This can be viewed better in Internet Explorer
Materials information
Metals and Alloys
Aluminium alloys
Mild steel
Alloy steels
Stainless steels
Cast iron
Copper
Brasses
Nickel alloys
Titanium alloys
Magnesium alloys
Zinc alloys
Lead
Gold
Glasses
Ceramics
Alumina
Silicon carbide
Silicon
Diamond
Zirconia
Brick
Concrete
Polymers
Porcelain
Polycarbonate
Polythene
Polystyrene
PMMA
Polypropylene
PET
Nylon
Urea formaldehyde
uPVC
Composites
CFRP
GFRP
Wood and Wood Products
Pine
Balsa
Oak
MDF
Paper
Overview
Aluminium is a lightweight, reasonably cheap metal widely used for packaging and transport. It has only been widely available and used for the last 60 years.
- Raw aluminium has low strength and high ductility (ideal for foil). Strength is increased by alloying, e.g. with Si, Mg, Cu, Zn, and heat treatment. Some alloys are cast, others are used for wrought products.
- Aluminium is quite reactive, but protects itself very effectively with a thin oxide layer. The surface can be "anodised", to resist corrosion and to give decorative effects.
Design Issues
Design strengths:
- High strength-to-weight ratio
- High stiffness-to-weight ratio
- High electrical and thermal conductivity
- Easy to shape
- Easy to recycle
Design weaknesses:
Typical Products
- Aircraft
- Bicycles
- Car engines
- "Space frame" car bodies
- Drinks cans
- Window frames
Environmental issues
- Aluminium production uses lots of energy (4% of total US energy consumption!)
- Aluminium is easily recycled - this only uses 1% of the energy needed to produce the metal.
- Aluminium use in cars is growing rapidly - low weight means good fuel economy and low emissions metal.
Overview
- Steels are the most important engineering materials, and cover a wide range of alloys based on iron and carbon. The strength of iron-carbon alloys, particularly after heat treatment, has been exploited for thousands of years (since the "Iron Age"). Modern steels and ferrous alloys have mostly been developed since the Industrial Revolution.
- Mild steel contains 0.1-0.2%C. They are cheap, strong steels used for construction, transport and packaging.
- All steels have a high density and a high Young's modulus. The strength of mild steel is improved by cold working. It is inherently very tough.
- Mild steel rusts easily, and must be protected by painting, galvanising or other coatings.
Design Issues
Design strengths:
- High strength-to-weight ratio
- High stiffness-to-weight ratio
- Good strength with high toughness
- High stiffness
- Very cheap
- Easy to shape
- Easy to weld
- Easy to recycle
Design weaknesses:
- High density
- Poor electrical and thermal conductivity
Typical Products
- Large structures - bridges, buildings, oil rigs
- Car body panels, trains
- Machine tools
- Pressure vessels
- Food packaging
- Nails
Environmental issues
- Steel production uses a lot of energy, but less than most metals.
- Steel is easily recycled - as it is usually magnetic it is easily sorted from mixed waste.
Overview
- Steels are the most important engineering materials, and cover a wide range of alloys based on iron and carbon. The strength of iron-carbon alloys, particularly after heat treatment, has been exploited for thousands of years (since the "Iron Age"). Modern steels and ferrous alloys have mostly been developed since the Industrial Revolution.
- Alloy steels are mostly fairly cheap, covering a range of carbon contents (0.1-1.0%). The medium to high carbon content steels respond well to heat treatment (such as "quenching and tempering") to give very high strength and good toughness for gears, driveshafts, pressure vessels, tools.
- Alloy steels containing other elements as well as carbon are classified into low alloy and high alloy, depending on the amount of additional alloying elements. Heat-treated high alloy steels give very high strengths, but are more expensive.
- All steels have a high density and a high Young's modulus. The strength and toughness of alloy steels can be varied enormously by alloying, working and heat treatment.
- Alloy carbon steels rust easily, and must be protected by painting or other coatings.
