mmm lab manual draft.pdf

7/26/2019 mmm lab manual draft.pdf

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DEPARTMENT OF MECHANICAL ENGINEERING

MECHANICAL MEASUREMENTS

AND

METROLOGY LABORATORY MANUAL

( 10 MEL 37 B / 47 B)

(Document No. SCE/ME/LM/MMM-02/2013)

Prepared by :

P.RAGHUTHAMA RAO

Asst.Prof. Gr2

Department of Mechanical Engineering

BANGALORE


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DEPARTMENT OF MECHANICAL ENGINEERING

MECHANICAL MEASUREMENTS & METROLOGY LA

MANUAL

(Document No. SCE/ME/LM/MMM-02/2013 as per VTU syllabus 10MEL37B/47

Prepared by :

P.RAGHUTHAMA RAO

Asst.Prof. Gr2, Department of Mechanical Engineering


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TABLE OF CONTENTS

S.NO. DESCRIPTION PAGE

NO.

1

2

3

VTU syllabus of Mechanical Measurements & Metrology LaboratoryList of Equipments in MMM Laboratory

Introduction to experiments of MMM Laboratory

I PART A MECHANICAL MEASUREMENTS

1

2

34

4 Calibration of Pressure gauge 5

5 Calibration of Thermocouple 8

6 Calibration of Linearly Variable Differential Transformer(LVDT) 11

7 Calibration of load cell 14

8 Determination of Modulus of Elasticity of a Mildsteel specimen using strain

gauges16

9 II PART B METROLOGY 21

10 Measurements using optical(Profile) Projector 2211.1 Measurements of angle using Bevel Protractor 25

11.2 Measurements of angle using Sine bar 27

11.3 Measurements of angle using Sine centre 30

12 Measurements using Roller set 32

13 Measurement of cutting tool forces using (a) Lathe tool dynamometer and 35

(b) Drill tool Dynamameter 35

14 Measurement of Screw thread parameters using 2wire/3wire method 3915 Measurements using Mechanical Comparator 42

16 Measurement of gear tooth Profile using GeartoothMicrometer/Vernier caliper 4417 Calibration of Micrometer using Slipgauges 48

18 Measurement using Optical flats 5119 Viva-Voce Question bank 54


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MECHANICAL MEASUREMENTS AND METROLOGY LABORATORY

VTU SYLLABUS

Subject Code : 10MEL37B / 47B IA Marks : 25 Hours/Week : 03

Exam Hours : 03 Total Hours : 48 Exam Marks : 50

PART-A: MECHANICAL MEASUREMENTS

1. Calibration of Pressure Gauge

2. Calibration of Thermocouple

3. Calibration of LVDT

4. Calibration of Load cell

5. Determination of modulus of elasticity of a mild steel specimen using strain gauges.

PART-B: METROLOGY

1. Measurements using Optical Projector / Toolmaker Microscope.

2. Measurement of angle using Sine Center / Sine bar / bevel protractor

3. Measurement of alignment using Autocollimator / Roller set

4. Measurement of cutting tool forces using

a) Lathe tool Dynamometer b) Drill tool Dynamometer.

5. Measurement of Screw thread Parameters using Two wire or Three-wire method.

6. Measurements of Surface roughness, Using Tally Surf/Mechanical Comparator

7. Measurement of gear tooth profile using gear tooth vernier /Gear tooth micrometer

8. Calibration of Micrometer using slip gauges

9. Measurement using Optical Flats

Scheme of Examination:

ONE question from part -A: 20 Marks

ONE question from part -B: 20 Marks

Viva -Voice: 10 Marks

Total : 50 Marks


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LIST OF EQUIPMENTS & INSTRUMENTS IN MMM LABORATORY, SCE

1.Granite Surface plates (2 nos.) of sizes 1 metre x 1 metre & 400mm x 400mm

2.Micrometer Mitutoyo make ranges 0 to 25mm & 25 to 50 mm with base stand(one no.digital 0-25mm(0.0

3.Vernier caliper (2 nos.) both Mitutoyo make 0 to 150 mm range (1no. digital)

4.Geartooth vernier caliper & 0 to 100 mm range horizontal scale & 0-80mm vertical scale( s.no.n1-26)

5.Gertooth Micrometer(Flanged anvil) Mitutoyo make and 0 to 25 mm range(0.01)

6.Slip gauge set Yamayo make- M-87 as per DIN 861(1.001 to 100mm) with 2 protectoe slips.

7.Bevel Protractor Mitutoyo make (5 min. accuracy)

8.Sinebar 200 mm size supremo make

9.Sine centre 200 mm size supremo make

10. Ground,polished Rollers of sizes 3mm to 10mm(in steps of 1 mm & each size3 nos.) & I no. 2mm roller

11.Dial Test Indicator(DTI) Mitutoyo(2nos.), range 0 to 10mm(0.010) & base stand1no. Digital-12.7mm(0.

12.Optical flats : 1 no. specimen convex & 1 no. optical flat

13. Monochromatic light source(Wave length : )

14.Bourdon Pressure gauge(Kamc make) range 0 to 14 Kg/cm2 mounted on compressor unit.

15.Pressure Transducer1 no.

16.Load cell unit range 0 to 10Kg(0. 1kg )(M/s Contech. )

17. Mechanical Measurement unit for calibration of thermocouple (stainless steel container with water hea

& provisions for mounting (i) thermocouple(ii)RTD (iii) thermometer ) & digital readout. (M/s Contech.

Microsystems)

18.Mechanical Measurement unit for measuring E value of M.S. (A cantilever strip with loading provision,

Strain gauges mounted & connected to measurement system with digital readout)(M/s Contech.)

19.Air compressor unit of make M/s METRO of 1 H.P. & 650 rpm with provisions for calibration of Pressure

gauge & mounted with PressureTransducer

20.LVDT Measurement system mounted with Micrometer(Mitutoyo).(M/s Contech.)

21.Profile Projector unit (with a 300mm circular angular scale & 2 micrometers(Mitutoyo))(M/sBombay Too

supplying agency.)

22.Drill tool dynamometer unit with digital readout system (M/s Contech.)

23.Lathe tool dynamometer unit with digital readout system.(M/s Contech.)

24. Wire set (for 2/3 wire method) of sizes : 0.17; 0.195; 0.22; 0.25; 0.29; 0.335; 0.390; 0.455; 0.530; 0.620;

0.725; 0.895; 1.100; 1.350; 1.650; 2.050 ( 3 nos. of wires for each size)

25.Thread plug gauges M11x1.5-6H & M7x6H1 no. each

26.Magnetic v block- 1 no.

27.Magnetic stand for DTI Jafuji make- 1 no.

28.Tapered cones- 6 nos.& angle specimens(plates)- 2 nos.

29. Rigid base & stand for dial test indicator (comparator)

30. Bore gauge 0 to 34 mm range with DTI (0.01mm

3


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INTRODUCTION TO EXPERIMENTS OF MECHANICAL MEASUREMENTS & METROLOGY LABORATORY

Quality control & Inspection methods are very important steps in the realization of quality products

for any system realized by Industrial organization or research establishment. Success or failure of a system,

product depends primarily on the Quality control & inspection methodology adopted. Reliable & accurate

Measurements of dimensions & parameters form basis of Inspection & quality control . The basics of

CALIBRATION is introduced.Measurements can broadly be categorized as (a) Linear & Angular measureme

such as length,diameter,thickness etc.

(b) Mechanical parameters such as force,pressure,stress,strain,temperature etc.

I METROLOGY / DIMENSIONAL MEASUREMENTS :

Metrology is the science & technique of measurements.Dimensions can be Linear or

Angular.Compared to Mechanical measurements of parameters , Dimensional measurements are direct

measurements using Precision & accurate Instruments of Metrology. A mechanical Engineer is responsible f

guaranteeing quality of product supplied either for an industry or for research.

One part of MMM lab. Experiments are meant for imparting practical knowledge & some basic

in handling Measuring Instruments , taking accurate measurements,understanding the advantages,limitatio

standard set of metrology Instruments such as : Micrometer,Vernier caliper,BevelProtractor,Sinebar,Sine

Centre,Slipgauge set; & special instruments like :

(a)Geartooth Micrometer & calipers & Dial Test Indicator,Profile Projector & Tool makers microsc

for 2/3 wire methods for thread measurements

(b)Auto collimator for angular & other alignments of systems/assemblies,

(c) Tally surf for surface roughness inspections .

(d) Optical flats for flatness & contour measurements

II MECHANICAL MEASUREMENTS ;

Another part of MMM lab. Experiments tries to impart basic knowledge of measurements o

mechanical parameters viz Force, Pressure,Torque,Stress,Strain,linear dimension,temperature,Youngs Mod

These are indirect methods of measurement & the principles behind these measurements are enumerated

Transducers for linear,force,pressure,temperature,stress,torque used in different experiments gives direct

knowledge of conversion of mechanical parameters into electrical signals, its amplification,modifications,&

finally to measurable signals by digital display devices such as oscilloscope,digital meters etc.


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PART -- A

MECHANICAL MEASUREMENTS

1.0 CALIBRATION OF PRESSURE GAUGE


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1.0 AIM :To calibrate Pressure Gauge with reference to pressure transducer.

