Advanced Metrology | Measurement Interview Question and Answers

Advanced Metrology | Metrology Interview , Viva, Oral Question and Answers

1. Explain briefly the three important fields of machine vision system?

Inspection: it is the ability of an automated vision system to recognize well-defined pattern and if these pattern match these stored in the system makes machine vision ideal for inspection of raw materials, parts, assemblies etc.

Part identification: It is the ability of part recognition provides positive identifications of an object for decision-making purposes. Guidance and Control. Machine vision systems are used to provide sensor feedback for real time guidance.

2 What is interferometer?

Interferometer is optical instruments used for measuring flatness and determining the lengths of slip gauges by direct reference to the wavelength of light.

3. Name the different types of interferometer?

1) NPL flatness interferometer.
2) Michelson interferometer.
3) Laser interferometer.
4) Zesis gauge block interferometer.

4.Name the common source of light used for interferometer?

a. Mercury 198.
b. Cad minus.
c. Krypton 86.
d. Helium.
e. Hydrogen.

5. What is crest and trough?

The light is a form of energy being propagated by electromagnetic waves, which is a sine curve. The high point of the wave is called crust and the low Point is called is trough.

6. What is meant by alignment test on machine tools?

The alignment test is carried out to check the grade of manufacturing accuracy of the machine tool.

7. List the various geometrical checks made on machine tools.

a. Straightness of guide ways and slide ways of machine tool.
b. Flatness of machine tables and slide ways.
c. Parallelism, equidistance and alignment of the slide ways.
d. True running and alignment of shaft and spindle.
e. The pitch error or lead of lead screw.
f. Pitch errors of gears.

8. What is wavelength?

The distance between two crusts or two rough is called the wavelength.

9. Distinguish between geometrical test and practical test on a machine tool.

The alignment test is carried out to check the grade of manufacturing accuracy of the machine tool. Performance test consist of checking the accuracy of the finished component. Alignment test consist of checking the relationship between various machine elements when the machine tool is idle. Performance test consists of preparing the actual test jobs on the machine and checking the accuracy of the jobs produced.

10. What are the main spindle errors?

a) Out of round.
b) Eccentricity.
c) Radial throws of an axis.
d) Run out.
e) Periodical axial slip.

11. Write the various tests conducted on any machine tools?

1. Test for level of installation of machine tool in horizontal and vertical planes.
2. Test for flatness of machine bed and for straightness and parallelism of bed ways on bearing surface.
3. Test for perpendicularity of guide ways to other guide ways.
4. Test for true running of the main spindle and its axial movements.

12. Why the laser is used in alignment testing?

The alignment tests can be carried out over greater distances and to a greater degree of accuracy using laser equipment. Laser equipment produces real straight line, whereas an alignment telescope provides a, imaginary line that cannot be seen in space.

13. Classify the machine tool test.

It can be classified into
1. Static tests.
2. Dynamic tests.

14. What are the different types of geometrical tests conducted on machine tools?

1. Straightness.
2. Flatness.
3. Parallelism, equi-distance and coincidence.

15. What is CMM?

It is a three dimensional measurements for various components. These machines have precise movement is x, y, z coordinates which can be easily controlled and measured. Each slide in three directions is equipped with a precision linear measurement transducer which gives digital display and senses positive and negative direction.

16. What is the principle of laser?

The photon emitted during stimulated emission has the same energy, phase and frequency as the incident photon. This principle states that the photon comes in contact with another atom or molecule in the higher energy level E2 then it will cause the atom to return to ground state energy level E, by releasing another photon. The sequence of triggered identical photon from stimulated at In is known as stimulated emission. This multiplication of photon through stimulated emission’ leads to coherent, powerful, monochromatic, collimated beam of light emission. This light emission is called laser.

17. Define axial length measuring accuracy.

It is defined as difference between the references lengths of gauges aligned with a machine axis and the corresponding measurement results from the machine.

18. Write the types of coordinate measuring machines?

1. Bridge type.
2. Horizontal bore mill.
3. Vertical bore mill.
4. Spherical coordinate measuring machine.

19. Explain CNC, CMM briefly.

A computer numerical control system can be used with CMM to do calculations while measuring complex parts. Error can be stored in memory while doing calculations. For automatic calibration of probe, determination of co-ordinate system, calculation, evaluation and recording etc., special software’s are incorporated.

20. Write some features of CMM software.

Measurement of diameter, center distance can be measured as follows:
1. Measurement of plane and spatial curves.
2. Minimize CNC programme.
3. Data communications.
4. Digital input and output command
5. Interface to CAD software.

21. What are the four basic types of machine, vision system?

(i) Image formation.
(ii) Processing of image.
(iii) Analyzing the image.
(iv) Interpretation of image.

22. Write the advantages of machine vision system.

(i) Reduction of tooling and fixture cash.
(ii) Elimination of need for precise part location.
(i) Integrated automation of dimensional verification
(ii) Defect detection.

23. Define machine vision.

Machine vision can be defined as a means of simulating the image recognition and analysis capabilities of the human system with electronic and electromechanical techniques.

24. Mention the advantages of CMM.

(i) The inspection rate is increased.
(ii) Accuracy is reduced.
(iii) Operator’s error can be minimized. Skill of the operator is reduced.
(iv) Reduction in calculating, recording and set up time.
(v) No need of GO/NOGO gauges.
(vi) Reduction of scrap and good part rejection.

25. Mention the disadvantages of CMM.

(i) The table and probe may not be in perfect alignment.
(ii) The stylus may have run out.
(iii) The stylus moving in z-axis may have some perpendicularity errors.
(iv) Styius while moving in x and y direction may not be square to each other.
(v) There may be errors in digital system.

26. Mention the application of CMM.

(i) CMM’s to find application in automobile., machine to,,electronics, space and many other large companies.
(ii) These are best suited for the test and inspection Of test equipment, gauges and tools.
(iii) For aircraft and space vehicles of hundred Percent inspections is carried out by using CMM.
(iv) CMM can be used for determining dimensional accuracy of the component.
(v) CMM can also be used for sorting tasks to achieve optimum pacing of components within tolerance limits.

27. Describe the features of a flexible inspection system.

(i) A powerful computer serves as a real time processor to handle part dimensional data and as a multi ‘programming system to perform such tasks as manufacturing process control.
(ii) The terminal provides interactive communication with personnel Computer where the programmes are stored.
(iii) Input devices microprocessor based gauges and other inspection devices are used in CMM.