Design Issues
Design strengths:
- High strength with good toughness
- High stiffness
- Mostly very cheap
- Quite easy to shape
- Easy to weld
- Easy to recycle
Design weaknesses:
- High density
- Poor electrical and thermal conductivity
Typical Products
- High integrity structures - oil rigs
- Bicycles
- Railway track
- Bearings, gears, shafts
- Cutting tools
- Pressure vessels
- Hand tools (spanners, hammers etc)
Environmental issues
- Steel production uses a lot of energy, but less than most metals.
- Steel is easily recycled - as it is usually magnetic it is easily sorted from mixed waste.
Overview
- Steels are the most important engineering materials, and cover a wide range of alloys based on iron and carbon. The strength of iron-carbon alloys, particularly after heat treatment, has been exploited for thousands of years (since the "Iron Age"). Modern steels and ferrous alloys have mostly been developed since the Industrial Revolution.
- Stainless steels are more expensive steels containing typically 25% of Chromium and Nickel, which gives excellent corrosion resistance and also high strength and toughness (used for cutlery, chemical plant and surgical instruments).
- All steels have a high density and a high Young's modulus. The strength and toughness of stainless steels can be varied by alloying, working and heat treatment.
- Stainless steels are mostly very resistant to corrosion, and do not need to be protected.
Design Issues
Design strengths:
- High strength with good toughness
- High stiffness
- Mostly very cheap
- Quite easy to shape
- Quite easy to weld, but not as easy as for carbon steels.
- Easy to recycle
Design weaknesses:
- High density
- Poor electrical and thermal conductivity
Typical Products
- Bearings
- Pressure vessels
- chemical plant
- Cutlery
- Surgical instruments
Environmental issues
- Steel production uses a lot of energy, but less than most metals.
- Steel is easily recycled - though most stainless steels are not magnetic, so they are harder to sort from mixed waste.
Overview
- Cast irons were the forerunners to steels, being iron alloys of high carbon content (2-4%). The strength of iron-carbon alloys, particularly after heat treatment, has been exploited for thousands of years (since the "Iron Age"). Modern steels and ferrous alloys have mostly been developed since the Industrial Revolution.
- Cast irons are cheap, high carbon alloys of moderate strength and which can easily be cast to shape. Cast irons have a high density and a high Young's modulus. They tend to have poor toughness, but their strength and toughness can be improved by alloying and heat treatment.
- Cast irons rust easily, and must be protected by painting or other coatings.
Design Issues
Design strengths:
- High strength with good toughness
- High stiffness
- Mostly very cheap
- Easy to weld
- Easy to recycle
- Easy to machine
Design weaknesses:
- High density
- Poor electrical and thermal conductivity
Typical Products
- Car engines
- Brake discs
- Machine tools
Environmental issues
- Iron production uses a lot of energy, but less than most metals.
- Cast iron is easily recycled - as it is magnetic it is easily sorted from mixed waste.
Overview
- Copper is a quite expensive metal with high electrical conductivity (good for electrical wiring) and good corrosion resistance (good for plumbing).
- Pure copper has low strength and high ductility. Its strength may increased by alloying with tin (to make bronze), with zinc (to make brass) or with nickel (for coins).
- Bronze has been used for thousands of years for cast artefacts such as statues and has been worked for weapons since the "Bronze Age". It has been used since medieval times for large castings such as bells.
Design Issues
Design strengths:
- High electrical and thermal conductivity
- Corrosion resistant
- Easy to shape
Design weaknesses:
- Low strength
- Quite expensive
Typical Products
- Electrical wire
- Domestic water pipes
- Coins
Environmental issues
- Copper production uses quite a lot of energy
- Copper is easy to recycle, but the volume of copper in use is small and it can be difficult to sort (e.g. most copper wiring has a plastic sleeve).
Overview
- Brasses are quite expensive alloys of copper and zinc.
- Alloying, working and heat treatment give them much better strength than copper, but with good corrosion resistance.
