Transcript A564 - Technical aspects of designing and making

Technical aspects of designing
and making
2nd Part of A565 Theory
What topics are covered in the exam?
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Designing & Product Planning
Materials
Tools, Equipment & Processes
Computer Applications
Industrial Production
Health & Safety
Quality
Product Evaluation
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What are the main stages of the design
process?
Explain the differences between the 4
different types of strength
What is the main difference between
softwoods and hardwoods?
Name 4 good things about MDF
Why would you put a finish on wood?
What is the main difference between the 2
different types of plastic?
Designing & Production Planning
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Identification of a design need
Analysing a design brief
Research, data and analysis
Identification of complex associations linking principles of
good design and technological knowledge
• Developing a design specification
• Generating ideas and communicating design
– Modelling and trialing techniques
– Digital media and new technologies
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Production planning
Material selection
Make product
Critical evaluation skills
Material Properties
Performance characteristics of different materials have to be
considered when choosing what products should be made of,
you need to know the definitions of the following properties;
• Hardness – resist cutting and indentations
• Toughness – withstand shocks such as hammering
• Strength = 4 types include the ability to withstand...
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Being pulled apart or stretched
Crushed or compressed
Twisted
Sheared as a result of sideways force like scissors
Elasticity – can be stretched and then return to original length
Flexibility – bend but not break and return to original shape
Ductility – can be stretched into wire
Durable – can withstand bad weather conditions
Malleability – can be hammered, pressed into a shape
Materials - Hardwoods
These come from ‘deciduous’ trees which shed their
leaves in autumn. They are generally hard, tough, and
durable and are reasonably expensive because they
take longer to grow than softwoods.
Beech
UK, Europe
Very tough,
hard, straight,
polishes well
Toys, chairs,
tools
Oak
Europe
Heavy, hard,
tough, good
outdoors,
finishes well
High-class
furniture, boat
building, floors
Mahogany
South America,
Africa
Easy to work,
wide boards
available
Indoor
furniture,
veneers
Materials - Softwoods
• Softwoods come from coniferous trees that remain evergreen
all year round
• Pine is the most common type;
– grown mainly in Northern Europe it is easy to work,
knotty, durable, widely available and cheap
– It is most commonly used for construction work and cheap
furniture
Materials – Manufactured boards
• These are wood-based materials that are
made by compressing and bonding thin sheets
of wood (plywood) or particles (chipboard or
MDF) together with adhesive.
• Advantages over solid woods;
– More stable as they don’t have grain
– Available in large sheet sizes
– Easier to buy from DIY shops
– Less expensive
THEY DON’T GROW ON TREES!!
Wood Finishes – Protect or Decorate
Wood Finish Details
Paints
Water-based paints are not durable. Oil-based paints
are tough, hard wearing and weatherproof. Acrylic
paints are quick drying.
Varnishes
Polyurethane varnishes give clear, tough and hardwearing finish = plastic coating that doesn’t go into
wood. Can get them in quick-drying. ‘Yacht’ varnish
provides waterproofing.
Stains
Do not protect wood. Used to enhance the look of
wood by showing off grain or colouring it to look like
different, more expensive wood or bright colour. Not
easy to apply and can look patchy.
Wax
Beeswax is sustainable, natural finish for wood that
leaves dull gloss shine. It is applied straight on bare
wood after it has been sanded and sealed with oil.
Polishing
Build up layers of clear polish, sanding between each
coat, which enhances look of grain. Also used to seal
wood before waxing.
Example Product
Materials - Plastics
There are 2 ‘families’ of plastics;
Key Terms;
• THERMOPLASTICS = such as acrylic, can be heated to make them
soft so they can be shaped, this can be repeated many times.
– PLASTIC MEMORY = is the ability of thermoplastics to return to their
original state after reheating
• THERMOSETTING PLASTICS = such as epoxy resin, can also be
heated to make them soft so they can be shaped, but this can
only be done once. They are particularly useful for making plastic
products that are resistant to heat
• DYES = can be added to plastics to make them a specific colour all
the way through unlike woods or metals that can only be coloured
on their surface.
