Engineering - Exam Papers - HL - Paper - 1993
300 Marks
Answer Question 1, Sections A and B and FOUR other questions.
Section A - 50 Marks
Give brief answers to any ten of the following :
| (a) |
Distinguish between the narcotic
and systemic effects of toxic materials. |
| (b) |
Identify two properties of materials
used to facilitate ore dressing. |
| (c) |
Why does slip occur more easily in face-centered
than in body centered cubic materials? |
| (d) |
What is meant by metal fatigue? |
| (e) |
Name processes used to manufacture |
| (i) |
machine beds, |
| (ii) |
spanners and |
| (iii) |
plastic
bins. |
| (f) |
State two ways of minimising corrosion
in metals. |
| (g) |
What is the function of an additive
in polymers? |
| (h) |
Differentiate between ionic and covalent bonding in
solids. |
| (i) |
What is meant by Young's Modulus of a material? |
| (j) |
Indicate the contribution of any one of the following to technology: |
| (i) |
John T. Parsons |
| (ii) |
Charles
Babbage |
| (iii) |
Thomas Seebeck. |
| (k) |
State the difference between RAM
and ROM in a computer. |
| (l) |
Identify the pneumatic symbols (i) and (ii). |
| (i) |
|
(ii) |
|
| (m) |
State any function of secondary memory related to
CAD. |
Section B - 50 Marks
Answer all of the following :
| (n) |
State three functions of a CNC system. |
| (o) |
The first three lines of a part
program are shown in the table. Explain
what is represented by the lines 300, 310 and
320. |
| N |
G |
M |
X |
Z |
I |
K |
S |
| 300 |
00 |
05 |
30 |
10 |
|
|
|
| 310 |
|
06 |
|
|
05 |
|
|
| 320 |
00 |
04 |
0 |
3 |
|
|
2500 |
|
| (p) |
Differentiate between: |
| (i) |
absolute and
incremental coordinates; |
| (ii) |
line editing and block
editing. |
| (q) |
Identify and state the function of a device
which enables a computer to control a machine. |
| (r) |
State
any three safety features
incorporated in the design of a CNC machine. |
| (a) |
Discuss three reasons for testing materials. |
| (b) |
Compare Brinell and Vickers methods of hardness
testing with regard to: |
| (i) |
the principle of the
test; |
| (ii) |
the type of indentor
used; |
| (iii) |
the range of hardness
values. |
| (c) |
Name two non-destructive tests and explain in each case: |
| (i) |
the principle of the test; |
| (ii) |
the type of defect for which the
test is used. |
| (a) |
Temperature zones for various
heat-treatment processes for carbon steel are
marked A, B, C and D on the diagram.
Identify and explain each of these processes. |
|
| (b) |
Answer any two of the
following:
Differentiate between: |
| (i) |
austentite and martensite; |
| (ii) |
grey cast iron and white cast iron; |
| (iii) |
flame hardening and nitriding. |
| (c) |
Explain how temperature control is
achieved in a heat-treatment furnace. |
| (a) |
Explain why a solid solution of two
metals is generally harder and stronger than either
of the metals concerned, with reference to unit
cell structure. |
| (b) |
The
melting points of two metals A and B are 700°C
and 1,500°C respectively. The given table
shows the solidification temperatures for various
alloys of the two metals. |
| Amount of B in Alloy
(%) |
0 |
20 |
40 |
60 |
80 |
100 |
Temperature at start
of
Solidification (°C) |
700 |
990 |
1,220 |
1,360 |
1,460 |
1,500 |
Temperature at end of
Solidification (°C) |
700 |
790 |
950 |
1,140 |
1,340 |
1,500 |
|
| (i) |
Using the graph paper supplied,
draw the thermal equilibrium diagram according to
the given data. |
| (ii) |
Label the diagram and discuss its
main features. |
| (c) |
For the alloy with 30% B at 960°C,
determine from the diagram (i) the composition and
(ii) the ration of phases which exist. |
| (a) |
State three safety
precautions associated with oxy-acetylene welding. |
| (b) |
Explain: |
| (i) |
the two-stage combustion process in
oxy-acetylene welding; |
| (ii) |
the difference between carburising
and oxidising flames; |
| (iii) |
two functions of the
flux in oxy-acetylene welding. |
| (c) |
Describe, with the aid of a
diagram, the main features of semi-automatic
welding. |
OR |
| (c) |
What possibilities do robots offer
to both manual and automated welding? |
| (a) |
Explain the following terms
relating to polymerisation: |
| (i) |
monomer; |
| (ii) |
addition
polymer; |
| (iii) |
copolymer; |
| (iv) |
condensation polymer. |
| (b) |
What are the main differences between elastomers,
thermoplastics and thermosets?
Reference should be made to internal structure, chemical
bonding and properties. |
| (c) |
Describe, with the aid of diagrams,
any two forming processes for thermosetting
plastics. Give an example of a product of
each process. |
| (a) |
Distinguish between the three types of
chip formed in the machining process. |
| (b) |
Show, with the aid of a diagram, |
| (i) |
the forces acting at the tip of a single-point
cutter and |
| (ii) |
state three factors which affect these
forces. |
| (c) |
Answer any two of the
following: |
| (i) |
calculate the power consumed when
the cutting force is 1,200 N on a shaft of 60mm
diameter and at a cutting speed of 400 rev/min; |
| (ii) |
what is upcut milling; |
| (iii) |
describe taper turning; |
| (iv) |
explain the terms loading and glazing. |
OR |
| (c) |
Explain clearly the term CADCAM |
| (a) |
Identify clearly the device used to achieve any three of the following: |
| (i) |
to control the operating speed of
a cylinder in a pneumatic circuit; |
| (ii) |
to detect changes in
temperature electronically; |
| (iii) |
to transform kinetic
energy of water into electrical energy; |
| (iv) |
to slow down the action
of the suspension springs of a vehicle; |
| (v) |
to change the voltage
of an alternating current without changing its
frequency. |
| (b) |
Explain the function of any two of the following: |
| (i) |
mechanical clutch; |
| (ii) |
rectifier; |
| (iii) |
universal joint; |
| (iv) |
electrical relay. |
| (c) |
With the aid of a
suitable diagram, explain the action of a
quick-return mechanism. How can the length
of stroke of such a mechanism be altered? |
OR |
| (c) |
Explain how the
pneumatic circuit shown in the diagram operates.
Give an application of such a circuit. |
|