Design Issues
Design strengths:
- Reasonable strength
- Corrosion resistant
- Easy to shape
Design weaknesses:
Typical Products
- Ornamental fittings
- Plumbing fittings
- Screws
- Bullets
Environmental issues
- Copper and brass production uses quite a lot of energy.
- Brass is easy to recycle, but the volume in use is small.
Overview
- Nickel alloys are dense, stiff, strong alloys used primarily for their strength and corrosion resistance at high temperatures (jet engines).
- Pure nickel has moderate strength, like iron, but alloying with Cr, Co, Mo, W gives the high strength needed in a jet engine. Nickel is also alloyed with copper to make coins.
Design Issues
Design strengths:
- High strength at high temperature
- High corrosion resistance
- High stiffness
- Easy to shape
Design weaknesses:
Typical Products
- Jet engines for aircraft
- Coins
- Tanks for chemicals
Environmental issues
- Nickel production uses quite a lot of energy, but the volume in use is small.
Overview
- Titanium alloys are quite low density, stiff, strong alloys and are expensive. They are used most in sports products (e.g. golf clubs and bicycles) and in aircraft (e.g. engine fan blades).
- Pure titanium has moderate strength, but the standard titanium alloy contains 6% aluminium and 4% vanadium, which gives the high strength needed in a jet engine.
- Titanium is a reactive metal when hot, but has good corrosion resistance at room temperature. It is inert in the body, and is used for medical implants (e.g. hip replacements).
Design Issues
Design strengths:
- High strength, even at high temperatures
- High stiffness
- Chemically inert in body
Design weaknesses:
- High cost
- Chemically very reactive when hot
- Quite difficult to shape - usually cast
Typical Products
- Golf clubs
- performance bicycles
- Fan blades for aircraft jet engines
- Hip replacements, and other medical implants
Environmental issues
- Titanium production uses quite a lot of energy, but the volume in use is small.
Overview
- Magnesium alloys are the lowest density metals, with good stiffness and strength relative to their weight.
- Pure magnesium is alloyed to improve its strength. It has a low melting point. Most alloys are cast, as it has poor formability.
- Magnesium is a reactive metal, which burns intensely. It therefore requires careful handling during casting.
Design Issues
Design strengths:
- Low density
- High stiffness-to-weight ratio
- High strength-to-weight ratio
Design weaknesses:
- Difficult to shape - usually cast
- Chemically reactive
- Poor corrosion resistance
Typical Products
Motorcycle and car wheels
Automotive castings
Environmental issues
- Magnesium production uses quite a lot of energy, but the volume in use is small.
Overview
- Zinc alloys are low density, low melting point alloys used for simple castings of low strength.
- Zinc is resistant to corrosion, and is used to protect steels from rusting by galvanising (e.g corrugated sheet, car bodywork, motorway crash barriers).
Design Issues
Design strengths:
- Corrosion resistant
- Easy to cast
Design weaknesses:
- Low strength
- Poor formability
Typical Products
- Galvanised steel sheet
- Pump housings
- Model cars and toys
Environmental issues
- Zinc production uses quite a lot of energy, but the volume in use is small.
Overview
- Lead alloys are very dense, with the lowest stiffness and strength of all metals. They are used either for their weight (e.g. lead shot), or for their corrosion resistance (e.g. roof cladding), or for their low melting point (e.g. solders, which are lead-tin alloys).
- Lead is a toxic metal, used historically as an additive to paints and petrol. These additions are being systematically removed due to health concerns.
Design Issues
Design strengths:
- Low melting point
- High density
- Corrosion resistant
- Easy to shape
Design weaknesses:
- Low strength
- Low stiffness
- High cost
- Environmental concerns
Typical Products
- Bullets, lead shot
- Roof cladding
- Solders
Environmental issues
- Lead production uses quite a lot of energy, but the volume in use is small.
- Lead in paint and petrol is being reduced or eliminated due to health concerns.
