# Linear and Angular Measurement | Metrology Interview Question and Answers

Linear and Angular Measurement | Metrology Interview , Viva, Oral Question and Answers

1. What are the considerations while manufacturing the slip gauges?

The following additional operations are carried out to obtain the necessary qualities in slip gauges during manufacture.

1. First the approximate size of slip gauges is done by preliminary operations.
2. The blocks are hardened and wear resistant by a special heat treatment process.
3. To stabilize the whole life of blocks, seasoning process is done.
4. The approximate required dimension is done by a final grinding process.

2. How do you calibrate the slip gauges?

Comparators are used to calibrate the slip gauges.

3. List the various linear measurements?

(i) Length.
(ii) Heights and
(iii) Thickness.

4. What are the various types of linear measuring instruments?

The various devices used for measuring the linear measurements are
i. Vernier calipers.
ii. Micrometers.
iii. Slip gauge or gauge blocks.
iv. Comparator.

5.List out any four angular measuring instrument used in metrology.

(i) Angle gauges.
(ii) Divided scales.
(iii) Sine bar with slip gauges.
(iv) Autocollimator.
(v) Angle dekkor.

6. Classify the comparator according to the principles used for obtaining magnification.

The common types are:
(i) Mechanical comparators.
(ii) Electrical comparators.
(iii) Optical comparators.
(iv) Pneumatic comparators.

7. What are comparators?

Comparators are one form of linear measurement device which is quick and more convenient for checking large number of identical dimensions.

8. How the mechanical comparator works?

The method of magnifying small movement of the indicator in all mechanical comparators are effected by means of levers, gear trains or a combination of these elements.

9. State the best example of a mechanical comparator.

A dial indicator or dial gauge is used as a mechanical comparator.

10. Define least count and mention the least count of a mechanical comparator.

Least count. – The least value that can be measured by using any measuring instrument known as least count. Least count of a mechanical comparator is 0.0 1 mm.

11. How the mechanical comparator is used? State with any one example.

Let us assume that the required height of the component I s 32.5mm. Initially, this height is built up with slip gauges. The slip gauge blocks are placed under the stem of the dial gauge. The pointer in the dial gauge is adjusted to zero. The slip gauges are removed- Now, the component to be checked is introduced under the stem of the dial gauge. If there is any deviation in the height of the component, it will be indicated by the pointer.

12. State any four advantages of reed type mechanical comparator.

(i) It is usually robust, compact and easy to handle.
(ii) There is no external supply such as electricity, air required.
(iii) It has very simple mechanism and is cheaper when compared to other types.
(iv) It is suitable for ordinary workshop and also easily portable.

13. Mention any two disadvantages of reed type mechanical comparator.

(i) Accuracy of the comparator mainly depends on the accuracy of the rack and pinion arrangement. Any slackness will reduce accuracy.
(ii) It has more moving parts and hence friction is more and accuracy is less.

14. What are the major types of on electrical comparator?

An electrical comparator consists of the following three major parts such as
(i) Transducer.
(ii) Display device as meter.
(iii) Amplifier.

15. On what basis the transducer works?

An iron armature is provided in between two coils held by a leaf spring at one end. The other end is supported against a plunger. The two coils act as two arms of an A.C. wheat stone bridge circuit.

16. How is the accuracy of an electrical comparator checked?

To check the accuracy of a given specimen or work, first a standard specimen is placed under the plunger. After this, the resistance of wheat stone bridge is adjusted that the scale reading shows zero. Then the specimen is removed. Now, the work is introduced under the plunger.

17. State the working principle of an electronic comparator.

In electronic comparator, transducer induction or the principle of application of frequency modulation or radio oscillation is followed.

18. Mention the important parts of an electronic comparator.

(i) Transducer.
(ii) Oscillator.
(iii) Amplifier.
(iv) Demodulator.
(v) Meter.

19. Classify pneumatic comparators.

(i) Flow or Velocity type.
(ii) Back pressure type.

20. What are the advantages of electrical and electronic comparator?

(i) It has less number of moving parts.
(ii) Magnification obtained is very high.
(iii) Two or more magnifications are provided in the same instrument to use various ranges.
(iv) The pointer is made very light so that it ‘IS more sensitive to vibration.

21. What are the disadvantages of electrical and electronic comparator?

(i) External agency is required to meter for actuation.
(ii) Variation of voltage or frequency may affect the accuracy of output.
(iv) Due to heating coils, the accuracy decreases.
(v) It is more expensive than mechanical comparator.

22. List the various parts of an optical comparator.

The optical comparator consists of the following parts such as

(i) Pivoted lever.
(ii) Objective lens
(iii) Scale.
(iv) Plunger.
(iv) Table
(v) Base.

23. What are the advantages of pneumatic comparators?

(i) The wear of measuring heads is avoided due to absence of direct contact.
(ii) Friction is less due to less number of moving parts.
(iii) Work piece is cleaned by supplying of all during the measurement.
(iv) High magnification is possible.
(v) There is no interference of measuring head and indicating device because the measuring head is kept away from the indicating device.
(vi) It is a suitable method to check taperness of circular bore.