2.0 APPARATUS:

Pressure Gauge , Pressure Transducer(calibrated), air compressor unit

3.0 THEORY :

Pressure is force exerted per unit area and is measured in N/m2=Pascal in SI units; atmospheric pressure is

1bar=760mm of Hg=1.013Kg/cm2. Pressure is measured by several methods such as Bourdon pressure gauge

Pressure transducers, manometer, pirani gauge, penning gauge, dead weight tester etc.

Bourdon pressure gaugeis fully mechanical device which is an elastic pressure transducer. C-type bourdon

pressure gauge inner mechanism is indicated in the sketch above.

It consists of an elliptical cross sectional tube (Bourdon tube) bent into a circular shape and the end of the tub

closed and connected to a lever, toothed sector, pinion & linkage. The other end of the tube is assembled to a

threaded adopter for entry of air under pressure. As the air at high pressure enters the C tube it exerts a force

the circularly bent tube and tries to straighten the tube but due to constraint of lever and other linkages, it tran

into linear, angular and rotational motion and ultimately rotates a pointer with magnification on a circular sca

which is calibrated for a pressure.

This pressure gauge is a transducer which converts pressure energy in to mechanical energy, that is, an angulalinear motion using elastic transducing property; the uncertainty of measurement is 0.5% for a pressure gauge


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Pressure transduceris another transducer where an elastic membrane converts pressure energy into an elect

signal with the help of strain gauges bonded onto mem,brane & by using elastic transuding property.

It consists of a thin membrane in a housing of stainless steel,or phosphor bronze or beryllium- copper.

One side of the membrane is subject to the pressure p and on the other side of membrane strain gauge Rtis b

and the 3 strain gauges R1,R2,R3 along with Rt form a balanced wheatstone bridge circuit which is powered

external battery voltage Vin. Without pressure p all the strain gauge resistances are balanced. When the press

applied the membrane deflects and thus cause strain in the strain gauge Rtwhich cause change in the resistanc

This changes in strains cause imbalance of the wheatstone bridge. This unbalance can be measured as a voltag

output by the galvanometer as Vout in milli volts. This output of galvanometer can be amplified & measured

electrical signal & also can be calibrated in terms of pressure applied as it is a function of pressure. The

uncertainty of the measurement of a pressure transducer is 0.25% or much better.

4.0 EXPERIMENTAL SET UP : (Assumed Pressure transducer is calibrated)

It consists of an air compressor unit with air storage reservoir mounted with an outlet pipe with exhaust valve

Exit pipe line is fitted with a Pressure transducer & A Bourdon Pressure gauge as shown in the sketch below:


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5.0 PROCEDURE :

1) Empty the air in the air compressor fully so that pressure is zero.

2) Connect the pressure transducer cable to the digital instrument. After warm up, adjust the digital readizero if not showing zero already. Pressure gauge also should show zero.

3) Close the outlet valve of the compressor and start the compressor and the pressure increases continuou

4) After compressor reaches maximum pressure, switch off the compressor and allow the digital reading

stabilize.

5) Read the stabilized pressure gauge reading which reads in bar/Kg/cm2and convert this into N/m2unit

it is P1. Both pressure transducer and pressure gauges give gauge pressures only. (For absolute pressu

atmospheric pressures have to be added to pressure gauge readings)

6) By opening the exhaust valve of compressor reduce the pressure in steps of 1Kg/cm2. With respect to

transducer digital meter readings for every step, note down the pressure gauge readings.

7) After reaching 1Kg/cm2 start the compressor so that pressure starts building up & again the readings Pressure gauge w.r.t. Pr. Transducer digital instrument to be noted down while pressure is ascending a

final reading at highest pressure may be taken.

8) Calculate the error of pressure gauge readings w.r.t the pressure transducer readings & also % errors.

9) Plot a graph of pressure gauge reading Vs % error both during ascent & descent of pressures.

s.no.

Pressure

Gauge

Readings

Pg (2) bar

Pressure

transducer

reading Pt (1) bar

Difference in

the readings Pt

Pt (1)- Pg (2)

bar

% of error of Pg

reading= Pt(1)-Pg(2) x 100

Pt(1)

6.0 OBSERVATIONS,RESULTS & DISCUSSION:

Record the data of measurements in table shown above. Make your own observations about the two instrume

and record them.


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2.0 CALIBRATION OF THERMOCOUPLE

1.0AIM:To calibrate the given thermocouple using RTD & thermometer as refence for calibration.

2.0APPARATUS:RTD(Resistance Temperature Detector), thermocouple,test setup for heating water,setup f

positioning RTD&thermocouple inside the hot water bath,digital indicators,power supply,thermometer.

3.0EXPERIMENTAL SETUP:

4.0THEORY :

Thermocouple:Two dissimilar metals when joined into two junctions & if both the junctions are kept atdifferent temperatures then an e.m.f. will be produced across the junction & the current would flow in t

circuit if the loop is closed.The phenomenon is called seebeck effect.

The dissimilar metal loop is called as Thermocouple.The higher temperature junction is called hot junc

& the other one as cold junction


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A thermocouple can be used to measure an unknown temperature by maintaining one junction

known temperature & 2nd

junction , the unknown temperature & by measuring e.m.f produced .The rela

between emf & temperature is nonlinear.

e.m.f developed =eAB= aAB+ bAB T2; aAB, bAB are constants.; T = temperature in Celsius

The thermocouple materials are (i) Rare earth materials: Platinum;Rhodium;Iridium;Rhenium etc.

(ii) Base metals : copper-constantan;Iron-constantan;Chromel-Alumel;

Chromel-constantan etc.

Note: Law of Intermediate metals allows introduction of measuring wires & devices without affecting e.m

generated.

RTD:Resistance temperature detector: Electrical resistance of a conductor increases with increase of

temperature.The relation of resistance Vs temperature is non linear as given by equation:

RT= R0( 1+AT+BT2) where A,B are constants & T is temperature

Normally the change of resistance is measured thro a wheatstone bridge circuit in which RTD forms on

the resistances which is a balanced circuit.When temperature changes RTD resistance changes & the bri

un balanced & the unbalance is measured as e.m.f. thro the potentiometer & is calibrated.The

potentiometer can be calibrated to measure temperature directly.This is the principle of RTD measurem

Materials of RTD are : Platinum,Copper,or Nickel.

INSIDE CROSS SECTIONAL VIEW OF RTD

Calibration: In this experiment a calibrated RTD is taken as reference & however it is recalibrated at two

temperatures namely boiling point of water & room temperature(otherwise ice temperature also can be

taken) & further RTD readings are taken as reference & the thermocouple readings are taken & compare

with RTD & errors are computed.

5.0PROCEDURE OF CALIBRATION OF THERMOCOUPLE :

5.1Fill the container with water to 3/4 level

5.2Connect digital indicator instrument to the mains.(230 V,50Hz AC)

5.3Allow it to warmup & adjust zero reading by zero knob without connecting any thermocouple.

5.4Select one of the thermocouples say J type(iron-constantan) or K type(Chromel-constantan) or

type(copper-constantan) & connect it as per colour code.


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5.5Keep the thermocouple & RTD probes into the water of bath & allow it to acquire the water

temperature & allow it to stabilize.

5.6Using zero knob adjust the thermocouple temperature to the same value indicated by RTD for ro

temperature(water temp.)

5.7Heat the water by switching on the heater power supply & raise the temperature of water to boi

point.

5.8Change the function knob to cal. Position & at boiling point temp. (100 or 95 or whatever is the.

indicated by RTD) & adjust with cal. Knob thermocouple temp. to the same temp. indicated by RT

5.9With this thermocouple is calibrated at room temp. & boiling temp.(keeping RTD as Ref.)

5.10 Switch off heating & remove both RTD & thermocouple probes from hot water bath/containe

place them in air or cool water ensuring both probes are separated.

5.11 As both probes cool down notedown temp. of thermocouple probe with respect to RTD temp

every 50C till it reaches room temp.These values are recorded in descending table.

5.12 After reaching RT keep both probes into hot water container & switch on heater & notedown

thermocouple & RTD readings while ascending in steps of 50C till boiling point.

5.13 Calculate errors indicated by thermocouple temperatures w.r.t. RTD as reference & calculate

percentage errors w.r.t. RTD both for ascending & descending order .

5.14 Plot RTD temp. Vs % error of thermocouple for both ascending & descending orders of

temperatures.

TABULATION OF OBSERVATIONS

s.no Type of

thermocouple

RTD temp.

T1 c

Thermocouple

Readings

Ascending Descending

T2 T3

Error

E

T1-T2

Or

T1-T3

%

error

Temp as

Per

thermometer

1 J-type

2 K- type

3 T- type

6.0 RESULTS & DISCUSSIONS:

Make your own observations of experiment,comments & results etc.

Draw the graphs of (i) RTD Temperature vs Thermocouple reading & (ii) RTD Temp. vs % error in

thermocouple reading.


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3.0 CALIBRATION OF LVDT (Linearly variable Differentional Transformer)

1. AIM:To measure the LV D T output readings with respect to the micrometer linear movements & determine err

LVDT with respect to the micrometer readings.

2. APPARATUS /EQUIPMENT:LVDT Cell with micrometer. Sketch & images are as shown.

3.0 THEORY:Linearly variable differential transformer is a transducer which transduces linear displacement i

electrical signal and consists of hollow transformer(cylindrical) with hollow core. The main winding is at the cente

the hollow cylinder while the secondary coils are at the ends, one secondary winding is in the opposite direction to

other winding ;hence when e.m.f is induced they oppose each other & hence cancel. The hollow core is filled with a s

core cylinder which is a part of a micrometer that is extension of spindle. The movement or rotation of the thimble of

micrometer makes the solid core move in and out of the hollow core of the transformer.

