This set of Advanced Engineering Metrology Questions and Answers focuses on “Parallelism, Equidistance and Coincidence”.
1. Which of the following is true for testing parallelism between two trajectories?
a) Dial indicator is attached on a fixed machine component
b) Moving parts are moving in different directions in testing the parallelism
c) The two parts are moved by the same amount
d) Parts are moving together
Explanation: The dial indicator is attached to one of the moving machine components and its feeler rests against a specified point on the other moving part. The two parts are moved together by the same amount in the same direction and the variations in the reading are noted.
2. Which of the following is true for coincidence between two axes?
a) Light weight dial indicator is used
b) Direction of measurement doesn’t varies
c) There is no effect of gravity force
d) Mandrel is used to represent the plane
Explanation: Light weight dial indicator is used in this test. The direction of the measurement varies during rotation in relation to the gravity direction. The sensitivity of the apparatus to the gravity force is taken into account.
3. Which of the following is true to check parallelism between two straight lines formed by the intersection of two planes?
a) V-blocks are used for large distance between two lines
b) No need of V-blocks
c) If there is a small distance between straight lines then use of V-blocks is the most necessary
d) It can be checked only by a straight edge
Explanation: If the distance between two lines is not small or large then the V-blocks are used. V- blocks are covered by a straight edge is used. Check for this is made by spirit level. For small distance there is no need of these.
4. What is the tolerance of parallelism of straight lines?
a) 0.015 on 300 mm
b) 0.15 on 300 mm
c) 0.015 on 600 mm
d) 0.15 on 600 mm
Explanation: Permissible deviations or tolerance of parallelism of two plane surfaces or straight lines is 0.015 mm on 300 mm. Free end of the spindle relative to the table surface is in upward direction only.
5. Which of the following is not true for coincidence?
a) Two axes merged in each other
b) Coincidence and perpendicularity are same
c) One axis extends beyond the other
d) Sometimes coincidence is used with is used with more general meaning of parallelism
Explanation: Two lines or axes are said in alignment or coincident when their distance apart at several points is measured over a specified length and this distance doesn’t exceed a specified value. The measured distance may be located either on the actual lines or on their prolongation.
6. Which of the following is true for measurement of equidistance?
a) Related to distance between two axes
b) Related to distance between two planes
c) Related to distance between reference plane and the axes
d) There is no relation with axes and planes
Explanation: When plane passing through the axes is parallel to the reference plane then there is an equidistance. It is related to the distance between reference plane and the axes. It may be different axes, or the same axis.
7. Test for parallelism of 2 planes is carried out in two different directions. What is correct for these directions?
a) Parallel to each other
b) Perpendicular to each other
c) At 45 degree to each other
d) At 60 degree to each other
Explanation: Two planes are parallel when the difference between the maximum and minimum dimension obtained that is maximum error over a given length does not exceed a specified value. The test is carried out in two directions which are perpendicular to each other.
8. Which of the following is not true for mandrel?
a) It represent the axis of rotation of spindle
b) Mandrel is always centred
c) Axis of rotation of mandrel may be hyperboloid
d) Axis of rotation of mandrel may be conical
Explanation: When a mandrel has represented the axis of rotation of spindle etc. It is not necessary that mandrel have been exactly centred and under such conditions the axis of the rotation of mandrel may describe a conical or hyperboloid.
9. Which of the following option is correct for given statements about parallelism?
Statement 1: A dial indicator is used to test parallelism of two planes.
Statement 2: Parallelism defines the distance between two surfaces that are parallel to each other and the datum surface.
a) T, F
b) F, F
c) F, T
d) T, T
Explanation: To test the parallelism, dial indicator can be used. The dial indicator is held on a support with base or flat base and is moved in one plane over a specified length, and the feeler is made to rest against the 2nd plane and the deviations are noted down.
10. How many minimum sides to be measured of a cylinder to test parallelism?
Explanation: Parallelism can be defined as the tolerance which controls the parallelism between two features. It is possible to find the parallelism of the cylinder by measuring the two sides of a cylinder.
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