3. 1 proccesses, techniques and specialist tools

Question 1

Heat treatments:

3.1a

Answer 1

hardening and tempering

case hardening

annealing

normalising

Question 2

hardening and tempering

3.1a

Answer 2

The piece of work will

need to be first hardened to allow it to take the pressure of the work, but then tempered to remove the brittleness.

Question 3

define heat treatments:

3.1a

Answer 3

Heat treatments is the term given to the process of heating and cooling metal in a controlled manner, to alter its properties in order to obtain certain desired characteristics

Question 4

Hardening and tempering

step 1- harden the steel

step2- temper the steel

3.1a

Answer 4

step 1
 Heat gradually until red hot

 Plunge into cold water

 Steel becomes hard and brittle

step 2
 Clean using emery cloth until shiny

 Reheat slowly and carefully

 A thin line of oxide will appear and change colour with heat

 Stop at the colour associated with the product

 Quench in water

Question 5

case hardening

3.1a

Answer 5

This technique is used for steels with low carbon content. Carbon is added to the outer surface of the steel, to a depth of approximately 0.03mm. One advantage of this method of hardening steel is that the inner core is left untouched and so still processes
properties such as flexibility and are still relatively soft.

Question 6

annealing

3.1a

Answer 6

Annealing is a heat process whereby a metal is heated to a specific temperature /colour and then allowed to cool slowly. This softens the metal which means it can be cut and shaped more easily.

Mild steel is heated to a red heat and allowed
to cool slowly.

Aluminium- The flame should be held at a distance
to the aluminium so that it gives generalised heating to the metal. Rub soap on to the surface
of the aluminium and then heat it on the brazing hearth. It takes only a short time for the soap to turn black.

Question 7

normalising

3.1a

Answer 7

Normalising is a process that is undertaken on ferrous metals that have become hardened, in order to return them to their original unhardened state. The steel is heated until cherry red, 900°C and then allowed to cool in the air.

Question 8

which process applies to which material?

heat treatment
tempering
case hardening

mild steel 
aluminium 
high carbon steel 
steel
copper 

3.1a

Answer 8

Heat treatment
aluminium
steel
copper

tempering
high carbon steel

case hardening
mild steel

Question 9

why carry out alloying?

3.1b

Answer 9

Pure metals are rarely used in manufacturing because they are too soft. Usually, other elements are added to the molten metal so that the resulting solid is harder and has other desirable properties.

Question 10

alloy examples include:
1
2
3

3.1b

Answer 10

 Stainless steel - 87% carbon steel for strength and rigidity and 13% chromium for resistance to wear and corrosion.
 Duralumin – 93.5% aluminium for strength and lightness, 4.4% copper for strength, 1.5% magnesium and 0.6%
manganese.
 Brass – 65% copper and 35% zinc

Question 11

printing methods

3.1c

Answer 11

offset printing lithography

flexography

screen printing

gravure

Question 12

offset lithography

3.1c

Answer 12

Principle:
Oil and water
don’t mix

Products:
Posters
Books
Newspapers
Packaging
Brochures

Question 13

flexography

3.1c

Answer 13

Principle -
Relief printing
(raised surface)

Products –
Carton board
containers
Plastic bags
Wrappers

Question 14

screen printing

3.1c

Answer 14

Principle -
Stencil method

Products –
Posters
PoS displays
T-Shirts
Signage

Question 15

Gravure

3.1c

Answer 15

Principle -
Intaglio printing
(engraved
surface)

Products –
Labels
Vinyl flooring
Magazines
Postage stamps

Question 16

offset lithography
proccess

3.1c

Answer 16

 Printing plate made from flexible
aluminium
 Plate fixed to plate cylinder
 Rollers apply water – water is repelled
from the image areas
 Ink is applied – ink is repelled by the water
and adheres to the dry image areas
 Print transferred to a rubber blanket
cylinder to avoid the paper getting wet.
 Blanket cylinder absorbs the water and
picks up the ink
 Ink transferred to the paper
 Repeat for CMYK

Question 17

flexography
proccess

3.1c

Answer 17

 A plastic or rubber plate is made with a
raised surface for the image areas
 Plate fixed to plate cylinder
 A fountain roller is submerged in the ink
 An anilox roller and doctor blade produce
an even distribution of ink
 This is then transferred to the printing
plate
 Then pressed onto the printed surface
 Repeat for CMYK

Question 18

screen printing
proccess

3.1c

Answer 18

 A wooden or aluminium screen has a
finely woven fabric stretched over it
 The non-image areas are blanked out
using a photo-emulsion
 Place screen over the material to be
printed on to
 Ink is applied to the screen
 A squeegee is used to push the ink
through the screen onto the material
 Repeat for CMYK

