Specialist Technical Principles

Static load

Applied force that doesn’t move e.g. book resting on table

Dynamic load

Applied forces that does move e.g. book falling on table

They produce larger forces than static load

Tension

Pulling force applied to the ends of an object e.g. chains supporting swings

Tensile strength

Ability of a material to resist being stretched out

Compression

Pushing force applied to the ends of an object e.g. chair supporting a person is under compression

Compressive strength

Ability of a material to resist being squashed

Torsion

Rotational forces act in opposite directions on the ends of an object causing it to twist e.g. wringing a wet towel

Torsional strength

The ability of a material to resist being twisted out of shape

Bending

A force where one side of an object experiences tension whilst the opposite side experiences compression e.g. when 2 people are sitting on a see-saw - the top is stretched over the fulcrum whilst the bottom is compressed

Stiffness

The ability of a material to resist being bent out of shape

Shear

A force that acts on an object at 90° to its length, or when an object is being pulled apart on different planes and the forces travel in opposite directions e.g. scissors cutting paper

Strengthening

Designers consider possible forces on a product - dynamic or static, use techniques to enhance its functionality so that it can withstand more force

Reinforcement

A method of strengthening an object by adding material to it so that it can better withstand forces e.g. a car tyre has steel belts to resist puncture

Reinforced concrete

Reinforced material - a combination of steel and concrete, more flexible than concrete, still very hard - safer to use than standard concrete

Composite material

Permanent combination of 2 or more materials

Reinforcement in clothes

Denim clothes have metal rivets where lots of fabric needs to be stitched for greater tear resistance

Webbing

A strong fabric woven into strips from yarns that are often made from synthetic materials e.g. nylon or strong materials e.g. kevlar. Very light, strong and flexible

Uses for webbing

It is used belts e.g. seatbelts, securing loads on vehicles and climbing equipment

Stiffening

Some forms of reinforcement that make a material stiffer through manipulation

Lamination

Bonding 2 or more materials to improve strength, stability, aesthetics and sometimes flexibility

Examples of strengthening through lamination

Paper laminated in a plastic pouch - still flexible, water-resistant, more durable, harder to tear

Chair frames e.g. Ikea’s POÄNG chair - laminating wood is stronger and stabler, but still slightly flexible

Lamination process

A former/mould shapes the material by holding and pressuring the material against it. Can use clamps.

Fabric interfacing

An extra layer in textiles for additional support, shaping or structure

Ensures garment sits correctly/doesn’t hang limp

Commonly interfaced areas

Collars, cuffs, and waistbands

2 types of interfacing

1. Fusible
2. Sew-in

Fusible interfacing

Heat used to bond interfacing onto textile

Sew-in interfacing

Interfacing sandwiched between layers of material

Folding and bending

Changing the shape/rigidity of a material to increase strength e.g. folding paper so that it can hold more weight

A net

2D shape that can be glued and folded to form 3D shape

Drawing shows cut-lines, score-lines and tabs

Cut-lines

Solid lines on a net

Show where material needs to be cut

Score-lines

Dotted/dashed lines on a net

Indicates where net needs to be bent

Some materials need to be scored with a blade/heat/pressure to bend

Greenhouse gases

6 gases that are damaging the atmosphere to various degrees

Gases (not needed to know):

Methane, carbon dioxide, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride

Carbon footprint

Amount of carbon dioxide released during process e.g. product manufacture

Can use to estimate greenhouse gas emissions of a person, product, process, event or organisation

CO2e (kg of carbon dioxide equivalent)

Method of measuring the greenhouse gases damage to the planet

Ecological footprint

Measures impact of person’s life on environment by quantifying amount of natural resources used.

Measured in CO2 emitted to sustain lifestyle __or__ in terms of area of land/water needed to supply their needs and dispose their waste.

Can calculate area needed for activity/individual/city/country/globe.

Social footprint

Measure of impact that company policies have on workers/subcontractors/partners/society.

Duty to consider social as well as ecological footprint

e.g. if health and safety for employees is a primary concern due to company policies

Safe working condition legislation

Most developed countries have rules for employee working conditions, some don’t to same extent as UK

No protection = low wages, long hours, poor conditions

Britain has laws to protect worker rights. Employer/ee can be held accountable in court.

