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

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

METROLOGY AND SURFACE ENGINEERING

(Mechanical Engineering)

SET-III

1. A hole and mating shaft are to have a nominal assembly size of 55 mm. The assembly is to have a maximum clearance of 0.34 mm and a minimum clearance of

0.25 mm. The hole tolerance is 1.5 times the shaft tolerance. Determine the limits for both hole and shaft: By using

(a) Hole basis system

(b) Shaft basis system.

2. Design general type GO and NO-GO gauges for components having 35 H8/f9 fit.

The basic size falls in the diameter range of 30-50mm. the fundamental deviation for âfâ shaft= (-5.5 D0.4) microns. The multipliers for 8 and 9 grades are 25 and 40.

Take wear allowance as 10% of gauge tolerance. Sketch the gauges with values.

3. What are the most common aberrations found in optical projector? Explain how they are caused. How can you overcome these?

4. Explain the working of profilometer with a neat sketch.

5. Describe the methods to check the thread angle and flank angles of a screw thread?

6. What is meant by alignment tests on machine tools? Why they are necessary? Explain.

7. (a) What are the possible causes of errors in coordinate measuring machine CMM?

(b) Define the term constant chord. Calculate the chord length and its distance below the tooth tip for a gear of module 3 and 200 pressure angle.

8. What is diffusion coating? Explain various types of diffusion coatings.