WHAT IS METROLOGY

SCIENCE OF MEASUREMENTS

Everything has to do with measurement

Designing

Conducting

Analyzing Results

Experiment or test

within the Metrology realm

Allowing people to plan their lives

and make commercial

exchange with confidence

CAN BE SEEN EVERYWHERE

Metrology is mainly concerned with:

(1) Establishing the units of measurements, ensuring the uniformity of measurements.(2) Developing methods of measurement.(3) Errors of measurement.(4) Accuracy of measuring instruments and their care.(5) Industrial inspection and its various techniques.

Linear and Angular Linear and Angular MeasurementMeasurement

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Linear and Angular Linear and Angular Measurement Measurement The Linear Measurement includes

measurements of length, diameters, heights and thickness

The Angular measurement includes the measurement of angles or tapers

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Dimensions Dimensions A very common measurement is

that of dimensions, i.e., length, width, height of an object

Dimensions of the measuring instruments are classified as follows◦Low resolution devices (up to 0.25mm) ◦Medium resolution devices (up to

0.0025mm) ◦High resolution devices (less than

microns)

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Low resolution devicesLow resolution devicesSteel ruleSteel rule with assistance of

◦Calipers◦Dividers &◦Surface gauges

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Medium resolution Medium resolution devicesdevicesMicrometer Micrometer with assistance of

◦Telescoping ◦Extendable ball gauges

Vernier calipers Dial indicators Microscope

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High resolution devicesHigh resolution devicesGauge blocks Gauge block with assistance of

◦Mechanical comparator ◦Electronic comparator ◦Pneumatic comparator ◦Optical flats

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Linear Measuring Linear Measuring Instruments Instruments Vernier caliperMicrometer Slip gauge or gauge blocks Optical flats Interferometer Comparators

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Vernier caliper Vernier caliper Components of vernier calipers are

◦Main scale ◦Vernier scale ◦Fixed jaw ◦Movable jaw

Types of vernier calipers ◦Type A vernier caliper ◦Type B vernier caliper ◦Type C vernier caliper

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Type A Vernier CaliperType A Vernier Caliper

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Type B Vernier CaliperType B Vernier Caliper

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Type C Vernier CaliperType C Vernier Caliper

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Vernier caliperVernier caliperVERIER CALIPER WITH 0.02MM LEAST COUNT IS GENERLY USED IM WORK SHOP.

In this Vernier caliper main scale division (49mm) are divided in to 50 equal part in the Vernier scale.

i.e. 1 main scale division =1 mm

(MSD)

1. Vernier scale division =49\50 mm

(VSD)

Least count is 1mm – 49\50 =1\50 mm

THE DIFFERENCE BETWEEN 1.MSD and 1. VSD=0.02MM

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Example Example Main scale reading =35mm The vernier division coinciding with the main scale is the 20th division. Value=20 multiplied by 0.02=0.40mm. Total reading is 35mm+0.40= 35.40mm

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Vernier Depth GaugeVernier Depth Gauge

A vernier depth is very commonly used precision instrument for measuring depth of holes recesses, slot and step.

Its construction and method of reading are similar to those of a vernier caliper.

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VERNIER DEPTH GAUGEVERNIER DEPTH GAUGEBaseGraduated beamClamping screwFine adjustment

mechanism Vernier scale

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VERNIER HEIGHT GAUGEVERNIER HEIGHT GAUGE

The main parts of a vernier height gauge and their function are given.

1.base 2. beam 3.vernier slide 4. fine setting device 5. vernier plate 6. locking screws 7. scriber

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Gear Tooth VernierGear Tooth Vernier

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Profile ProjectorProfile Projector

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MICRO METER MICRO METER

A micro meter is a precision instrument used to measure a job, generally within an accuracy of 0.01mm.Micrometer used to take the outside measurements are know as outside micrometer.

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PARTS OF MICROMETERPARTS OF MICROMETER

Frame

Anvil and spindle

Screwed spindle

Graduated sleeve or barrel

Ratchet or friction stop

Spindle clamp

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Interval measurements Interval measurements Slip gauges InterferometerOptical flats and limit gauges Comparators

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SLIP GAUGESLIP GAUGESlip gauges are rectangular

blocks of steel having a cross-section of about 30 by 10 mm

Normal setRange Step Pieces

1.001 to 1.009 0.001 91.01 to 1.09 0.01 91.1 to 1.9 0.1 9

1 to 9 1 910 to 90 10 9

Total 45

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Special SetRange Step Pieces

1.001 to 1.009 0.001 91.01 to 1.49 0.01 49

1.5 to 9.5 0.5 1910 to 90 10 9

Total 86

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Limit gauges Limit gauges

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GaugesGaugesBasic dimension: exact size of part from

which all limiting variations madeLimits: maximum and minimum

dimensionsTolerance: permissible variation of part

◦unilateral: one direction only◦Bilateral: both plus and minus (two directions)

Allowance: intentional difference in dimensions of mating parts

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Cylindrical Plug GaugesCylindrical Plug Gauges

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Cylindrical Plug gaugeCylindrical Plug gauge

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Taper Plug GaugesTaper Plug Gauges

Used to check size of hole and taper accuracy

Made with standard or special tapers

Some have "go" and "no-go" rings scribed◦gauge fits into hole between two rings

means within required tolerance

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Taper Plug and Ring Taper Plug and Ring GaugesGauges

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Thread Plug GaugesThread Plug GaugesUsed for checking internal threads of

the "go" and "no-go" varietyBased on same principle as cylindrical

plug gauges"go" end (longer end)

◦Should be turned in flush to bottom of hole

"no-go" end◦Should just start into hole and become

snug before third thread enters

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Thread Plug GaugesThread Plug Gauges

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Thread Ring GaugesThread Ring Gauges

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FEELER GAUGEFEELER GAUGEA feeler gauge

(also known as a thickness gauge) is an accurately manufactured strip of metal that is used to determine the gap or clearance between two components.

FEELER GAUGEFEELER GAUGE A feeler gauge can

be used to check the following:◦ Piston ring gap◦ Piston ring side

clearance◦ Connecting rod side

clearance

Radius GaugeRadius GaugeA radius gauge is a tool used to

measure the radius of an object.

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Thread Pitch GaugeThread Pitch GaugeIt used to quickly determine the

pitch of various threads by matching the teeth on the leaves with teeth on the work.

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Comparators Comparators Mechanical comparatorsElectrical comparatorsOptical comparatorsPneumatic comparators

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Mechanical comparators Mechanical comparators

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It is a precision instrument employed to compare the dimension of a given component with a working standard

It does not measure the actual dimension but indicates how much it differs from the basic dimension

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Electrical comparators Electrical comparators

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Tool Makers MicroscopeTool Makers Microscope

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Telescopic GaugeTelescopic Gauge

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Bore diameter measurement using micrometer

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CMMCMM

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