RAW MATERIAL TO FINAL PRODUCT: UNIT 4 REVISION

PROPERTIES OF MATERIALS: the essential idea is materials are selected for manufacturing based on

their properties. This includes physical properties, mechanical properties and aesthetic properties.

Physical properties includes mass (amount of matter an object

contains - measure it by how hard it is to change direction/slow down), weight (the gravitational force exerted on a body), volume (amount of

space a body takes up - metric cubed), density (a measure of how

much mass is in a certain volume), electrical resistivity (material’s

ability to conduct electricity. Low resistance = high conduction.

Conductivity and resistivity is inversely proportional), thermal

conductivity (how fast heat is conducted through a material), thermal

expansion (measure of the degree of increase in dimensions when an

object is heated), hardness (resistance to penetration or scratching).

Mechanical properties include tensile strength (ability to withstand

pulling forces), compressive strength (ability to withstand ‘crushing’

forces), stiffness (resistance of an elastic body to deflection by an

applied force), toughness (ability of a material to withstand

propagation of cracks), ductility (ability to be drawn or extruded into

an extended shape), elasticity (ability to absorb and flex in different

directions, returning to its original shape), plasticity (ability to be

shaped permanently), malleability (ability to be reshaped in all

directions without cracking).

Aesthetic properties include taste, smell, appearance, colour and

texture.

MATERIAL

WOOD Tables element of strength, manufacturing it, clean, simple, honest, minimalist, traditional.

PLASTIC Toys colourful, silly (for children), modern, inexpensive, fun, disposable, hygienic, bright

METAL Curtain Rods satin finish, smooth texture, grey and neutral, dominant, professional, clinical, shiny, hard

CONCRETE Roads heat expansion, rough, postmodern, industrial, neutral, easy to manufacture with

FABRIC Bags soft texture, flexible, modern, easy to colour, comfort, cool, inexpensive

TESTING MATERIALS FOR HARDNESS, STRENGTH: tests for hardness include MOHS, BIERBAUM, PENCIL, BRINELL.

STRESS STRAIN GRAPHS: can tell more about the elasticity/plasticity of a material as well as its

stiffness and strength. The area under the graph gives information on the toughness.

YOUNG’S MODULUS: measure of stiffness of a material subjected to tensile strength. The angle of the

line on the graph indicates how stiff it is (higher gradient = higher stiffness level). Proportionality limit

and elastic limit are the yield point and failure points.

E = initial gradient of stress-strain curve.

HOOKE’S LAW, ELASTIC DEFORMATION AND PLASTIC DEFORMATION: the force needed to extend

or compress a spring by some distance is proportional to that distance. A temporary shape change

that is self-reversing after the force is removed, so that the object returns to its original shape, is called

elastic deformation.When the stress is sufficient to permanently deform the metal, it is called plastic

deformation.

SMART MATERIALS

Smart materials react to changes in their environment. This change is reversible and can be repeated

several times.

PIEZOELECTRIC: produces a voltage when stress is applied, and

vice versa. Piezoelectric materials can be used to measure the

force of an impact. For example, activating the airbag in a car.

THERMOCHROMIC: change colour according to temperature

changes. Baby products that change colour when something is

cool enough to use with a baby is an example of a design context.

PHOTOCHROMIC: change colour according to lighting conditions. Used in

sunglasses → darkens when light is shone to protect the eyes.

POLYMORPH: material can be shaped and reshaped numerous times.

Supplied in granules and soaked in hot water then shaped according to the

user’s shape. Good for specific hand sizes or similar.

THERMOELECTRIC: capture heat and turn it into electricity. It is useful for

reusing wasted energy emitted through a vehicle’s tailpipe.

SHAPE MEMORY ALLOY: thermo-responsive materials. Deformation induced

by temperature changes. Can remember their original shape so when they

become strained or deformed they can return to their original shape through

the application of heat. Example: nitinol in braces, glasses or anti-scalding

valves.

ELECTRO-RHEOSTATIC MATERIALS: ER and MR (magneto-rheostatic) are

fluids that can undergo a dramatic change in viscosity (how thick/thin a fluid

is). Design contexts include: damping washing machine vibration, prosthetic

limbs, exercise equipment and more.

TIMBER

“timber is a major building material that is

renewable and uses the sun’s energy to renew

itself in a continuous cycle. while timber

manufacture uses less energy and results in less

air and water pollution than steel or concrete

consideration needs to be given to deforestation

and the potential negative environmental impact

the use of timber can have on communities and

wildlife.”

HARDWOODS AND SOFTWOODS: have similar features but the main difference is the thickness of

the tubular cell walls, resulting in difference densities and mechanical properties. However, some

hardwoods are light in weight and easy to break (balsa), whereas some softwoods are hard and

heavy. Hardwoods come from deciduous

trees, and softwoods come from

coniferous trees.

Timber has tensile strength, resistance to

damp environments, longevity and

aesthetic properties.

SOFTWOODS:

Grow faster, straighter

Cheaper

Easier to cut long

straight planks

Often used as a

building material

LESS DENSE (instead

of saying “soft”)

Scots Pine, Parana

Pine, Spruce, Red

Cedar, Yellow Cedar,

European Redwood.

HARDWOODS:

Grow more

slowly

More

Expensive

MORE DENSE

Beech, Oak,

Mahogany,

Teak, Balsa.

A. SEASONING AND PREPARATION OF TIMBER: seasoning timber is the process by which

water is removed from newly cut trees or ‘green’ timber.

There are two main ways of seasoning timber:

1. Air/ Shed Seasoning → cheap but slow. The drying out process can be uneven. The timber is

exposed to pests and the risk of fire.

2. Kiln Seasoning → quick but expensive. The wood dries out more evenly and avoids warping.

B. THE IMPORTANCE OF GRAINS: timber will break more easily

across the grain.

What is warping? When wood isn’t properly seasoned or stored, it is

likely to warp or bend in different directions as it dries out. When this

happens, it can no longer be used.

C. MANUFACTURED BOARDS (5 TYPES)

Advantages: purpose built, stronger, cheaper, variety of sizes,

recycled so more environmentally friendly

Disadvantages: not particularly

aesthetically appealing

CHIPBOARD: made of chips of wood glued together. It is usually veneered or covered in plastic

laminate. Used for kitchen/bedroom furniture, shelving and general DIY work.

BLOCKBOARD: similar to plywood but the centre layer is made of blocks/ strips of timber. Used where

heavier structures are needed like shelves and worktops.

MEDIUM DENSITY FIBREBOARD (MDF): smooth, even surface that is easily machined, painted or

stained. Available in water and fire resistant forms. Used for furniture, interior panelling and veneered.

HARDBOARD: cheap particle wood with a laminate plastic surface. Used for furniture backs, covering

curved structures and door panels.