Overview
- Gold is a precious metal, with a very high cost. Its use for jewellery is due to its natural appearance, but also its chemical stability - it does not oxidise at room temperature.
- In engineering applications, gold is used in small quantities in electronics for making electrical contacts since it has a very high electrical conductivity, and does not oxidise.
Design Issues
Design strengths:
- Corrosion resistant
- Easy to cast
Design weaknesses:
- Low strength
- Poor formability
Typical Products
- Jewellery
- Electrical contacts
- Dental fillings
Environmental issues
- Due to its value, gold is mined from rocks containing very small quantities of the metal - it is therefore an energy intensive metal to produce. Its recycling value is of course very high.
Overview
- Glasses are amorphous solids based on silicon oxide (the same as sand).
- Glass is soft and mouldable when hot, making shaping straightforward; when cool and solid it is strong in compression, but brittle and weak in tension.
- Glass is transparent or can be easily coloured. Special glasses are made into fibres for optical communications.
Design Issues
Design strengths:
- Transparent, or easily coloured
- High resistance to corrosion
- Easy to shape
Design weaknesses:
- Low tensile strength
- Low toughness
Typical Products
- windows
- bottles
- ovenware
- optical fibres
Environmental issues
- Silicon oxide (silica) is naturally occurring, but energy is used to purify it to make glass for engineering applications.
- Because of the large energy costs in making glass it is cost effective to recycle it.
Overview
- Alumina is an ionic ceramic, aluminium oxide. It is mainly used for its electrical insulation (e.g. spark plugs) or for its hardness (e.g. cutting tools).
- Like all ceramics, alumina is intrinsically hard and strong in compression, but has low toughness and tensile strength.
- Due to its high melting point, alumina can only be processed in powder form.
Design Issues
Design strengths:
- Excellent corrosion resistant
- Low density
- Resistant to high temperatures
- High electrical resistance.
Design weaknesses:
- Low tensile strength
- Low toughness
- Difficult to shape
Typical Products
- spark plugs
- electrical insulators (e.g. on pylons)
- cutting tools
- grinding wheels
- fuse bodies
Environmental issues
- Alumina is naturally occurring, but energy is used to purify it for engineering application.
Overview
- Silicon carbide is a covalent ceramic. It is mainly used for its very high hardness (e.g. cutting tools), and for its electrical properties.
- Like all ceramics, silicon carbide is intrinsically hard and strong in compression, but has low toughness and tensile strength.
- Due to its high melting point, silicon carbide can only be processed in powder form.
Design Issues
Design strengths:
- Excellent corrosion resistant
- Low density
- Resistant to high temperatures
- High electrical resistance.
- High hardness
Design weaknesses:
- Low tensile strength
- Low toughness
- Difficult to shape
Typical Products
- electrical insulators (e.g. semiconductor substrate)
- cutting tools
- grinding wheels
Environmental issues
- Silicon and carbon are abundant materials, but energy is used to purify them and to produce silicon carbide powder for engineering application.
Overview
- Silicon is the base material used for the manufacture of computer chips, and is therefore one of the most important materials.
- Silicon is doped with very low levels of other elements to give it the particular "semiconducting" electrical properties needed for transistors and microchips.
- To supply the huge demand for computer chips, processes have developed so that it can be produced as very large high purity crystals.
Design Issues
Design strengths:
- Semiconducting properties
Typical Products
- transistors
- computer chips
Environmental issues
- Silicon is an abundant material, but energy is used to purify it for electronic applications.
- It is not yet recycled from computers on any scale, but this may develop in future.
Overview
- Diamond is covalently bonded pure carbon, and has the highest Young's modulus and hardness of all materials.
- It is naturally occurring but can also be manufactured.
- High purity diamonds are used as gemstones in jewellery.
- Diamond is increasingly used for its very high hardness in cutting tools.
- Due to its high melting point and hardness, diamond can only be processed by machining and polishing.
Design Issues
Design strengths:
- Excellent corrosion resistance
- Low density
- High electrical resistance.
