Screw , Gear , Surface Finish Measurement | Interview Question and Answers

Screw , Gear , Surface Finish Measurement | Interview , VIva , oral  Question and Answers

1. Name the various types of pitch errors found in screw?

(i) Progressive error.
(ii) Drunken error.
(iii) Periodic error.
(iv) Irregular errors.

2. Name the various methods of measuring the minor diameter of the thread.

(i) Using taper parallels.
(ii) Using rollers and slip gauges.

3. Name the various methods used for measuring the major diameter?

(i) Ordinary micrometer.
(ii) Bench micro meter.

4. Name the various methods for measuring effective diameter.

(i) One wire method.
(ii) Two wire method.
(iii) Three wire method.

5. Name the various methods for measuring pitch diameter.

(i) Pitch measuring machine.
(ii) Tool maker.
(iii) Screw pitch gauge.

6. Name the two corrections are to be applied in the measurement of effective diameter.

(i) Rake corrections
(ii) Compression correction.

7. What is best size of wire?

Best size of wire is a wire of such diameter that it makes contact with the flanks of the thread on the pitch line.

This is one, having erratic pitch, in which the advance Of the helix is irregular in one complete revolution of thread.

9. What is the effect of flank angle error?

Errors in the flank cause a virtual increase in the effective diameter of a bolt and decrease in that, of nut.

10. What are the applications of toolmaker’s microscope?

(i) Linear measurement.
(ii) Measurement of pitch of the screw.

11. Define: Periodic error.

The periodic error repeats itself at equal intervals along the thread.

12. What are the commonly used forms of gear teeth?

(1) Involutes.
(2) Cycloidal

13. What are the types of gears?

(i) Spur.
(ii) Helical.
(iii) Bevel.
(iv) Worth and Worm wheel.
(v) Rack and pinion.

14. Define: Module.

Module= pitch circle diameter/ number of teeth.

It is the angle between the tangent to the helix and plane perpendicular to the axis of cylinder.

16. What are the various methods used for measuring the gear tooth thickness?

(i) Gear tooth Vernier.
(ii) Constant chord method.
(iii) Base tangent method.
(iv) Measurement over pins.

17. Name four gear errors.

(i) Pitch error.
(ii) Alignment error.
(iii) Composite error.
(iv) Thickness error.

18. Name the method used for checking the pitch of the gear.

(iii) Step by step method.
(iv) Direct angular measurement.

19. What are the direct angular measurements methods?

1. Profile checking:
a) Optical projection method.
b) Involutes measuring method.
2. Thickness measurement:
a) Chordal thickness method.
b) Constance chord method.

20. Define: constant chord.

Constant chord is the chord joining those points, or opposite Aces of the tooth.

22. What are the two methods used in measuring radius of concave surface?

a) Edges are well defined.
b) Edges are rounded up.

23. What are the factors affecting surface roughness?

a) Vibrations.
b) Material of the work piece.
c) Tool
d) Machining type.

24. What are the methods used for evaluating the surface finish?

a) Peak to valley height method.
b) The average roughness method.
c) Form factor method.

25. Define fullness and emptiness in form factor.

1. Degree of fullness (K)= area of metal /Area of enveloping rectangle
2. Degree of emptiness = 1 – K.

26. What are the methods used for measuring surface roughness?

a) Inspection by comparison
b) Direct instrument measurements.

27. What are the stylus probe instruments?

a) Profilo meter.
b) Taylor Hobson Talysurf.
c) Tomlinson surface meter.

28. Define: Straightness of a line in two planes.

A line is said to be straight over a given length, of the variation of the distance of its points from two planes perpendicular to each other and parallel to the direction of a line remaining within the specified tolerance limits.

29. Define: Roundness. Name the four measurement of roundness.

It is a surface of revolution where all the surfaces intersected ‘by any plane perpendicular to a common axis in case of, cylinder and cone.
a. Heart square circle.
c. Maximum inscribed circle.
d. Minimum circumscribed circle.

30. Name the devices used for measurement of roundness.

1. Diametral.
2. Circumferential confining gauge.
3. Rotating on center.
4. V-Block.
5. Three point probe.
6. Accurate spindle.

31. What is run out?

Run out. -Total range of reading of a fixed indicate Or with the contact points applied to a Surface rotated, without axial movement, about 3 fixed axis.