product design

product design a level

electrical conductivity

a measure of how well electric currents move through a substance

thermal conductivity

the rate at which a substance transfers heat

strength

the ability to stand up to forces being applied without it bending, breaking, shattering or deforming in any way

tensile strength

the ability to stretch (placed under tension) without breaking or snapping

torsional strength

a load usually expressed in terms of torque, at which the fastener fails by being twisted off about it axis

elasticity

the amount of stretch in a material

hooke’s law

the extension of an elastic object is directly proportional to the force applied to it

plasticity

the ability to be permanently shaped or moulded e.g. thermoforming plastics

malleability

the ability to be permanently deformed in all directions without fracture

ductility

ability to be drawn out without breaking

hardness

the ability to resist deformation, indentation or penetration. can resist abrasion, drilling, impact, scratching

toughness

can withstand impact or shock

durabilty

the ability to resist wear, weathering deterioration or corrosion

biodegradability

the capability to be degraded into more simple substances through the enzymatic activity of microorganisms

hardwoods

deciduous
take over 100 years to grow

oak

strong, durable, attractive grain
expensive, heavy, corrodes iron and steel, splits

mahogany

attractive finish, durable, easy to work
warps, oils give rash, rainforests

beech

tough, doesn’t crack/splinter, hard, polishes well
expensive, difficult to work, not resistant to moisture, not suitable for outside

balsa

lightweight, floats, easy to cut
expensive, soft

jelutong

even/close grain, easy to cut/shape
soft, poor structural use

softwoods

coniferous, grow for about 30 years, cheaper

pine

durable, easy to work, straight grain, cheap, strong, lightweight
can warp/crack/splinter, knots

cedar

water resistant, fewer knots, aromatic quality
expensive, not as strong

larch

tough, durable, resistant to water, used outside
expensive, few knots

redwood

easy to work, finishes well, durable, used outdoors with preservatives, few knots, straight grain, tensile strength
knots difficult to work

errors in wood

mildew, fading, cracking, warping, splintering, uv damage, cupping, nail popping

ferrous

contain ferrite or iron, rust, magnetic

non-ferrous

contain no iron, do not rust, are not magnetic

alloy

metals formed by mixing metals to produce metals with enhanced properties

mild steel

iron + 0.3% carbon
melting point 1400C
tough, ductile, malleable, tensile strength, easily joined
poor corrosion resistance

high carbon steel

iron + 1.4% carbon
melting point 1800C
very hard, magnetic, tough, conductivity, hardened/tempered
difficult to cut, less ductile than mild steel

cast iron

iron + 4% carbon
melting point 1200C
hard skin, magnetic, good in compression, self-lubricating, easily machined, corrosion resistant
brittle, soft core

aluminium

melting point 650C
corrosion resistant, malleable, ductile, easily machined, good conductor, polishes well
can crack under stress, does not withstand great loads, oxidises

copper

melting point 1100C
corrosion resistant, malleable, ductile, tough, easily machined, good conductor, polishes well, non-toxic
danger of electrolysis

zinc

melting point 420C
corrosion resistant, doesn’t react to water or oxygen
becomes brittle when worked, difficult to paint

tin

melting point 232C
high corrosion resistance, soft, ductile, malleable, low melting point
weak

stainless steel

carbon steel + 18% chromium + 8% nickel + 8% manganese
melting point 1400C
tough, hard, corrosion resistant, magnetic, resists wear
difficult to cut/form

duralumin

aluminium + copper + manganese
melting point 350C
lightweight, ductile, malleable, strong, excellent machining properties
age hardens over time

brass

65% copper + 35% zinc
melting point 940C
harder than copper, corrosion resistant, easily machined, good conductor, casts well, polishes well

polymers

good insulators, colour can be changed with pigments
made from crude oil, polymerisation

thermoplastics

can be reheated and reshaped, mouldable after reheating, do not undergo significant chemical change
can be recycled

PET

good alcohol and oil barrier, barrier against atmospheric gases, prevents gas from escaping, chemical resistant, high impact resistance, high tensile strength, non-toxic, waterproof, impact resistant
can discolour, can effect taste of products
blow moulded water bottles

polyethylene

high density (hdpe) and low density forms (ldpe)
good electrical insulator, chemical resistant, water barrier, tough, durable, flexible, impact resistant (hdpe)
colour fades, can break over time
injection moulded