- High hardness
Design weaknesses:
- Low tensile strength
- Low toughness
- Difficult to shape
Typical Products
- Gemstones
- Cutting tools
- Grinding wheels
Environmental issues
- Mining of diamond is very expensive, as the proportion of diamond in the rocks is very small. Manufacture of artificial diamond is also a slow, expensive process.
- Partly for its intrinsic value, and partly because of its energy-intensive production routes, diamonds are almost entirely recycled.
Overview
- Zirconia is an ionic ceramic, zirconium oxide.
- Like all ceramics, zirconia is intrinsically hard and strong in compression. Compared to other classes of materials it has low toughness. Mixing zirconia with a small amount of magnesium oxide gives a "ceramic alloy" which has good fracture resistance and tensile strength for a ceramic material.
- Due to its high melting point, zirconia can only be processed in powder form.
Design Issues
Design strengths:
- Excellent corrosion resistant
- Low density
- Resistant to high temperatures
- High electrical resistance.
Design weaknesses:
- Low tensile strength
- Low toughness
- Difficult to shape
Typical Products
Overview
- Bricks were the first man-made structural materials. They are made by firing a mixture based on natural silica of ceramic particles with a glassy binder.
- Like all ceramics, bricks are intrinsically hard and strong in compression, but have low toughness and tensile strength.
- Due to their high melting point and good tolerance of thermal shock, bricks are often used in furnaces.
Design Issues
Design strengths:
- Excellent corrosion resistant
- Low density
- Resistant to high temperatures
- Low cost
- Good strength in compression.
Design weaknesses:
- Very low tensile strength due to pores and defects.
- Low toughness
- Can only be shaped before firing.
Typical Products
- Household bricks
- Fire bricks
Environmental issues
- Making bricks is an energy intensive process, with a very high scrap rate.
- The higher the quality of the brick (the smaller the pores), the more firing required, increasing energy costs.
- The lifetime of brick buildings can be very long. In many cases building bricks can be recovered and reused, or used as hard core for road building, etc.
Overview
- Concrete is a composite of cement and gravel - the gravel increasing stiffness and lowering cost. It is used widely for large-scale construction of roads, buildings, bridges etc.
- Concrete is formed by a chemical reaction between silicates and water; it is rather like network polymerisation.
- Like all ceramics, concrete is intrinsically hard and strong in compression, but has low toughness and tensile strength. It is often reinforced with mild steel bars to improve its tensile properties.
Design Issues
Design strengths:
- Adaptable building material
- Low cost
- Can be pre-fabricated and reinforced
Design weaknesses:
- Low tensile strength (unreinforced) due to pores and defects
- Low toughness
- Can take months to fully harden
- Cannot be reshaped once hardened.
Typical Products
- Beams for bridges (reinforced)
- Road surfaces
- Paving slabs
- Railway sleepers
Environmental issues
- Concrete structures cannot be reshaped so concrete can only be broken up and re-used as hard core for roads, etc.
- Cement production is quite energy intensive, so gravel and sand used to reduce cost.
Overview
- ?Porcelain (and other types of pottery) has been used for containers and decorative artefacts for thousands of years. Like cement it is made from naturally occurring alumino-silicates.
- Like all ceramics, porcelain is intrinsically hard and strong in compression, but has low toughness and tensile strength.
Design Issues
Design strengths:
- Good electrical insulator
- Resistant to high temperatures
- Low density
- Can be easily shaped (prior to firing)
Design weaknesses:
- Low tensile strength (unreinforced) due to pores and defects
- Low toughness
- Can take months to fully harden
- Cannot be reshaped once hardened.
Typical Products
- Cups and saucers
- Insulators on telegraph poles
- Kitchen sinks
- Toilets
Environmental issues
- The higher the quality of the pottery (the smaller the pores), the more firing required, increasing energy costs.
Overview
- Polycarbonate (PC) is a quite expensive thermoplastic, used for its relatively high strength and toughness.
