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Manufacturing Process 3 Question Paper
Manufacturing Process 3
Course:Bachelor Of Science
Institution: Kenyatta University question papers
Exam Year:2008
KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2008/2009
FIRST SEMESTER EXAMINATION FOR THE DEGREE OF BACHELOR OF
SCIENCE
SET 511: MANUFACTURING PROCESS 3
DATE: Tuesday 2nd December, 2008 TIME: 2.00 p.m. – 4.00 p.m.
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INSTRUCTIONS
Attempt any THREE questions.
QUESTION 1
(a) What are the four basic types of NTM process? [8 marks]
(b) What are the steps in chemical machining using photosensitive chemicals?
[6 marks]
(c) Differentiate Electro Chemical Machining and Chemical Machining. [3 marks]
(d) What effects does work-material hardness have on the metal removal rates
in (i) ECM and (ii) EDM? [3 marks]
QUESTION 2
(a) Draw a rough sketch of the electro discharge machine circuits.[4 marks]
(b) In electro discharge machining what influence on surface finish and machining
rate do the following have
(i) current density [4 marks]
(ii) frequency [4 marks]
(iii) duty factor [4 marks]
(c) List three functions of the dielectric in EDM. [4 marks]
QUESTION 3
(a) (i) Explain and illustrate the two stages in the combustion of oxygen and
acetylene? [2 marks]
(ii) Show the location of maximum temperature. [2 marks]
(b) (i) Explain which functions are served by the outer zone of the welding
flame. [2 marks]
(ii) What types of flame is produced by varying the oxygen fuel ratio?[2 marks]
(c) (i) What modification must be incorporated into a cutting torch t permit it to
cut metal underwater? [2 marks]
(ii) If a curved plate is to be straightened by flame straightening, should the heat be applied to the longer or shorter surface of the arc? [2 marks]
(d) Describe five basic components of a robot. [5 marks]
(e) Give three examples where a robot is the best choice in manufacturing.[3 marks]
QUESTION 4
(a) (i) Describe three basic types of current and polarity that are used in arc
welding. [2 marks]
(ii) What is the difference between a consumable electrode and a non-consumable electrode? [2 marks]
(b) (i) What is the function of the slag coating that forms over a shielded metal
arc weld? [2 marks]
(ii) What are some of the commonly used shielding gases in the gas tungsten arc process? [2 marks]
(c) (i) When spot welding, describe the three components that comprise the total
resistance between the electrodes. [3 marks]
(ii) What measures can be taken to reduce the resistance between the electrodes and the work pieces? [1 mark]
(d) Briefly describe machining centre, numerically controlled machine, flexible manufacturing system, transfer machines. [4 marks]
QUESTION 5
A base for a special machine tool will weigh 635 kg if made as a grey iron casting.
Pattern cost would be Kshs 60000 and the foundry has quoted a price of per pound
Kshs 100 per kg for making the casting if the part is made as a weldment, it will require
363 kg of steel costing Kshs 120 per kg. Cutting, edge preparation and set up will require
30hr at a rate of Kshs 200 per hour for labour and overhead. Welding time will be
55 hour at an hourly rate of Kshs 150 and 91kg of electrode will be required, costing
Kshs 200 per kg.
a. Which method of fabrication will be more economical if only one part is required?
[7 marks]
b. What number of parts will be required for welding and casting to break even?
[7 marks]
c. Draw a graph to illustrate your results. [6 marks]
………….
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