Engineering - Exam Papers - OL - Paper - 1990
200 Marks
Answer Question 1, Sections A and B and THREE other questions.
Section A - 30 Marks
Give brief answers to any six of the following :
| (a) |
List two safeguards related
to the use of hand cutting tools. |
| (b) |
Distinguish between the pitch and
the lead of a screw. |
| (c) |
Give an example of the application
of a rack and pinion mechanism. |
| (d) |
Identify a method used to measure
furnace temperature. |
| (e) |
State two types of crystal
structure to be found in metals. |
| (f) |
What is meant by the term fettling? |
| (g) |
What are the main safety precautions
required when turning a long slender shaft on
the lather? |
| (h) |
Give a typical application of vacuum
forming. |
| (i) |
Why are v-belts more effective than
flat belts? |
| (j) |
What is an inactive flux? |
Section B - 35 Marks
Answer any three of the following :
| (k) |
Answer one of
the following: |
| (i) |
Name the mechanism shown
in the diagram and describe its purpose
and use. |
|
OR |
| (ii) |
Describe the
operation of an electrical generator. |
OR |
| (iii) |
Describe the
operation of any electrical or electronic
device of your choice. |
| (a) |
Select any metal and describe,
with the aid of a diagram, how it is produced
from its ore. |
| (b) |
Identify clearly the method used
to produce each of the following: |
| (i) |
cast iron; |
| (ii) |
mild steel; |
| (iii) |
high speed steel. |
| (c) |
Name the metals used to produce
each of the following binary alloys: |
| (i) |
soft solder; |
| (ii) |
brass; |
| (iii) |
bronze. |
| (a) |
Distinguish between three
different methods used in the heat treatment
of carbon steel. |
| (b) |
Name a non-ferrous or alloy and
give an example of a suitable heat treatment,
explaining the effects. |
| (c) |
Discuss two means of strengthening
metals other than heat treatment. |
| (a) |
Answer each of the following
briefly with regard to the soldering of components
on a circuit board: |
| (i) |
Identify the heat source used. |
| (ii) |
Why is the selection of flux
important? |
| (iii) |
How is the flux usually applied? |
| (iv) |
Select one of the following
as the melting temperature of solder: |
| 32°F |
1080°C |
183°C |
509°C |
75°F |
|
| (b) |
Explain with the aid of a diagram
how the flame for oxy-acetylene welding can
be varied.
What is |
| (i) |
a neutral, |
| (ii) |
an oxidising and |
| (iii) |
a carburising flame? |
| (c) |
State the purpose of each of
the following related to welding: |
| (i) |
a transformer; |
| (ii) |
a generator; |
| (iii) |
a high pressure regulator. |
| (a) |
Give two main differences
between the properties of thermoplastics and
thermosets and state how these differences
influence their selection for manufacturing
purposes. |
| (b) |
In each of the following cases,
state whether the material is thermoplastic
or thermosetting and give an example of its
use: |
| (i) |
phenolic resin; |
| (ii) |
polystyrene; |
| (iii) |
acrylic. |
| (c) |
Name three methods used
to manufacture plastic components. Describe
one such method in detail. |
| (a) |
Explain, with the aid of a diagram,
how rake and clearance angles provide a cutting
angle at the point of a lathe tool. |
| (b) |
Differentiate clearly between
the cutting speed and the feed rate of a machining
process. |
| (c) |
Explain how a range of spindle
speeds is provided on a machine tool. |
OR |
| (c) |
Describe the main features of
computer numerical control (CNC) of a machine
tool. |
| (a) |
A steel pin, dimensioned
in mm as shown, has a tolerance of
(i) 0.032 mm on diameter and (ii)
0.2 mm on length.
Explain clearly what these values
mean in practice. |
|
| (b) |
Given the limits of a
hole and shaft assembly as shown,
find: |
| (i) |
the minimum clearance; |
| (ii) |
the maximum clearance. |
| |
HOLE |
SHAFT |
| HIGH LIMIT |
30.021 |
29.960 |
| LOW LIMIT |
30.00 |
29.927 |
|
| (c) |
Explain clearly the purpose of
each of the following: |
| (i) |
plug gauge; |
| (ii) |
gap gauge; |
| (iii) |
telescopic gauge; |
| (iv) |
dial gauge. |