The main coil of the transformer is excited by AC which generates e.m.f in secondary coils by mutural induction, but

coils are wound in opposing direction they cancel each other and when core is at the center exactly, the secondary o

is zero and this is called null position. When the core is moved on either side of the null position, it gives an output wh

keeps on increasing on either side of null position of the core. It reaches a maximum and reduces as shown in sketch.U

some range of movement of the core the output is linear on either side ofnull position of the core.The movement of tcore can be accurately read by the micrometer reading. The output of secondary coils can be directly calibrated in te

linear movement of the core.

This transducer calibration involves comparison of the linear movement of the micrometer with the output of LVDT a

estimating the errors and deviations. This transducer has the intermediate and terminating devices such as signal

conditioner,amplifier ,A/D converter & digital meter where output data is converted in to digital by AD converter and

finally displayed by seven segmented LED.(Light Emitting Diode.)


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1

4.0 PROCEDURE:

1) Switch on the digital instrument by connecting to the single phase AC 230v,50Hz mains and adjust reading

zero

2) Connect the LVDT output to the digital instrument and allow to warm up and stabilize. After stabilization ch

the digital reading and move the micrometer thimble till such position so as to get zero reading on the

instrument. This is the null position of LVDT. When LVDT reading is zero note down the micrometer reading

3) Move the micrometer thimble such that the micrometer reading is increased by 1 mm and at this positiondown the LVDT reading.

4) Further move the micrometer reading so as to get 2mm above null reading in the micrometer and at this p

note down the LVDT reading.

5) Repeat movement of micrometer in steps of 1 mm up to 10mm above null readings and note down LVDT

readings at every 1 mm step.

6) Move the micrometer in reverse direction untill null position is obtained and note down the micrometer r

at null position.

7) Further continue in the same direction and reduce the micrometer reading by 1 mm from null position an

down LVDT Reading,

8) Further continue movement of micrometer such that in steps of 1 mm ,the micrometer reading reduced f

null position & note down corresponding LVDT readings.9) Calculate error & % errors of LVDT readings with respect to reference of micrometer readings.

10)The null position readings of micrometer taken at center of graph & either side of null position. micromete

readings Vs LVDT readings are plotted on graph.

Plot the following graphs :

(a) Micrometer reading from both sides of null position Vs errors

(b) Micrometer reading from both sides of null position and percentage errors

Observations may be recorded as follows in tabular column:

L.C. of micrometer =L.C. of L.V D.T =

S.No Actual micrometer

reading

a

LVDT Digital

output reading

b

Error

(a-b)

Percentage error

=(a-b)x100

a

5.0 OBSERVATIONS, RESULTS & DISCUSSIONS:

Make your observations about the behavior,calibration,easiness etc. of LVDT


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4.0 CALIBRATION OF LOAD CELL

1.0 AIM OF EXPERIMENT :

To calibrate the Loadcell measuring device using deadweights.

2.0 EQUIPMENTS/ APPARATUS: Loadcell & deadweights

3.0 THEORY :

Loadcell is a Mechanical devise & a Transducer which transforms mechanical parameter(Force) into

electrical signals.It consists of an elastic member such as metal cylinder which undergoes strain when fo

applied on it & resultant strain is measured by strain gauges mounted on the faces of cylinder.The strain

induced in the strain gauges is measured by a wheatstone bridge circuit & when properly calibrated can

directly indicate the force applied on the cylinder. A Loadcell unit is as shown above & the sketch showsstrain gauges are mounted.

4 strain gauges are used for compensations of transverse strains & temperature effects.An external pow

supply gives the voltage for excitation of the wheatstone bridge.


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4.0 PROCEDURE :

4.1 The electrical power to loadcell unit is switched on & allowed to warm up.

4.2 With no load kept on the load cell , the digital display reading is adjusted to zero reading if it doe

read zero with no load.

4.3 A 1 Kg deadweight is kept on the loadcell & digital reading is noted & the weights are continuous

increased in steps of 1 Kg & cumulatively upto 10 Kg. For every dead weight kept on loadcell, the

cell readings are noted in a tabular column as shown below.

4.4 The above experiment is done for descending order of weights kept on the loadcell.

4.5 The difference in reading of loadcell & deadweights are recorded.

4.6 The % error of load cell readings are calculated with respect to (w.r.t.) dead weights as referenc

TABULATION OF OBSERVATIONS

s.no. Dead weight W Kg Loadcell digital reading P Kg Error = (W-P) Kg Percentage Error

5.0 OBSERVATIONS, RESULTS & DISCUSSION:

Make your own observations of instruments,procedure,accuracies etc. in the experiment.

Plot a graph of dead weight readings vs error and % error of load cell readings.


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16

6.0 DETERMINATION OF MODULUS OF ELASTICITY BY STRAIN GAUGE METHOD

1.0 AIM:

To determine the modulus of elasticity of the given material by measuring bending stress & direct strain

measurement on a beam(cantilever)2.0 APPARATUS:

Measurement setup consisting of:Cantilever beam with strain gauges bonded,loading arrangement

instrument box with wheatstone bridge & strain measurements.

3.0 THEORY :

3.1 The strain gauges are thin foil or wire wound in a particular fashion so that they will be strained or

stretched in one direction predominantly & the strain or stretching & compression in the other direction wh

are very small & negligible.Most common materials used for strain gauges are copper,nickel& iron.The wire

forming as a gauge are enclosed between two thin paper sheets or epoxy material & these are to be bonded

bonding material such as Duco cement etc.

These gauges are highly sensitive to strains,stretch & when strained their resistance change appreciably.Thi

change in resistance is used as a measure of strain.Since the strain gauge is well bonded with the base . As t

base is strained the strain gauge also faithfully strained to the same extent as it is rigidly bonded with the b

material on which it ismounted.

3.2:Measurement of strain:Strain gauges are bonded in a wheatstone bridge circuit with either one,or two

three or four active strain gauges. Remaining strain gauges are part of the bridge but not active (not mount

the beam) that is they are not subject to strain.They are used to compensate for axial strains or temperatur

effects/compensation.The details are as shown in the sketches below:


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WHEATSTONE BRIDGE: When balanced, R1/R2 = Ra/Rb TYPICAL STRAINGAUGE


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1

4.0EXPERIMENTAL SET UP : It consists of a thin rectangular M.S. flat rigidly fixed at one end & with a

provision for suspending weight at the other end of the flat as shown in the sketch below :On the fla

strain gauges are mounted R1,R2,R3,R4 which are in turn connected in a wheatstone bridge & powe

by an exciting voltage E.The output of the bridge is connected to an electronic unit consisting of an

amplifier,A/D converter & a digital display unit.


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5.0PROCEDURE:

5.1Switch on the digital indicator instrument box by connecting to main supply.(230V,50Hz)

5.2Connect the sensor wires to the instrument box as per colour coding.Short the yellow to blue

on the sensor/beam connections.

5.3Full bridge: (i=4)

Turn the selector arm knob switch to 4 on instrument box.Allow the instrument to warm up.

5.4Turn the selector switch to G.F. & check the display.If it shows 500 it is o.k. if not adjust with

knob to 500.

5.5Turn the selector switch to zero and set it to zero using zero knob.

5.6Turn the selector switch to CAL.And change the display to 1000 using cal.Knob (if it shows 1

leave it)

5.7Turn the selector switch to zero & check the display & if found zero leave it if not adjust it to

using zero knob.

5.8Turn the selector switch to CAL.& check whether it reads 1000, if not adjust it using CAL.Kno

1000.

5.9Repeat this 3 to 4 times & ensure zero in zero---------------.Knob position & if any driftnoticed,adjust it each time.

Now place 100 gm. Weight on the pan & notedown the strain gauge readings in micro strains.P

weights in steps of 100gms. & load upto 1000gms. & for each 100gm. Step take the straingauge

readings & tabulate as shown.Remove all weights.

5.10 HALF BRIDGE:

Change the selector position to 2.Remove the shorted yellow withblue from sensor beam and ye

wire from instrument box.

5.10.1 The instrument should automatically read zero but if found different from zero ad

with zero knob to zero and check in CAL. Position it should automatically read 10

if not readjust using CAL. Knob to 1000.Repeat this checking and adjusting if need

4 times so that zero in zero position and 1000 in CAL. Position.Once stabilized put

selector switch to zero position.

5.10.2 Now place 100gm. Weight on the pan and note the strain reading.Take strain read

for every 100gm. And upto 1000 gms. Remove all the weights.

5.11 QUARTER BRIDGE:

Remove black pin connection on instrument box.Change the selector switch position to position

Instrument should automatically read zero in zero position, if not make zero using zero knob and

in CAL. Position instrument should read 1000.If not using CAL. Knob adjust it to 1000and repeat t

2-3 times to ensure zero in zero position.

Finally put in zero position.Place 100gm.weight and note down strain reading.

Place in steps of 100gm. On the pan and upto 1000gmand note the strain readings and tabulate.

