Question 1: Multiple Choice Questions

TIME: 3 hoursMARKS: 200

QUESTION 1: MULTIPLE CHOICE QUESTIONS

1.1 / A√ / (1)
1.2 / C √ / (1)
1.3 / B √ / (1)
1.4 / B √ / (1)
1.5 / C√ / (1)
1.6 / A√ / (1)
1.7 / A√ / (1)
1.8 / C√ / (1)
1.9 / B√ / (1)
1.10 / D√ / (1)
1.11 / D√ / (1)
1.12 / A√ / (1)
1.13 / C√ / (1)
1.14 / C√ / (1)
1.15 / B√ / (1)
1.16 / A√ / (1)
1.17 / C√ / (1)
1.18 / D√ / (1)
1.19 / C√ / (1)
1.20 / C√ / (1)

[20]

QUESTION 2: SAFETY

2.1 / Wheel dresser – steps for using

Adjust the work rest away from the wheel so that the heel of the dresser can hook over the work rest which guides it √
Wear goggles or put on the eye shield √
Start the machine and allow the grinder to attain full speed √
Hook the heel of the dresser over the work rest and lift the handle slowly until the wheels of the dresser touch the grinding wheel √
Hold the dresser firmly in position and move slowly across the face of the grinding wheel, lifting the handle slightly after each pass √
Repeat this procedure until the wheel is clean and square √
Keep the dresser moving to prevent grooves forming in the wheel √
Adjust the work rest back so that it just clears the grinding wheel √

/ (8)
2.2 / Safety precautions on a lathe
AnySIX of the following:
2.2.1 / Loose clothing are is not allowed √
2.2.2 / Wear safety goggles √
2.2.3 / Clamp the work piece solidly √
2.2.4 / Secure all the guards before starting a machine √
2.2.5 / Keep the machine clear of tools √
2.2.6 / Always remove the key from the chuck √
2.2.7 / Stop the machine before you take measurements or make adjustments √
2.2.8 / Do no put tools on the lathe sideways √
2.2.9 / Never attempt to run the chuck on or off of spindle using power √
2.2.10 / Stop the machine immediately if you hear an unusual noise or vibration √
(any 6 x 1 = 6) / (6)
2.3 / List SIX safety measures when using a milling machine
Any SIX of the following:

make sure that all guards are in place √
do not use a machine or come close to its moving parts while wearing loose clothing √
check that there is no oil or grease on the floor around the machine √
do not leave spanners or keys on rotary parts √
never apply a wrench to revolving work √
always clamp work pieces and holding devices safely and firmly √
do not use your hands to remove cutting while a machine is in motion √
never adjust the cutting tool while the machine is running √
resist the habit of leaning on machinery √
do not attempt to stop a machine by placing your hand on the chuck while the machine is slowing down √
give attention to cutting-fluid control before switching on a machine√

(any 6 x 1 = 6) / (6)

[20]

QUESTION 3: TOOLS AND EQUIPMENT

3.1 / Dial indicator
3.1.1 / Dial indicator√√ / (2)
3.1.2 / 1 = Rotating bezel and dial √
2 = Millimetre dial √
3 = Spigot √
4 = Plunger √ / (4)
3.2 / Screw cutting
1
2
3 / Use cutting paste
Use a square to set up the dies perpendicular √
Turn the die one full turn and a then a quarter of a turn back – repeat until finished. √ / (2)
3.3 / Inside micrometer reading
75,00√
+ 10,00√
+ 0,04√
= 85.04 mm √ / (4)
3.4.1 / Micrometer√ / (1)
3.4.2 / Parts:
1 = anvil √
2 = spindle√
3 = locknut√
4 = barrel√
5 = thimble√
6 = ratchet√
7 = frame√
8 = measuring faces√ / (8)
3.5 / Vernier reading
12.00√
+0.86√
12.86 mm√ / (3)
3.6 / Grinding machine
3.6.1 / Surface grinding machine √ / (1)
3.6.2 / 1 = box √
2 = saddle √
3 = table √
4 = wheel head √
5 = column √ / (5)

[30]

QUESTION 4: MANUFACTURING PROCESS

4.1 / Screw thread on a centre lathe
4.1.1 / Meaning of M 12 x 2:
M= Metric√
12= Diameter √
2 = pitch of thread √ / (3)
4.1.2 / Advantages of a three jaw chuck
Any TWO of the following:

Can hold a wide range of hexagonal and cylindrical work pieces √
There are jaws available for external and internal work √
You can do work on the end face of the workpiece √
You can easily mount the workpiece (self centering) √

(any 2 x 1 = 2) / (2)
4.1.3 / Cutting tool - sharpening
√
√
√
/ (3)
4.1.4 / Changes to the lathe:

Set the compound slide to the angle of 60o with reference to bed ofthe lathe√
Place the cutting tool in the tool holder and set it centre height √
Set the cutting tool square to the axis of the work, using the centre gauge √
Set the lathe to a low speed√
Set the screw cut gearbox to a pitch of 2 mm.√

/ (5)
4.2 / Milling machine
4.2.1 / Purpose of milling:

Cut gears and splines√
Cut angles and unfamiliar sizes and forms on work pieces√

/ (2)
4.2.2 / Milling process:

Cutter is rotating√
Work pieces is clamp down in a vice or with clamping accessories √
Work piece position can be changed while the cutter is rotating√