Health and Safety Executive

Organisation that looks after welfare of workers

Enforces Healthy and Safety at Work Act (1974) - companies must provide safe working environment/visitor protection

Minimum wage created in 1999 - protects low-paid workers, amount regularly reviewed

Designer responsibilities

Try to source items/components where working conditions are safe, even if costlier

Try to find conditions where item is produced to ensure they’re adequate

Fairtrade

Organisation that promotes buying items from companies that fairly pay/offer good conditions to workers

Specialise in farming, clothing, food production, gold mining

Ecological issues in design/manufacture of products

Natural resources used in making products - designer/manufacturer decisions directly impact consumption

Efficient design/reducing need of finite resources makes products eco-friendlier

Problems of harvesting materials

Inevitable disruption of environment - amount depends on mineral being extracted/plant being harvested

Processing into usable form also requires energy - modern processes becoming more efficient

Deforestation

80% of planet’s forests destroyed since 1900

Caused by need of timber for domestic needs as well as more area needed for growing more food for population

Many species becoming extinct

Slash and burn

Technique for converting forest to farmland: trees felled then burned - ash has nutrients - crops grown or cattle grazed

Forest doesn’t grow back - wildlife permanently loses home

Deforestation in developing countries

Developing countries view forests as commodity - sell harvesting rights to rich nations - timber/animals raised/food grown exported

Desertification

Land dries out and can’t support vegetation ∵ less rainfall ∵ rain forests are diminished

Threat to many dry areas

Types of mining

1. Surface mining
2. Underground mining

Mining

Essential to gather materials, minerals and metals to needed to supply manufacturing needs

Problems include soil erosion, sinkholes, air pollution and water contamination

Both types produce much CO2 - materials are mined, transported, processed

Underground mining

Less visual impact

Dangerous for miners, surface instability - subsidence or sinkholes

Surface mining

Scars landscape, increased habitat loss for wildlife

Drilling

Resources like gas/shale gas and oil best harvested like this

Borehole

Large hole drilled into Earth’s crust to reach resources

Can be 12km deep, average is 2km

Less surface impact than mining, __pipelines__ needed to store oil

Farming

Creates 15% of greenhouse gas emissions globally - mostly livestock: meat diet possible unsustainable as it needs 2.5x land of veg diet, 5x land of vegan diet

Product miles

A way of measuring CO2 emissions of product - adding up total miles travelled by a product in its lifetime including obtaining components/raw materials and waste disposal

Lifecycle assessment

Responsible companies do them to estimate product’s CO2 emissions from cradle to grave

Material extraction → processing/manufacture → transportation → usage/retail → waste disposal

Includes product miles

Oceanic pollution

Waste production/management led to massive ocean pollution.

Rubbish dumps are a problem - plastic doesn’t degrade and is eaten by animals which kills them

Sewage from industry/cities & oil spills also dangerous - oil spills less frequent because regulations but devastating

Atmospheric pollution

Increased use of fossil fuels in transport/energy product ∵ growing population means many harmful emissions - cleaner energies needed

Poor air quality in many places globally

Paris Agreement intends to hold global temp increase to below 2°

Consumer/designer role in reducing burden on finite resources

Designers/manufacturers must make products as sustainable as possible, consumers must choose products carefully to reduce impact on environment

All can follow 6R’s

Hierarchy of sustainability

Places best strategies for environment above ones with worse impact - can work through them to choose best option for product

Refuse → rethink → reduce → reuse → repair → recycle

(best → worst)

Saves resources, reduces energy use and CO2 emissions

Refuse (6R’s)

Asking if proposed thing is necessary - not using saves 100% of it

E.g. own carrier bag instead of new plastic bag every time for groceries, alternative transport

Rethink (6R’s)

Consumers rethink where they spend income e.g. sea travel instead of air travel

Designers/manufacturers rethink how product is made e.g. source of materials, if material is necessary - rethinking can lead to more responsible design

Reduction (6R’s)

Often result of rethinking - materials/energy saved due to better design

E.g. reducing number of parts in product, motion-sensitive lights, turning off unused appliances

Miniaturisation

Modern materials are lighter than traditional ones so item is made very small saving material/energy e.g. silicon chips are very small