Measure the length between pan bolt centre and the strain gauge position on the beam as dista

L

Measure the width & thickness of the cantilever beam using vernier caliper b & h


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5.12 Tabulate the observations as given below: 2

s.no. Load

Kg Newton

Strain Reading Measured strain

ex10-6

= m

i

i=4 for full bridge

i=2 for half bridge

i=1 for quarter bridge

Theoretical stress

b = 6WL/(bh2) N/mm

2

E= b/m

1

2

5.13 Standard value of Elastic modulus E= ----------(2x105 N/mm

2for M.S.)

5.14 Compare the calculated values of E with the standard value of material of the beam(M.S.) &

record the deviations.

6.0OBSERVATIONS & DISCUSSIONS:

Make your own observations about the experiment & the results & record them in Record book.


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21

PARTB

METROLOGY


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6.0 MEASUREMENTS OF SCREW THREAD PARAMETERS BY PROFILE PROJECTOR

1.0 AIM OF THE EXPERIMENT :

To measure & determine screw thread parameters viz (namely) major diameter;minor

diameter;pitch;thread angle & helix angle

2.0 EQUIPMENT,INSTRUMENT :

Profile Projector fitted with 2 micrometers and circular angular scale

3.0 TEST SPECIMENS :

Thread gauges(M-7;M-11) & a commercial bolt.

4.0 THEORY :

A thread may be either right-hand or left-hand. A right-hand thread on an external member advances into an

internal thread when turned clockwise; a left-hand thread advances when turned counterclockwise. If a singlehelicalgroove is cut or formed on a cylinder, it is called a single-thread screw. Should thehelix anglebe incr

sufficiently for a second thread to be cut between the grooves of the first thread, a double thread will be formthe screw. Double, triple, and even quadruple threads are used whenever a rapid advance is desired, as on val

Helix angle on a straight thread is the angle made by the helix of the thread at the pitch line with the axis of

thread.The angle is measured in axial plane & Helix Angle = p/d(d=pitch dia.). It changes at each diameterlowest at major diameter,;highest at minor diameter & it is hence defined at pitch diameter or effective diame
http://www.answers.com/topic/helicalhttp://www.answers.com/topic/helicalhttp://www.answers.com/topic/helix-angle-2http://www.answers.com/topic/helix-angle-2http://www.answers.com/topic/helix-angle-2http://www.answers.com/topic/helix-angle-2http://www.answers.com/topic/helical


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23

Pitch and major diameter designate a thread. Lead is the distance advanced parallel to the axis when the screw

turned one revolution. For a single thread, lead is equal to the pitch; for a double thread, lead is twice the pitcha straight thread, the pitch diameter is the diameter of an imaginarycoaxialcylinder that would cut the thread

forms at a height where the width of the thread and groove would be equal.

Pitch can also be defined as : Distance measured parallel to the thread axis between corresponding points on

adjacent thread forms in the same axial plane & on same side of axis.

Thread forms have been developed to satisfy particular requirements. Where strength is required for thetransmission of power and motion, a thread having faces that are more nearlyperpendicularto the axis is pref

These threads, with their strong thread sections, transmit power nearly parallel to the axis of the screw. Squarthreads used in screwjack is a power thread

.

The standards of Metric threads are : ISO 4032-- 1986 & IS 1364 - 1992

5.0 PROCEDURE :

5.1 Read & calculate & record Least counts of both micrometers of profile projector.5.2 Read & record Leastcount of angular circular scale of profile projector5.3 Place the threaded specimen at the centre of the table aligned properly.Switch on power supp5.4 Reposition job properly aligned so as to get major dia. parallel to movement of micrometer &

magnified image of the screw threads sharply.

5.5 Rotate the circular scale knob & align the horizontal lines of projector with the tips of screwthreads as shown below on both top & bottom :

5.6 First align the projector line with top edges of all threads(1) by micrometer thimble & then nodown the micrometer reading , the intial reading for major diameter(R1)
http://www.answers.com/topic/coaxialhttp://www.answers.com/topic/coaxialhttp://www.answers.com/topic/coaxialhttp://www.answers.com/topic/perpendicularhttp://www.answers.com/topic/perpendicularhttp://www.answers.com/topic/perpendicularhttp://www.answers.com/topic/coaxial


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25.7Next align the projector line by micrometer -1 thimble with bottom edges of threads(2) & not

down reading of micrometer which is intial reading of minor diameter in micrometer-1(R2)

5.8Next align the projector line with 2ndminor diameter edges(3) of screw threads by micrometethimble & note down the micrometer-1 reading, this being final reading for minor diameter(R

5.9Next align the bottom most line of screw threads (4) of major diameter by using thimble ofmicrometer-1 for the final reading (R4)

5.10 Rotate circular scale to match the vertical line with the centre of V- threads.at top majodiameter as at (5); use micrometer-2 thimble & adjusrt finally to coincide this vertical line wi

centre of V threads.Note down the intial reading for pitch p1 on micrometer-2.5.11 Then move the vertical line of projector to centre line of next thread (6) & note down f

reading of pitch p2.5.12 Take these pitch readings at two threads on top & two threads bottom,threads.Calculat

average pitch.5.13 Calculate the Major Dia. = R1-R4; Minor Dia. = R2-R3; Pitch (Av.) = p1-p2;5.14 Then rotate circular scale & align the projector line with one line (8) of thread & note

down circular scale l reading Q1.

5.15 Rotate circular scale to align with 2ndside of thread(9) & note down the circular scalereading Q2.

5.16 Calculate thread angle = Q1-Q2 degrees5.17 Calculate tangent of Helix angle(Av.) = Average Pitch/(d Average) or

Helix Angle = tan -1(pmean/(dmean)5.18 Calculate Depth of threads = (Major Dia.-Minor Dia.)/2

6.0 OBSERVATIONS,RESULTS & CONCLUSIONS :Record all observations in the table indicated.Make your own observation of the

procedure,instrument,accuracy,easiness etc.

TABULATION OF OBSERVATIONS BY PROFILE PROJECTOR

READINGS OF PARAMETER SPECIMEN -1 SPECMEN 2 SPECIMEN 3

MAJOR DIAMETER(INTIAL)R1

MAJOR DIAMETER(FINAL)R2

MINOR DIAMETER(INTIAL)R3

MINOR DIAMETER(FINAL)R4

PITCH MEASUREMENTS(Q1,Q2)

1

2

3

4

5

6AVERAGE

ANGLE MEASUREMENTS

1

2

3

4

AVERAGE


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2

7.1 MEASUREMENTS OF ANGLES USING BEVEL PROTRACTOR

1.0 AIM:

To measure the angles of the given specimens using vernier Bevel Protractor.

2.0 INSTRUMENTS/EQUIPMENTS USED:

Bevel Protractor,surface table,v-block

VERNIER BEVEL PROTRACTOR WITH MAGNIFYING GLASS

3.0 THEORY:

Bevel protractor is an instrument used for measurement of angles accurately.The mechanical,optical ve

bevel protractors have vernier scale & magnifying device.It has a detachable blade(available in 150,200,

mm lengths) which can be fixed to the outer main circular scale & base /stock.The body has main circula

scale divided into 4 quarter segments of 0 to 90 degrees .The centre turret has vernier scale.The centre

turret can be locked at centre & in this locked condition,the blade can be mechanically moved by a knobthe turret by a gear mechanism.

The least count on the main scale is I degree & 23 divisions of the main scale is divided into 12 equal div

on vernier scale.

The value of 1 division on vernier scale = 23/12 degree= 1 &11/12 DEGREE.But the vernier scale has 60

minutes marked on either side of its zero reading.

L.C. of Bevel protractor = 2 MSD-1 VSD = 2x60-23 x60/12 mts.= 5 Minutes.


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26

By proper adjustment & manipulation of blade, all angles can be measured conveniently to an accuracy

minutes.

The instrument is periodically checked with sine bar.Bevel protractors are made as per IS 4239.

4.0 PROCEDURE:

Read the bevel protractor angle markings. Read vernier scale markings & also note the readings

main scale are not 0degree-360degree but 0degree-90 degree in every quarter segment.

Calculate the least count of vernier scale & main scale & finally calculate Least count of Bevel

protractor.

Fix the blade in the grove correctly which can be varied as per the requirement to measure diffe

angles.

Place the bevel protractor on the surface plate & coincide the edges of specimen for which angle

to be measured with the base/stock edge & blade edge of bevel protractor without any gap by

holding it very tight.

Lock the central screw on the turret & note down the main scale & vernier scale readings & calc

the angles.

Angle measured = Main scale reading + vernier readingx5minutes

Tabulate all the angles to be measured.While recording the final angles ,note the measured ang

acute or obtuse

Place the specimen in proper orientations on the surface table & then match the edges of the an

to be measured without any gap.

5.0 RESULTS & DISCUSSION

Tabulate all the measured data.Make your own observation of the procedure,instrument regardingeasiness,accuracy etc. & write them in the record.

Least Count of Bevel Protractor :

Calculation:--------------------------------------------------------------------------------------

Tabulation of Angle measurements by Bevel protractor

S.NO. SPECIMEN SKETCH OF SPECIMEN

1

ANGLES

2 3

MEASURED

4

1 Block-1

2 Block-2

3 Block-3

4 Block-4

5 Block-5


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7.2 MEASUREMENT OF ANGLES USING SINE BAR

1.0 AIM OF THE EXPERIMENT : To measure angles of given specimens using sinebar & verify using

bevel protractor & linear measurements.