PLYWOOD: strong board consisting of layers of veneer or plies glued at 90 degrees to each other

(always an odd number of layers). Used for strong structural panelling, building construction, furniture

making and boat building/exterior work.

D. LAMINATES AND VENEERS

A type of finish for wood which gives the illusion of a high quality, expensive piece of wood.

Veneer is a thin strip of wood cut through rotary cutting that is glued onto a

cheaper man-made board. However, laminate is made from paper and

plastic resin that overlays cheap wood.

Laminates are easier to maintain. They are scratch-resistant, waterproof

and usually retain their look for years. In comparison, veneers require more

maintenance. They need to polished from time to time, so that they look as

beautiful as ever.

E. FINISHES FOR TIMBER

Almost all timber will need a “finish” to protect it from wear and tear or environmental damage caused

by moisture. The most common finishes for timbers include:

➔ Veneer

➔ Varnish

➔ Paint

➔ Lacquer

➔ Stain

➔ Lamination

➔ Wax

➔ Oils (such as linseed)

➔ Polish

➔ Polyurethane

F. HOW TIMBER CAN BE RECLAIMED/RECYCLED

Recycling old or damaged pallets prevents unnecessary landfill and reduces the need to chop down

trees for new wood to make new pallets.

➔ Wood can often be reused to make other items, such

as a bird table for your garden.

➔ Wood can often be added to your compost heap, such

as sawdust and wood shavings.

The fact that the wood has been weathered and aged making

each piece unique is one of its greatest qualities but can also

be problematic to some people who do not favour the

non-uniform appearance of flooring or furniture made from it.

Reclaimed wood can also have scars and indentations caused by the removal of old nails and pegs.

Again, some people love the character of these marks, others see them as flaws.

METALS

FERROUS AND NONFERROUS: has iron (ferrous and can rust) and metals which do not have iron

(non-ferrous). Metals are typically hard and shiny with good electrical and thermal conductivity.

A. PURE METALS AND ALLOYS: most pure metals are too soft, brittle or chemically reactive for

practical use.

Mild Steel: a low carbon alloy of iron. Low tensile strength. Rusts very easily. Used in general metal

products and engineering.

Cast Iron: strong but brittle, resistant to rust and stains. Used in castings, manhole covers and car

components.

Stainless Steel: tough, resistant to rust and stains. Used in cookware, cutlery and medical instruments.

Aluminium: light, soft, malleable and easy to machine. Conducts electricity and heat well. Used in

aircraft, packaging, bicycles.

Copper: ductile, conducts electricity and heat well. Used for pipes, electrical insulators, cookware,

coins and roof cladding.

Brass: low melting point and malleable. Used for door handles, musical instruments and casting and

ornaments.

B. METHODS OF EXTRACTION OF METALS FROM ORES: electrolysis and carbon or carbon

monoxide.

1. Most metals are found in the ground and

combined with other elements (e.g. oxygen,

sulfur, silicon) in the form of minerals called ores. 2. Gold is the only metal that is found in the ground in usable form.

3. Once a metal ore has been mined it has to be processed industrially to extract the metal and

refine it into the pure metal used practically.

Smelting = converting iron ore into iron or copper ore into copper.

Electrolysis = converting bauxite into aluminium.

C. WORK HARDENING

A metal’s structure contains minute defects called dislocations. They influence its physical properties.

Working a metal (e.g. by forging) increases the number of dislocations, so that it gets harder. This is

work-hardening. It also gets more brittle, and may then have to be tempered. A mild steel screwdriver

blade will have been hardened and tempered.

D. ANNEALING

In annealing, a metal is heated to a specific temperature and then allowed to cool slowly. This softens

the metal, which means that it can be cut and shaped more easily. To anneal mild steel, it is heated to

a red heat and then allowed to cool. Metals such as aluminium, which have lower melting points, will

melt if they are heated for too long.

E. TEMPERING STEEL

In quenching, a metal is heated to a specific temperature and then cooled rapidly. This hardens and

strengthens the metal.

It may also make it too brittle. It is softened by heating it more gently, to a lower temperature. This

process is called tempering.

F. USES FOR SUPER ALLOYS

An alloy is a mixture or solid solution of two or more metals, or of other elements and a metal. For

example, brass is an alloy of copper and zinc; bronze is an alloy of copper and tin; and carbon steel is

an alloy of iron and carbon. Other alloys include Nitinol, a shape memory alloy of nickel and titanium;

and duralumin, an alloy of aluminium that contains copper, manganese, magnesium, iron and silicon.

Alloying is a way of improving the properties of a metal: increasing its corrosion resistance, hardness,

strength or electrical properties. By changing the melting point, or improving the flow of the metal in

the molten state, it can improve the quality of the casting.

A superalloy is an alloy that exhibits excellent mechanical strength and creep resistance at high

temperatures, good surface stability and corrosion and oxidation resistance. Applications include the

aerospace industry, industrial gas turbines and marine turbine industry.

★ Incoloy 800

★ ALTEMP A 286

★ HS21 HS25

★ Elgiloy

★ MAR 322

★ Hastelloy

★ Inconel

★ Udimet

★ Waspalloy

★ Nimonic

★ Rene 41

What is creep? It is the tendency of a solid material to slowly move or deform permanently under the

influence of stresses. It occurs as a result of long term exposure to levels of stress that are below the

yield strength or ultimate strength of the material.

What is redox? It is reduction/oxidation reaction, describing the chemical reactions in which atoms

have their oxidation number changed.

What is fatigue? The progressive and localized structural damage that occurs when a material is

subjected to cyclic loading. The fatigue life is the number of stress cycles of a specified character that

a specimen sustains before failure of a specified nature occurs.

What is corrosion? The breaking down of essential properties in a material due to chemical reactions

with its surroundings.

G. FINISHES FOR METAL: would help to enhance the metal by

➔ Increased durability

➔ Improved decorative appeal

➔ Enhanced electrical conductivity

➔ Higher electrical resistance

➔ Higher chemical resistance

➔ Higher tarnish resistance

➔ Potential for vulcanization

Metal plating, Buff polishing, Brushed metal, Metal grinding, Sandblasting, Powder coating, Metal

Vibratory finish, Hot Blackening, Lacquer, Paint.

H. RECYCLING METALS: virtually all metals can be recycled into high quality new materials.

➔ Metals recycling protects the environment and saves energy

➔ Using secondary raw materials means less use of natural resources

➔ There are considerable savings in energy

➔ Fewer greenhouse gases are produced

➔ Far less water is consumed in producing recycled metals

➔ 75% less environmental pollution is created

GLASS

The rapid pace of technological discoveries is very evident in the manufacture and use of glass in

electronic devices. Different properties have been presented in glass for aesthetic and safety reasons

for many years but the future of glass seems to be interactively alongside electronic systems. The

structure of glass is not well understood but as more is learned its use is becoming increasingly

prominent in building materials and structural applications.