Question 19

Gravure
proccess

3.1c

Answer 19

 Produce a digitally engraved copper plate
cylinder
 Plate cylinder is partially submerged in the
ink fountain
 The recessed cells are filled with ink
 A doctor blade scrapes the cylinder,
removing the ink from the non-recessed
areas
 An impression cylinder is then used to
press the paper onto the plate cylinder.
 Repeat for CMYK

Question 20

offset lithography
pros and cons

3.1c

Answer 20

Pros 
 Good quality
 Inexpensive
 Wide range of
surfaces
 High speed
 Widely available

Cons
 Colour variation
due to ink and
water
 Paper can get
wet
 Expensive set up
costs
 Only flat prints

Question 21

flexography
pros and cons

3.1c

Answer 21

pros
 High speed
 Fast drying

cons
 Difficult for fine
detail
 Colour may be
inconsistent
 Set up costs high

Question 22

screen printing
pros and cons

3.1c

Answer 22

pros 
 Easy to produce
stencils
 Print onto any
surface
 Good for short
runs
 Can produce
large volumes

cons
 Can be hard to
produce fine
detail
 Longer drying
times

Question 23

Gravure
pros and cons

3.1c

Answer 23

pros
 Consistent colour
 High speed
 High quality

cons 
 Expensive plates
 Only long runs
 Can see the dots
printed
 Very expensive
set up costs

Question 24

Casting methods

3.1f

Answer 24

sand casting

investment casting

die casting

resin casting

plaster of paris casting

Question 25

sand casting
products

advantages

disadvantages

3.1f

Answer 25

Products:
Engine block
Garden furniture

Advantages:
 Inexpensive
 Complex shapes
can be produced
 Large components
can be made

Disadvantages:
 Sand moulds can
only be used once
 Surface finish not
always good
 Labour intensive
 Slow production
rates

Question 26

incestment casting
products

advantages

disadvantages

3.1f

Answer 26

Products:
Mechanical parts
Fan blades

Advantages:
 Excellent surface
finish
 High dimensional
accuracy
 Extremely intricate
parts are castable
 Almost any metal
can be cast
 No flash or parting
lines

Disadvantages:
 Overall cost,
especially for
short-run
productions.
 Specialized
equipment
 Many operations
to make a mould
 It can be difficult
to cast objects
requiring cores.
 Usually limited to
small casting
 Requires longer
production cycles
compared to other
casting processes.

Question 27

die casting
products

advantages

disadvantages

3.1f

Answer 27

Products:
Traditional toy cars
Engine parts

Advantages:
 High dimensional
accuracy is
achievable
 Fast Production
 Thinner walls are
achievable when
compared to
investment casting
(0.6mm -0.8mm)
 Wide range of
possible shapes
 Good finish

Disadvantages:
 Castings must be
smaller than
600mm and the
thickest wall
section should be
kept below 13mm
 High initial cost
(Cost of moulds
and machine set
up)
 A large production
volume is required
to make the
process cost
effective

Question 28

resin casting
products

advantages

disadvantages

3.1f

Answer 28

Products:
Industrial prototypes
Dentistry
Model making

Advantages:
 Cheaper moulds
than injection
moulding
 Resin casting
enables the
casting of intricate
designs
 Can be casted or
painted in any
desired colour

Disadvantages:
 Drying time
 Not good for
batch/mass
production

Question 29

plaster of paris casting
products

advantages

disadvantages

3.1f

Answer 29

Products:
Lock components
Gears
Valves
Fittings
Tooling
Ornaments

Advantages:
 Excellent surface
finish
 Good dimensional
accuracy
 Produces minimal
scrap material

Disadvantages:
 can only be used with non-ferrous
materials
 The used plaster
cannot be reused.
 Metal cools more
slowly than in a
sand mould

Question 30

sand casting
process

3.1f

Answer 30

 Make a two part wooden pattern (replica of the product to
be made) – the pattern must have sloping sides so it can be
removed from the sand. It should have rounded edges and
no undercuts. This is then often finished with gloss paint.

 Prepare the sand – it needs sieving to remove any lumps.
 The mould in sand casting is produced in two open boxes
called the ‘cope’ and the ‘drag’.

 The drag (bottom half) – turn this mould upside down and
place half the pattern face down in the centre.
 Sand is then packed around the pattern.
 Ram the sand down and levelled off.
 Turn the drag over and place on the cope.
 Place the second part of the pattern onto the first half.
 Place the sprue pins into the sand – this is where the molten
metal is poured in.
 Fill the cope with sand.
 Remove the sprue pins.
 Carefully separate the cope and drag.
 Remove the pattern.

 Re-assemble the cope and drag.
 Pour molten metal into the sprue pin holes.
 The metal is allowed to cool and solidifies.
 Cope and drag is separated, the sand is broken up and the
product is removed.
 The product now requires ‘fettling’ to remove excess metal
from the process.

