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SECTION 5:material and component consideration
5.1 what factors influence the selection of materials that are used in products?
Look around the room, what products can you see? I bet you can't see one that isn't made out of a material...
This section is all about understanding why particular products are made from the materials they are.
before you go any further, have a look at and remind yourself of the gcse content relating to the section below
Take a look below to explore the reasons we select and make the products from the materials we do.
Functional performance
How well does a material perform?
Think about whether it needs to be tough, strong or malleable etc? Is it a suitable material for the job? would a different material do the job better? Why are bridges not made out of sliced bread?
aesthetics
This is all to do with the appearance of a material or component and the overall look it gives the product.
What does a material look like?
how does it feel?
what appearance/ texture does it have?
properties and characteristics
each material you come across has a different set of properties and characteristics. It is these that determine whether it is suitable for a particular job. They can be broken down into the following categories:
Mechanical properties - how the material reacts to forces
Physical properties - the handling properties of a material
Chemical properties - how a material reacts to contact with substances
manufacturing properties - how a material can be manipulated with tools and machinery.
a materials properties and characteristics can be enhanced by adding a surface finish such as paint, dip coating or powder coating.
Stylish looking product
vs
garish looking product
cost and availability
Cost - this is quite obvious, what is the cost of the material? Things that might influence this are material origin, transportation costs, availability or demand. Think back to the example of china and steel we spoke about in lesson.
Cheaper materials often lack quality or meet the standards of many manufacturers.
Consider what you need to do to the raw material. can you save time and money by buying it pre-treated, pre-machined or prefinished?
Availability - this relates to how how easy it is to get your hands on the material. can you pop down to your local Wickes or B&Q to pick it up or is it more specialist than that? consider the type of material and what size you are needing it to be.
environmental considerations
it would seem that the whole world their dog has an interest in being gentler to the environment - this is great as there is a lot of things we need to reduce to improve its existence and quality for future generations.
When you design a product and select materials to build that product you must consider the impact they have on the environment. This can range from issues like:
recyclability - transportation - material sourcing - energy use
There are lots of incentives and government run schemes to help encourage manufactures to consider their impact.
You as a designer must consider sustainability and the 6R's
social, Moral, cultural & ethical considerations
Social - the impact of what we do, on peoples lives or community
moral - making the right decision to have a positive impact on our environment. e.g. not designing something that might allow someone to commit an illegal act. think drugs/ guns etc.
cultural - this is related to culture and not causing offence to a particular group of people. a simple example might be that in china red is the colour for luck, but in Africa it is the colour for mourning, or that the use of particular animal produce is offensive to particular religions, etc.
ethical - no clear right or wrong answer (often opinion) but impact peoples lives, habitats or the environment. Ethical Trade refers to us having confidence that workers have been treated appropriately in terms of health & safety, fair pay, working hours etc.
consider these
Materials that are a bit different:
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Softwoods
From coniferous (cone bearing trees) that grow all year round, these are generally softer (easier to work with) and need more treatment than hardwoods to enhance their properties. They grow quicker and are more easily available, making them more affordable. Most softwoods originate from the northern hemisphere.
Examples are:
> Pine (strong and stiff - joinery and building frames)
> Spruce (soft and low density - good for structural use)
> Fir (soft, strong and medium density - structural use and joinery)
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5.2 what materials and components should be selected when designing and manufacturing products and prototypes?
There are many different types of materials available for product manufacture and when designing your own, you must carefully consider the most appropriate. Considering the factors above, you may find some of the following right for you.
timbers & manufactured boards
Timber varies hugely, from tree to tree - aesthetics, size, strength (bending, compression, tension & shear), density, machinability, natural defects and more. Around the world there are numerous types that are harvested and then converted to be used for the manufacture of all sorts of products, from chairs to houses, spoons to pencils.
So the question is, which would you choose?
