Solution MQC
Solution MQC
Solution MQC
Unit I
1 Q. Differentiate between line and end standards. Discuss the characteristics of line and end standard
2 Q. List linear measuring instrument and angular measuring instrument used in metrology draw any
one sketch
List down instruments used for angular measurement.
Bevel protractor, sine bar, angle gauges, autocollimator, angle dekkor, clinometers,
sprit level Angle gauges. Divided scales. Sine bar with slip gauges. Autocollimator. Angle
dekko
a) Precision:
• Accuracy is the degree to which the measured value of the quality characteristic agrees with
the true value.
• The difference between the true value and the measured value is known as error of
measurement.
It is practically difficult to measure exactly the true value and therefore a set of observations
is made whose mean value is taken as the true value of the quality measured.
c) Sensitivity:
d) Readability :
• It is the ability of measuring instrument to repeat the same results for the measurements for
the same quantity, when the measurement is carried out,
• By the same observer,
• With the same instrument,
• Under same conditions,
• Without any change in location,
• Without the change in method of measurement,
• And the measurements are carried out in short interval of time.
e) Calibration:
5 Q. Define metrology. And state its objective? and explain in brief importance and need
Define metrology.
Metrology is the science of measurement which deals with the measuring instruments,
measuring techniques and measuring standards.
Metrology is defined by the International Bureau of Weights and Measures as "the
science of measurement, embracing both experimental and theoretical determinations
at any level of uncertainty in any field of science and technology"
What is the basic Principle of measurement?
It is the physical phenomenon utilized in the measurement. If energy kind of quantity
measured, there must be a unit to measure it. So this will give the quantity to be measured
in
number of that unit
What is the need of inspection?
To determine the fitness of new made materials, products or component part and to
compare the materials, products to the established standard, inspections are needed
6 Q. Explain with neat sketch hole basis system. and shaft hole basis system.
7 Q. Differentiate between Precision and Accuracy also clearly depicts from figure
Accuracy Precision
It is concerned with closeness to true value Degree of repetitiveness
It is related to single measurement It is related to group of measurement
It represents average of spread It represents measure of spread
Various sources of error can affect accuracy Various influences can affect accuracy
8 Q. State the Classification of Gauge Draw the different of sketch of gauges
ü The sine bar is used to measure angles based on the sine principle. Its upper surface forms the
hypotenuse of a triangle formed by a steel bar terminating in a cylinder near each end. When
one of the cylinders, called rollers, is resting on a flat surface, the bar can be set at any desired
angle by simply raising the second cylinder.
The required angle is obtained when the difference in height between the two rollers is equal to the
sine of the angle multiplied by the distance between the centres of the rollers
ü Sine bars are made of corrosion resistant steel, hardened, ground and stabilised. The size is
specified by the central distance between the cylinders, which is 100mm, 200mm or 300mm.
ü The upper surface has high degree of flatness up to 0.001 mm for 100 mm length and is
perfectly parallel to the axis joining the centres of the two cylinders.
10 Q. List any four methods of measurement & Give classification of measuring instruments.
12 Q Explain the term Sine and Cosine error giving a suitable example
13 Q. What are the possible sources of errors in measurements? Discuss the different reasons for the
occurrence of systematic errors
Least count = ( smallest division on main scale) / ( total no. of divisions on vernier scale )
= 0.1/10 = 0.01 cm
Total reading = ( MSR) + (VSR* LC)
= ( 13) + ( 5*0.01 )
= 13.06 cm
Unit II
ü Sine bar can also be used to measure unknown angles to a high degree of precision.
ü The angle of the work part is first measured using an instrument such as bevel protractor.
Then, the work part is clamped to the sine bar and set on top of a surface plate to that angle
using slip gauges as shown in.
18 Q. List out any four angular measuring instrument used in metrology explain with suitable example
sine of angle Ɵ with the help of sine bar
ü The sine bar by itself is not a complete measuring instrument. Accessories such as a surface
plate, slip gauges, etc are needed to accomplish the measurement process.