MAIN INGREDIENTS

The most common type of glass is commercial or soda-lime glass as soda ash is used in its

manufacture… (sodium carbonate)

Most commercial glasses are made up of:

★ 70% silica

★ 12% sodium oxide

★ 5% calcium oxide

★ 1% magnesium oxide

★ 1% aluminium oxide

It has an ability to transmit light in a variety of wavelengths that makes it so versatile. The presence of

impurities account for its various colours.

Glass is produced from sand, limestone and sodium carbonate and requires large amounts of energy

for its manufacture.

Tempering glass: Toughened or tempered glass is a type of safety glass processed by controlled

thermal or chemical treatments to increase its strength compared with normal glass. Tempering puts

the outer surfaces into compression and the inner surfaces into tension.

Annealing glass: Annealing is a process of slowly cooling glass to relieve internal stresses after it was

formed. The process may be carried out in a temperature-controlled kiln known as a lehr. Glass which

has not been annealed is liable to crack or shatter when subjected to a relatively small temperature

change or mechanical shock.

CHARACTERISTICS

➢ Transparency (functional and

aesthetic)

➢ Chemically inert (ideal for storage)

➢ Non toxic ( ideal for use with food)

➢ Biocompatible

➢ Hardness: resists scratching

under normal conditions..long

service

➢ Aesthetic appeal: when molten it can be

shaped and coloured

➢ Electrical insulator: used in high power

installations

➢ Main drawback: brittle, and can be a cut

danger if broken

➢ Easy to recycle

➔ Glass can be altered for use at high temperatures. This type of glass has BORON OXIDE

added to make borosilicate glass

➔ LEAD is also added to make glass sparkle. This is used in decorative uses such as lead crystal

glass

➔ Glass can be laminated to prevent breakage or hold shards together. Glass can be annealed

or have polymers added.

➔ Glass can be tempered to make it tougher: it is heated to about 650 degrees then quenched.

➔ Glass is increasingly used as a building material by creating glass bricks and floors. Glass can

be given tensile and compressive strength

DESIGN CONTEXTS - ELECTRONICS AND BUILDING

★ Packaging (jars, bottles, food containers, medicines

★ Tableware: glasses, cups, plates, bowls

★ Building materials: windows, structures

★ Interior Design: mirrors, partitions, balustrades, tables, lights, shelves

★ Appliances: oven doors, cooktops, screens, smart phones

★ Transport: windscreens, lights, structural components

★ Medical Technology: life science engineering, X Rays, nuclear power

★ Fibre optic cables

★ Solar energy power & wind turbines

Glass in the future could become smarter and respond to the environment and surroundings.

➔ For example, windows could become translucent but also photovoltaic properties that

generates power with the solar energy from the sun. Some glass panels or windows have

electrochromic properties, photosensitive, switchable lights or similar.

➔ Anti-reflection properties and technologies for clean energy generation is also being

considered. Companies are thinking of incorporating flexible glass, bendable glass, scratch

resistant and thinner glass used for mobile phones - although innovative, it might be difficult

to overcome the brittle properties of glass.

➔ Glass could become interactive and react to the user: LED could be used more prominently in

jewellery; mirrors could assess physical health and transfer this to an application on your

phone; smart bottles and containers as well as more complex shapes for glass.

HOW IS GLASS RECYCLED?

What is meant by cullet? Small shards of glass that is recycled and makes up the main components of

glass.

The consumer throws glass into a recycle bin. Glass is taken from the bin and taken to a glass

treatment plant. The glass is sorted by colour and washed to remove any impurities. The glass is then

crushed (into cullets) and melted, then moulded into new products such as bottles and jars.

TEXTILES

NATURAL FABRICS SYNTHETIC FABRICS

COTTON NYLON

SILK RAYON

WOOL POLYESTER

LINEN LYCRA

A. METHOD OF CREATING YARN FROM RAW MATERIALS

Raw materials are turned into yarn

● This is done by spinning the raw fibres into thread, either by hand or more usually by machine

● The fibres are collected on a cylinder called a bobbin

Yarn is connected together into fabric

● This is done by weaving the threads together

● Two sets of yarn are woven together on a LOOM

The fabric is processed

● The material has to be cleaned/bleached/coloured

B. METHODS OF CONVERTING YARN INTO FABRICS

Fabric is a planar textile structure produced by interlacing yarns, fibers, or filaments. It may be woven,

knitted and nonwoven.

A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye

is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye

on the fiber.

Synthetic fibres can be made by extruding a polymer, through a spinneret into a medium where it

hardens. Wet spinning (rayon) uses a coagulating medium. In dry spinning (acetate and triacetate),

the polymer is contained in a solvent that evaporates in the heated exit chamber. In melt spinning

(nylons and polyesters) the extruded polymer is cooled in gas or air and then sets.

Microfibres: Polyester or nylon microfibres are 60 to 100 times finer than a human hair. They can be

blended with synthetic or natural fibres and are used for clothing for outdoor pursuits and active

sportswear. Thermoplastic polyester or nylon microfibres can be heat-treated to give them coils,

crimps and loops, which makes these textured yarns stretchy and warm. They are used for

underwear, sportswear, knitwear and carpets.

Modern microfibres: Elastane (Lycra) is always used in a blend with other fibres. It is used to make

sportswear, body-hugging clothes and bandages. It has good handle and drape, is durable, crease

resistant, stretchy (more comfortable) and is easy care. It has low warmth and is absorbent.

Weaving: a method of fabric production in which two distinct sets of yarns or threads are interlaced at

right angles to form a fabric or cloth.

Knitting: a number of consecutive rows of loops, called stitches. As each row progresses, a new loop is

pulled through an existing loop. The active stitches are held on a needle until another loop can be

passed through them. This process eventually results in a fabric, often used for blankets or garments.

Knitting may be done by hand or by machine.

Felting: one of the oldest fiber crafts, it is a process to create an object made with wool fibers. There

are two types- one is dry (needle) felting and the other one is wet felting. Wet felting is one of several

methods which can produce felt from wool and other animal fibres. Warm soapy water is applied to

layers of animal hairs placed at 90 degree angles to one another. Repeated agitation and

compression causes the fibres to hook together into a single piece of fabric.

Needle felting is a popular fibre arts craft that creates felt without the use of water. Special needles

that are used in industrial felting machines are used by the artist as a sculpting tool.

Lacemaking: a delicate fabric made of yarn or thread in an open weblike pattern, made by machine

or by hand.