2.0 APPARATUS / EQUIPMENT/ INSTRUMENTS sinebar ,Bevel protractor, specimens slipgauge set ; Dial te

Indicator with stand; vernier caliper, surface table;

3.0 THEORY :

Sine bar is a mechanical device by which angular measurements can be made very accurately

specially for acute angles & its uncertainity of measurements increases for angles 45oas the error in angu

measurements is proportional to tan(=angle of measurement).

Principle of sinebar measurement is that sine of an angle is the ratio of opposite side & hypoten

in a right angled triangle.Sinebar is as shown in the sketch.It consists of 2 precision machined rollers assemb

with an accurately machined rectangular bar /prism & cutout is made inside rectangular bar and almost an

integral part. A small plate can be fixed to one end face of sinebar(removable piece)

The distance between the centres of rollers is most accurately maintained & the centre distances are of sta

lengths : 100mm;200mm;300mm. It is made as per IS 5359- 1987

When sinebar is kept inclined & inline with the angle /to be measured without gap , the height

slip gauge set combination if it is h & sinebar length is l then angle is given by :

Sin /= h/l or /= asin(h/l) = Sin-1

(h/l)


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28

Knowingh&lthe actual angle can be calculated.There are several methods in which the sin

can be used for measurement of angles.The methods are :

(a) lifting the work piece & placing it on top of sinebar or

(b) lifting the sinebar & placing it on workpiece

Depending on the height of the job , slip gauges to be arranged either on one side or both sides which are p

below the roller of sinebar.

4.0 PROCEDURE :

4.1Measure & record the L.C. of bevel protractor,DialTest Indicator & vernier caliper.

4.2 Using vernier caliper measure all the dimensions of the specimen & record it.

4.3 Measure the angle of the specimen by bevel protractor & record it.

4.4 Place the sine bar on the job& if job can be accommodated between rollers,build up slip gauges on one

or both sides & record the heights h1 & h2 (h=h1-h2) .If job cannot be accommodated between rollers, the

place sinebar in reverse position on the job (use end plate to avoid sliding of sinebar) & dial top most points

rollers by DTI fixed on a stand as shown & let the readings of DTI on top of rollers be h1 & h2& h=h1-h2

4.5 Place the job above the flat surface of sinebar & insert the slipgauge set H below one of the rollers of t

sine bar.(H can be determined approximately, after having measured distances of sides of job calculate the


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29

approximate angle & height of slip gauges needed to make the inclined edge as horizontal = say H.Buildup

gauge combination for value H & fix end plate on sinebar)

4.6 Using DTI dial the top surface /edge of the specimen to make horizontal & change the slip gauge set

combination (if needed) to get 0 reading on DTI throughout length as DTI is moved from one end of specim

the other end.

4.7After achieving horizontality of top edge record the actual slipgauge set reading/s

4.8 Tabulate all observations & calculations as per table :

TABULATION OF READINGS

Length between roller centres = L = (200mm)

Least count of vernier caliper =

Leastcount of bevel protractor =

Leastcount of DialTest Indicator(DTI) =

TABLE-1

s.no. Specimen type Angle by direct measurements

a b l = Sin-1

((h1-h2)/l)

Angle by Bevel

Protractor

1 Specimen-1

2 Specimen-2

TABLE-2

s.no.

Specimen

type

Method of lifting sinebar

h1 h2 = = Sin-1

((h1-h2)/l)

Method of lifting workpiece

Approx.ht. Actual Angle

h=(a-b)/l x200 Slipgauge =

Height h Sin-1

h/l

1 Specimen-1

2 Specmen-2

5.0 RESULTS & DISCUSSION :

Record your own observations regarding the experiment such as easiness,accuracy,repeatability of

measurements etc. by the 3 methods adopted.


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7.3 MEASUREMENT OF ANGLE USING SINE CENTRE

1.0 AIM:To measure taper angle of solid conical work(Axi symmetrical 3D specimen) using sine centre

2.0 INSTRUMENT/EQUIPMENT:sine centre, slip gauge set, dial indicator with stand, Bevel protractor, digital vernier caliper, surface table andspecimen to be measured.

3.0 THEORY:

Sine centre is an angle measuring device for solid tapered specimen. It is a modified version of sine bar as sh

it is a sine bar with built in supports for two dead centres, whose centre distance can be adjustable for

accommodating specimen of different lengths.

The distance between centres of rollers is fixed and accurately known ( e.g.200.000).

To measure the taper angle of a conical work, one end of roller is raised using wrung slip gauge set as shown

the angle 2 of conical work can be calculated as follows: = Sin-1

(h/L)

4.0 PROCEDURE :

Using digital vernier caliper ,measure the diameters d, D and length L and calculate the angle

tan = (D-d)/2L

Using bevel protractor measure the angle .

Take the dial indicator and note down its least count and take a few readings using standard slip gaugesay 2mm and 1.1mm.

Place the tapered job in between dead centres of the sine-centre as shown.


34/59

3Fix the dial indicator in the stand with magnetic V-block and using this dial indicator arrangement, measure t

height variation of the job h.Using slip gauge below one of the rollers suitably the taper of the job is madehorizontal as checked by the dial indicator moved over the surface of the tapered specimen.

Measure the total of the slip gauges wrung together and let it be h.

If 2is the angle of the tapered job given, then sin= h = h for the given sine-centre

L 200


Record the measured data in table as shown & make your observations of the different instruments used,easin

of use, their accuracy and record them

Measurements by sine centre of two specimens

Specimen1 : Rough surface

Specimen2 : specimen with good surface (morse taper1)

Sl.No Specimen

Angle measured by

direct linear

measurements

tan = (D1-d2)

2L

Angle measured by

Bevel protractor

Angle measured by

sine centre

Sin = (h2-h1)

l

1 Sp-1

2 MT-3


35/59

8.0 MEASUREMENT OF DIMENSIONS BY ROLLER SET

1.0AIM:

To measure the Internal Diameter(ID of bore) of the gauge using two accurate hardened & ground rolle

& slip gauges accurately.

2.0INSTRUMENTS/EQUIPMENT:

Surface plate,Micrometer/digital vernier caliper,slipgauge set,roller pins.

SLIP GAUGE SET WITH BOX GROUND, POLISHED, ROLLERS

3.0THEORY:

The inside diameters can be measured by vernier calipers or by inside micrometer or bo

gauge or inside caliper with micrometer etc.The inside caliper does not give accurate dimension.The ins

micrometer can be used for large size bores . Bore gauges are used for very accurate measurements.Ve

caliper measurements are not so reliable.

For measurements of internal diameters alternately & accurately the roller set with slipg

gives an easier,quick method but for smaller diameters.

This method consists of choosing a biggest roller of accurate dimension for the given bor

& the balance dimension made up of combination of slip gauges chosen suitably & as shown in sketch.T

final accuracy depends on the feeling of the snug fit.A snug fit is an assembly fit not loose & not tight; t

mating parts assemble with ease but fit is not loose also.Roller pins are ground & polished & are made a

IS 11108-1984


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33

If d1 & d2 are the diameters of rollers & t is the total thickness of the slipgauge set wr

together, then I.D. = d1+d2+t

4.0PROCEDURE:

Measure/calculate & note down the least count of micrometer & vernier caliper.

Measure the internal diameter of the gauge using vernier caliper

Note down the standard marked diameter of the gauge as per marking on the gauge

Select suitable biggest diameter of a roller such that (sum of dia of 2 rollers) is less than dia. Of g

The method as explained above is ID to be measured =d1+d2+t where t is the thickness of slipga

set(wrung together).Hence select suitable slipgauge either one or a combination of 2 or more w

total thickness is = t. such that ID of bore=d1+d2+t.One has to calculate t=ID-(d1+d2) & with

trial & error exact tcan be finally selected so as to get a snug fit of rollers+slipgauge set with t

bore to be measured.

Use the slipgauge always after cleaning with acetone & with lint free clean cloth for prop

bonding of slipgauges.

Wringup slipgauge set finally selected & insert along with 2 selected rollers at ends & slip

gauge in between rollers into the bore to get a snug fit by trial & error by varying smalles

slipgauge in the set.The fit must neither be loose nor tight.

After achieving the correct fit measure the diameters of rollers using micrometer.

Add up the slipgauges wrung(t) & the diameters of both rollers(d1&d2) & calculate the ID

the bore of the gauge.

Repeat the experiment for all specimens/gauges to be measured.

ID of bore = d1+d2+t mm

5.0 RESULTS & DISCUSSION:

Record the data as per the table.Give your comments of the instruments used for

easiness,accuracy,reliability etc.


37/59

CALCULATION OF LEAST COUNT OF VERNIER CALIPER: 1 MSD =---------; 1VSD = ----------------

L.C. = 1 MSD- 1 VSD =

TABULATION OF MEASUREMENTS :

S.NO SPECIMEN STANDARD/

REFERENCE

GAUGE

READING

ID AS

PER

VERNIER

CALIPERREADING

ROLLER

SIZE

SELECTED

FINAL

SLIPS

SELECTED

FOR SNUG

FINAL ID AS

PER ROLLER

SET METHOD

=d1+d2+t

DIFFERENCE

BETWEEN

GAUGE &

ROLLERSETREADINGS

1 GAUGE-1

2 GAUGE-2

3 BUSH


38/59

3

9.0 MEASUREMENTS WITH DRILL TOOL DYNAMAMETER AND LATHE TOOL

DYNAMAMETER

1.0AIM OF EXPERIMENT : To measure cutting tool forces & torque during

(a) drilling operation on drilling machine

(b) turning & facing on a lathe machine

LATHE TOOL DYNAMAMETER DRILL TOOL DYNAMAMETER

2.0 APPARATUS / EQUIPMENT :

Bench/sensitive drilling machine,drill tool dynamometer unit(sensor & instruments),Centre lathe,lathe tool

dynamometer, drill bits,specimen for drilling,cuttingtool on lathe,specimen for turning

3.0THEORY :

Dynamameter is a devise which measures the force & torque .The drill tool dynamometer measures ver

cutting force & torque in a drilling machine.