PVC

chemical resistance, weather resistance, moisture resistance, preserves gases, stiff, tough, flexible, hard/abrasive resistant, lightweight
can become brittle from uv, can break when moved

polypropylene

hard, lightweight, impact/chemical resistant, low moisture absorption, food grade, non-toxic
uv causes degradation, oxidation problems possible during manufacture

acrylic

stiff, durable, good electrical insulator, chemical resistant, weather resistant, impact resistant
brittle, scratches easily, splinters easily

ABS

chemical resistant, hard, tough, impact resistant, electrical insulator
uv light causes degradation
injection moulding

thermosetting

can only be heated and shaped once. if reheated they cannot soften as polymer chains are interlinked

epoxy resin

corrosion resistant, electrical resistant, good bond qualities
can cause allergic reactions, suspected health problems

urea formaldehyde

strong, hard, heat resistant
can’t be recycled, brittle, can emit toxic vapours during manufacture

polyester resin

electrical insulator, heat resistant
brittle, can crack
used as part of grp aka fibreglass

elastomers

natural rubber is an elastic material obtained from the latex sap of trees
flexible and extensible

thermoplastic elastomer

physical mix of polymers, consist of materials with both thermoplastic and elastomeric properties
can be repeatedly stretched without permanently deforming the shape of the component

rubber

excellent abrasive resistance, tensile strength, elasticity, tough, impact strength, water resistance
poor chemical resistance, allergy to latex, can’t reshape/recycle

composites

two or more materials are combined by bonding
improved mechanical, functional and aesthetic properties
excellent strength-to-weight ratio

glass reinforced plastic

manufactured from a thermosetting resin that has been reinforced using very fine glass, additional tensile strength
health and safety: resin and catalyst can give off toxic fumes, gloves must be worn, ventilation
high mechanical strength, lightweight, corrosion resistant, temp resistant, thermal insulation, water resistant, easy to form, easy to repair
brittle, can be prone to osmosis where water seeps in and causes delamination

carbon fibre

produced in a similar way to grp
can be sprayed other colours to black, tensile strength
hard to repair/recycle, expensive, only black, , highly specialised manufacturing process

MDF

cheap, made from waste wood, flat ungrained surface, easily machined, large size sheets, consistent strength in all directions, can be moulded into complicated shapes
blunt tools due to glue, ugly, weak compared to real wood, cannot be recycled

hardboard

cheaper than plywood when strength is not needed, made from wood fibre extracted from chips and pulped wood waste
heat and steam applied to leave fluffy brown fibres, transformed into mats held together by lignum, pressed between steam-heated metal plates to give sheets with one smooth side and one textured side
good flat ungrained surface, easily machined
absorbs water, not very strong

plywood

veneers of laminated hardwood at 90 degrees to each other, always an odd number of layers
flat, structurally strong, resistant to warping/cracking/twisting, looks like wood
expensive, edges can be rough, can warp with water

chipboard

gluing wood particles together with adhesive under heat and pressure
cheaper than mdf, smooth surface, rigid. easily veneered, fire-retardant, can be covered with laminate to protect from moisture
absorbs water

plywood grades

AA - best quality

AB - one side has imperfections

BB - both sides have imperfections

BC - one has more imperfections

paper making process

1. west end - pulp pumped through thin slot onto a wire gauze belt to drain

2. wet press section - rollers remove majority of water and stretches material into rough paper, rollers determine thickness

3. dryer section - steam-heated rollers continue to remove water, sizing agents/starches/resins added to enhance properties

4. calendar section - paper passes through series of rollers to smooth and give uniform thickness, roller pressure determines finish

paper and board

made primarily from hard and softwoods
wood made from cellulose fibres bound together with lignin, these need to be separated to make pulp, softwood fibres are longer, offering greater strength whilst hardwood fibres are shorter giving smoother finish

units of size and weight

stock sizes keep cost down, easier/quicker to obtain, predictable production times, fit printers and copiers, international standard, readily available

gsm - grams per square metre

layout paper

50gsm
translucent with smooth surface
used for outline sketches of proposed page layout, sketching and developing ideas, marker rendering
translucent allows tracing, accepts most drawing media except paint
expensive

tracing paper

60-90gsm
thin transparent paper with smooth surface, grey
used for outline sketches of proposed page layouts, heavier weight preferred, sketching and developing ideas
allows tracing through onto another sheet in order to develop design ideas
heavier weights can be expensive