Natural timbers
Things to consider when selecting natural timbers:
> Strength - compression and tension
> moisture content - changing in shape
> machineability
> aesthetic properties
> cost
> available sizes
> consistency
> joining and assembly methods
> defects
> finish types
Hardwoods
From deciduous (broad leaved trees) that grow during the summer months, these are generally harder (harder to machine) and have improved properties compared to softwoods. They grow slower, are less easily available and are more expensive.
Examples are:
> Oak (strong & tough (red oak is more durable than white oak) - joinery & furniture)
> Beech (Stronger than oak - furniture & tools)
> Teak (Very durable & high resin content - outdoor furniture)
Manufactured boards
Naturally, natural timbers are only available up to certain sizes. Because of this, and our demand/ desire to manufacture with timber, we have developed a range of timber based material which can be used for various applications. Examples of these are:
> Laminboard: Plywood
> Compressed board: Blockboard
> Compressed board: Medium density fibreboard (MDF)
> Flexi-ply - flexible plywood
Things to consider when selecting manufactured boards:
> Available in large sheets - 1220mm x 2440mm
> Dimensionally stable (all directions)
> Boards are consistent in quality
> Are available prefinished - pvc or veneer
> can be flame retardant
Trees are also turned into paper and boards
Find out how here
Metals
Similar to timbers, there are many different types of metal, many with different uses and applications. Most metals use huge amounts of energy to process them from a raw state but can be recycled and reused repeatedly. Metals can be categorised into ferrous, non-ferrous and alloy metals.
Ferrous Metals
The term 'ferrous' comes from the term 'ferrite', which refers to iron - so ferrous metals contain iron, and because of this they rust when exposed to moisture.
iron can be converted into steel by adding carbon. Different amounts of carbon (high tensile strength) added can produce different types of steel:
> Mild steel - up to 0.25% carbon (easier to machine)
> medium carbon steel - 0.25 - 0.5% carbon
> high carbon steel - 0.5 - 1.5% carbon (tool steel)
Non-ferrous metals
These metals do not contain ferrite (iron) and do not rust. the most commonly used is aluminium as it has so many uses. Other non-ferrous metals include:
zinc
copper
tiN
tungsten
brass (alloy of copper & zinc)
bronze (alloy of copper & tin (others used too)
what will cut what? who is harder?
Refer to the textbook
P153
Refer to the textbook
P154
Things to consider when selecting metals:
Depending on the product you are going to manufacture, you will need to select a material appropriate for the job. A metal may be the best selection and may be because of one of the following characteristics:
> strength
> Hardness
> Elasticity
> toughness
> brittleness
> ductility
> malleability
How would you test your metal for its suitability?
There are numerous ways to work metals (see section 7) but you need to know that they behave differently depending on the temperature they are at. They can be:
> normalised
> hardened
> Hardened and tempered
> Annealed
> Cold-worked
* A Carbon steel
* A Non-ferrous alloy
thermosoftening & tHermosetting polymers
'Plastics' ... generally speaking, they are misunderstood as planet killing materials when actual fact they are incredible and if approached and planned correctly, don't have to have a negative impact on the environment.
So, what is a polymer?
A 'poly' (meaning many), and a 'mer', (meaning single unit)
In short, it's a collection/ string of monomers joined together. by joining different monomers you can create different polymers, aka, plastics.
Polymers are fantastic. There are various types available which can be used for a huge number of different applications. Some examples of their qualities are:
thermal insulators
electrical insulators
easily moulded
good strength-to-weight ratio
flexibility
rigidity
toughness
Aesthetically appealing
*it's key to note that different polymers hold different qualities
What is the difference between a thermoploymer and a thermosetting polymer?
Thermopolymer
These can be reheated and reshaped many times and can be used for processes such as vacuum forming, blow moulding and injection moulding.