Drill tool

Fa= feed force on tool; Fr= force by tool due to depth of cut; Fp= vertical drill force

Ft= vertical cutting force on cutting tool; Torque = Fpd/2 Nm


39/59

36

The lathe tool dynamometer measures only the forces acting on the single point cutting tool fixed in the too

in x,y & z directions as shown in the sketch.

3.1PRINCIPLE OF MEASUREMENT: The forces & torque are measured by transducers based on

gauge principles..The force measuring transducer is a strain gauge setup with proving ring &

strain gauges R1,R2,R3,R4 forming part of a wheatstone bridge with compensation for

temperature,bending etc. Torque measuring transducer is a cylindrical specimen mounted wstrain gauges R5,R6,R7,R8 at 45 deg., to the longitudinal or vertical axis so that shear strains

resulting from torque are only pickedup by these strain gauges.

3.2The lathe tool dynamometer is also similar devise but measures only forces in all 3 direction

suitable strain gauges in all 3 axes.

4.0PROCEDURE : 4.1 DRILL TOOL DYNAMAMETER


40/59

37

The sensor unit is rigidly bolted to the table of bench drilling machine.

The digital indicator instrument is connected to power supply.

The dynamometer output terminals for thrust is connected to the thrust connector on

instrument.The dynamometer torque output is connected by cable to the torque

connector input of the instrument.A M.S. block is fixed in the vice portion of dynamometer & a drill bit is fixed inside dr

chuck of drilling machine.

When instrument is switched on the knob is put in read position & if digital readout o

both torque & thrust does not show zero, using zero knob readings are adjusted to ze

The knob position of thrust is changed to CAL. & digital reading of thrust is adjusted to

using CAL. Knob.

Then knob position of torque is changed to CAL. Position & digital reading is adjusted

20.0 using CAL. Knob

Then the knob position is changed back to read position both for thrust & torque.

The drill spindle is switched on & lowering feed handle drilling is done in specimen &

readings e taken for bith thrust & torque at different speeds & depths of cut.

Drilling is done on different materials at different speeds & using different drill bit size

the thrust & torque values for each of these settings are recorded.

The variations of thrust & torque for varying speeds with different drillbit sizes & diffe

materials are all observed & these relationships can be shown on graphs.

4.1LATHE TOOL DYNAMAMETER (LTD)

THE EXPERIMENTAL SETUP FOR MEASUREMENT OF CUTTING FORCES BY USING LTD

IS AS SHOWN IN FIG

The normal tool post above compound slide is removed including the bush & the spac

except the central bolt.The centre hole of sensor box of LTD is inserted & the sensor b

with the cutting tool is fixed such that cutting tool tip is at centre position of job.The

is rigidly fixed with nuts and locknuts.


41/59

3

The output ports of x,y,z on sensor box are connected to exactly x,y,z terminals

/connectors on digital instrument by 3 cables.

The instrument is connected to mains power supply.

The selector knob switches are changed to read & digital readouts of all (X,Y,Z) correc

to zero by zero knob.

The selector knob changed to CAL. Position & all 3 digital readouts are corrected to 50

using CAL. Knobs.

Selector switches are changed to read position,checked & ensured it reads zero or els

corrected to zero by zero knob.

The lathe machine is switched on & by turning, cuts are given on specimen which ap

forces on the sensor of LTD .As the cutting progresses the x,y,z force readings are

continuously recorded for different depths of cut,speeds & for different materials.

The cutting parameters can be varied as required & cutting forces are recorded as per

tabular columns provided in the enclosure.

TABLE-1 : OBSERVATIONS & MEASUREMENTS IN DRILL TOOL DYNAMAMETER

S.NO. SIZE OF

DRILLBIT

SPEED OF

SPINDLE

MATERIAL THRUST FORCE/CUTTING

FORCE

Kgf

TORQUE OF

SPINDLE

Kgf METRE

1 Dia. 4mm M.S.

2 Dia. 5mm M.S.

TABLE-2 : OBSERVATIONS & MEASUREMENTS IN LATHE TOOL DYNAMAMETER(LTD)

S.

NO.

OPERATION MATERIAL SPINDLE

SPEED

RPM

DEPTH

OF

CUT

in

mm

FEED

mm

PER

REV.

CUTTING FORCES OBSERVED BY LTD

X direction Ydirection Z direction

Parallel to Vertical Horizontal

Lathe axis axis axis

I TURNING MS 45 0.1

0.5

MS 120 0.1

0.5

II FACING MS 45 0.1

0.5

MS 120 0.1

0.5


42/59

10.0 MEASUREMENT OF THREAD PARAMETERS USING 2 WIRE AND 3 WIRE METHODS

1.0AIM/OBJECTIVE:

To measure & calculate the effective diameter of screw threads by 2 & 3 wire methods.

2.0INSTRUMENT/EQUIPMENT :

Micrometer with flanged anvils.micrometer with stand,small diameter wires.profile projector,bolt specim

3.0THEORY:

The screw thread parameters are as shown in the sketch below :

Pitch of a screrw thread is the distance measured parallel to the axis between the two corresponding po

on adjacent thread forms in the same axial plane.The basic pitch is equal to the lead divided by the num

thread starts. Lead is the axial distance advanced by the thread in one revolution..The lead & pitch in sin

start thread are identical but in multi start thread lead is the same multiple pitches as the number of sta

Angle of Thread( ): This is the angle between the flanks or slope of the thread measured in an axial plan

Effective Diameter (E) or Pitch diameter: This is the diameter of the pitch cylinder, imaginary cylinder w

is coaxial with the axis of the screw & intersects the flank of the threads in such a way as to make width

the threads & width of the spaces in between the threads equal.Along the pitch line of the threads the w

of thread & width of space is equal on a perfect thread.The Effective diameter E can be calculated by

measuring the distance M between 2 or 3 wires of known diameters d1 as per the theoretical equations

shown in sketch-2


43/59

SKETCH-2

E = Pitch Dia. =Effective Dia. = M-G(1+CosecA/2)+P/2xCotA/2

The values of pitch p , thread angle or A & the wire dia. Can be directly measured by profile projector

micrometer & thus E can be calculated.

The method of measurement is same for both 2 wire & 3 wire methods except that one uses 2 wires on

opposite sides of thread in 2 wire method & it may be difficult or result in inaccuracies; whereas by 3 w

method 2 wires on one side & one wire on the opposite side of thread and it will be more accurate.

4.0PROCEDURE:

4.1Read,calculate the leastcounts of micrometers on the profile projector.

4.2Read & calculate the leastcount of flanged micrometer

4.3Select suitable diameter diameter wire which will fit into screw thread grove of specimen to be

measured & measure the diameter of the wires by a vernier caliper or micrometer & record the

values.

4.4With some trial & error insert 2 wires into the groves of 2 adjacent threadgroves on one side.

4.5Fix the flanged micrometer on the micrometer stand & insert the threaded specimen between fl

of micrometer.The micrometer along with the stand to be located at a suitable location where go

amount of light is incident on the instrument & preferably on a surface plate.Insert 3 wires insert

thread grooves such that 2 wires are placed on one side of thread & 3rd

wire on other side& i9n

between the 2 wires by trial & error.

4.6Use magnifying glass to ensure correct fitting of the wires & ensure flanges of anvil of micrometeparallel to the axis of the threads.

4.7Note down the reading of micrometer as M.Repeat the same experiment with 2 wires that is one

on each side of the thread.

4.8Place the threaded specimen on the glass plate of profile projector & take the pitch & thread ang

measurements as is done in Profile projector experiment.

4.9Using the equation E=M-d(1+CosecA/2)+ P/2xCotA/2.Calculate the effective diameter for all spec

for both 2 wire & 3 wire methods.

4.10 Calculate best wire size using the equation Dbest= P/2xSec A/2.


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4

5.0RESULTS & DISCUSSION :

Make your own observations of ease,difficulty,accuracy,precision of the procedure of experiment & abo

the results obtained.

TABULATION OF OBSERVATIONS AND RESULTS

Leastcount of micrometers of profile projector: Micrometer 1 =

Micrometer 2 =

Leastcount of circular angular scale of Profile projector =

Leastcount of geartooth micrometer(flanged micrometer) =

s.no. Threaded

specimen

Wire

dia.

Chosend

Dia.

Measured

On top ofwires

M mm

Pitch

Of

ThreadsP mm

Angle

Of

ThreadA/deg.

Effective

Diameter

E mm

Best wire

Size Dia.

mm

1 Specimen-

1

M-11

thread

Plug gauge

2 Specimen-

2

M-7 threadPlug gauge

3 Specimen-

3

Bolt


45/59

42

11.0 MEASUREMENTS BY MECHANICAL COMPARATOR

1.0AIM:

To calibrate the mechanical comparator (dial indicator) & segregate & group acceptable & not accept

parts using the mechanical comparator.A hexagonal nut is the specimen.