C. CHARACTERISTICS OF A VARIETY OF TEXTILES

Cotton: Used for making jeans, T-shirts and towels and has the following qualities:

● cool to wear

● very absorbent,

dries slowly

● soft handle

Linen: Used for summer clothing, tea towels and tablecloths and has the following qualities:

● fresh and cool to

wear

● very absorbent, dries

quickly

Wool: Used for jumpers, suits and blankets and has the following qualities:

● warm to wear

● absorbent, dries slowly

● breathable, repels rain

● soft or coarse handle

● can shrink, should be dry

● good drape

● durable

● creases easily

● can be washed

and ironed

● Comfortable

● Colour retention

● Prints well

● strong

● stiffer handle

● good drape

● durable

● creases badly

● can be washed and

ironed

● Sturdy and difficult to crush as it has “body”

● It has a rough texture

cleaned

● good drape

● creases drop out

● Insulating: does not trap heat,

traps hair which can circulate

the skin.

● Strong and durable

● Fire resistant

● Accepts dye easily

● Fibres mesh well

Silk: Used for evening wear and ties and has the following qualities:

● warm to wear

● absorbent

● soft handle

● good lustre and

drape

● durable

● creases drop out

● dry clean

● Takes on bright

colours

Nylon: Used for active sportswear, fleece jackets, socks, ropes, tents, nets, pipes and seat belts and has the following qualities:

● Smooth, lightweight,

strong, lustrous,

elastic, Resistant,

Waterproof, easily

dyed

● melts at low

temperature, warm

to wear

● absorbent, dries

slowly, breathable,

repels rain

● soft or coarse handle

● can shrink, should be

dry cleaned

● good drape, durable,

creases drop out

Polyester: Used for raincoats, fleece jackets, children's nightwear, medical textiles and working clothes and has the following qualities:

● low warmth

● non-absorbent, dries quickly

● soft handle

● good drape

● very durable

● crease resistant

● easy care

● can be recycled

● Extremely strong

● Resistant to chemicals

● Resists shrinkage, wrinkles

and abrasion

● Doesn’t need ironing

● Ideal for outdoor clothing,

sportswear and cheap suits

● Can be uncomfortable to wear

● Not environmentally friendly

Rayon: Used for shirts, can be blended and has the following qualities:

● Very absorbent

● Can be dyed to vivid colours

● Comfortable

● Breathable

● Flammable

● Easily creased

● Cheap

● Can be blended with other expensive fabrics

● Fragile when wet

D. DESIGN CONTEXTS FOR NATURAL AND SYNTHETIC FABRICS

➢ Protection and fastenings, like Velcro

➢ Building and tents

➢ Food packaging for tea bags, for

example

➢ Furniture

➢ Decorative items

➢ Bookbinding

➢ Dental floss

➢ Uniforms

➢ Bedding and carpets

➢ Road building

➢ Health care products

➢ Recreational products

➢ Bags

➢ Sound proofing

➢ Insulation

➢ Millinery

E. RECYCLING/RECLAIMING TEXTILES

❏ Problems associated with collection

❏ Re-use

❏ Conversion to rags

❏ Carding to create “shoddy” & loose fibres

❏ Repurpose as wipes, padding, building materials, insulation.

PLASTICS

THERMOPLASTICS AND THERMOSET PLASTICS: thermosetting plastics can be heated and shaped

once, whereas thermoplastics can be reheated and reshaped several times.

A. MAIN DIFFERENCES BETWEEN THE TWO

Plastics can be either found in natural substances or may be man-made. Most of the plastics used today are man-made. Man-made plastics are known as synthetic plastics. Natural 'plastic products' occur in such things as animals' horns, animals' milk, insects, plants and trees.

Thermoplastics: The molecules of thermoplastics are in lines or long chains with very few entanglements. When heat is applied the molecules move apart, which increases the distance between them, causing them to become untangled. This allows them to become soft when heated so that they can be bent into all sorts of shapes.

When they are left to cool the chains of molecules cool, take their former position and the plastic becomes stiff and hard again. The process of heating, shaping, reheating and reforming can be repeated many times.

Each time a thermoplastic is reheated it will try and return to its original shape, unless it has been damaged due to overheating or overstretching. This property is called plastic memory.

Thermosetting Plastics: The molecules of thermosetting plastics are heavily cross-linked. They form a rigid molecular structure. Whereas in thermoplastics the molecules sit end to end, the molecules in thermoplastics sit end-to-end and side-by-side. Although they soften when heated the first time, which allows them to be shaped they become permanently stiff and solid and cannot be reshaped. Thermoplastics remain rigid and non-flexible even at high temperatures. Polyester resin and urea formaldehyde are examples of thermosetting plastics.

Thermoplastics Thermoset plastics

PP polypropylene POLYURETHANE

PE polyethylene UREA FORMALDEHYDE

HIPS high impact polystyrene MELAMINE RESIN

ABS acrylonitrile butadiene styrene EPOXY RESIN

PET polyethylene terephthalate

PVC poly vinyl chloride

Thermoplastic Thermoset plastic

Long chains of molecules Molecules are cross linked

Molecules lie end to end Molecules lie end to end and side by side

When heated they soften, when cooled they harden

Once heated and set they cannot be reshaped

HEAT creates a physical change that can be reversed Similar to chocolate

HEAT creates a chemical change that cannot be reversed Similar to an egg

B. INGREDIENTS OF SYNTHETIC PLASTICS

The main source of synthetic plastics is crude oil. Coal and natural gas are also used to produce plastics. Petrol, paraffin, lubricating oils and high petroleum gases are bi-products, produced during the refining of crude oil.

These gases are broken down into monomers. Monomers are chemical substances consisting of a single molecule. A process called Polymerisation occurs when thousands of monomers are linked together. The compounds formed are called polymers. Combining the element carbon with one or more other elements such as oxygen, hydrogen, chlorine, fluorine and nitrogen makes most polymers.

C. CHARACTERISTICS OF A VARIETY OF PLASTICS

D. DESIGN CONTEXTS FOR THE MAIN PLASTIC GROUPS

Polypropylene (PP): Used in furniture, ropes, packaging, flexible hinges, automotive parts and characteristics are:

● Good resistance to

Polythene (PE): Used in the form of HDPE or LDPE with packaging, furniture, boxes, bottles and characteristics are:

● It is extremely versatile

High Impact Polystyrene (HIPS): Used for packaging, structural cases, CD cases and characteristics are:

● Good impact

wear and fatigue

● Rugged

● Cannot be made

transparent, only

translucent

● Dyes easily and can

take print and images

● Used in extrusion and

moulding

● Lightweight

● Good heat resistance

● Can be soft and pliable

or rigid

● Good insulator

● Almost unbreakable

● Responds well in a

range of temperatures

● Light, but hardwearing

● Can be used in a wide

variety of processes:

sheet, moulding,

casting, extrusion.

resistance

● Excellent machinability

● Stable

● good aesthetic

qualities

● Easy to paint and glue

● Low cost

● Excellent insulator

● Does not biodegrade

and is environmentally

damaging

● Extremely flammable

acrylonitrile butadiene styrene (ABS): Used for toys, domestic appliance, luggage, safety helmets, car interiors and characteristics include:

● High impact resistance

● Toughness

● Heat resistance

● Excellent surface

quality

● Easily coloured

● Easy to mould and

extrude

polyethylene terephthalate (PET): Used for water bottles, food containers, food packaging and characteristics include:

● Excellent transparency

● Tasteless and

odourless

● Lightweight

● Processability

● Hygiene barrier both

directions

● Durable

● Recyclable

● Won’t biologically

degrade

Polyvinyl Chloride (PVC): Used for water pipes and solid structures like door and window frames. Characteristics are:

● Cheap

● Hard wearing

● Melts at low

temperatures

● Used as a textile for

fake leather

● Can be recycled

approximately 7 times

and has a life span of

140 years.