- Like all thermoplastics, polycarbonate is easy to shape and join.
Design Issues
Design strengths:
- Good strength (for a polymer)
- Low density
- Transparent, or easily coloured
- High toughness
Design weaknesses:
Typical Products
- crash and safety helmets
- lightweight armour (e.g. riot shields)
- street light covers
Environmental issues
- Polymers are derived from hydrocarbons, and require energy to extract and purify them.
- Thermoplastics can be reheated and reshaped.
- No toxic fumes when burnt.
Overview
- Polythene (polyethylene, PE) comes in various forms, of which LDPE (low density) and HDPE (high density) are the most common.
- Low density polythene is the only polymer which floats, high density polythene does not.
- Polythene is the polymer used in the largest quantities
- Like all thermoplastics, polythene is easy to shape and join.
Design Issues
Design strengths:
- Very simple polymer structure, so easy to process.
- Transparent, or easily coloured
- Can be drawn to very large elongations, and very thin sheet
Design weaknesses:
Typical Products
- dustbins
- water and gas pipes
- carrier bags
- food packaging
- sandwich boxes
Environmental issues
- Polymers are derived from hydrocarbons, and require energy to extract and purify them.
- Thermoplastics can be reheated and reshaped.
- No toxic fumes when burnt.
Overview
- Polystyrene (PS) is a common thermoplastic, which is relatively stiff and brittle.
- Polystyrene is used in a solid form for simple moulded components, but is more familiar in the form of white "polystyrene foam" for packaging.
- Like all thermoplastics, polystyrene is easy to shape and join.
Design Issues
Design strengths:
- Cheap high stiffness polymer.
- Transparent, or easily coloured
- Can be made into foam for packaging (different properties as foam).
Design weaknesses:
- Chains slide over each other at 95?C (polystyrene cups go soft if boiling water used).
- Brittle at room temperature (e.g. rulers often snap)
Typical Products
- disposable cups
- pens
- rulers
Environmental issues
- Polymers are derived from hydrocarbons, and require energy to extract and purify them.
- Thermoplastics can be reheated and reshaped.
Overview
- Poly methyl methacrylate is often called perspex
- Like all thermoplastics, PMMA is easy to shape and join.
- It is hard and brittle at room temperature
Design Issues
Design strengths:
- Transparent, or easily coloured
Design weaknesses:
Typical Products
- domestic baths
- tool handles
- road signs
- inner aircraft windows
Environmental issues
- Polymers are derived from hydrocarbons, and require energy to extract and purify them.
- Thermoplastics can be reheated and reshaped.
Overview
- Polypropylene (PP) is a simple thermoplastic polymer, similar to polythene.
- Like all thermoplastics, polypropylene is easy to shape and join.
Design Issues
Design strengths:
- Cheap polymer
- Slightly higher stiffness and strength than polythene
- Transparent, or easily coloured
- Relatively high toughness polymer
- Typical Products
- pipes
- ropes
- containers
Environmental issues
- Polymers are derived from hydrocarbons, and require energy to extract and purify them.
????Thermoplastics can be reheated and reshaped.
????No toxic fumes when burnt.
Overview
- PET is a polyester, which is usually thermoplastic, but is also modified to produce a thermoset
- PET is made into transparent or coloured sheet (as in fizzy drink bottles), or into fibres which are woven into clothing (e.g. "terylene")
Design Issues
Design strengths:
- PET is above average strength and stiffness (for a polymer)
- Relatively easy to recycle coloured
Design weaknesses:
- Thermoplastic PET has low fracture toughness
Typical Products
- cassette and video tape
- drinks bottles
- fibres for clothing
- glass fibre composites (in thermoset form) used for boats, car bodies
Environmental issues
- Polymers are derived from hydrocarbons, and require energy to extract and purify them.
????Thermoplastics can be reheated and reshaped.
???? As a polymer used for bottles and clothing, PET is potentially easier to separate and recycle
Overview
- A partially crystalline thermoplastic polymer.