2.0INSTRUMENTS/EQUIPMENTS :

Dial Indicator with stand,slipgaugeset,vernier caliper

3.0THEORY:

A comparator is a measuring device(not instrument) with high precision & cannot directly give absolute

measurement but gives relativemeasurements.It is hence used for inspection & disposition of parts in la

quantities in fast mode. The parts can be segregated for acceptance,rejection & repair based on lower &

upper limits of dimensions in comparison with a standard instrument.A dial indicator is a mechanical comparator using gear magnification system togethe

with rack & pinion. A suitable spring gives constant plunger pressure,whilst hair springs are employed to

eliminate play or backlash.If a dial indicator is to provide faithful magnifications of the plunger movemen

dimensional & functional features of the gears ,racks & pinions used must possess a high degree of

precision.The range of magnifications in the dial indicator mechanism are about 250 to 1000.The least co

of the instrument is of order of 0.01mm,0.02mm to 0.002mm.It is made as perIS2092-1983

4.0PROCEDURE:

4.1The dial test indicator(DTI) is calibrated by using slipgauges.The DTI is mounted on

the comparator stand as shown. By using suitable clamping DTI is made to just touch the machined base comparator stand & the dial is adjusted to zero reading exactly.(Note that DTI is very rigidly clamped)

4.2 :A slip gauge of 1mm is inserted below the plunger of DTI & thr reading of DTI is checked & note4.3 Simi

readings are taken for 2,3,4,5,6,7,8,9 & 10mm slips. Errors & % errors are calculated.

4.3The dimensions of hexagonal nuts across flats : A,B,C are measured using vernier calipers & recorded.

4.4The mean specified dimension say H & Using slipgauge this H dimension is builtup by wringing.

4.5DTI is raisedup changing the clamping position & the above slipgauge combination is inserted below the D

plunger & DTI is loaded to some reading on dialgauge.

4.6Each of the nuts is introduced below the DTI one by one & deviations noted & recorded..


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4.7From the recorded dimensions & deviations the dispositions of the nuts based onacceptance criteria are

recordede for all nuts.

4.8Data recorded as per the following tables:

I CALIBRATION OF Dial Test Indicator(DTI)

SLIP GAUGE THICKNESS 1.0 2.0 3.0 4.0 5.0 6.0 6.5 7.0 7.5 8.5 10.0DTI READING

ERROR & %ERROR

II MEASUREMENTS OF HEXAGONAL NUTS

CRITERIA FOR DISPOSITION: DIMENSIONS A,B,C TO BE WITHIN SPECIFIED LIMITS

(A,B,C = WITHIN 20.60.2MM TOLERANCE LIMITS)

S.NO.OF

NUT

VERNIER CALIPER READINGA B C

DTI READINGA B C

DISPOSITION OF NUTACCEPT REJECT

1

2

3


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12.0 GEAR TOOTH MEASUREMENTS BY GEAR TOOTH VERNIER CALIPER & MICROMETER

1.0 AIM:

To measure some of the gear dimensions using available instrumentation and calculate some of the gear

tooths parameters of the spur gear.

2.0 INSTRUMENTS/ EQUIPMENT:

Gear tooth micrometer/ flanged micrometer, gear tooth vernier caliper, vernier caliper, profile projector gear specimen.The images of both Geartooth Micrometer & vernier caliper are shown below:

3.0 THEORY:

3.1 A Gear is a mechanical device which has tooth shaped profiles on its cylindrical body& is used for

transmission of motion or power or both. Involute profile is the mostly used tooth profile due to several

advantages. The basic gear tooth parameters of an involute

profile spur gear is as shown in the sketch below: there are several instruments and equipments to measu

parameters and several machines to test the performance of gears such as Parkinsons gear tester & speci

involute profile testing machine.

3.2 Pitch circle diameter :It is the diameter of an imaginary cylinder which by pure rolling action would pro

the same motion as the toothed gear wheel.

3.3 Base circle diameter :It is the diameter of an imaginary circle from which the involute profile of gear is

generated by an imaginary straight line generator rolling tangentially on the base circle (Db)


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3.4 Circular Pitch :It is the arc distance measured around the pitch circle from the flank of one tooth to a sim

flank on the next tooth. Pc=Dp/n=m.

3.5 Blank Diameter:It is the same as addendum diameter or the material blank diameter from which gear is

made.(D0) & D0= pcd+2m = m(N+2)

3.6 Tooth thickness :It is the arc distance measured along the pitch circle from its intercept with one flank to

intercept with the other flank of the same tooth.

3.7 Base pitch :it is the arc distance between the starting point of involute of one gear tooth on the base circl

the corresponding starting point of involute on the flank of next tooth.

Pb=Db/N.= m Cos ( = pressure angle)

3.8 GEAR TOOTH MICROMETERIt is the flanged micrometer & is shown in sketch-1 . It is used for

measurement of gear tooth distances between one, two, three or four gear teeth using which the base circ

pitch can be calculated per sketch indicated

Pbx3.5=M ; 2.5 Pb=a; 1.5 Pb=b

Pb=M-a = a-b

The gear tooth micrometer is used for the measurement of distance between 2gear teeths, 3 gear teeth, 4g

teeth and also the blank diameter.

3.9 GEAR TOOTH VERNIER CALIPER:Gear tooth vernier caliper is as shown in sketch and consists of

vernier calipers viz one horizontal and one vertical vernier caliper combined in to one.The instrument is

exclusively used for the measurement of gear tooth thickness at the pitch circle height h given by the

equation h=mN(1+2/N-cos 90/N )/ 2.

This calculated value of h is set on vertical vernier scale and gear tooth thickness is measured at the pitch

circle.

4.0 PROCEDURE :

1. The least counts of vernier caliper, gear tooth micrometer and gear tooth vernier calipers are measured an

recorded including zero errors if any.2. Usingboth vernier caliper and gear tooth micrometer the blank dia is measured(D0)

3. Using tooth vernier caliper and gear tooth micrometer, the distance between 2 teeth, 3teeth and 4 teeth ar

measured and recorded.

4. Using vernier calipers the dedendum circle dia is measured.

5. For smaller gear the dedendum circle dia can also be measured using profile projector also.

6. Using gear tooth vernier caliper the gear tooth thickness at pitch circle is measured by setting heights h

per sketch-1 & calculation.

7. The following parameters are calculated ba using standard relationships as per equations &

sketch-1given below.

Gear tooth height for thickness measurement, h= mN/2 [ 1+2/NCos90/N]

Module m = D0/[N+2]

Pitch circle diameter =Dp=mN

Circular pitch = m

Base circle pitch=Pb=(M-a)=a-b

M=distance between 4 teeth; a = distance between 3 teeth;b = distance between 2 teeth;

Gear tooth depth = (D0-Dd)/2 = (Addendum dia.-Dedendum dia.)/2

Base circle dia. = Db = Pbx N/

Pressure angle = = Cos-1

(Db/ Dp)


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8. Record the observations as follows in the table below :

PARAMETER GEAR SPECIMEN-1Distance using Distance using

Vernier caliper geartooth micrometer

GEAR SPECIMEN-2Distance using Distance using

Vernier caliper geartooth micromet

Blank dia. Or

Addendum dia.

Not possible

Dedendum dia. Not possible Not possible

Distance between4 teeth



9. Final results may be tabulated as follows:

specimen Geartooth

Height thickness

module Pitch

circledia .

Circular

pitch

Base

CircleDia.

Gear

toothdepth

Base

CircleDia.

Pressure

angle

5.0 OBSERVATIONS,RESULTS & CONCLUSIONS/DISCUSSION

Make your own observations of instruments used,orocedure,ease,accuracy etc.of the experiment.


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13.0 CALIBRATION OF MICROMETER USING SLIPGAUGES

1.0 AIM :

To calibrate the given micrometer & determine the periodical & progressive errors.

2.0 INSTRUMENTS/ EQUIPMENTS : Micrometer with stand & slipgauge set

t

3.0 THEORY :Micrometer is an accurate linear measuring instrument . It is as shown in sketch below

The thimble of micrometer rotates on precision threads inside barrel & thimble.The spindle advancesaxially as thimble rotates in a perpendicular plane.The faces of anvil & spindle are parallel & both ax

are coaxial,collinear.

The barrel scale is in millimeters , 0.5 mm being the least count of barrel (main scale).Thimble has 50

divisions around it's circumference(circular scale).When the thimble revolves one full revolution the

spindle advances by 0.5mm that is the Leastcount ofbarrel scale.One division of thimble corresponds

to 0.5/50 = 0.01mm.This is the least count of the Micrometer.It is made as per IS2967-1983

The errors on the screw threads of micrometer would result in errors on the readings

of micrometer.There are two types of errors of the micrometer:

3.1 Periodical errors: These errors occur during every revolution of the thimble due to

errors on thread form of thimble namely errors on thread angle,pitch,profile etc. and so

these errors are likely to occur during every revolution of the thimble periodically.

These periodical errors can be determined by taking few readings of micrometer with

revolution of the thimble.These measurements can preferably be done at both ends of

the range of the micrometer.

3.2 Progressive errors : These errors occur during full range of the instrument that is

from zero to full range of the micrometer.These errors occur due to basic errors in the inner screw

threads such as major dia.,minor dia.,effective dia. And small taper of axis of screw threads w.r.t. The

anvil.These errors can be determined by taking about 6 to 10 readings from zero to the full range of

instrument.