Polyurethane: Used for construction, insulation, automotives, furniture, cushions, car seats

Urea Formaldehyde: Used for toilet seats, electrical sockets, glue and characteristics include:

Melamine Formaldehyde: Used for kitchen utensils, plates, bowls, surface coating for chipboard as table tops

and characteristics include: ● Extremely hard

wearing

● Resists water, oils,

chemicals, mould and

abrasion

● Has tensile strength

● Can be bonded to

wood or metal to give a

protective layer

● Can be foamed or

used as a liquid

● Excellent insulator of

sound and heat

● High tensile strength

● Hard and durable

● Easy to mould into

shape

● Brittle

● 1 million tons is

produced a year. Of

that 70% goes as a

bonding agent to wood

products such as MDF

and particleboards

● Rarely colourful or

transparent

and characteristics are: ● Hard

● Shiny

● Often colourful

● Remains safe with hot

food

● Durable

● Hygienic

● Cheap

Epoxy Resin: Used primarily as a strong adhesive, casting, electrical components, paints, coating, mechanical repair and characteristics include:

● Strong

● Durable

● Dries quickly when

applied together

E. WHICH PLASTICS CAN BE RECYCLED AND HOW?

Most plastics are produced from

petrochemicals. Motivated by the

finiteness of oil reserves and threat

of global warming, bio-plastics are

being developed. These plastics

degrade upon exposure to

sunlight, water or dampness,

bacteria, enzymes, wind erosion and in some cases insect attack. But in most cases this does not lead

to the full breakdown of the plastic. When selecting materials, designers must consider the moral,

ethical and environmental implications of their decisions.

1. Material recovery… mechanical recycling

2. Energy Recovery… Turning the stored energy of plastic into electricity by creating heat/steam

as a substitute for fossil fuel

COMPOSITES

Materials made from two or more constituent materials with significantly different physical or chemical properties, that when combined, produce a material with characteristics different from the individual components.

HOW COMPOSITES ARE CONSTRUCTED

Terminology: Matrix is the main constituent - such as concrete, resin, liquid plastic - into which other

materials are mixed.

matrix example

POLYMER (plastic) Glass reinforced plastic GRP

METAL MMCs Metal reinforced by silicon

CERAMIC CMCs High temperature ceramics

METHODS OF PRODUCTION

Form: fibres/sheet/particles and matrix.

Process: weaving, moulding, pultrusion and

lamination.

Composition and structure: concrete, engineered

wood, plywood, particle board, fibre glass, Kevlar,

carbon reinforced plastic, laminated veneer lumber.

Pultrusion: a continuous process for manufacture of composite materials with constant cross section.

CHARACTERISTICS OF COMPOSITE MATERIALS

● Weight saving

● Strength

● Specific properties such as stiffness or tensile strength

● Can be designed for specific environments and tasks

● Cost

● Fire retardant or water repellence

● aesthetics

ADVANTAGES AND DISADVANTAGES OF COMPOSITES

Particle Reinforced Composite: A relatively soft matrix strengthened by evenly sized particles. They

are isotropic - equally strong in all directions. Example: concrete. Mixed with aggregate such as stones

& pebbles

Fibre Reinforced Composite: The underlying matrix is reinforced by fibres of equal length, such as the

steel rods (rebar) in reinforced concrete. This composite exhibits

strength along the direction of the fibres.

E.g. Carbon Fibre or Glass Fibre Reinforced Polymers.

Laminar Composites: Where materials are laid down together in

layers, for example in plywood or laminated glass.

Kevlar: High strength composite that can be turned

into a fabric, or included with other materials to make tyres, rope or bicycle frames. It

is said to be bulletproof and is used by the military and law enforcement agencies for

protection equipment. It is also used in automotive parts manufacture, marine

construction, musical instruments.

Ceramic Composites: Ceramic matrix composites use a ceramic matrix with ceramic fibres in order to

reinforce it. Ceramic composites have large resistance to cracking at high temperatures, less

compressive strength than conventional ceramics, are widely used in aerospace situations, gas

turbines, combustion chambers and blades for jet engine turbines because they are lightweight and

highly resistant to corrosion. Main disadvantage is the high cost of ceramic composites. Advantages:

★ Lightweight compared to standard materials ★ High strength: designed to function a particular way ★ Excellent strength to weight ratio ★ Corrosion resistance ★ High impact resistance ★ Design flexibility: can be shaped, moulded etc as required ★ Stable: they keep their shapes under stress and under

adverse conditions ★ Non conductive ★ Non magnetic ★ Radar transparent ★ Durable

Disadvantages: ➔ High cost ➔ Difficult to repair ➔ Needs careful

designs because they are not isotropic and have to be pre-engineered to be stable

➔ More calculation is needed before using a composite.

DESIGN CONTEXTS FOR COMPOSITE MATERIALS

Buildings Bridges Structures, e.g. boat hulls Swimming pool panels Cultured marble sinks and countertops

Race car bodies Shower Stalls Bathtubs Storage tanks Imitation granite

SCALE OF PRODUCTION

The scale of production depends on the number of products required. One-off production, batch production, mass customization and mass production would be the main types.

Industrial production methods There are four main types of industrial production methods: One-off production is when only one product is made at a time. Every product is different so it is labour intensive. Products may be made by hand or a combination of hand and machine methods. Batch production is when a small quantity of identical products are made. Batch production may also be labour intensive, but jigs and templates are used to aid production. Batches of the product can be made as often as required. The machines can be easily changed to produce a batch of a different

product. Mass production is when hundreds of identical products are made, usually on a production line. Mass production often involves the assembly of a number of sub-assemblies of individual components. Parts may be bought from other companies. There is usually some automation of tasks (eg by using Computer Numerical Control machines) and this enables a smaller number of workers to output more products. Continuous flow production is when many thousands of identical products are made. The difference between this and mass production is that the production line is kept running 24 hours a day, seven days a week to maximise production and eliminate the extra costs of starting and stopping the production process. The process is highly automated and few workers are required. “Mass customization is a marketing and manufacturing technique that combines the flexibility and personalization of "custom-made" with the low unit costs associated with mass production.” “Mass customization is producing goods or services for a relatively large market that exactly meets the needs of every individual customer with regard to product characteristics, at a cost comparable to those of standard mass produced goods.”