copier paper

80-90gsm
lightweight grade of quality paper, good quality bleached surface
used for photocopying, printing from inkjet and laser printers, sketching and writing
bright white, available in other colours
inexpensive when purchased in bulk
surface is slightly rough to take ink well

cartridge paper

120-150gsm
creamy white paper, smooth surface with slight texture
used for drawing, heavier weights with paint
opaque, accepts most drawing and painting media
more expensive than copier paper

bond paper

>50gsm
high quality durable writing paper, often carries a watermark
used for letterheads, legal documents, paper for electronic printers, graphic work using a pencil, ink, markers etc.
largely made from rag pulp, which produces a stronger paper than wood pulp, long-wearing, range of colours
inexpensive when purchased in bulk

coated paper

70-300gsm
covered with a suspension of china clay, pigment and adhesive to give smooth surface finish
used for wide range of high quality printing
coating levels off pits between fibres of paper giving smooth flat surface for printing, range of finishes (high gloss, matte, silk, satin)
relatively expensiv

mounting board

1000-1500gsm
relatively thick card with colour on one side only
used for mounting work for presentations and displays, work can be mounted flat or behind frame mounting, mount drawings for exhibitions
very high quality, strong and rigid board, wide range of colours
expensive

carton board

used extensively in retail packaging industry where specific properties are needed
suitable for high speed, automated processes or die-cutting, printing, folding, gluing etc. total graphic coverage and excellent print quality, structural protection

corrugated board

constructed from a fluted paper layer between two liner papers
used for protective packaging of fragile products, most common box-making material
impact resistant, recyclable, strength-to-weight ratio, heat insulation, lightweight
inexpensive

foam board

core of the board is foam glued to layers of printable white paper
used for model making, mounting images
lightweight, rigid, print surface, easily damaged, not waterproof
expensive

folding box board

usually consists of bleached virgin pulp top surface, unbleached middle layers and bleached inside layer, bright white for printing
used for majority of food packaging and general carton application
scoring, bending, creasing without splitting, print surface, food grade safe
inexpensive

foil lined board

a layer of foil glued to any card, available in matte and gloss finish
used for cosmetic cartons, pre-packaged food packages, takeaway boxes
strong visual impact, foil provides moisture barrier, foil can be easily scratched unless varnished, food grade safe

textiles

refers to all flexible fabrics created from fibres, which are fine hair-like structures that can be made into fabrics by weaving, knitting or felting
natural - from plants or animals
synthetic - artificial, made using coal, oil

cotton

natural fibre produced from plants that grow in tropical climates, fibres from bolls that form after the flower has died

1. the boll has seeds , stalks and leaves removed during ginning

2. cotton is then sent to mills to be carded, which uses brushes to raw out the cotton into a thin film which is drawn into slivers

3. this process is repeated until fibres are very fine when they are spun into twisted thread, can or used for sewing or woven into fabric

use a lot of water to produce
can be used for clothing, towels, denim
cool, absorbent, dyed, printed, resists abrasion, good drape, static and cling resistant, various weights/thicknesses, good colour retention, recyclable
creases easily, flammable, damaged by uv

linen

strong fabric woven from fibres produced from flax, a plant grown in cool damp places, northern hemisphere
flax plants are harvested then laid out in fields for weeks tp allow micro-organisms to attack gum that holds fibre to stem, flax is then processed through gathering, drying and scutching (rolling and scraping) to obtain fibres
fibres are spun into yarn to produce linen
expensive and has smooth texture, range of weights
lightweight used for blouses and shirts, heavier used for embroidery
absorbs water well so good for bed linen and tea towels
withstands high temp, good conductor of heat
creases easily, difficult to dye, frays easily, expensive

wool

animal fleece, made of protein molecules, produces short fibre with kink or crimp with scales on fibre that trap air, may be soft or coarse depending on breed of sheep
warm, high absorbency, breathable, durable, repels rain, dyed, crease drop
expensive, can shrink, heavy when wet, itchy

nylon

forms a long filament when produced, can be cut into short fibres
light fibres and smooth with some silk properties, good strength
can be woven into very close weave to be windproof and water repellent
nylon 6 and nylon 6.6 - 6 through chemical reaction and 6.6 from single compound
excellent abrasion resistance, range of finishes, durable, lightweight
low absorbency, can shrink, poor resistance to uv, create static

