DT GCSE AQA

crowdfunding

crowdfunding

buissnesses/individuals promote an idea on a platform, and people can choose to invest

CAD advantages and disadvantages

- Ease to modify - can make changes to manufacturing
- Manufacture directly - from CAD drawing
- Virtual testing - avoid destructive testing
- Less human error - fewer mistakes
- expensive to set up
- needs a skilled workforce
- difficult to keep up with constantly changing and improving technology

CAM advantages and disdvantages

- creates CAD designs using laser cutters, 3D printers etc
- saves time, labour and costs in industry
- can produce large number of products in short time
- provides consistency and accuracy in finished product
- helps provide safer workplace
- expensive to set up
- needs a skilled workforce of engineers

Flexible manufacturing system

CNC machines work alongside a production line, and are easily adaptable. Good because allows manufacturers to adapt quickly to consumers needs by altering designs

Just in time manufacturing

example of lean manufacturing, materials are only ordered when needed.
- reduces cost, stock less likely to go out of date reduces wasted materials
- lack of stock if supplier mistakes occur, increased transport cost due to more frequent deliveries

life cycle assessment

- extracting and processing raw materials
- manufacturing final product
- distribution and packaging
- use
- disposal

continuous improvement

manufacturers constantly looking to make small improvements to products top boost efficiency

technology push

new adavancemnts in technology allow designers to create new products

market pull

new product development driven by changing consumer demands

the six Rs

Reduce
Reuse
Recycle
Rethink
Repair
Refuse

planned obsolesce

product designed to have a set lifespan (e.g car 10-15 years)

design for maintenance

product designed so when. component is worn out, it can be repaired or replaced without throwing the whole product away

FSC

FSC labeled timber means it has come from a sustainable source

fossil fuels advantages and disadvantages

- bad for the environmental as enhance greenhouse effect
- contribute to climate change and will eventually run out
- cheap, easy and reliable

wind energy use, advantage and disadvantages

- generators in wind turbines convert kinetic energy into electricity
- no greenhouse gases
- once turbines et up, energy is cheap
- set up costs are high
- turbines cause noise pollution and are ugly

solar

solar panels convert suns energy into electricity
- no greenhouse gases
- once panels set up, energy is cheap
- no electricity when no sunlight
- solar panels are expensive

tidal

turbines convert kinetic water energy into electricity
- tides are guaranteed and predictable
no greenhouse gases
- costly to build
- can disrupt ecosystems

hydro-electric

trapped water released from dams kinetic energy turns electric turbines
- once set up, is cheap
- reservoirs provide water supply during shortages
- set up costs are high
- dams built destroy habitats

biomass

organic material burners for energy or processed into biofuel
- renewable if resources are replaced
- releases co2
- using wood for fuel leads to deforestation

nuclear

heat generated by splitting uranium atoms in nuclear reactors
- very efficient and generate a lot of energy
- use far less greenhouse gases than fossil fuels
- depends on uranium (non renewable)
- produces radioactive waste that are hard to dispose of
- highs et up and decommissioning costs

shape memory alloys

- can return to original shape after being deformed through heating or electrical current

thermochromic pigments

- change colour in response to changes in temperature

photochromic pigments

- change colour in response to light levels

coated metals

- to increase strength and resistance to corrosion, metals are coated with another metal
- e.g nickel plated steel, polymer coated aluminium

liquid crystal displays

- flat panel displays that use liquid crystals to control light emission and create an image
- who voltage is applied to crystals, they change shape and allow different levels of light to pass through, creating an image

nano materials

- contain particles less than 100 nanometers in size and have different properties to larger particles of same material
- large surface area to volume ratio, which improves strength, conductivity and reactivity

composite materials

made from more than one material, usually with contrasting properties
- e.g glass reinforced plastic > combines glass fibres with a thermosetting plastic to create a lightweight, strong and resistant material used in boat hulls and car bodies
- e.g carbon reinforced plastic> combines carbon fibres with thermosetting plastic making it more rigid, strong and lighter, however also more expensive and brittle