Advantages:

⬜ There’s less waste. When things are built to order nothing is made until there is customer for it.

⬜ Localization not globalization: MC needs to be near its customers. Skilled jobs move overseas, blue collar jobs return. MC disrupts large scale global models

⬜ No need for a full inventory. Firms don’t have to keep huge stocks of everything in all sizes. Lowers their exposure to risk.

⬜ Better cash flow: customers pay up front rather than after manufacture

⬜ Higher margins: customers pay more for a product that is personalised.

⬜ Data mining: firms gather more information about their customers

⬜ Customer satisfaction: customer feels creative and gets a product that matches their needs and distinguishes them from others.

Disadvantages:

⬜ Prices rise: customers are expected to pay more for a customised product. Firms use value based pricing rather than cost based

⬜ Incorrect customer input information leads to unwanted products: wrong size/fit/incorrect colour etc

⬜ Loss of customer privacy: companies can hold large amounts of data about their customers

⬜ MC has a bad effect on traditional shops who are excluded from the supply chain

⬜ Difficult for customers to make comparisons on price and quality

⬜ Manufacturers are currently working without a proven business model. Big changes are required in factory organisation, staffing, investment in IT etc

MANUFACTURING PROCESSES

ADDITATIVE SUBTRACTIVE SHAPING JOINING

RAPID

PROTOTYPING or 3D

printing

LAMINATED OBJECT

MANUFACTURE

STEREO

LITHOGRAPHY

WASTING

CUTTING

MACHINING

TURNING

ABRADING

MOULDING

THERMOFORMING

LAMINATING

CASTING

KNITTING

WEAVING

PERMANENT JOINS

TEMPORARY JOINS

FASTENING

ADHESION

FUSING

Additative: ⬜ Relatively new processes

⬜ Quick manufacture of models or prototypes

⬜ Relatively cheap materials

⬜ Direct from computer

⬜ Still small scale

⬜ Tends to be used for prototyping not full scale

⬜ Largest 3D printer is 6MX6MX6M

⬜ Increasing range of materials that can be 3D printed, Building metals, Chocolate, plastics,

paper

⬜ Less manual skill needed to create intricate shapes

Subtractive: ⬜ Cutting

⬜ Machining

⬜ Turning

⬜ Abrading

⬜ Cutting is probably the oldest manufacturing process

⬜ A piece of material is reduced from a basic form into the desired shape

⬜ Requires specialised tools, skill and power

⬜ Many cutting processes are inherently dangerous

⬜ There are inevitable waste products produced

⬜ Time consuming

Abrading:

Shaping Techniques:

- Moulding

- Thermoforming

- Laminating

- Casting

- Knitting

- Weaving

Temporary joins vs. Permanent joins

⬜ SCREWS

⬜ NUTS

⬜ BOLTS

⬜ CLAMPS

⬜ FASTENERS

⬜ NAILS

⬜ SOLDERING

⬜ BRAZING

⬜ WELDING

⬜ GLUE

⬜ FUSING

⬜ RIVETS

PRODUCTION SYSTEMS

Craft production: A production process that based on manual skills. It is a small-scale production.

Advantages:

A lot more care is put into making the product as good/nice as possible, therefore the quality tends to be seen as considerably higher than something that was mass-produced. The product can also be customised to fit personal needs, and there is a good deal of flexibility for the designer, customer and craftsman. Much skill is often required for the craftsman; therefore they are able to charge more for the manufacturing of the product.

Disadvantages:

Although the manufacturing process does not require machines for the producer, it takes a great amount of time and effort; therefore it becomes much more expensive for the buyer. Also, with craft production it is not possible to produce on a larger scale. This could mean a loss of profit for the manufacturer, however the higher prices of craft produced products can sometimes make up for this. Another disadvantage may be that the product is not designed for disassembly, so if something goes wrong during the making of it, there are no interchangeable parts. Every piece also becomes more valuable so any defects will be more important.

Design Contexts include: one-off products such as custom made furniture, pottery, art and crafts, 

Mechanized production: A volume production process where machines are controlled by humans.

Advantages

❖ The creation of economies of scale … the product is cheaper than craft production ❖ The quality of the product is improved as fewer human errors will occur, the finish of the

product will also be improved. ❖ Increased wages due to training and becoming skilled. ❖ Efficiency of production: less time is taken to produce goods

Disadvantages

❖ Redundancy – machinery for labour substitution ❖ Health and safety. Work conditions are usually poor in the factories, lack of safety standards

can be an issue in some cases. Repetitive strain injury. ❖ Cost of energy, training and capital machinery. Increased wages due to highly skilled

operators needed. ❖ Environmental pollution. ❖ Boredom for the workers ❖ Low job satisfaction for workers

Design Contexts include: bicycles

Automated production: A volume production process involving machines controlled by computers.

When discussing advantages and disadvantages, consider cost, quality of product, social conditions and labour.

Design Contexts include: toilet paper, plastic drink bottles,

Computer numerical control (CNC)

(CNC) refers to the computer control of machines for the purpose of manufacturing complex parts in metals and other materials. Machines are controlled by a programme commonly called a “G code”. Each code is assigned to a particular operation or process. The codes control X, Y and Z movement and feed speeds.

Assembly line production

A volume production process where products and components are moved continuously along a conveyor. As the product goes from one workstation to another, components are added until the final product is assembled.

Design Contexts include: automobile manufacture, computer or laptops, most electronic consumer products.

Mass production

is the production of large amounts of standardized products on production lines, permitting very high rates of production per worker.

Mass customization

It is a sophisticated CIM system that manufactures products to individual customer orders. The benefits of economy of scale are gained whether the order is for a single item or thousands.

Production system selection criteria

Production system selection criteria include time, labour, skills and training, health and safety, cost, type of product, maintenance, impact on the environment and quality management

Design for manufacture (DfM):

DfM means designers design specifically for optimum use of existing manufacturing capability. There are four aspects of DfM.

● Design for materials ○ designing in relation to materials during processing

● Design for process ○ designing to enable the product to be manufactured using a specific manufacturing

process, for example, injection moulding. ● Design for assembly

○ designing taking account of assembly at various levels, for example, component to component, components into sub-assemblies and sub-assemblies into complete products.

