# JNTU-Previous Papers-III-B Tech-Metro logy- Supplementary Examinations-Aug/Sep 2008

JNTU III B.Tech Supplimentary Examinations, Aug/Sep 2008

METROLOGY

(Mechanical Engineering)

SET-III

1. (a) Explain terms : Interchangeability and selective assembly. Enumerate the differences between them.

(b) Determine and sketch the limits of tolerance and allowance for a 25mm shaft and hole pair designated H8?d9. The basic size lies in the range of 18-30mm. The multipliers for grades 8 and 9 are 25 and 40 respectively. The fundamental deviation for ādā shaft is (-16 D0.44) microns.

2. (a) Describe the selection of minimum number of slip gauges for a dimension of 29.759mm from M112 set. What care of slip gauges is essential ?

(b) Describe the working principle and uses of Lever type dial test indicator.

3. (a) Enunciate the use of sine bar for checking the angles of large sized components

(b) The angle of wedge shaped block is being checked with 100mm Sine bar. With slip gauges of 26.867mm height at one end of Sine bar, the dial gauge readings at each end of the work piece vary by 0.06mm, the gauge block end being low. If the work piece is 30mm long what should be the next height of the gauge block tried ? Also calculate the angle of the work piece?

4. (a) Differentiate between workshop gauges and inspection gauges.

(b) Design general type GO and NO-GO gauges for components having 45 H7/g8 fit. The basic size falls in the diameter range of 30-50mm. The fundamental deviation for āgā shaft=(-2.5 D0.34) microns. The multipliers for 7 and 8 grades are 16 and 25. Take wear allowance as 10% of gauge tolerance. Sketch the gauges with values.

5. What are the uses of optical flats? Describe testing of optical flats for flatness.

6. (a) Describe surface roughness evaluation by profilo-graph

(b) Define terms: RMS value; CLA value.

7. (a) Differentiate among measuring instrument, gauge and comparator. What are the uses of a comparator?

(b) Describe the working principle of Reed type mechanical comparator with special reference to amplification ranges available.

8. (a) Elucidate the Effective diameter measurement by two wire method

(b) Explicate gear metrology of spur gears with reference to