Materials – THERMOPLASTICS
Metal
Picture
Properties
Uses
Acrylic
Stiff, hard, clear, durable
outdoors, easily machined
and polished, good range of
colours, does scratch easily
Illuminated signs,
aircraft canopies,
perspex sheet, car
rear-light clusters,
school projects
ABS
Tough, high-impact strength,
lightweight, scratch-resistant,
chemical resistance, excellent
appearance and finish. Good
for injection moulding
Kitchenware,
safety helmets, car
parts, telephones,
food mixers, toys
Low-density
Polythene
Range of colours, tough,
flexible, good electrical
insulator and chemical
resistance
Washing-up liquid,
detergent and
squeezy bottles,
bin liners, carrier
bags
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9.
What is the main difference between softwoods and
hardwoods?
Name 4 good things about MDF
Why would you put a finish on wood?
What is the main difference between the 2 different types
of plastic?
What are the 2 parts of Araldite glue (epoxy resin)?
What are the 2 main types of metals? What are the
differences between them?
What is the main difference between an alloy and an
element?
What is ‘work hardening’? And what is the heat treatment
method that you can use to remedy it?
Name 3 finishes that can be used to stop mild steel from
rusting.
Materials – THERMOSET PLASTIC
Metal
Picture
Properties
Uses
UreaFormaldehyde
Stiff, hard, brittle, heatresistant, good electrical
insulator, range of colours
White electrical fittings,
domestic appliance parts,
wood glue
Epoxy resin
Good chemical and wear
resistance, resists heat to
250ºC, electrical insulator
Adhesives such as Araldite
used to bond different
materials such as wood,
metal and porcelain
Polyester Resin
When laminated with
glass fibre becomes
tough, hard and strong,
brittle without
reinforcement
GRP boats, chair shells, car
bodies
Materials - Metals
Key Terms;
• FERROUS metals contain iron, like steel – they rust and are
magnetic
• NON-FERROUS metals don’t contain iron, like aluminium and
copper – they don’t rust and aren’t usually magnetic
IRON
PURE METALS are made
from one single element
ALLOYS are made from
mixtures of different elements
Materials – FERROUS Metals
Metal
Picture
Composition
Properties
Uses
Mild Steel
Alloy of iron
and 0.150.30% carbon
High tensile
strength,
ductile, tough,
poor resistance
to corrosion
General
purpose, nails,
car bodies,
nuts & bolts,
girders
Stainless Steel
Alloy of steel
with 18%
chrome and
8% nickel
Resistant to
corrosion ,
hard, tough,
difficult to
work
Sinks, dishes,
cutlery,
kitchenware
High-speed
Steel
Mediumcarbon steel
with tungsten,
chromium,
vanadium
Retains
hardness at
high temps.
Can only be
ground
Drills, Lathe
cutting tools
Materials – NON FERROUS Metals
Metal
Picture
Composition Properties
Uses
Aluminium
Pure Metal
Light, soft, ductile,
malleable, corrosion
resistant, polishes
well
Aircraft bodies,
saucepans,
cooking
utensils, cans,
foils, packaging
Copper
Pure Metal
Corrosion resistant,
malleable, ductile,
tough, good
conductor of heat
and electricity,
easily joined
Electrical wire,
printed
circuits, central
heating pipes
Brass
Alloy of 65%
copper, 35%
zinc
Corrosion resistant,
heat and electrical
conductor, casts
well, polishes well
Castings,
forgings,
ornaments,
boat fittings
Heat Treatment of Metals
Key Point – The properties of some metals can be altered to suit
particular applications by the use of heat treatment, which involves
heating and cooling the metal in a carefully controlled way.
• Hardening – make steel much harder but can be brittle.
Do this by heating until cherry red and then quenched in oil.
• Tempering – make steel that has been hardened more tough.
Do this by heating to certain temperature
(between 230ºC – 300ºC) and then quench in oil.
• Case hardening – make outer surface of steel very hard.
Do this by heating to cherry red, dipping in carbon powder,
quench in water.
• Annealing – Relieve problems caused by work hardening
(when you hit/bend a metal it can become fragile and brittle).
