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Metrology
Dr. Ahmed Hassan Backar
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2011/2012 - 1432/1433
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804445-3 Metrology
Lab (oral discussions and lab reports) 25%
Mid-term exam 20%
Attendance 5%
Final exam 50%
Team working and active learning techniques will be used in some
topics during the course.
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Textbook
1. Fundamentals of Dimensional Metrology, Bonnie L.
Dotson, Delmar publishers, 2006, 5th edition.
2. Metrology for Engineers, By J. F. W. Galyer, C. R.
Shotbolt, Cassell Publishers Ltd, Hong kong, 1990.
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References
Handbook of Dimensional Measurement, Mark Curtis and
Francis Farago, Industrial press, 2007, 4th edition.
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Course contents
Introduction
Line graduated Measuring Instruments
Fixed Gauges
Gage Blocks
Angle Measurements
Comparative Measurements
Surface Metrology
Measurements of Roundness
Measurements of Surface-Texture
Screw Thread Measurements
Gear Measurements
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Week Date Lecture Tutorial
1 19/10/1430 Introduction
2 26/10/1430 Line graduated Measuring
Instruments Lab Safety
3 3/11/1430 Fixed Gauges Vernier Calipers
4 10/11/1430 Gage Blocks Micrometers
5 17/11/1430 Angular measurements Fixed gauges
6 24/11/1430 Comparative Measurements Gage Blocks
7 2/12/1430 Practical Measurements Angle measurements
8 9/12/1430
9 16/12/1430 Practical Measurements Dial indicators
10 23/12/1430 Surface Metrology Practical measurements
11 1/1/1431 Measurements of Roundness Surface Metrology
12 8/1/1431 Measurements of Surface-
Texture
Measurements of Roundness
13 15/1/1431 Screw Thread Measurements Measurements of
Surface-
Texture
14 22/1/1431 Gear Measurements Screw Thread Measurements
15 29/1/1431 Revision Gear Measurements
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Introduction
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Engineering metrology Is the science concerned with the
measurements of linear
dimensions, angular dimensions, form errors and, surface
quality. This includes the used units, standards, measuring tools,
measuring techniques, and analysis of the results.
Dimension: It is a geometrical characteristic of which the size
is specified, such as a diameter, length, angle, location, center
distance.
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Measurement
process
operator procedure
standard equipment
Ambient environmental
characteristics
output input
Product or
Process to be
Measured
measurement
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Measurement Standard Units
Inch, foot; based on human body
4000 B.C. Egypt; Kings Elbow=0.4633 m, 1.5 ft, 2 handspans, 6
hand-widths, 24 finger-thickness.
AD 1101 King Henry I yard (0.9144 m) from his nose to the tip of
his thumb.
1872, Meter (in Greek, metron to measure)- 1/10 of a millionth
of the distance between the North Pole and the equator.
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Measurement Standard Units
Platinum (90%)-iridium (10%) X-shaped bar kept in controlled
condition in Paris39.37 in
In 1960, 1,650,763.73 wave length in vacuum of the orange light
given off by electrically excited krypton 86.
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Measurement Concepts
Precision; the degree to which the instrument gives repeated
measurements of the same standard
Accuracy; The degree of agreement of the measured dimension with
its true magnitude
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Measurement Concepts
Sensitivity:
the smallest difference in dimensions that the instrument can
detect or distinguish
Resolution:
the smallest dimension that can be read on an instruments.
Standard measuring temperature: 20 0C
Standard Humidity: 50%
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Measurement Concepts
Feature:
It is a specific portion of a part, such as a surface, hole,
slot, screw thread, or profile.
Size:
A number expressing, in particular unit, the numerical value of
a linear dimension.
Actual size:
The actual size of a dimension is the value that would be
obtained by measurement under standard conditions of
measurement.
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Measurement Concepts
Basic size (Nominal size):
The basic size of a dimension is the theoretical size from which
the limits for that dimension are derived.
Limits of size:
The limits of size are the maximum and minimum permissible sizes
for a specific dimension.
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Measurement Concepts
Maximum limit of size: The greatest permissible size of a
feature.
Minimum limit of size: The smallest permissible size of a
feature.
Tolerance: The tolerance on a size dimension is the total
permissible variation in its size, which is equal to the
difference between the maximum and minimum limits of size.
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Measurement Concepts Bilateral Tolerance: A bilateral tolerance
is a tolerance which is expressed as plus and
minus values, which neither is zero, to denote permissible
variations in both directions from the specified size.
Unilateral Tolerance: A unilateral tolerance is one which
applies only in one direction from
the specified size, so that the permissible variation in the
other direction is zero.
Fit: The fit between two mating parts is the relationship
between them
with respect to the amount of clearance (space) or interference
(friction) present when they are assembled.
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Measurement Concepts
INSPECTION Inspection is an essential operation in production
process Where,
Products are examined and checked to insure its conformability
with the required specifications. There are two techniques to
achieve this operation. The first is the measuring technique , the
second is checking or gauging technique.
MEASURING TECHNIQUE The product is measured by the conventional
measuring tools. The
measured value is then compared with the required ones in order
to accept or reject the product.
GAUGING (CHECKING) It is the operation of detecting whether the
inspected part is
consistent with the required specifications or not, ( Accepted
or rejected), without regard to its parameter values
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Measurement Concepts
MEASURING RANGE If the maximum reading of the measuring tool is
Xmax and, its
minimum reading is Xmin, then
Measuring range = Xmin to Xmax
MEASURING SPAN If the maximum reading of the measuring tool is
Xmax and, its
minimum reading is Xmin, then
Measuring span = Xmax - Xmin
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