Kevlar

- A strong synthetic material with a high. tensile strength to weight ratio, used in protective armour

conductive textiles

- conduct electricity
- metal fibres either spun into fabric or metal based powders are impregnated into fabric

fire-resistant fabrics

- (e.g nomex) have flame resistance built into their chemical structures to protect the wearer

microfibres

- made of extremely fine synthetic fibres
- breathable and durable, often used in sports clothing

Automation impact on industry

- machines programmed to carry out multiple procedures at a time
- cost to set up machinery is high, but running costs are lower once set up and waste is reduced

Robotics

- part of automation, use AI to collect information and improve the performance of a procedure
- increase efficiency, and can handle harmful materials that humans cant
- very expensive

Specialist buildings

- Buildings that use smart technologies to improve building efficiency
- sources try to minimise environmental impact
- modular buildings can be erected quickly and at a low cost
- improvements in stock control mean less storage space is needed

virtual marketing and retail

- promotion of products online and sharing experiences, reviews, and recommendations
- algorithms can generate information about. users buying habits and suggest relevant retail sites for them to try using search engine optimisation (SEO)
- cost of retailing from a website is far lower than from a shop

cooperatives (impact on enterprise)

- organisations with lots of people working towards common goals
- E.g John Lewis & partners, Nationwide Building Society

Fair trade (impact on enterprise)

- trading partnership which ensures suitable working conditions and fair wages for workers in developing countries

continuous improvement (impact on environment)

- making small adjustment to production techniques to improve speed, quality, and save resources

change in job roles (impact on people)

- rapid changes in technology and automation> decline in the need for traditional skills. - - workers have had to be retrained/'up-skilled' to manage the new technologies.

changes in fashion trends (impact on culture)

- fashion trends are impacted by changing technology, and employers embracing this allows them to remain popular with a modern market
- trend forecasts can predict future patterns, and manufacturers can buy this to influence their designs and keep them ahead of competitors

respecting faiths and beliefs (impact on culture)

- it is important for designers to design products for a range of cultures within the mass market (e.g modest outfits, no animal ingrediants)

physical disabilities (impact on society)

- user needs are met by the designer understanding the nature of the disability
- they create everyday products that help increase independence

age (impact on society)

- older people may experience more difficulties, such as mobility issues, visual impairments, or hearing loss
- e.g long shoehorn helps older people put on a shoe without bending down

Environmental design

- make products from renewable materials to create less waste
- transport materials in a more efficient way to cut down greenhouse gas emissions
- cut down use of finite resources

fossil fuels

coal, oil, natural gas

single use batteries

- commonly alkaaline batteries
- readily available in supermarkets and shops
- has to be replaced once it runs out
- contain harmful chemicals that can contaminate the ground/wildlife if disposed of incorrectly

rechargeable batteries

- more expensive than single use
- can be recharged
- more economical in the long term
- still have a limited lifespan
- contain harmful chemicals that can contaminate the ground/wildlife if disposed of incorrectly

kinetic pumped storage systems

- During the night, excess electricity produced, meaning the cost of the electricity is much lower, so a kinetic-pump plant will pump the water from a lower reservoir up to a higher reservoir
- When there is a need for more electricity during the daytime, the dam is opened and the water from the top reservoir passes through pipes, spinning turbines to quickly produce the electricity needed

what is a modern material

- a material that has been engineered to have improved properties
- e.g concrete, aluminium, steel

Graphene (modern material)

- single layer of carbon which is (hypothetically) 100 times stronger than steel

Titanium (modern materials)

- modern metal used in sporting and medical applications (e.g replacement hip joints, high performance bicycles)
- ideal because it has a high strength to weight ratio, and is resistant to corrosion

metal foams (modern material)

- strong but lightweight modern material produced by injecting a gas or foaming agent into a molten metal
- usually only 5-25% of the foam is metal, allowing it to retain strength without the density
- often used in cars or planes as they absorb shock if the vehicle crashes

liquid crystal displays (LCDs) (modern material)

- when charge is applied to each crystal, the shape changes to either block ro let light through
- require backlight to work, and many modern devices use organic light emitting diodes (OLEDs)which allows the device to be thinner and lighter, however they are more expensive

nanomaterials (modern materia)

- tiny particles that can be used in thin films or coatings (e.g on a smartphone to repel greasy fingerprints)

Smart materials

materials which exhibit a change in response to an external stimuli

shape memory alloys (smart material)

