The document discusses various topics in metrology and measurement. It begins by defining metrology as the science of measurement and discusses standards used for measurement. It then describes different types of linear and angular measurement tools, including rules, calipers, micrometers, height gauges, protractors, and sine bars. The document also covers measurement terminology, types of errors, calibration, and comparators used for inspection.

1. Sanjivani College Of
Engineering, Kopargaon,
Dist: Ahmednagar
Prof H.P.Varade
Assistant Professor
Engineering Metrology
Linear and Angular Measurements

2. UNIT- I
METROLOGY
AND MEASUREMENTS
06/06/16
Mr.Harshal
P.Varade,Asst.Professor,Sanjivani 2

3. Metrology
Metrology defines as the Science of pure
measurement. But in engineering purposes,
it in restricted to measurements of length
and angles and other qualities which are
expressed in linear or angular terms.
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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4. Definition of Standards:
• A standard is defined as “something that is set up
and established by an authority as rule of the
measure of quantity, weight, extent, value or
quality”.
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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5. Line and End standard measurements
• Line standard
Length is expressed as the distance between two lines.
• End standard
Length is expressed as the distance between two flat
parallel faces
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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6. • Precision  Degree of repetitiveness. If an
instrument is not precise it will give different results
for the same dimension for the repeated readings.
• Accuracy  The maximum amount by which the result
differ from true value(ie) Closeness to true value
Terminology in Measurment
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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7. • Accuracy
Accuracy is how close a measured value is to the actual
(true) value.
• Precision
Precision is how close the measured values are to each
other.
Examples of
Precision and
Accuracy:
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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8. Types And Sources Of Errors
Systematic Errors
• Systematic errors are regularly repetitive and can be
eliminated.
• They results from improper condition or procedure of
experiment .
• These error can be controlled & reduced if properly
analyze, so called as Controllable errors.
Errors may be of four kinds;
1. Instrumental : For example, a poorly calibrated
instrument such as a thermometer that reads 102° C
when immersed in boiling water and 2°C when
immersed in ice water at atmospheric pressure. Such a
thermometer would result in measured values that are
consistently too high.
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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9. 2. Observational : For example, parallax in reading a
meter scale.
3. Environmental : Variation in atmospheric condition
i.e. temperature, pressure etc. at place of
measurement.
4. Stylus pressure :
Variation in Force applied by anvils of micrometer on
component to be measured results in different
reading.

10. Random Errors
• Random errors in experimental measurements are caused by unknown and
unpredictable changes in the experiment. These changes may occur in the
measuring instruments or in the environmental conditions.
• Sources of random errors cannot always be identified. Possible sources of
random errors are small variations in the position of setting standards and
work piece, slight displacement of lever joints in the measuring joints in the
measuring instrument.
• Examples of causes of random errors are:
1. electronic noise in the circuit of an electrical instrument,
2. Irregular changes in the heat loss rate from a solar collector due to changes
in the wind.
• These error cannot be eliminated.
1. Observational : For example, errors in judgment of an observer when
reading the scale of a measuring device to the smallest division.
2. Environmental : For example, unpredictable fluctuations in line voltage,
temperature, or mechanical vibrations of equipment.06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
10

11. Parallax Error :
• Parallax is a displacement
or difference in the apparent
position of an object viewed
along two different lines of sight,
and is measured by the angle or
semi-angle of inclination
between those two lines.
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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12. Calibration
• Calibration is one of the primary processes used to maintain
instrument accuracy.
• Calibration is the process of configuring an instrument to provide a
result for a sample within an acceptable range.
• Measurement of Accuracy.
• Establishment the relation of an instrument’s accuracy to the
international standard.
Success of Calibration
• Consistency of results obtained
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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13. Need of Calibration
• Quality control & quality assurance in production.
• To meet requirement of ISO
• To comply with requirement of global market.
• To promote international recognition.
Benefits of Calibration
• Fulfils requirement of ISO 9000, ISO 14000.
• As a proof that the instrument is working properly.
• Confidence in using instrument.
• Reduce rejection, failure rate.
• Improved product & service quality leading to satisfied
customer.
• Cost saving, safety.06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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14. . Classification of measuring Instruments.
According to the functions:
• Length measuring instrument
•Angle measuring instrument
•Instrument for checking deviation from geometrical
forms
•Instrument for determining the quality of surface finish.
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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15. Linear measuring instruments
• Straight edge (Steel rule)
• Outside caliper
• Inside caliper
• Vernier caliper
• Outside micrometer
• Inside micrometer
• Vernier height gauge
• Vernier depth gauge
• Dial gauges
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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16. Angular measurements
• Measuring the angle of Taper.
1. Bevel Protractor
2. Tool Makers microscope
3. Sine bar
4. Auto Collimator
5. Sine Centre
06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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17. Slip Gauges
•Gauge blocks (also known as gauge blocks, Johansson gauges, slip gauges)
are a system for producing precision lengths. The individual gauge block is a
metal or ceramic block that has been precision ground and lapped to a specific
thickness.
•For checking accuracy of venire calipers, micro metes, and such other
measuring instruments.
•Setting up a comparator to specific dimension.
•For measuring angle of work piece and also for angular setting in conjunction
with a sine bar.
•The distances of plugs, spigots, etc. on fixture are often best measured with the
slip gauges or end bars for large dimensions.
•To check gap between parallel locations such as in gap gauges or between two
mating parts.
•Slip gauges are rectangular blocks of high grade steel with exceptionally close
tolerances. These blocks are suitably hardened though out to ensure maximum
resistance to wear. They are then stabilized by heating and cooling successively
in stages so that hardening stresses are removed.06/06/16 Mr.Harshal
P.Varade,Asst.Professor,Sanjivani
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18. Measuring tools and instruments
Direct (contact) measurement
(e.g. micrometer or caliper)
Indirect (non-contact) measurement
(advanced methods such as optical,
ultrasonic, laser, etc.)
h Calipers
h Gauges and Gauge Blocks
h Sine Bar
h Special-purpose tools
h Rules
h Vernier Calipers
h Vernier Gauges
h Micrometers
h Protractors
h Dial Indicators
Measuring tools and instruments
Graduated
(either linear or angular
graduations incorporated
into measuring system of
the tool)
Non-graduated
(gauges or adjustable
tools which compare
the measurements)