/ (3)
4.2.3 / Movement of table::
√√√ / (3)
4.2.4 / Names of cutters:
Any THREE

End mill√
Gear cutter√
Side and face cutter√
Helical face cutter√

(any 3 x 1 = 3) / (3)
4.3 / The lathe
4.3.1 / Parts::

Head stock√
Main spindle√
Carriage√
Tail stock√
Splash guard√
Quick change gearbox√

/ (6)
4.3.2 / Cutting procedures:

Diameter cutting√

Taper cutting√

Screw cutting√

/ (3)
4.3.3 / Clamping:

3 – jaw chuck√
4 – jaw chuck√
Driver plate√

/ (3)
4.3.4 / Cutting fluid:

Cool down the work piece√
Cool down the cutting tool√
Sharpness of the cutter is extended√
Prevents rust on the bare lathe material√

/ (4)

[40]

QUESTION 5: JOINING METHODS

5.1 / Welding joints
5.1.1 / / (2)
5.1.2 / / (2)
5.1.3 / / (2)
5.1.4 / / (2)
5.2 / Soft and hard soldering
Soft soldering is the low temperature form of soldering √
Hard soldering includes brazing and silver soldering which is a high temperature form of soldering. √ / (2)
5.3 / Oxy-acetylene apparatus

Close all pressure regulator valves √
Open acetylene cylinder valves slowly√
Open acetylene valve on the welded torch √
Set the acetylene pressure on the regulator by turning the regulator valve clockwise and close the welding torch √
Open the oxygen cylinder valve slowly √
Open the oxygen valve on the welding torch √
Set the oxygen pressure on the regulator by turning the regulator valve anti-clockwise and close the welding torch √ √
The apparatus will now be ready for use √

/ (9)
5.4 / Welding joints
5.4.1 / Single bevel butt joint √
√ / (2)
5.4.2 / Fillet joint √
√ / (2)
5.4.3 / Double bevel butt joint √
√ / (2)
5.4.4 / Single v-butt joint √
√ / (2)
5.5 / Sectional view on a arc-welded joint
5.5.1 / 1 = Parent or base metal √
2 = Face of weld √
3 = reinforcement √
4 = toe of weld √
5 = parent or base metal √
6 = fusion zone √
7 = heat affected zone √
8 = root penetration√
9 = root gap √
10 = root face √ / (10)
5.5.2 /

protect the joint from unwanted gases
help in gradual cooling for the joint √

/ (1)
5.5.3 / Penetration is the depth of the root run, normally below the surface of the base plate √ / (1)
5.5.4 / Any TWO of the following

incorrect manipulation of the molten pool √
incorrect root face, root gap and angle of bevel √
too rapid welding speed √
too large electrode diameter√
too low current too √
long arc length √

(any 2 x 1 = 2) / (2)
5.6 / Welding and cutting nozzle
A welding nozzle has one hole and is used for gas welding and brazing purposes
A cutting nozzle has eight holes and oxygen booster flame and is solely used for cutting purposes. √ / (1)

[40]

QUESTION 6: FORCES

6.1 / Force “Y”
6.1.1 / Clockwise moments = Anti-clockwise moments
(Y x 5.8)+ (30 x 2.8) = 60 x 3.2 √√
5.8Y + 84= 192 √
5.8 Y = 192 – 84 √
Y = 108 √√
5.8
= 18.62N√√ / (8)
6.1.2 / Load on support = Total of all downward forces
Load = 60+30+18.62 √
= 108.62N √ / (2)
6.2 / Bridge
Taking moments about point P:
(Q x 10) = (650 x 9) + (400 x 5) + (500 x 2)√
= 5850 + 2000 + 1000
= 8850
Q = 885 N √√
Taking moments about point Q:
(P x 10) = (500 x 8) + (400 x 5) + (650 x 1)√
= 4000 + 2000 + 1000
= 6650

P= 665 N √√

Total load = (885 + 665) / 10 = 155 kg √
The bridge is safe to be used as the maximum load that can be carry is
250 kg. √ / (8)
6.3 / Basic lifting machine - torque
Converting the mass into force:
F = mg √
= 10 x 10 √
= 100 N √
Converting mm to m:
150 mm√
1000
= 0.15 m √
Converting diameter to radius:
Radius = Diameter √
2
= 0.15
2
= 0.075 m √
Torque = Force x Radius √
= 100 x 0.075
= 7.5 Nm √√ / (10)
6.4 / Uniformly load
6.4.1 /
Taking moments about R:
RL x 6= (600 x 4) + (400 x 3) + (500 x 2) √√
= 2400 + 1200 + 1000 √
= 4600
L= 766.67 N √
Taking moments about L:
RR x 6 = (500 x 4) + (400 x 3) + (600 x 2) √√
= 2000 + 1200 + 1200 √
= 4400
R= 733.33 N √ / (8)
6.4.2 / Upward forces = Downward forces
766.67 + 733.33 = 600 + 400 + 500 √
1500 = 1500 √ / (2)
6.5 / The carport
Taking moments about Q
P x 16 = (20 x 11) + (40 x 5) + (30 x 2) √ √
= 220 + 200 + 60√
= 480

P = 30 N √

Taking moments about P
Q x 16 = (30 x 14) + (40 x 11) + (20 x 5) √√
= 420 + 440 + 100√
= 960

Q = 60 N √

/ (8)
6.6 / Torque wrench
Torque = Force x Radius√
And Force = Torque
Radius
= 78
0.3√
P = 260 N √√ / (4)

[50]

***************************************