● Design for disassembly ○ designing a product so that when it becomes obsolete it can easily and economically

be taken apart, the components reused or repaired, and the materials repurposed or recycled.

● Adapting designs for DfM

○ Designs will need to be adapted in some way in order to utilise the different DfMs.

These include: using standard parts, reducing the number of parts, employ modular design principles, rude the number of sub-assemblies

ROBOTS IN AUTOMATED PRODUCTION

A robot transforms the way products are made as it is an automatically controlled, reprogrammable, multipurpose manipulator that is programmable in three directions/ axes (x, y and z) that is either fixed or mobile for use in industrial automation applications.

It is comprised of:

1. A power source which provides the basic electrical or hydraulic power. 2. Tooling, either fixed or multiple interchangeable tools. 3. Mechanical unit, such as the arm, sensors, joints and actuators. 4. A control system like a computer.

The characteristics of a robot include: 1. Programmable 2. Able to move 3. Able to interact with its environment 4. Able to respond to stimulus

Robots can carry out many jobs, the 5 main jobs are automated car industry; movement of objects; manipulating objects; counting/ quality control; assembling/ welding/ spraying/ edge smoothing (deburring); palleting/ retrieving components/ transport/ locating/ holding.

A work envelope is the distance where the robot can extend to and the reach towards without having to be strained. Naturally, a robot cannot reach for an item that is not in its work envelope.

What is the difference between single-task and multi-task robots? Single task robots would be used with only one task that would be seen from a human perspective as that single task would be repetitive and boring, which would mean the human might get easily bored and the quality of work would deteriorate. A multi-task robot would be expected to have interchangeable tools, movement incorporated and working on more than one task in a factory.

What is the difference between first generation and second generation robots? First generation robots would be designed for factory work where simple tasks with dangerous or unpleasant aspects would be completed, such as

welding, spray paint, moving heavy objects or handling hot objects.

Second generation robots would perform more complex tasks and simulate human functions. Some robots would move, sense surroundings and respond to changes in their environment.

Third generation robots would be medical robots that assist with surgery, transport materials, dispense medicine and communicate with humans. They might understand speech, have artificial intelligence or respond to human commands.

Advantages: Robots do not become bored or fatigued: this prevents error and maintains quality. They can work faster than humans and can monitor themselves and provide feedback, auto correct and apply such things as variable torque.

● Reducing waste in manufacture

● Consistency/repeatability/accurac

y

● Quality control functions

● Minimize scrap and waste

● Better products, more reliable

● Safer: especially in higher risk

areas/hazardous work areas

● Speed, strength

● Reduced long term costs

● Greater hygiene

● More competitive

● Faster design cycles

● Fewer staff issues… Robots aren’t unionised

● More efficient, consistent and reliable

production

● Better health & safety

● Increased knowledge economy

Disadvantages:

● Unemployment/deskilling

● Limited functionality: robots are only good at specific things

● Capital intensive in the short term

● Separation of living standards between industrialized and non industrialised societies

● They are also potentially dangerous

● More mass consumption and planned obsolescence

● Dirtier industries are moved to developing parts of the world

● Power and maintenance issues

Primary characteristics of robots:

Work envelope: The 3D space a robot can operate within, considering clearance and reach

Load capacity: Within this context, the weight a robot can manipulate.

Single-task robots – can only carry out one task at a time

Multi-task robots – can carry out more than one task at a time

Teams of robots – groups of robots carry out similar tasks

What is M2M? How is it used in the present day? How might it be developed in the future? Machine to machine (M2M) – where wireless and wired systems communicate between devices to

share information or send instructions. Any technology that enables networked devices to exchange

information and perform actions without the assistance of humans. M2M forms the basis of a concept

known as IoT, the internet of things.

Benefits include:

A) Automation

B) Monitoring

C) Supply networks

D) Feedback

E) Optimized power use

F) Predictive maintenance

G) Health and safety

H) Inventory control

I) Productivity gains

KEY CONCEPTS - QUESTIONS!!

● DESCRIBE A STRESS STRAIN GRAPH

The stress strain graph is based on the stress acting on an object, hence testing the plasticity and

elasticity. Stress is on the y-axis and strain is on the x-axis. The stress-strain graph is a straight line

from the origin to the point called the proportional limit. Within that line, the stress is directly

proportional to strain (Hooke’s Law). Young’s modulus is the k in that equation - the constant - and is

equal to the slope of the stress-strain diagram. The stages of the stress-strain graph include:

proportional limit, elastic limit, yield point, ultimate stress point and breaking point.

● EXPLAIN HOOKE’S LAW

Hooke’s law is the equation f=kx relating the force to the load to the extension. K is the constant and is

known as young’s modulus, whereas the relationship between the load and the extension is directly

proportional until the limit of elasticity.

● WHAT DOES A HIGH YOUNG’S MODULUS NUMBER TELL YOU ABOUT A MATERIAL?

The stiffness of the material is calculated by dividing stress by strain, which gives the value of young’s

modulus to the material. This also provides quantitative data relating to strength and stiffness in

structures. A high young’s modulus indicates a very stiff material.

● LIST FOUR AESTHETIC CHARACTERISTICS OF A MATERIAL

Taste, smell, appearance, texture.

● DEFINE A SMART MATERIAL

A smart material is a material which responds and reacts to the surrounding environment several

times and in several ways.

● DESCRIBE A DESIGN CONTEXT FOR A PHOTOCHROMIC MATERIAL

A photochromic material reacts to changes in light, therefore a design context for a photochromic

material would be sunglasses/glasses which protect the user’s eyes from bright lights or the sunlight.

● HOW ARE PIEZOELECTRIC MATERIALS USED?

Piezoelectric materials give off small electric discharge when deformed. This can be used in lighters,

airbags or safety equipment in general as it is widely used as sensors in different environments. The

material senses a force of an impact on a car and sends an electric charge to blow up the airbag.

● HOW IS POLYMORPH USED TO PERSONALISE SURGICAL TOOLS?

Polymorph is used to fit the user’s specific shape and thus personalise surgical tools to ensure the fit is

just right and the ergonomic requirements and anthropometric data is suited to the user. The

polymorph mimics the user’s hand measurements and fit when it is manufactured.

● DISTINGUISH BETWEEN FERROUS AND NONFERROUS METALS

Ferrous metals contain iron and are therefore magnetic and liable to rust, whereas non-ferrous

metals do not contain iron, are not magnetic and do not rust in the same way as ferrous metals.

● LIST FOUR CHARACTERISTICS OF METALS

Metals are typically good electrical conductors, thermal conductors, hard and shiny.

● NAME TWO METHODS OF EXTRACTING METALS FROM ORE

Metals can be extracted from ore through electrolysis or carbon monoxide, depending on the

reactivity of the metal to chemicals. Reactive metals such as aluminium are extracted by electrolysis,

whilst iron - a less reactive material - would be extracted by carbon monoxide.