19. Imperial steel rule with various lengths
having graduations on each side
Same rule with relatively larger
graduations
Metric steel rule with various lengths
having graduations on each side
resolution?
How to read a rule:
h A = 12 mm (12th graduation)
h B = 22 mm (22nd graduation)
h C = 31.5 mm (between
h D = 40.5 mm (between
31st
40th
and 32nd)
and 41st)
Graduated Linear Measurement - Rules

20. Graduated Linear Measurement - Vernier Calipers

21. Direct reading of an internal length
using digital Vernier caliper Direct reading of an external length
using digital vernier caliper
Vernier caliper with a dial indicator
Graduated Linear Measurement - Vernier Calipers

22. Designed for use in toolrooms, workshops, inspection departments to measure or mark off vertical
heights and locating center distances.
Standard Height gauge Dial Height Gauge Digital Height Gauge
Graduated Linear Measurement - Vernier Height Gauges

23. Designed for use in toolrooms, workshops, inspection departments to measure depths of holes, slots,
recesses, and so on.
Standard Depth Gauge Dial Depth Gauge Digital Depth Gauge
Graduated Linear Measurement - Vernier Depth Gauges

24. THIMBLE READINGVERNIER READING
Metric Micrometer
SLEEVE (BARREL) READING
Metric Vernier
Micrometer
Graduated Linear Measurement - Outside Micrometers

25. V-anvil Micrometer (measuring odd-fluted taps, milling
cutters, reamers, and checking out of roundness)
Dial-indicating Micrometer
Screw Thread Micrometer
(measuring pitch diameter
of screw threads)
Direct-reading
Micrometer
Graduated Linear Measurement - Outside Micrometers

26. Standard Inside Micrometers Digital Inside Micrometers
Graduated Linear Measurement - Inside Micrometers

27. h Standard calipers have a fine adjustment screw and a quick-adjusting spring nut.
h Accuracy obtained with these tools depends mostly on the inherent skill of users.
h The measurements are carefully transferred to a graduated measuring tool.
Caliper for inside
measurement
Caliper for outside
measurement
Caliper used
as a divider
Non-Graduated Linear Measurement - Calipers

28. Screw Pitch Gauges (consisting of a metal case containing
many separate leaves. Each leaf has teeth corresponding to
a definite pitch. By matching the teeth with the thread on
work, the correct pitch can be read directly from the leaf)
Tap and Drill Gauges (consisting
of a flat rectangular steel plate with
holes accurately drilled and
identified according to their size)
Radius Gauges (available as individual leaves and each
leaf is marked with its radius. They are designed to check
both convex and concave radii)
Non-Graduated Linear Measurement - Special Purpose Gauges

29. Non-Graduated Linear Measurement - Rectangular Gauge Blocks
Slip Gauge Box

30. (a)
(b)Simple
Protractor
(measuring
angles from
0 to 180º) Universal Bevel Protractor (main
scale consists of 4 portions of 90º)
Measuring acute (a) and
obtuse (b) angles
How to read an angle on a bevel protractor:
Main div. = 1º = 60´
Vernier div. = 1/12th of main div. ≈ 0.0833º = 5´
h The highest figure: 50 * (main div.) = 50º
h The matching figure: 4 * (vernier div.) ≈ 0.333º = 20´
h The final reading is: ≈ 50.333º or 50º 20´
Graduated Angular Measurement - Protractors

31. *
Limitations of Sine Bar:
Maximum angle 45°
Sine Center – Maximum angle that can be measured is 60°
Non-Graduated Angular Measurement - Sine Bar

32. Comparators
• Classification of comparators
1.Mechanical
2.Electrical and Electronics comparators
3.Optical comparators
4.Pneumatic comparators
5.Fluid displacement comparators
6.Projection comparators.
7.Multi check comparators
8.Automatic Gauging Machines
9.Electro-Mech. Comparators.
06/06/16 Mr.Harshal P.Varade,Asst.Professor,Sanjivani College of
Engg,Kopargaon
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