ü The sine of the angle ‘θ’ formed between the upper surface of sine bar and the surface plate
(datum) is given by :
Advantages of Interchangeability:-
i) Assembly time is reduced, as the operator is not required to waste his/her skill in fitting the mating
components by trial and error.
ii) There is an increased output with reduced production cost.
iii) Improve quality and reduce the time for operation.
iv) The replacement and worn-out or defective parts and repairs becomes very easy.
v) The cost of maintenance and shutdown period is also reduced to minimum.
21 Q. Discuss the essential requirements for maintaining accuracy in the construction of a sine bar. How is
a sine bar specified?
ü Sine centre provides convenient means for measuring angles of conical work pieces, which
are held between centres as shown in figure.
ü One of the rollers is pivoted about its axis, thereby allowing the sine bar to be set to an angle
by lifting the other roller.
ü The base of the sine centre has high degree of flatness and slip gauges are wrung and placed
on it in order to set the sine bar to the required angle.
23 Q. How does an angle dekor differ from an autocollimator? Discuss the applications of an. angle decor
in metrology.
ü Angle dekkor is a small variation on the autocollimator. This instrument is essentially used as
comparator and measures the change in angular position of the reflector in two planes.
ü It has an illuminated scale, which receives light directed through a prism. The light beam
carrying the image of the illuminated scale passes through the collimating lens as shown in
figure and falls on to the reflecting surface of the work-piece.
ü After getting reflected from the work piece it is refocused by the lens in field view of eyepiece.
While doing so, the image of the illuminated scale would have undergone a rotation of 900
with the optical axis.
ü Now, the light beam will pass through the datum scale fixed across the path of the light beam
as shown in figure.
ü
ü When viewed through the eye-piece, the reading on the illuminated scale measures angular
deviations from one axis at 90 ° to the optical axis and the reading on the fixed datum scale
measures the deviation about an axis mutually perpendicular to this.
ü The view through the eye-piece, which gives the point of intersection of the two scales is
shown in figure. The scales usually measure up to accuracy of 1 minute. This reading actually
indicates changes in angular position of the reflector in two planes.
ü The initial reading of the angle dekkor corresponds to the reading on the two scales before
shifting of the position of the reflector.
ü After the reflector undergoes angular tilt, the second reading is noted down by recording the
point of intersection on both scales. The difference in readings on the two scales indicates the
tilt of the reflector in two planes at 900 to each other.
24 Q. Describe with a sketch the principle behind the working of an autocollimator. Discuss any. two
important uses of an autocollimator in the industry
Auto-collimator is an optical instrument used for the measurement of small angular differences,
changes or deflection, plane surface inspection etc. For small angular
26 The main scale is graduated as one main scale division is 1° and Vernier is graduated into 12 divisions
on each side of zero. Calculate least count Vernier bevel protractor
27 Q. Design the general type of GO and NOT GO for plug gauge gauges a 90 mm hole pair designated as
90 H8 given that
(a)
(b) 90 mm lies in the diameter range of 80–100mm
(c) IT8 = 25i
Meaning of 27H5f6
Basic size is 27 mm. ----------------------------------------------- 01 Mark
H type of hole with tolerance grade IT 5 ----------------------------------------------- 01 Mark
F type of shaft with tolerance grade IT6 ----------------------------------------------- 01 Mark
Type of Fit :- Clearance Fit ----------------------------------------------- 01 Mark
Sr.
Tolerance Allowance
No.
It is the permissible variation in It is the prescribed difference
01 dimension of a part (Either a hole or between the dimensions of two
shaft) . mating parts ( hole and shaft) .
It is the intentional difference
It is the difference between higher and
02 between the lower limits of hole
lower limits of a dimension of a part.
and higher limit of shaft .
The tolerance is provided on a
Allowance is to be provided on the
dimension of a part as it is not possible
03 dimension of mating parts to
to make a part to exact specified
obtain desired type of it.
dimension .
Allowance may be positive
04 It has absolute value without sign. ( Clearance) or negative
( Interference ).
30 Q. Explain the working of autocollimator with neat sketch
ü It is a special form of telescope, which is used to measure small angles with high degree of
resolution. It is used for various applications such as precision alignment, verification of angle
standards, and detection of angular movement and so on.
ü The reticle is an illuminated target with cross hair pattern, which is positioned in the focal
plane of an objective lens. A plane mirror perpendicular to the optical axis serves the purpose
of reflecting an image of the pattern back on to the observation point.