Measurements and Metrology Laboratory Manual
-
Upload
bossanand05 -
Category
Documents
-
view
1.128 -
download
8
Transcript of Measurements and Metrology Laboratory Manual
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