Do this by heating it to a certain temperature (depending on
type of metal) and then allowing it to cool as slowly as possible.
Metal Finishes – Protect or Decorate
Metal Finish
Details
Primers and Paints
This creates a thin barrier between ferrous
metal and oxygen. Must clean surface first
and then apply evenly. Primer and then Paint.
Electroplating
Ferrous metal is coated in thin layer of nonferrous metal by fusing it on using electricity.
The most common is chrome-plating on car
parts.
Anodising
Used on aluminium, passing electricity
through it thickens an oxide layer on it’s
surface. Coloured dyes can be added to
process – Maglites.
Dip-coating
Heat metal to 180ºC in oven and then dip in
thermoplastic powder. Good for making
grippy handles on metal tools.
Polishing
Polishing compound is added to non-ferrous
metal and then buffed to high shine. Can be
protected with clear lacquer (spray-on
varnish)
Example Product
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10.
What are the 2 parts of Araldite glue (epoxy resin)?
What are the 2 main types of metals? What are the differences
between them?
What is the main difference between an alloy and an element?
What is ‘work hardening’? And what is the heat treatment
method that you can use to remedy it?
Name 3 finishes that can be used to stop mild steel from
rusting.
What type of material is an SMA? What does it do?
What is an LCA? Why are they important?
‘Knobs’, ‘screws’ and ‘nuts’ are all funny words but what are
they all types of?
In RM what does the word ‘wasting’ mean?
What tool is used to make wood and metal components with
cylindrical cross sections?
SMART Materials
Metal
Picture
Properties
Uses
Shape Memory
Alloys
SMAs can be bent to a shape
at room temp. but will then
return to original shape when
heated to certain temp.
Move parts in robots,
open and close valves,
teeth braces.
Thermochromic
pigment
This is paste that can be added
to acrylic paint. When it is
heated the paint goes clear.
When it cools the colour
comes back.
Kitchenware, baby
feeding spoons, drink
stirrers, and childrens’
toys
Thermochromic
sheet
This is a black plastic material
that when it reaches a certain
temperature turns different
colours.
Electronic circuitry,
food containers,
children’s
thermometer.
Environmental & Sustainability Issues
You need to know about;
• Selection of materials based on a consideration of
the environment and sustainability
• The application of the 6Rs: Reduce, Reuse, Rethink,
Refuse, Repair and Recycle.
• ‘Life Cycle Analysis’ (LCA).
• ‘Design for disassembly’ and the
importance of recovering parts and
materials from end-of-life products.
Pre-manufactured Components
SCREWS – ROUND
HEAD
SCREWS –
COUNTER SINK
NAILS
NUTS & BOLTS
KNOCK-DOWN
FITTINGS
HINGES
KNOBS
CATCHES
Design Issues – Making products easy
and safe for humans to use
• Anthropometrics
– “The measurement of humans”
Design Issues – Making products easy
and safe for humans to use
• Ergonomics
– Using anthropometric data to design products so
they are easier and more comfortable for humans
to use
How is ergonomics involved in the Design Process?
Product Designer
Basic Product
Ergonomically
designed chair
Anthropometric Data
Tools & Processes - WOOD
MARKING OUT
Tool
Picture
Use
Safety
Pencil
Create lines that
are clearly visible
on wood and can
be erased
Sharp point
Steel Rule
Measure accurately
and draw straight
lines
None
Try Square
Marks line at 90º to None
square edge
Marking Gauge
Scratches parallel
lines to edge
Sharp point
Tools & Processes - WOOD
WASTING (CUTTING & SHAPING)
Tool
Picture
Use
Safety
Coping Saw
Cut curved lines in
thin wood and
plastic
Sharp blade
Tenon Saw
Cut straight lines in
thicker wood
Sharp blade
Scroll Saw
Same as coping saw Sharp blade but
but faster because
moves faster. Blade
it’s electric
can snap which
makes scary BANG!
Band Saw
Cuts curved and
straight lines very
quickly in wood and
plastic
VERY DANGEROUS!
Not for students as
it can cut bits off!