3.3Slip gauge : These are the most accurate and standard made of material of high wear

resistant,thermally and metallurgically stable and low coefficient of thermal expansion such as high

carbon high chromium steel, Tungsten carbide etc. Their accuracies achieved due to high

flatness,parallelism,surface finish and dimensional accuracy upto fraction of micron by applying

lapping process of manufacture.Different grades of slip gauge sets with different dimensional

combinations are available.It is made as per IS 2984- 1981


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For checking the correctness or errors of micrometer readings different slipgauges are taken and

micrometer readings are checked & difference in micrometer & slipgauge values give the errors of

micrometer.

4.0 PROCEDURE:

4.1 check & record leastcount of micrometer.

4.2 place the micrometer on its base stand and measure micrometer readings for the

following slipgauges: For (a) Periodical error :

1.01, 1.11, 1.21 1.31,1.41,and 1.49

21.001, 21.101, 21.201, 21.301, 21.401, 21.501(10+9+1.1+1.001 = 21.101)

(b) For progressive errors:

1.005, 3.01, 5.005,8.01, 10.005, 13.01, 15.005, 17.01, 20.005, 23.01, 24.005

4.3 Tabulate the above readings

4.4 Calculate the errors, % errors and plot graphs of

(a) slipgauge readings Vs errors

(b) slipgauge readings Vs % errors.


Tabulate the observations in the table given below. Make your own observations of the

results & discuss about the instrument,accuracy,procedure etc.


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TABULATION OF THE OBSERVATIONS

s.no. Nominal size of slip gauge

In mm

Actual size as

measured By

micrometer

Progressive error

Microns

1 1.005; 3.01; 5.005; 8.01;

10.005;

2 13.01; 15.005;

17.01;20.005;23.01

24.005;

3

4

s.no. Nominal size of the slip gauge

In mm

Actual size as measured

By micrometer

Periodical

error

Microns

1 1.01; 1.11; 1.21;

1.31;1.41; 1.49

2 21.001;

21.101;21.201;21.301;21.

401; 21.501

3

4


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14.0 MEASUREMENTS USING OPTICAL FLAT

1.0 AIM:

Study & qualitative assessment of nature of surface of specimen using optical flat & principle of

Interferometry.

MONOCHROMATIC LIGHT SOURCE OPTICAL FLATS

2.0 APPARATUS:

Optical flat(OF); monochromatic light source;optical specimen;slipgauge specimen

3.0 THEORY:

Interference of light waves occur when two sources of monochromatic light have equal or almost equal

amplitude & the two waves are out of phase . The two sources should be narrow & the surfaces must b

reflective. When Interference occurs , alternate dark & bright fringe bands appear & such phenomena is

called Interference of light.

An optical flat (OF) is a disc of glass or quartz highly polished & flat.It may be highly polished

one side or both sides.When both faces are polished the faces are perfectly parallel to each other to a lv

25 to 100 microns.The material of optical flat ifs of very low coefficient of thermal expansion. OF is used

measurement of flatness of surfaces accurately & for testing of surfaces of measuring instruments.OF is

made as per IS:5444 / IS 919-1963


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By the principle of Interference of monochromatic light falling on a flat surface such as an optical flat &

because of phase difference & consequential Interference, fringe pattern of light is created by an optica

flat.Depending on the type of surface which is inclined with respect to an optical flat , the pattern of fri

vary.Some of the typical fringe patterns observed are as given in sketches below:

Optical flats are used as part of Interferometers for precise estimation s of

flatness or linear distances , checking of curvature etc.If Interference fringes are straight & parallel,the

specimen is perfectly flat & if fringe pattern is curved the specimen is not flat.The error in flatness can b

estimated by measuring the distance between fringes & the wavelength of monochromatic light.

4.0 PROCEDURE:

Switch on the monochromatic source & allow it to warm up for about ~5 minutes.

Take a bigger slipgauge,clean & polish the bright surface & place it below the OF & place both be

the monochromatic light source & observe from an angle for the interference fringes and by cha

gap and inclination between OF and slip gauge,the fringes can be observed.Note down the type

fringes with the perfectly flat slip gauge surface both with & without hand pressure.

Similarway place the specimen-A & specimen-B below the OF & observe the type of fringe patte

& based on the type of fringes observed ,assess the nature & quality of surfaces of specimen-A

specimen-B.Sketch them & record it both the specimens with hand pressure & without hand

pressure.

5.0 RESULTS & DISCUSSION/CONCLUSION

Record the results & observations with varying gap & angle between OF & test specimen may be ana

TABULATION OF OBSERVATIONS:

S.NO. SPECIMEN TYPE SKETCH OF

INTERFERENCE

FRINGES

DESCRIPTION

OF TYPE OF

FRINGES

TYPE OF SPECIMEN

SURFACE(ESTIMATED)

1 SLIP GAUGE

(a)with pressure

(b)without pressure

2 SPECIMEN-A

(a)with pressure

(b)without pressure

3 SPECIMEN-B

(a)with pressure

(b)without pressure


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MMM LAB VIVA VOCE QUESTIONS

1. Define accuracy & precision of an instrument & differences between them.

2. An instrument measures a dimension 100.00 ten times & the dimensions measured vary from 10

to 101.05.Is the instrument Accurate? Or Precise? Or both?

3. A vernier has 24 div. on main scale=25 div. on vernier scale with 0.5mm as smallest readable dime

on main scale.What is the L.C. of the instrument?

4. Which of the following is the most important of all important characteristics of an

instrument:accuracy;precision;repeatability;sensitivity;readability.

5. What is the purpose of a ratchet on a micrometer?

6. How is a sine bar designated?

7. Which type by a of gear can be measured & which dimension is measured by a geartooth vernier

caliper?

8. Howa pitch diameter of screw thread can be measured?

9. What is the purpose of a protector slip?

10.What do you understand by wringing a slip gauge?

11.One micron is equal to what?

12.What is helix?what is helix angle?how is it measured?

13.What is module of a gear?What is the speciality of numerical no. of module?

14.What is the best size wire w.r.t. screw threads?

15.Optical flats are made in which material?

16.What are the geometrical properties of a slip gauge?

17.Which dimension of a thread is measured by a thread micrometer?

18.External taper of a 3D body can be measured by which instrument?

19.What is the accuracy of a bevel protractor?

20.What are the sizes of slipgauge pieces of M-87 available in the MMM lab.?

21.By which equipment all screw thread parameters can be measured?

22.What type of fringe patterns are observed with(a)sphere(b)cylinder(c)v-grove(d)perfect flat

23.What is the limitation of a sine bar ?what is its principle of measurement?

24.Which is more accurate? A bourdon pressure gauge or a pressure transducer?

25.What is LVDT? What is the principle of LVDT measurements?

26.What is a strain gauge?Where & how are they used in measurement of E of M.S.?

27.What is the principle of load cell?

28.What is LTD? & LTD?What is the principle of DTD & LTD?

29.What is a thermocouple?How does it measure temperature?

30.What is a comparator?which comparator did you handle?what is its principle?

31.Which the most preferred material for resistance thermometers?

32.How the flatness of a gauge is measured?

33.Which are the important geometrical parameters in an optical flat?

34.What type of light source is needed for interference of light?Which is the light source in lab.?

35.What are absolute & gage pressure?Does pressure gauge give absolute or gage pressure?

36.What is a transducer?which are the transducers in MMM laboratory?


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Gauge factor ( GF) LAWS OF THERMOCOUPLE

Thegauge factor is defined as: GF = R/RG 1.FirstLaw ofThermocoupleslaws of thermoelectric circuitse explains thermocouple consisting of 2 dissimilar metals

where generates an e.m.f. across the junction kept at different Tem

is the change in resistance caused by strain, junctions when junctions are kept at different temperatu

is the resistance of the undeformed gauge, and 2.The Law of Intermediate Metalswhich explains that a circ

is strain. EMFs are algebraically additive unless the circuit is at a unif

temperature

(J)Iron vs Constantan (Most Common) 3.The Law of Intermediate Metals:which indicates an EMFMay be used in vacuum, oxidizing, reducing, cannot be created unless another type of metal exists . If twoand inert atmospheres. Heavier gauge wire is dissimilar homogeneous metals produce a thermal EMF of Xrecommended for long it will remain at that number if a third material is introduced interm life above 1000F since the iron element the circuit, if both ends of that third material are at the same

temperature

oxidizes rapidly at these temperatures.

(T)Copper vs Constantan (Most Common Cold)May be used in vacuum, oxidizing, reducing, and inert atmospheres.

It is resistant to corrosion in most atmospheres.High stability at sub-zero temperatures and its limits of error areguaranteed at cryogenic temperatures.

(K)Chromel vs Alumel (Most Common Real Hot)Recommended for continuous use in oxidizing or inert atmospheresup to 2300F (1260C), especially above

1000F. Cycling above and below 1800F (1000C), is not recommendeddue to EMF alteration from hysteresiseffects. Should not be used in sulfurous or alternating reducing and oxidizingatmospheres unless protected withprotection tubes. Fairly reliable and accurate at high temperatures.
http://en.wikipedia.org/wiki/Gauge_factorhttp://en.wikipedia.org/wiki/Gauge_factorhttp://en.wikipedia.org/wiki/Gauge_factorhttp://en.wikipedia.org/wiki/Gauge_factor


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