- metal alloys that remember their shape when heated
- e.g nickel titanium (nitinol)> contracts when heated, whereas most metals expand
- used in braces so when they heat up in the mouth they 'pull' on the teeth

Thermochromic pigments (smart materials)

- change colour when they are heated
- can be mixed with paint/polymers to give the materials the same colour changing properties as the pigment
- can be used in colour changing mugs, or bath toys

photochromic pigments (smart material)

- change properties when exposed to UV light
- e.g glasses where lenses become sunglasses when exposed to bright sun light, or on windows to prevent rooms getting too hot in warm weather

polymorph (smart material)

- polymer that becomes malleable when heated
- when cooled is hard enough to drill and cut
- can be used for modelling as it can be reheated, and ergonomic handles

composite materials

- made up of two or more different materials combined to improve their properties
- fibre based, particle based, or sheet based

fibre based composites

- resin gives ability to mould complex shapes, fibre makes them very strong
- glass reinforced plastic> glass fibres and resin, sued for boats and instrument cases
- carbon reinforced plastic> carbon fibre and resin, used for formula 1 car bodies, crash helmets, and sports equipment
- glass reinforced concrete> glass fibre and concrete, used for street furniture and urban features

particle based composites

- made with small particles mixed with larger ones to create a strong and dense material good for building large structures
- concrete> made from cement, sand and aggregate, used for buildings and street furniture
- cermet> made from ceramic and metal, used for electronic components that need to operate under very hot temperatures

sheet based composites

- mix wood fibres or thin slices of wood veneers with resin, form large and stable sheets for furniture panels and interior construction
- MDF> wood pulp and resin, used for furniture and interior cladding
- plywood> wood veneers and resin, used for furniture and construction
- chipboard> wood chip and resin, used for furniture panels and construction

Nylon/Polyamide (technical textile)

- synthetic material which can be pulled into very thin strands when heated and spun

conductive fabrics (technical textile)

- allow a small electrical current to safely pass through them
- used to dissipate static charge from tough screen gloves

fire-retardant fabrics (technical textile)

- textiles made more resistant to fire through chemical treatment or manufactured fireproof fibres
- often used in furniture and furnishings where safety is a paramount

kevlar (technical textile)

- tightly woven fabric that has great impact resistance
- used in racing tyres, racing sails, gardening gloves and bulletproof vests

microfibres (technical textile)

- thinner than human hairs and can be coiled to provide a warm, soft absorbent material
- used in winter clothes or cleaning cloths

micro-encapsulation (technical textile)

- encapsulates liquid or solids in tiny thin walled bubbles, which gradually release active agents when rubbed
- can make products smell good, to cover body odour in sports clothings, or be used for scratch and sniff perfumes

input devices

- take a signal from the physical world and turn it into an electronic signal that a process device can understand and act upon
- e.g LDR, thermistors (switches or sensors)

switches

- allow current to flow when contacts inside are joined
- push to make/break> console controller buttons
- reed (magnetic)> window sensors on alarms
- toggle> power switch
- rocker> light switch
- tilt> detect if something is no longer level

sensors

- can detect changes in light, temperature, and pressure
- LDR> as light gets brighter, its resistance decreases, so can be used as a simple light sensor
- Thermistor> mostly NTC (resistance decreases as temperature increases), but some PTC, can be used to check the temperature in a room
- pressure sensors> produce a signal that varies with the amount of pressure placed on them, useful for security systems

microcontrollers

- example of a single board computer, which is manufactured as an integrate circuit and can be programmed to perform different programming functions (e.g PIC)

advantages and disadvantages of microcontrollers

- size of a circuit can be significantly reduced
- can be reprogrammed many times, so changes can be made without replacing components
- create flexibility buy having pins connecting several input and output devices
- cost more than traditional ICs
- programming software and hardware is expensive
- language of the system must be learnt (training costs)

programming microcontrollers

- text based programming languages (python, BASIC, C++)> add more flexibility but are harder to understand
- block based programming editors> simple to use but can be limiting
- flowchart software> simple and easy to read but can be bugs in the system

outputs

- take a signal from the process device and turn it back into a physical signal (e.g light, sound)
- light output> when current flows through the filament, it heats up and light is produced
- sound outputs: buzzers> oscillator inside a plastic case, produce a buzzing sound when current flows through, e.g doorbell, alarm
- speakers> produce sound using electromagnetism, require a driver circuit to provide a signal

types of motion

linear> in a straight line (e.g train moving down track)
- rotary> moves around an axis or pivot point (e.g bike wheel)
- reciprocating> repeated up and down or back and forth motion (e.g pump)
- oscillating> curved backwards and forwards movement that swings on an axis or pivot point (e.g pendulum)