Primary recyling

Reusing product for same purpose as design

Secondary recycling

Reusing product for different purpose as design

Reuse (6R’s)

Primary/secondary recycling - reusing saves material/energy from buying new product

E.g. glass milk bottles, websites like eBay that sell/give away unwanted items

Upcyling

Reusing item to create a new one of higher quality

E.g. new coat of paint on household items or minor repairs/adaptations

Repair (6R’s)

Repairing broken products extends its life and delays new purchase

Positive as only specific parts replaced - saves material

Also creates jobs in skilled labour

Reconditioned items usually cheaper

Problems with repair

Has become harder recently - products designed to be irreparable e.g. sold as sealed units, so must be replaced if broken

Cheaper to make irreparable products

Planned obsolecence

Products designed to last short time only so that they require replacing by newer products

Tertiary recycling (recycling in 6R’s)

Lower down the hierarchy of sustainability

Reprocessing of materials to make new materials

Takes lot of energy, most materials made are lower quality e.g. recycled glass usually has green tint

Sometimes not possible

Recycling materials uses less energy than creating new ones

Recover or Rot

Once all recyclable materials removed, mostly organic waste remains

Recover - waste materials burned, heat released is used to heat water to heat homes or to produce electricity

Rot - food waste turned to compost and used in horticulture as a growing medium

Landfills

Special landfill sites used to collect rotting matter so methane produced can be burned (recover)

Waste can also be buried unsorted - happens on large scale, unsustainable, chemicals could possible leach into ground

4 scales of production

one off, batch, mass, continuous

Bespoke items

Designed for an individual - can’t be bought off the shelf

One-off production

Production is labour intensive - handmade by specialists

Can be expensive, long time to make

Only available to OG client - e.g. engraving AirPods not one-off

E.g. product prototypes, personalised wedding cakes/dresses, TV/theatre sets, GCSE projects

Batch production

Certain number of identical products - small or large amount

More automated than one-off, some high skill labour - small production lines/semi-skill labour for repetitive tasks

Templates/jigs/patterns/formers/moulds save time and make sure items are identical

More items = cheaper unit cost per item

Short lead time to get products to market ∵ adaptable machinery and staff

E.g. surfboards and kayaks, some furniture, clothing, food

Mass production

Items in constant use & design doesn’t change

Dedicated production for large numbers - highly automated, little labour, some skilled labour to operate lines

High set up costs, low unit costs - set up costs recovered fast

E.g. drink/food containers, electronic products, cars/bikes

Continuous production

Factory operates up to 24/7, low skilled staff operate in shifts

Limited range of products, rely on automation - saves time by avoiding changes to line

Products usually stock/standard material forms - assembled elsewhere

2 types of timber finishes

Rough sawnPlaned all round (PAR)

Uses of rough sawn timber

Exterior tasksWhere finish doesn’t matter

Uses of PAR

FurnitureInternal featuresWindowsDoors

Seasoning

Reduction of moisture content in timber

Common moisture contents

Green timber: \>50%Exterior use:

Air-drying

Timber is stacked so that air can circulate

Air-drying time

~25mm/year (plank thickness that seasons)

Air-drying results

Moisture content reduces to 18% (in the UK)

Kiln-drying

Heat and pressure is used to reduce moisture content

Kiln-drying advantages

Lower moisture contentLess prone to faultsKills bacteria/insects that might attack woodFaster process - can be sold soonerNo land needed for storage whilst seasoning takes place

Kiln-drying disadvantages

More expensiveBad for the environment

Manufactured board

Natural timber is combined with adhesive Waste, low-grade and recycled timber can be used Usually a pale brown natural finish

Methods of manufactured board production

LaminationCompression

Lamination

Layers of wood are bonded together with adhesives

Compression

Wood is shredded/chipped/pulped → heated and compressed under high pressure Normally adhesives bond the particles together

Laminated boards

PlywoodBlockboard

Compressed boards

OSB (oriented strand board)MDF (medium density fibreboard)ChipboardHardboard

Veneer

Thin slice of natural timber

Veneer uses

Manufactured boards are covered in them Commonly seen on MDF and plywood

Methods of veneer production

RotaryKnife cut

Rotary veneer production