You must be trained
Tools & Processes - WOOD
WASTING (CUTTING & SHAPING)
Tool
Picture
Use
Safety
Jig Saw
Cut curved lines in
wood – good for
cutting holes of
weird shapes
Must clamp wood
down and careful
what you are
cutting underneath
Hand Drill
Cut holes in thin
wood, plastic or
metal
Not much
Cordless
Rechargeable Drill
Cut holes in wood,
plastic, wood –
VERY MOBILE! 
Make sure work
doesn’t move –
wear goggles, no
loose clothes
Pillar Drill
Powerful way to
drill holes in most
things – as long as
they fit on bed
Make sure work is
clamped – wear
goggles, no loose
clothes, long hair
Tools & Processes - WOOD
WASTING (CUTTING & SHAPING)
Tool
Picture
Use
Safety
Twist Drill
Cut holes in wood,
metal and plastic.
Fit in a chuck.
Must clamp work
down and careful
what you are
cutting underneath
Saw Tooth Bit
(Forstner Bit)
Cut holes in wood
which have smooth
sides and flat
bottoms
Wood can burn and
catch fire so drill
slowly and clamp
strongly
Hole Saw
Cuts large discs out
of quite thin wood
– you can’t stop
halfway
Wood can burn and
catch fire so drill
slowly and clamp
strongly
Chuck &
Chuck Key
Used to fit drill bits
in pillar drills
Make sure chuck is
done up tightly and
then remove key
before turning on!
Tools & Processes - WOOD
WASTING (CUTTING & SHAPING)
Tool
Picture
Use
Safety
Files
Shape and smooth
metal, plastic and
wood. Have lots of
‘teeth’
Clamp work
Chisels
Used to cut and
shape wood. Often
used to make joints.
Hit with mallet.
Super sharp!
Always point chisel
away from body
and clamp work
Wood Planes
Remove shavings
from wood to make
surfaces flat and
right size.
Plane blade is super
sharp so keep away
from body and
clamp work
Wood-Turning
Lathe
Used to make
cylindrical shapes
and bowls from
wood
Big stuff spinning
quickly and very
sharp tools!
Goggles etc.
Tools & Processes - WOOD
WASTING (CUTTING & SHAPING)
Tool
Picture
Use
Safety
Power Router
Cutting grooves,
fancy edges and
complex shapes in
wood
Really dangerous
because of exposed
spinning blade and
lots of stuff flying off
CNC Milling
Machine
Example 1
Cutting really
complex shapes very
accurately and
quickly in wood
Follow safety
procedures for
machine – all guards
working?
Tools & Processes - METAL
MARKING OUT
Tool
Picture
Use
Safety
Scriber
Create lines that
are clearly visible
on metal by
scratching the
surface
Sharp point
Centre Punch
Marks centre of
Have to hit it with a
hole to be drilled by hammer – so mind
making a dent for
your fingers!
bit to fit into
Engineer’s Square
Marks line at 90º to None
square edge
Dividers
Scratch circles and
arcs of different
sizes on metal
Sharp points
Tools & Processes - METAL
WASTING (CUTTING & SHAPING)
Tool
Picture
Use
Safety
Hack Saw
Cut straight lines in
metal and plastic –
small teeth
Sharp blade
Tin Snips
Cut straight lines
and curved lines in
thin metal sheet
Sharp blades with
scissor action
Bench Shears
Same straight lines
in slightly thicker
metal sheet = long
handle
Sharp blade with
scissor action – very
dangerous!
Wire Wool
Removes scratches
on the surface of
metal ready for
finishing
Wash hands after
so filings do not go
in eyes
Tools & Processes – METAL & PLASTIC
WASTING & SHAPING
Tool
Picture
Use
Safety
Metal Work Lathe
Make work with a
cylindrical profile
Big stuff spinning
quickly and very
sharp tools!
Goggles etc.
Milling Machine
Cut grooves and
remove very
precise layers of
material
Large powered tool
with spinning cutter
– goggles and
guards needed
Vacuum Forming
Machine
Mould plastic into
different shapes by
sucking around
mould
Grill area gets hot
so keep hands out
and don’t touch
work until cool
Strip heater
Used to bend
plastic along a line
Filament gets very
hot – wear gloves
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9.