Levers

- First order> load closer to fulcrum, when fulcrum is moved nearer the load it takes less effort to move (e.g seesaw, crowbar)
- Second order> fulcrum at one end and effort at the other, with load in the middle, closer together load and fulcrum are, the easier to move (e.g wheelbarrow)
- third order> effort between fulcrum and load, further apart they are, easier to lift (e.g tweezers)

mechanical advantage

divide load by effort, or divide distance from effort to pivot by distance from load to pivot

linkages

- Reverse motion> change direction of input to the output goes the opposite way (e.g foldable clothes horse)
- parallel motion or push/pull> two fixed pivots make the input and output travel in the same direction (e.g toolbox with draws that open up)
- bell crank> change the direction of the force through 90 (e.g bicycle brakes)
- crank and slider> change rotary motion into reciprocating motion (e.g car engine)
- treadle> use rotary input to turn a crank on a fixed pivot (e.g windscreen wipers)

angles in linkages

- when two lines intersect, opposite angles are equal
- where two lines sit on a horizontal line, the total angle together is 180

cam mechanism

- two main parts> cam attached to a crankshaft which rotates, and a follower which touches the cam and follows the shape

types of cams

- circular> off centre pivot to cause the follower to move up and down (e.g used in steam engines)
- pear> remains stationary for half of a turn then gently rises and falls (e.g used in carousel horses)
- snail/drop> causes follower to remain stationary for half a turn before gently rising and suddenly falling (e.g used in production lines to make regular holes in an item)
- heart shaped/constant velocity> follower rises and falls steadily with uniform velocity, no stationary period

followers

- flat> flat bottom sits on the cam, cope well under load but aren't accurate and have a lot of friction
- point/knife> have a narrow point that sits on the cam, very accurate and low friction but wear away pointed edge quickly
- roller> have a roller such as a ball bearing attached to the bottom, accurate, low on friction, can withstand load but are expensive to produce

gear train

- two or more gears joined together
- driver gear causes driven gear to turn in the opposite direction
- gear ratio= number of teeth on driven gear/number of teeth on driver gear

pulleys

- use mechanical advantage to lift up loads
- wheel shaped with a groove that allows a cord to sit inside
- block and tackle> using two pulleys means you need half the force to lift, and adding more increases the load it can lift
- mechanical advantage> number of sections of rope pulling up and object

belts

- transfer movement from one rotating pulley to another
- normally made from soft, flexible materials such as rubber
- the bigger the wheel, the slower the speed
(e.g treadmill, washing machine, winch)
- velocity ratio= diameter of driven pulley/diameter of driver pulley
- output speed= input speed/ velocity ratio

papers (5)

- bleed proof> coated to stop colour seeping
- cartridge> thick, expensive and opaque, used for ink and watercolour
- grid> grid lines (usually blue)
- layout> translucent, off-white, takes most media well
- tracing> translucent, shiny, takes pencil well

boards (6)

- corrugated card> paper bonded to the outside, corrugations make it strong, protective and insulating, used in packaging
- duplex> two layers of card bonded together, stiff, lightweight and printable for packaging
- foil lined> white card with foil backing, stiff, oil resistant, foil backing reflects heat so used fopr food containers
- foam core> smooth, laminated with white board, thick and rigid, available in variety of thicknesses, prone to creasing and cracking, used fro models
- inkjet card> bright white, smooth on both sides, deep colours as photographic ink sets on surface
- solid white> smooth on both sides, stiff, can be cut or scored

hardwoods (5)