polypropylene

good for clothing that needs to provide warmth but still be light, retains heat well and doesn’t absorb liquids easily so is ideal for outdoor clothing, doesn’t generate static electricity
abrasion resistant, lightweight, chemical resistant, quick drying, stain resistant
cannot be dyed, dry clean only, poor resistance to uv

polyester

can be easily dyed, resistant to shrinkage, wrinkling and stretching, quick drying process
synthetic material mostly comes from non-sustainable sources, although plastic bottles are increasingly being recycled to be used
monomers are joined to form polymers by polymerisation, polymer chains are spun into yarn
strong when wet, resistant to abrasion, dries quickly, durable, crease and stain resistant, recyclable, chemical/mould/sunlight resistant
low warmth, non-absorbent, static build up

flame resistant textile treatment

synthetic fibres are not flame resistant so need to be treated to increase flame resistance
phosphine gas, formaldehyde and mineral acid
slow down combustion process at stages such as heating, ignition and spreading

PTFE textile treatment

to provide protective surface to fabric, can result in fabric resistance to stain, works well on cotton and wool as doesn’t change feel or look
to apply protective coating to clothing, bedding, indoor furnishings, prevents liquids soaking in

smart materials

developed through invention of new or improved technologies
sense to changes in environment e.g. temp, light
have memory so can revert to original state once input is removed

modern materials

developed through invention of new or improved technologies
have been engineered to do a specific function

thermo-ceramics

advanced ceramic materials used in places where there is a need for stability and strength at high temperatures e.g. turbine blades in jet engines
produced by combining ceramic and metallic powders by sintering (making components using powders)
powders are heated then placed in a die and subjected to high pressure until particles bond together
durable, heat/pressure/chemical resistant, hard, stable at high temp, electrical insulator, lightweight
expensive, brittle

shape memory alloy

can be deformed having been given outside stimulus, once stimulus is removed the material reverts back to original state
most react to heat, some to light or pressure
nickel-titanium, gold-cadmium, iron-nickel-cobalt-titanium
braces, spring, stent
cycle can be repeated, lengthens life of product, reduces size and complexity
expensive, not as strong when placed under a similar loading

reactive glass

uses electrochromatic technology to change from transparent to opaque by applying voltage while allowing light to pass through from both sides
retains heat, instant privacy without blocking out light
expensive, requires electrical source

liquid crystal displays

organic, carbon-based compounds that exhibit both liquid and solid crystal characteristics
when a cell with a liquid crystal hasa voltage applied - and has light on it - it appears to go dark, caused by molecular rearrangement within liquid crystal
for colour screens each pixel is divided into 3 colours, by varying the voltage the intensity of each sub-pixel can range to over 256 colours
lightweight, low energy use, cheap
poor viewing angles, not easily seen in bright sunlight

photo-chromic materials

darken when exposed to light, have tiny particles of silver halide embedded in glass, react with uv light causing a chemical reaction that changes glasses colour
incoming light waves reflect off nearby crystals and add together by interference which produces the reflection, the colour of reflected light depends on how closely the crystals are together
adapts easily to changing conditions, can undergo thousands of changes without losing performance, doesn’t require electrical input
may be slow to react, user cannot control reaction

quantum tunnelling composites

when in relaxed state, it is a near perfect electrical insulator but when it is stretched, compressed or twisted it becomes an electrical conductor allowing a current to pass through
the greater the stress, the greater the conduction

heat treatment

a group of industrial and metalworking processes used to alter physical and chemical properties of a material
involves the use of heating or chilling to achieve hardening or softening a material

work hardening

occurs when a non-ferrous metal is cold worked, when metals are bent, rolled or hammered their crystal structure becomes distorted and the metals become work hardened, this makes the material harder to work and it becomes brittle

annealing

when a piece of metal has been worked hard it can become hard to bend and shape, process used to relieve internal stresses of non-ferrous metal
different metals are annealed in different ways, but all involve application of heat

annealing aluminium

1. apply soap as a temp indicator

2. heat gently until soap turns black

3. use tongs to remove from heat source

4. cool under running cold water

annealing copper

1. heat until dull red colour

2. use tongs to remove from heat source

3. cool either in air or quench

4. place in acid bath to remove oxides

5. remove acid by running under cold water