10.
What type of material is an SMA? What does it do?
What is an LCA? Why are they important?
‘Knobs’, ‘screws’ and ‘nuts’ are all funny words but what are they
all types of?
In RM what does the word ‘wasting’ mean?
What tool is used to make wood and metal components with
cylindrical cross sections?
Which is the simplest wood joint? Why is this weaker than a
hidden-dowel joint? Why are mitre joints sometimes used?
Why are injection moulding machines used in industry?
What is the main difference between soldering/brazing and
welding?
Explain 5 reasons for why CAD is so good
Explain 3 reasons for why CAM is so good
FIXING – WOOD JOINTS
Tool
Picture
Use
Butt Joint
The simplest of all wood joints. PVA glue is
used to stick plain ends together and then
held in place until dry. This is also the
weakest joint and usually needs to be
strengthened with pins, screws, knock-down
fittings, a metal plate etc.
Mitre Joint
Pretty simple joint. Ends are cut at 45º and
then glued together. Attractive joint as it
hides end grain, used for picture and mirror
frames. Can be strengthened with nails,
screws or staples
Hidden Dowel
Joint
More advanced joint – holes need to be
drilled in both surfaces and then small
dowel is glued in place. Can be used in lots
of situations – use this in the exam if you
can!!
If you’re keen then check out these other joints – they might ask you to name them (only 1-2 marks)
Tools & Processes – INDUSTRIAL
Tool
Picture
Use
Safety
PLASTIC
Injection Moulding
Machine
Video 1 Video 2
Making lots of
identical complicated
plastic shapes
Industrial machines
have loads of safety
equipment and fail
safes
PLASTIC
Blow Moulding
Machine
Making hollow plastic
shapes like bottles
Industrial machines
have loads of safety
equipment and fail
safes
PLASTIC & METAL
Extrusion moulding
Make long rods with
various cross-section
shapes
Industrial machines
have loads of safety
equipment and fail
safes
METAL
Die-casting
Making lots of
complicated metal
shapes
Industrial machines
have loads of safety
equipment and fail
safes
Joining Materials
Tool
Picture
Use
Safety
PLASTIC
Tensol Cement
Sticking Plastics
together
Nasty stuff – irritant and
toxic, wear gloves and
goggles
WOOD
PVA Wood Glue
Gluing wood
Not much – clamp work
together – used lots will help join
in joints to
strengthen them
METAL
Soldering
& Brazing
Its like gluing 2
metals together
with metal glue –
fairly versatile
Very hot process so gloves,
apron etc. need to be
worn
METAL
Welding
Used to
permanently melt 2
metals together –
very strong but
tricky to do
Very hot process so gloves,
apron etc. need to be
worn. Also need to wear
welding mask to protect
eyes
Computer Aided Design (CAD)
Designers can use computer packages like 2D Design, Autocad,
Google SketchUp to design, Model and Test ideas before they go
into production. It is particularly useful because;
• Computers can be used to make changes to a design and edit it
without having to redraw it.
• Computers can be used to produce very accurate drawings and
dimension exactly to what is drawn.
• Computers can produce photorealistic models without having to
make them
• You can see what it will look like in 3D – spin it around so you
can see all angles
• Computers can show or simulate how a product will behave
without having to undertake expensive testing.
Computer Aided Manufacture (CAM)
Designers can use machines that are controlled by
computers to cut and shape material. They are called
Computer Numerically Controlled (CNC). This is good news
because;
• Computers do not make mistakes if programmed
properly.
• Computers give reliable and consistently high standards
of manufacture.
• Computers achieve quicker production times. Complex
shapes and designs can be created easily.
• CNC Lathe
• CNC Miller/Router
• Laser Cutter
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2.
3.
4.
5.
6.
7.
8.
9.
10.
Which is the simplest wood joint? Why is this weaker than a
hidden-dowel joint? Why are mitre joints sometimes used?
Why are injection moulding machines used in industry?
What is the main difference between soldering/brazing and
welding?
Explain 5 reasons for why CAD is so good
Explain 3 reasons for why CAM is so good
What is main differences between; one-off, batch, and mass
production?