- Ash> pale, narrow grain, flexible, tough, used for sports equipment
- beech> slight pink tint, close grain, tough, durable and smooth to finish
- mahogany> dark reddish, very close grain, cuts and polishes easily, high quality finish, used for high quality furniture
- oak> moderate brown colour, unique and attractive grain markings, tough, durable, polishes well, used for quality furniture
- balsa> pale, wide spaced grain (fast growing), very soft, used to make models

softwoods (faster growing and cheaper) 3

- larch> pale with contrasting darker grain, knotty, durable, easy to machine, high sap content gives good water resistance, used for exterior building and flooring
- pine> pale, aesthetically pleasing grain, lightweight, easy to form, used for construction and decking
- spruce> pale, even grain, easy to form, takes stain well, used for construction and furniture

manufactured boards

- MDF> smooth, light brown, can be veneered, easy to finish, not waterproof, used for kitchens and flat pack furniture
- plywood> odd number of layers of veneer glued at 90 angles for strength, easy to cut and finish, can be stained or painted, used for shelving, construction and toys
- chipboard> compacted wood chips laminated, end cuts are difficult to finish, strong but absorbs water, used for veneered worktops and flooring

ferrous metals (contain iron ad are magnetic)

- low carbon/mild steel> alloy that is grey and smooth, rusts if not protected, ductile and tough, easy to form, versatile, used in construction, nuts, bolts and bike frames
- cast iron> dull grey, rusts easily, brittle if thin, used for manhole covers, pans and gates
- high carbon steel> alloy that is grey, smooth, doesn't rust easily, hard wearing, less ductile than LCS, sharpens well

non ferrous metals

- aluminium> light grey with matte finish, lightweight but strong, ductile, used for drink cans and kitchen utensils
- copper> polishes well but oxidises to green, good electrical conductor, welds easily, used for plumbing parts and electrical cable
- tin> silver, soft, malleable, used to make food cans
- zin> brittle, average malleability and conductivity, used to galvanise steel

alloys

- brass> non ferrous, alloy of copper and zinc, can be cast and machined, used for musical instruments and ornamental hardware
- stainless steel> ferrous metal, alloy of chromium, nickel, and manganese, hard and smooth, used fro cutlery and sinks
- high speed steel> can be alloyed with a variety of materials for different properties, can withstand high temperatures, used fro drill bits and saw blades

Thermoforming polymers (can be heated and formed repeatedly)> acrylic, high impact polystyrene, high density polythene, polypropylene, polyvinyl chloride, polyethylene terephthalate

- Acrylic> hard, brittle, resists weather, used for car lights, visors, and baths
- High impact polystyrene (HIPS)> rigid, cheap, food safe, used for CD cases and yoghurt pots
- High density polythene (HDPE)> stiff, strong, lightweight, flexile, used for washing baskets
- Polypropylene (PP)> easily coloured, tough, flexible, used fro plastic chairs
- polyvinyl chloride (PVC)> cheap, brittle but durable, used in blister packs/window frames
- Polyethylene terephthalate> clear, smooth finish, strong, tough, used for clothing and drink bottles

thermosetting polymers (can only be formed once)> epoxy resin, melamine formaldehyde, phenol formaldehyde, polyester resin, urea formaldehyde

- epoxy resin (ER)> resin and hardener combine to make an extra strong adhesive, rigid, durable, expensive, heat resistant, used to bond materials and in waterproof coatings
- melamine formaldehyde (MF)> hard, brittle, food safe, used for picnic wear
- Phenol formaldehyde (PF)> rigid, brittle, good insulator, used in snooker balls and bottle caps
- Polyester resin (PER> clear, smooth, strong, heat resistant, used as waterproofing
- Urea formaldehyde (UF)> smooth finish, heat resistant, brittle, used for electrical fittings

natural textiles

- Cotton> takes dye well, soft, strong absorbent, recyclable, used in clothing
- wool> takes dye well, warm, crease resistant, used in clothing and carpets
- silk> soft, shiny, difficult to wash, expensive, creases easily, used in luxury clothes, underwear and bedding

synthetic fibres

- polyester> strong, versatile, holds colour and washes well
- polyamide (nylon)> shiny, water resistant, used fro parachutes, clothing and sports equipment
- elastane> smooth, stretchy, heard-wearing, quick drying, used in sportswear and swimsuits

blended fibres

polycotton> easy to wash, cheaper than cotton