- Rumoured to have been named after New York and London where it was said to have been invented independently. This is not true however!
Design Issues
Design strengths:
- Good strength (for a polymer)
- Easily made as a fibre
- good heat resistance <2500C
Typical Products
- zip fasteners
- fishing line
- power tool cases
- clothes
- small gears
Environmental issues
- Polymers are derived from hydrocarbons, and require energy to extract and purify them.
Overview
- Urea formaldehyde (UF) is a thermosetting network polymer.
Design Issues
Design strengths:
- Heat resistant
- Stiff and strong
Design weaknesses:
- Few processing routes
- Cannot be reshaped or recycled
Typical Products
- electrical plugs
- household insulation (as foam)
Environmental issues
- Polymers are derived from hydrocarbons, and require energy to extract and purify them.
???? As a thermoset cannot be easily recycled.
Overview
- uPVC is unplasticised PVC, a general purpose thermoplastic used for moulded and extruded components
- uPVC is more resistant to ultra violet than many polymers, and is thus acceptable for window frames
- A variant of PVC called "plasticised PVC" has chemical additions to make it more flexible (lower Young's modulus) and easier to process in the form of sheet (e.g. plastic coats)
Design Issues
Design strengths:
- general purpose polymer
- good insulator
Design weaknesses:
- can degrade under prolonged exposure to sunlight
- environmental concerns
Typical Products
- uPVC
- window frames
- gas/ water pipes
- plasticised PVC
- raincoats
- electrical sleeving
- ring binder covers
- food packaging
Environmental issues
- Polymers are derived from hydrocarbons, and require energy to extract and purify them.
- Concerns over toxic fumes when burnt
Overview
- CFRP (carbon fibre reinforced polymer) is a composite of long, fine carbon fibres embedded in a polymer matrix (usually epoxy resin, or polyester).
- CFRP has low density, and high Young's modulus and strength.
- CFRP must be processed directly to shape by laying up partially-cured layers of material, and then hot pressing - this is expensive.
- Carbon fibres are also expensive to produce, and it is only 25 years since the process to manufacture them was invented.
Design Issues
Design strengths:
- High stiffness-to-weight ratio
- High strength-to-weight ratio
Design weaknesses:
- Moderately high cost
- Cannot be recycled
- Difficult to shape
- Difficult to join
Typical Products
- Sports goods (tennis racquets, golf clubs, fishing rods)
- Performance racing bicycles
- Formula I car bodies
- Military aircraft skins
Environmental issues
- CFRP mostly uses epoxy resin and fibres, which are difficult materials to work with, requiring special precautions against toxic fumes, fibre fragments, fire hazards etc.
Overview
- GFRP is a composite of long, fine glass fibres embedded in a polymer matrix (usually epoxy resin, or polyester). Some GFRP uses short chopped fibres (e.g. for moulding canoes).
- GFRP has low density, and fairly high Young's modulus and strength.
- GFRP must be processed directly to shape by laying up partially-cured layers of material, and then usually requires hot pressing - this is expensive.
Design Issues
Design strengths:
- High stiffness-to-weight ratio
- High strength-to-weight ratio
Design weaknesses:
- Cannot be recycled
- Difficult to shape
- Difficult to join
Typical Products
- Sports goods (tennis racquets, golf clubs, fishing rods)
- Boat hulls (yachts, canoes)
- Bathtubs
Environmental issues
- GFRP mostly uses epoxy resin and fibres, which are difficult materials to work with, requiring special precautions against toxic fumes, fibre fragments, fire hazards etc.
Overview
- Pine is an abundant softwood, which grows in temperate or cool climates. Like most woods pine is light and durable - wood has been used for building and construction for thousands of years.
- Like all woods, pine products must be sawn and machined from felled trees, which places some limits on the range of shapes for which it is suitable.
- All woods have an internal structure of aligned natural fibres and elongated hollow cells. This structure gives them very low density, and excellent specific properties.