How does rapid-prototyping work?
What is Globalisation? Why is it a good/bad thing?
Give 5 examples of health & safety equipment that could be used
in a factory.
What does the ‘corrosive’ safety symbol look like?
Basic Production Methods
What we do to a material in order to make something is called a
process, but a method is how we apply that process to manufacture
one or more products. A designer has to decide which production
method should be used to make their products based on the numbers
and quality required. There are 3 main methods;
One-off Production
Used to produce one or two very
special products, usually by highly
skilled craftsmen who are paid lots
of money. It is very time-consuming
as each part is made individually
and therefore is very expensive.
Products have a ‘hand made’ feel
and therefore are usually
considered high quality.
Batch Production
Batch production is used where a number of identical products are made,
and special tools are normally used to make them. The size of the batch can
be anything from 10 – 10000 but can be repeated at any time if more orders
are made.
Production processes like injection-moulding and die-casting are often used
as once the moulds are made for the parts they will be suitable for future reorders. These moulds are expensive to make at first but this cost is spread
over the number of products made so becomes cheaper as more are made.
The workers are not as skilled as those in one-off production and therefore
are paid less. Using moulds, jigs and templates improves consistency but as
products are usually hand assembled by low-skilled workers this can result in
lower build quality.
High-Volume Production
Sometimes referred to as ‘mass-production’ – this deals with the
production of very large numbers of identical products. A lot of
specialist equipment is needed and it is very expensive to set up
therefore it is only economical to use this method if large numbers of
products are made.
This is a very fast method of production and only a few skilled workers
are needed to maintain and manage the machine. Assembly lines are
often used which keep production almost continuous. Robots are used
to improve build quality, accuracy and consistency.
This type of production was first used by Henry Ford when he made
the Model T.
Rapid Prototyping
CAD packages allow the designer to view a 3D image of a
new design on-screen. A number of systems are now
available to quickly turn these designs into models which
can be handled and used for market research purposes.
These machines are called rapid-prototypers. First
computer software breaks the 3D drawing into thin
horizontal slices. These ‘layers’ are then sent to the
machine in sequence where they are built up to make the
model.
One of these rapid-prototyping systems is called stereolithography which uses a laser to harden layers of liquid
plastic resin to make the 3d shape.
Globalisation
This is where companies become multi-national, this means
they make products in countries all over the world and can also
sell their products all over the world.
This is good because;
• They can make products cheaper as labour costs are often less and
also they are closer to raw materials
• Factories can be closer to new markets – for example Nissan (Japan)
make cars in the UK to sell in Europe to save on transport costs
It can be bad because;
• Labour laws in emerging economies (like China, India etc.) are not as
strict and this can lead to mis-treatment of workers
• Companies often have to ship products long distances which can be
very bad for the environment because of all the CO2 produced
Health & Safety
Understand the importance of personal safety when
engaged in designing and making activities, including:
• Personal protective equipment
• Machine guards
• Dust and fume extraction
• Waste disposal
Use the link above to learn theory and complete activity
You also need to know about simple risk assessment
Risk = (How dangerous it is) X (How likely it is to happen)
C.O.S.H.H.
Control of Substances Hazardous to Health
The COSHH Regulations (2002) states general
requirements on employers to protect
employees and other persons from the hazards
of substances used at work by risk assessment,
control of exposure, health surveillance and
incident planning. There are also duties on
employees’ to take care of their own exposure
to hazardous substances and prohibitions on
the import of certain substances into the
European Economic Area.
Safety Symbols
• Blue signs are mandatory – you must do what
they say
• Black and Yellow signs are warnings
• Red diamonds are warnings of hazards
Quality
It is important that you know that products need to be a certain quality to be sold
commercially.
• Design – they have to be designed in such a way that they will
perform the correct function
• Manufacture – they need to be made so they are both safe and
don’t fall apart.
– To do this the correct materials need to be chosen and the product must be
made accurately
Quality Control
To help with this process companies will check a certain number of the
products. This is called inspection, and would generally include checks
on;
– Accuracy of sizes
– Overall appearance
– Surface finish
– The consistency, composition, and structure of the materials