = 6 mm

Minor diameter of the screw = 4.80 mm

Pitch of screw = 1 mm

Depth of screw = 1.2 mm

Angle of thread = 60º mm

TABULATION ( Profile Projector )

S.NO

Major diameter

D1 (mm)

Minor Diameter

D2 (mm)

Pitch

(mm)

Angle (º)

Depth (mm)

1.

6 4.80 1 60º 1.2