Design Issues
Design strengths:
- High stiffness-to-weight ratio
- High strength-to-weight ratio
- Corrosion resistant
- Easily recycled
- Low density
Design weaknesses:
Typical Products
- furniture
- railway sleepers
- pallets
- house construction
Environmental issues
- Pine is a relatively fast-growing timber which is a sustainable resource if well-managed.
- Intensive forestry can lead to environmental damage when trees are cleared without re-planting.
- Woods are naturally biodegradable, or can be shredded and used for wood-fibre products or burnt as fuel.
Overview
- Balsa is a tropical wood of very low density. Biologically, it is classified as a "hardwood", though its very low density makes it soft and easy to cut.
- Like all woods, balsa must be sawn and machined from felled trees, which places some limits on the range of shapes for which it is suitable.
- All woods have an internal structure of aligned natural fibres and elongated hollow cells. This structure gives them very low density, and excellent specific properties.
Design Issues
Design strengths:
- High stiffness-to-weight ratio
- High strength-to-weight ratio
- Corrosion resistant
- Easily recycled
- Very low density
Design weaknesses:
Typical Products
Environmental issues
- Tropical woods are not always produced from sustainable sources.
- Intensive forestry can lead to environmental damage when trees are cleared without re-planting.
- Woods are naturally biodegradable, or can be shredded and used for wood-fibre products or burnt as fuel.
Overview
- Oak is a slow-growing hardwood which is abundant worldwide in temperature or cool climates. Oak has been used for building and construction for thousands of years - particularly for ship-building. As one of the harder woods, it has been used extensively for furniture and for woodcarving.
- Like all woods, oak must be sawn and machined from felled trees, which places some limits on the range of shapes for which it is suitable.
- All woods have an internal structure of aligned natural fibres and elongated hollow cells. This structure gives them very low density, and excellent specific properties.
Design Issues
Design strengths:
- High stiffness-to-weight ratio
- High strength-to-weight ratio
- Corrosion resistant
- Easily recycled
- Low density
Design weaknesses:
Typical Products
Environmental issues
- Oak is slow-growing, so requires long-term forestry planning if it is to remain a sustainable resource.
- Woods are naturally biodegradable, or can be shredded and used for wood-fibre products or burnt as fuel.
Overview
- There are many types of fibreboard, of which MDF (medium density fibreboard) is the most common.
- Fibreboards are made by compacting wood fibres with a small proportion of polymer resin.
- Fibreboards, of which MDF is just one example, are a good way to use up waste wood from sawing and machining of solid timber.
- As the fibres are chopped into short lengths, the fibre-polymer mixtures can be moulded or pressed into shapes which cannot be made in one piece from wood (such as large panels or doors).
Design Issues
Design strengths:
- High stiffness-to-weight ratio
- High strength-to-weight ratio
- Corrosion resistant
- Easily recycled
- Low density
- Easy to shape
Design weaknesses:
- Usually needs veneering for a good finish.
Typical Products
- desktops
- doors
- fenceposts
Environmental issues
- Fibreboards largely use waste wood fibre, can be recycled and are mostly biodegradable.
Overview
- Papermaking was invented thousands of years ago, initially using fibres extracted from papyrus reeds. Paper and cardboard are now made from a variety of wood pulp or recovered fibres.
- Paper and cardboard can be made in a wide range of strengths, colours and textures.
- Cardboard can be corrugated to give good packaging properties at very low weight.
Design Issues
Design strengths:
- Easily shaped from flat sheet (e.g. for packaging).
- Easily recycled
- Low density
Design weaknesses:
Typical Products
- books
- newspapers
- electrical
- components
- packaging
Environmental issues
- Paper and cardboard are potentially a sustainable resource.
- Production is energy and resource intensive, and can produce a lot of waste vegetable matter which must be disposed of.
- Paper and cardboard can easily be recycled, though problems can be caused with some of the chemicals present in printing inks, and they are of course biodegradable.