# Pune University Previous Question Papers Metal Working Tribology

Time: 3 Hours]                                                                                              [Max. Marks :100

Instructions to the candidates:

1)            Answer one question from each Unit in Section -1 and Section – II.

2)            Answers to the two sections should be written in separate answer books.

3)            Figures to the right indicate full marks.

4)            Assume suitable data, if necessary.

SECTION – I Unit – I

Q1) a) What are the measurement systems of surface roughness.                                

b) Define a tribo-system and how do you monitor its functions. 

OR

Q2) a) Explain the structure of a tribo-system.                                                                

b) How do you characterize a surface.                                                                  

Unit – II

Q3) a) What are the sliding friction mechanisms?                                                          

b) Derive a modified Bowden and Tabor friction equation.                             

OR

Q4) a) Derive friction equation involving hard material.                                               

b) Explain ‘Pin-on-Disc’ method of friction measurement.                              

Unit – III

Q5) a) Enumerate different types of wear.                                                                        

b) Derive wear equation for hard material over a soft material in sliding.



OR

Q6) a) Derive ‘Archard’ equation of wear.                                                                    

b)            Discuss the parameters affecting wear and how do you prevent them.

SECTION – II

Unit – IV

Q7) a) Discuss different types of lubricant used in industries.                   

b)            What is meant by ‘Viscosity Index’ of lubricant.                               

c)            Describe some methods of applying lubrication to the system.       

OR

Q8) a) With figure explain in detail mode of lubrication.                         

b) What are the properties required in lubricants?                             

Unit – V

Q9) a) Derive the equation for hydrodynamic lubrication                        

dp h – h\— = [——] dx   h(all having usual symbols) b) Derive ‘Petroff’ equation involving concentric earing.                                                                                                                          

OR

Q10)a) Derive an equation for circular step bearing under hydrostatic lubrication.



b) Find out leakage in litres/min through a shaft of 25mm9 which is running concentric to sleeve of 25.03 mm 9, 25mm length using water under pressure of 5 bar.    

Unit – VI

Q11)a) Derive an equation for two circular plates approaching each other involving squeeze film operation.                                                                                        

b) Two circular plates of 125 mm 9 approaching each other with velocity of 12.5 cm/s in liquid of ^ = 0.035 Pas. Find out pressure, load and time for film thickness to come down from 0.25 mm to 0.005 mm. 

OR

Q12)a) Derive squeeze film equation for rectangular plate approaching a rigid surface.   

b) Write short notes on :