● DEFINE AN ALLOY

An alloy is a mixture or combination of various metals in order to combine properties or features.

Alloying increases strength and hardness, reduces malleability and ductility due to the process of

alloying.

● DISTINGUISH BETWEEN ELASTIC DEFORMATION AND PLASTIC DEFORMATION

A temporary shape change is called elastic deformation: where the material is changed and can be

changed but then returns to its original shape after the force is removed (self-reversing). The

permanent version of this - where the material is deformed in the way it is changed - is called plastic

deformation.

● HOW IS GRAIN SIZE IN METALS CONNECTED TO HOW LONG THE METAL TAKES TO COOL?

The longer it takes the metal to cool, the larger the crystals grow. This means that if a metal does not

take so long to cool, the grain size is relatively small.

● IS WORK HARDENING OF METALS A GOOD THING OR A BAD THING?

Work hardening of metals is a good thing in the way that it gets tougher when it is work hardened

(plastic deformation). However, it is mostly a bad thing as there is an increase in the brittle properties

of the material and therefore a higher risk of breaking the material after a lot of work hardening

occurs.

● DESCRIBE ONE CHARACTERISTIC OF A SUPER ALLOY

A super alloy has great mechanical strength, is resistant to thermal creep deformation and corrosion.

The strength of most metals decreases as the temperature increases, but superalloys can be used at

temperature close to their melting points.

● GIVE A DESIGN CONTEXT FOR ALUMINIUM

Aluminium is very lightweight and easy to use, which makes it perfect for ladders, aircraft

manufacture and window frames.

● DISTINGUISH BETWEEN HARDWOODS AND SOFTWOODS

Hardwoods come from deciduous trees with leaves and softwoods come from coniferous trees with

pines and needles and are evergreen.

● EXPLAIN “SUSTAINABLE FORESTRY”

Sustainable forestry is a term which is used to describe a forest that is carefully managed so that

when trees are felled (cut down) they are replaced by seeds (to re-grow the trees). This is a carefully

skilled and managed system.

● IN WHAT PARTS OF THE WORLD ARE FORESTS UNDER THREAT?

Pretty much anywhere and everywhere. The Amazon and tropical rainforests seem the most under

threat, however, countries like America and in Asia have forests that are under threat.

● WHY IS SEASONING IMPORTANT FOR THE PRODUCTION OF TIMBER?

Seasoning is important to remove the moisture (or greenness) of wood in order to make it highly

usable.

● DEFINE SHED SEASONING

Shed seasoning, otherwise known as air seasoning, is where the timber is kept in air-sheds where

there is little control over the drying elements or effects.

● GIVE A SUITABLE NATURAL WOOD FOR A CHILD'S TOY

Beech would be a suitable natural wood for a child’s toy as it is easy to work with, durable and can be

treated to suit the needs of the user.

● LIST 5 MANUFACTURED BOARDS

Hardboard, blockboard, MDF (medium density fibreboard), chipboard, plywood.

● DISTINGUISH BETWEEN VENEERS AND LAMINATES

Veneers are thin strips of wood that is glued onto the manufactured board in order to give the illusion

of an expensive, well-made natural wood. On the other hand, laminates are thin covering of wood with

another material like plastic, wood or veneer for protection and aesthetic requirements.

● EXPLAIN HOW WOOD CAN BE RECOVERED AFTER USE

Wood can be recycled and recovered after use in order to combat deforestation by reclaiming wood

and reusing it (and treating it) to create other vintage, bespoke products. Another way to recover

wood after use is to break it down even further and create manufactured boards with the leftover

pieces of wood.

● LIST THE MAIN CHARACTERISTICS OF GLASS

The main characteristics of glass include transparency, colour, strength, hardness, brittleness,

non-toxic and non-porous.

● DEFINE CULLET

Cullets are what recycled glass is turned into through crushing it which is added to new raw materials

in order to manufacture new glass. The recycled glass has to be separated into the same colours

before being crushed.

● LIST 4 NATURAL AND 4 SYNTHETIC TEXTILES

Natural textiles include: linen, cotton, wool and silk. Synthetic textiles include: rayon, nylon, polyester

and lycra.

● DISTINGUISH BETWEEN SPINNING AND WEAVING

Weaving is where two distinct sets of yarn/threads are interlaced at right angles in order to form a

fabric or cloth. Spinning, on the other hand, is the process of making thread out of raw fibres. In other

words, spinning comes first.

● DISTINGUISH BETWEEN THERMOPLASTICS AND THERMOSET PLASTICS

Thermoplastics can be reheated and reshaped, whereas thermoset plastics can only be shaped and

heated once. This is due to the molecular structure of the plastics.

● GIVE A DESIGN CONTEXT FOR POLYPROPYLENE

Polypropylene can be used in structural shells like calculator cases and cd cases.

● WHAT ARE THE CHARACTERISTICS OF ABS?

High impact strength, tough and scratch resistant, resistant to chemicals.

● DISTINGUISH BETWEEN CHEMICAL CHANGE AND PHYSICAL CHANGE

A chemical change changes what the substance is, whereas a physical change only changes the

appearance of the material not what it is.

● ARE BIOPLASTICS A GOOD THING OR A BAD THING?

Bioplastics are a good thing as it means the plastic substance can be recycled and break down after

a while, which means it is better for the environment and will release less polluting chemicals.

● EXPLAIN WHY PLYWOOD IS ISOTROPIC, BUT PINE IS NOT.

Plywood is isotropic because it is strong in all directions due to the layered plywood being odd

numbered and placed in right angles to each other (in terms of the grain). Pine is not strong in all

directions due to the single grain direction, therefore it is not isotropic.

● GIVE A DESIGN CONTEXT FOR GRP

Glass reinforced plastic can be used for grp piping or a swimming pool.

● WHAT ADVANTAGES FOR AIRCRAFT DESIGN ARE PROVIDED BY COMPOSITE MATERIALS?

Fibreglass, carbon fibre and fibre-reinforced matrix systems are used in aircraft designs as it reduces

weight, increased strength, smooth surface and increased fuel efficiency. They also do not corrode

easily and do not crack when fatigued which makes it ideal for high speed operations.

● LIST FOUR FINISHES FOR WOOD AND FOUR FOR METAL

Wood finishes include varnish, lacquer, paint and oil whilst four finishes for metal include satin finish,

paint, lacquer or galvanising.

● WHAT IS PREVENTING MORE WIDESPREAD RECYCLING OF MATERIALS?

The cost and energy to recycle materials makes it more difficult to implement the widespread of

recycling of materials. It takes energy to collect the material, energy to recycle and crush the material

and also expensive in order to rent the space required to do this until the material can be combined

with raw materials to create a new substance.

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