*P31*

Pre-Leaving Certificate Examination, 2019

Triailscrúdú na hArdteistiméireachta, 2019

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Engineering – MATERIALS AND TECHNOLOGY

(Higher level – 300 marks)

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Time: 3 Hours
 INSTRUCTIONS

1. Answer Section A and Section B of Question 1 and FOUR other questions.

2. All answers must be written in ink on the answer book supplied.

3. Diagrams should be drawn in pencil.

4. Squared paper is supplied for graphs, as required.

5. Please label and number carefully each question attempted.

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Question 1. (100 marks)

Section A – 50 marks

Give brief answers to any ten of the following:

(a) Give one advantage and one disadvantage of laser technology in metal cutting.

(b) Give two reasons why models or prototypes

are developed in the early stages of
the design process.

(c) Outline two environmental factors that

increase the rate of corrosion in steel fixings.

(d) Differentiate between systemic and narcotic effects of toxic materials.

(e) Explain one reason for the anodising of aluminium.

(f) The crash barrier shown is manufactured from steel and

must resist impact. Describe one suitable impact test.

(g) What contribution did any one of the following make to

technology?

(i) Mary Anderson (ii) Marie Curie (iii) Eileen Gray.

(h) Give two reasons why stainless steel is suitable for the manufacture of surgical devices.

(i) Evaluate the use of expanded polystyrene as a material in

the manufacture of hockey helmets, as shown.

(j) Describe two advantages of incineration as a means for

the disposal of expanded polystyrene.

(k) Describe the principle of operation of a single acting

hydraulic ram.

(l) Explain the association between conductivity and the metallic bond.

(m) The International Space Station shown

opposite is powered using photovoltaic solar
cells. This technology is becoming increasingly
familiar in the construction of houses here.
State one advantage and one disadvantage
for the use of photovoltaic cells.

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 Section B – 50 Marks

Answer all of the following:

(n) Nanotechnology was first considered in the 1950s with real examples becoming
evident is the electronics industry of the 1970s and further developed to the present
day. Describe briefly what you believe nanotechnology to be.

(o) With the aid of the diagram provided explain the operation of a Scanning Tunnel
Microscope (STM) in the production of nanotechnology.

Scanning Tunneling
Piezolelectric Tube

Microscopy (STM)
with Electrodes

Tunneling
Current Amplifier
Distance Control
and Scanning Unit

Tunneling Voltage

Data Processing
Tip and Display

Sample

(p) Explain each of the following in relation to nanotechnology:

(i) Graphene,
(ii) Nanotubes.

(q) Outline three applications of nanotechnology in society.

(r) Discuss briefly five advantages and five disadvantages of the use of nanotechnology in
society.

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Question 2. (50 marks)

(a) The plough shears shown are generally manufactured from

case hardened steel to allow them to cut through the soil
easily.
(i) Describe two critical properties to be considered in
the selection of case hardened steel as a material
used in the manufacture of the shears.
(ii) Describe, with the aid of a diagram(s), a mechanical
test suitable for measuring one of the properties
named above.

(b) The results shown below were obtained from tensile tests
on two non-ferrous metals, metal A and metal B.

Metal A: Stress (N/mm²) 50 100 150 215 275 325 355 365 345

Metal B: Stress (N/mm²) 16 28 40 53 66 75 79 78 75

Strain (× 1000) 0.5 1 1.5 2.25 3.25 4 5 6.5 7.5

(i) Using the graph paper supplied, plot the stress-strain diagram for metal A and
the stress-strain diagram for metal B using the same graph axes.

(ii) Find the ultimate tensile strength value for metal A and the ultimate tensile
strength value for metal B.

(iii) Compare metal A and metal B under the following headings:

• Ductility
• Tensile strength.

(c) An eddy current non-destructive testing device

is shown opposite.

(i) Describe, with the aid of a diagram(s), the

principle of eddy current testing.

(ii) Other than eddy current testing as above,

identify two NDTs that examine surface
imperfections and two NDTs that detect
internal flaws.

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Question 3. (50 marks)

(a) The leadscrew of the CNC router shown will be

subjected to wear.

(i) Identify a suitable heat treatment process to
harden the steel preventing wear on the lead
screw.

(ii) Describe, with the aid of a suitable diagram(s),

the heat treatment process selected.

(b) A simplified portion of the iron-carbon equilibrium diagram is shown.

A
Temperature °C

800

400
B

0
X 1.0 Y
% Carbon

(i) Identify the regions A and B.

(ii) Compare the main properties of the steel at X, which has 0.3% carbon, and the
steel at Y, which has 1.5% carbon.

(iii) Explain the process of normalising 1.5% carbon steel.

(c) A thermocouple pyrometer as shown opposite is used to

accurately measure furnace temperature during heat treatment.

(i) Explain, with the aid of a diagram(s), the principle of

operation of a thermocouple pyrometer.

(ii) Distinguish between soaking and water cooling when

carrying out heat treatment.

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Question 4. (50 marks)

(a) (i) Identify and describe the crystal point imperfections shown at both A and B.