Question 31

investment casting
process

3.1f

Answer 31

 The first step in investment casting is to manufacture the wax
pattern for the process – Since the pattern is destroyed in the
process, one will be needed for each casting to be made.
 When producing parts in any quantity, a mould from which
to manufacture patterns will be desired. The mould to create
wax patterns may be cast or machined from aluminium.

 Since the mould does not need to be opened, castings of
very complex geometry can be manufactured.
 Several wax patterns may be combined for a single casting.
Or as often the case, many wax patterns may be connected
and poured together producing many castings in a single
process. This is done by attaching the wax patterns to a wax
bar, the bar serves as a central sprue.
 A ceramic pouring cup is attached to the end of the bar. This
arrangement is called a tree, denoting the similarity of
casting patterns on the central runner beam to branches on
a tree.
 The pattern is then dipped in a ceramic slurry. A ceramic
layer is obtained over the surface of the pattern. The pattern
is then repeatedly dipped into the slurry to increase the
thickness of the ceramic coat.
 Once the refractory coat over the pattern is thick enough, it
is allowed to dry in air in order to harden.
 The hardened ceramic mould is turned upside down and
heated to a temperature of around 90°C-175°C. This causes
the wax to flow out of the mould, leaving the cavity for the
metal casting.
 The ceramic mould is then heated to around 550°C-1100°C.
This will further strengthen the mould.
 Molten metal is then poured while the mould is still hot.
 The casting is allowed to set as the solidification process
takes place.
 Break the ceramic mould from the investment casting and
cutting the parts from the tree.

Question 32

die casting
process

3.1f

Answer 32

 Clamping - The first step is the preparation and clamping of the two halves of the die. Each die
half is first cleaned from the previous injection and then lubricated to facilitate the ejection of the
next part. After lubrication, the two die halves, which are attached inside the die casting machine,
are closed and securely clamped together. Sufficient force must be applied to the die to keep it
securely closed while the metal is injected.
 Injection - The molten metal, which is maintained at a set temperature in the furnace, is next
transferred into a chamber where it can be injected into the die. The method of transferring the
molten metal is dependent upon the type of die casting machine, whether a hot chamber or
cold chamber machine is being used. Once transferred, the molten metal is injected at high
pressures into the die. Typical injection pressure ranges from 1,000 to 20,000 psi. This pressure
holds the molten metal in the dies during solidification. The amount of metal that is injected into
the die is referred to as the shot. The injection time is the time required for the molten metal to
fill all of the channels and cavities in the die. This time is very short, typically less than 0.1 seconds,
in order to prevent early solidification of any one part of the metal.
 Cooling - The molten metal that is injected into the die will begin to cool and solidify once it
enters the die cavity. When the entire cavity is filled and the molten metal solidifies, the final
shape of the casting is formed. The die cannot be opened until the cooling time has elapsed and
the casting is solidified.
 Ejection - After the predetermined cooling time has passed, the die halves can be opened and
an ejection mechanism can push the casting out of the die cavity. The ejection mechanism must
apply some force to eject the part because during cooling the part shrinks and adheres to the
die. Once the casting is ejected, the die can be clamped shut for the next injection.
 Trimming - During cooling, the material in the channels of the die will solidify attached to the
casting. This excess material, along with any flash that has occurred, must be trimmed from the
casting either manually via cutting or sawing, or using a trimming press. The scrap material that
results from this trimming is either discarded or can be reused in the die casting process.

Question 33

resin casting
process

3.1f

Answer 33

 Produce a pattern of the object you would like to produce
a resin casting of.
 Spray the pattern with the separating agent. This will help
to later remove the model from the mould. Allow to dry.
 Suspend the pattern in a container with sealed sides
 Pour silicon into the container half the way up the pattern
 Allow to set
 Apply a layer of silicon separation cream
 Pour the rest of the silicon over the top half of the pattern
 Allow to set
 Remove the silicon and separate the two halves
 Remove the pattern
 In the example shown here the model maker pours resin
into the two halves separately. Letting the first half fully set
before pouring the second and placing the first set mould
over the top of the wet second half.

 You can place a sprue inside with the pattern to allow the
resin to be poured into the mould in one go.

 You can see the sprue holes on the right hand side of this
mould.
 After removing the resin cast, you will need to clean the
model to remove any excess resin from the process.

Question 34

plaster of paris casting
process

3.1f

Answer 34

 Similar to sand casting except the moulding material is plaster of Paris instead of sand
 Make a pattern in the shape of the product you require. The pattern is usually made from metal.
 Spray a thin film of parting compound to prevent the plaster from sticking to the pattern.
 Mix the plaster. The plaster is not pure plaster of Paris, but rather has additives to improve green
strength, dry strength, permeability, and castability.
 The plaster is then poured over the pattern and the unit shaken so that the plaster fills any small
features.
 The plaster sets, usually in about 15 minutes, and the pattern is removed.
 The mould is then baked, between 120 °C and 260 °C, to remove any excess water.
 The dried mould is then assembled, preheated, and the metal poured.
 The metal solidifies.
 The plaster is broken from the cast part.