Examples include:
Polystrrene (PS/ GPPS/ HIPS/EPS)
Low density polyethylene (LDPE)
High Density Polyethylene (HDPE)
Polymethyl methacrylate (Acrylic)
polypropylene (PP)
Polyvinyl Chloride (PVC)
Acrylonitrile-butadine-styrene (ABS)
polyethylene-terephthalate (PET/E)
Thermosetting polymer
Unlike thermopolymers, these can not be reheated and reshaped. Once manufactured into their intended shape that is it.
Examples include:
Urea formaldehyde
Phenol formaldehyde
Melamine formaldehyde
Polyester resin
Epoxy resin (high melting point)
Epoxy resin (low melting point)
POLYMERS
Which is material is best for what?
How do you know which one to select?
Using the material selection charts you can look at comparative information about different materials - this may help you select the correct one for your project. In addition to this information, it is also worth considering how the material performs under a particular force -
'Traditional' materials might not always be the best choice for a solution, but with technological advancements and developments in manufacturing techniques, there are newer materials being made available to us all the time. Some have been discussed in other sections but below we will look at some:
composite materials
these are materials made up from a combination of two or more other materials, with one type being sandwiched between two layers of another or mixed to combine the positive properties of the materials.
Glass reinforced plastic (GRP)
Polyester Resin (or epoxy) used to glue fibres of glass together - the combination creates strength and rigidity.
+
Resistant to corrosion
light
hardwearing
thin section
low in cost
-
time consuming
Boat hulls & canoes
Carbon Fibre Reinforced Plastic (CFRP)
Polyester Resin (or epoxy) used to glue fibres of carbon fibre together - the combination creates strength and rigidity.
+
Resistant to corrosion
light
hard wearing
thin section
Lighter than GRP
Can be 3d printed
Strength to weight ratio
-
expensive
Stronger than steel and aluminium
Car parts / helmets / bikes
D30
a material like no other!
modern materials
These materials have been intentionally developed to have improved/ alternative characteristics to the original/ previous version.
Examples include:
E-Textiles
.
High - performance alloys
.
Carbon nanotubes
.
Nano materials
.
Super Alloys
.
Graphene
.
Bioplastics
.
nanocrystalline materials
.
Sandwich panels
.
Rare earth magnets
.
smart materials
These are materials that react to a stimulus such as light, heat, or current and can change in form or appearance. Examples are:
Thermochromic materials
.
Electrochromic materials
.
Piezochromic materials
.
Shape memory alloys (SMA)
.
Photochromic materials
.
Hydrochromic materials
.
Solvatochromic materials
.
Shape memory Polymers (SMP)
.
Polymorph
.
Conductive paint
.
Smart/ performance textiles
.
geotextiles
Fabrics used in construction, civil engineering and landscaping to help stabilise the ground are referred to as geotextiles. They are a woven or non-woven, polypropylene or polyester sheet which:
Are permeable (let water & air/ gas through)
block soil, silt & stones
reinforce & stabilise the ground
keep ground layers separate
promote drainage/ airflow
act as a weed barrier
use with:
roads, carparks, runways, patios, railways, etc
Woven
non-Woven
holes are needled to the appropriate size
5.3 why is it important to consider the properties/ characteristics of materials when designing and manufacturing products?
It is key that you have a comprehensive understanding of a range of material properties and characteristics. Understanding these will help you to determine/ choose the right material for the right job.
Refer to the textbook page 193 for definitions and contextual examples of the key characteristics/ properties. You can test/ quiz yourself using the Memrise link at the top of the page.
Video links to support are below:
Density
tensile strength
Compressive strength
strength-to-weight ratio
hardness
durability
thermal conductivity
electrical conductivity
corrosion resistance
stiffness
elasticity
plasticity
impact resistance- toughness
brittleness
malleability
ductility
machinability
Flammability
Absorbency
Washability
Resistance to decay
Biodegradability
Time to test your knowledge. Click on the link below and enter the room ncbdtfIVE
log into memrise and then click below
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test your section 5 key terms understanding here
Design Technology @ NCB
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