A B

(ii) Describe one effect of the movement of the line defect shown below.

(b) The given table shows the solidification temperatures for various alloys of metal A and
metal B.

% of Metal B 0 10 20 30 40 50 60 70 80 90 100

Start of Solidification (°C) 1085 1170 1220 1275 1320 1355 1380 1405 1430 1440 1456

End of Solidification (°C) 1085 1075 1085 1110 1140 1175 1220 1270 1330 1380 1456

Using the graph paper supplied:

(i) Draw the equilibrium diagram according to the given data.

(ii) Label the diagram and describe the main features.

(iii) Determine from the diagram, the ratio of the phases at 1250°C for the alloy
with 50% of metal B.

(c) A diagram of a cooling curve for a pure metal is shown.

X Y
Temperature °C

(i) Identify point X and point Y labelled on the diagram.

(ii) Identify two possible defects which may occur during

the solidification process.
Time

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Question 5. (50 marks)

(a) The staircase shown is fabricated from stainless

steel which is cut and welded in a factory.

(i) Select a suitable welding process to be used in

the manufacture of the staircase and give one
reason for your selection.

(ii) Describe, with the aid of a diagram(s), the key

principles of the welding process selected.

(b) Answer any three of the following:

(i) Describe the term dissolved acetylene.

(ii) Outline the reasons for porosity in welding.

(iii) Suggest a suitable method to protect against each of the following when welding:

• Electric shock
• Intense light from welding
• Welding fumes.

(iv) Outline two advantages of multi-run welds.

(v) Explain why submerged arc welding (SAW) is suitable for welding steel girders.

(c) Using the following guidelines, compare resistance seam welding and resistance spot
welding:

• Electrode shape
• Principle of operation
• Weld joint
• Application.

OR

(c) The robotic delivery vehicle shown has nine cameras and
ultrasonic sensors as well as a GPS system and is currently
in operation making food deliveries in Silicon Valley.

(i) Outline one advantage and one disadvantage of

robotic delivery vehicles.

(ii) Describe the importance of the cameras and ultrasonic

sensors incorporated in the vehicle.

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Question 6. (50 marks)

(a) The child’s teething ring shown is manufactured from

the thermoplastic copolymer, ethylene-vinyl-acetate
(EVA).

(i) Outline any two reasons why EVA is suitable for

the manufacture of the toy.

(ii) Describe, with the aid of a diagram, a suitable

polymer manufacturing process to mass-
produce a thermoplastic mouthguard.

(b) Describe any three of the following:

(i) Elastomer;

(ii) Pigment;

(iii) Plasticisers;

(iv) GRP;

(v) Laminate.

(c) Distinguish between thermoplastics and thermoset plastics using each of the following
headings:

(i) Polymerisation process;

(ii) Chemical bonding;

(iii) Internal structure;

(iv) Properties.

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Question 7. (50 marks)

(a) Answer any three of the following:

(i) Identify three safety features integrated into a lathe.

(ii) Discuss two reasons why inaccuracies may occur during precision measurement.

(iii) Outline one use of a vee-block and clamp.

(iv) Distinguish between a pilot hole and a tapping size hole.

(v) Explain the difference between a rake angle and a clearance angle in cutting
tools.

(b) The surface of the cylinder head in an engine, as shown, must be

ground flat and smooth before assembly.

(i) Describe, with the aid of a suitable diagram, a surface

grinding process for a cylinder head.

(ii) Outline two safety hazards associated with using a grinding machine.

(c) The face milling cutter shown is fitted with interchangeable

tungsten carbide inserts.

(i) Describe briefly how the tungsten carbide inserts are

manufactured.

(ii) Outline two advantages and two disadvantages of an

interchangeable tungsten carbide insert.

OR

(c) Describe each of the following with reference to CNC machining:

(i) The advantages of CNC machining in industrial

engineering.

(ii) Two safety features integrated into CNC software.

(iii) The role of simulation in CNC machining.

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Question 8. (50 marks)

(a) A rack and pinion mechanism is used to raise and lower the table of the
pillar drill shown opposite.

(i) Describe, with the aid of a diagram, how a rack and pinion
mechanism may be operated to move the table.

(ii) Other than a pillar drill, identify two applications for the
mechanism described in Q8(a)(i) above.

(b) Explain any three of the following:

(i) The advantages of toothed pulley belts.

(ii) The operation and one application of a solenoid.

(iii) One application for a resistor.

(iv) One mechanical device used to convert rotary motion into linear motion.

(v) Outline a suitable use for a cam and follower mechanism.

(c) The kart dune buggy shown opposite is designed

to reach high speeds and to perform quick turning
movements.

(i) Describe clearly, with the aid of a diagram(s), a

suitable steering mechanism for the kart shown.

(ii) Describe, with the aid of a diagram(s), a rear

wheel drive propulsion unit for the kart.

OR

(c) Relays are used in numerous electrical circuits, usually allowing low voltage circuits to
drive higher voltage circuits.

(i) Describe, with the aid of a diagram, the principle of operation

of a relay.

(ii) Identify two applications for a relay.

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