Question 35

Machining methods

3.1e

Answer 35

milling/ routing

drilling

turning

stamping/ pressing

Question 36

Milling

3.1e

Answer 36

Milling is the process of cutting away metal, by feeding a
piece of work past a rotating cutter.

A vertical milling machine is used to shape metals such
as mild steel and aluminium.

Question 37

drilling

3.1e

Answer 37

Drilling is the process of making holes by using a
rotating cutting tool that is either secured in either a
hand operated drill or drilling machine.

Question 38

drill bits

3.1e

Answer 38

Flat bits – deep
holes in wood

Forstner bits –
flat bottom
holes in wood

Auger bits –
deep holes using
a brace

Countersink bits
– angled sides
for screws

Hole saw – large
diamtre holes

Tank cutters –
circular cutters
for metal

Question 39

turning
method
-turning

3.1e

Answer 39

The work on a lathe turns. On a metalworking lathe
the cutting tools are securely fixed, whilst on
woodworking lathe, the cutting tools are held in the
hand and are rested on a tool rest.
On a metalwork lathe, work is held in a chuck and on
a woodworking lathe the material is usually secured
to a faceplate or turned between centres.

Question 40

turning
method
-centre drilling

3.1e

Answer 40

Centre drilling is when the lathe I used to drill a hole
in the end of a rod or bar. It is the work which rotates in the chuck
with the drill help securely in the tailstock.

Question 41

turning

• screw threads
  3. 1e

Answer 41

Screw threads can be cut using a
centre lathe. They are cut from a from
a bar to produce the correct thread
profile.

Question 42

turning
- knurling

3.1e

Answer 42

Knurling is a manufacturing process,
typically conducted on a lathe,
whereby a pattern of straight, angled
or crossed lines is cut or rolled into the
material

Question 43

turing
- parting off

3.1e

Answer 43

Parting is the operation of cutting a
piece off by slicing a groove all the
way through it with a special parting
tool.

Question 44

stamping/ pressing

3.1e

Answer 44

Stamping (also known as pressing) is the process of placing flat
sheet metal in either blank or coil form into a stamping press
where a tool and die surface forms the metal into a net shape.

Question 45

laminaton

3.1f

Answer 45

Lamination is where a material has been produced by gluing together thin sheets, or veneers, to make up that material.

Lamination can also be used for shaping material. This is where strips of veneer are glued together and clamped in a
former. When the glue has dried the work is removed and it retains the shape of the former.

Question 46

most common laminate materials

3.1f

Answer 46

lamin board (5-7 mm strips)

block coard (upto 25mm strips)

plywood

Question 47

moulding methods

3.1g

Answer 47

injection moulding

blow moulding (pre-form)

blow moulding (parison)

vacuum forming

extrusion

rotational moulding

Question 48

injection moulding
products

pros

cons

Answer 48

Casings for
electrical
products
Packaging
Toys

pros 
 Good for mass
production
 Low unit costs for
high volume
 Precision moulding
 Surface texture can
be added to the
mould

cons
 High set up costs
 Expensive moulds
to design and
make

Question 49

blow moulding (pre-form)
products 

pros

cons

Answer 49

plastic bottles

pros
 Intricate shapes
 Hollow shapes
 Thin walls to
reduce weight and
cost
 Good for mass
production

cons
 High set up costs
 Expensive moulds
to design and
make

Question 50

vacuum forming
products

pros

cons

Answer 50

Products:
Yoghurt pots
Blister packs
Chocolate box
inserts
Packaging

pros 
 Good for batch
production
 Inexpensive
 Relatively easy to
make the moulds

cons 
 Accurate mould
design needed to
prevent webbing
 Large amounts of
waste material
produced

Question 51

extrusion
products

pros

cons

Answer 51

drain pipes
tubes

pros 
 Continuous
 High production
volumes
 Low cost per unit
 Limited complexity
of parts

cons
 Uniform cross-
sectional shape

only

Question 52

rotational moulding
products

pros

cons

Answer 52

Buckets
Footballs
Oil drums
Traffic comes

pros 
 The investment in
equipment and
tooling is less than
vacuum forming
and blow
moulding.
 No seams
 Uniform wall
thickness
 Metal inserts can
be added to the
mould

cons
 Lower volume
production
 Labour intensive

Question 53

blow moulding (parison)
products

pros

cons

Answer 53

plastic bottles

pros 
 Intricate shapes
 Hollow shapes
 Thin walls to
reduce weight and
cost
 Good for mass
production

cons 
 High set up costs
 Expensive moulds
to design and
make