Mechanical Measurement and Metrology - Jun 2013

Mechanical Engineering (Semester 4)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) What is metrology? State the objectives of metrology.(6 marks) 1 (b) Briefly explain limits, fits and tolerances.(6 marks) 1 (c) Using M112 set of slip gauges, build the following dimensions:
(i) 52.498
(ii) 48.3275(8 marks) 2 (a) Explain universal interchangeability and selective assembly.(6 marks) 2 (b) What do you understand by line and end standard? Explain wavelength standard.(6 marks) 2 (c) Determine the tolerances on the hole and the staff for a precision running fit designated by 50 H₇g₆ Given:
(i) 50 mm lies between 30-50 mm
(ii) i(microns)=0.45(D)<sup1>1/3+0.001D
(iii) Fundamental deviation for 'H' hole=0
(iv) Fundamental deviation for 'g' shaft= -2.5 D^0.34
(v) 1T7=16i
(vi) 1T6=10i
State the actual maximum and minimum sizes of the hole and shaft and maximum and minimum clearances.</sup1>(8 marks) 3 (a) What is a comparator? Explain Johnson Mikrokartor comparator with a neat sketch.(6 marks) 3 (b) What are the advantages of electrical comparators? Explain the principle of optical comparator.(7 marks) 3 (c) Describe with a neat sketch, the construction and working of LVDT.(7 marks) 4 (a) Explain with neat sketch the terminology of screw threads.(6 marks) 4 (b) Explain the principle of auto collimator with a neat sketch.(6 marks) 4 (c) Derive an expression for the effective diameter of a screw thread by 3-wire method.(8 marks) 5 (a) Explain the suitable examples, the three stages of measurement system.(6 marks) 5 (b) Define :-
(i) Calibration
(ii) Precision
(iii) Accuracy
(iv) Sensitivity
(v) Linearity.(10 marks) 5 (c) Compare electrical and mechanical transducers.(4 marks) 6 (a) Explain with a sketch, the principle of :-
(i) Piezo-electric transducer
(ii) Ionization transducer(8 marks) 6 (b) Explain with a block diagram, the general telemetering system.(6 marks) 6 (c) Explain the working of:
(i) Stylus type oscillograph
(ii) X-Y plotter(6 marks) 7 (a) Explain with a neat sketch, multiple lever platform balance.(6 marks) 7 (b) What are the types of dynamometers? Explain with a neat sketch, hydraulic dynamometer.(8 marks) 7 (c) Explain the operation of McLeod gauge and pirani gauge.(6 marks) 8 (a) What are the methods of strain measurement? Explain the principle of electrical resistance strain gauge.(6 marks) 8 (b) What is a thermocouple? Briefly explain the laws of thermocouple.(6 marks) 8 (c) Write notes on:
(i) Strain gauge factor
(ii) Temperature compensation
(iii) Cross sensitivity
(iv) Strain gauge bonding materials(8 marks)