DT materials OCR (copy)

main categories of materials

main categories of materials

Paper/board, wood, metal, polymers, fabrics

physical properties

absorbency, density, fusibility, electrical conductivity, thermal conductivity

working properties

strength, hardness, malleability, toughness, elasticity

board classification

weighs over 200 gsm

paper classification

weighs under 200 gsm

3 types of paper

grid paper, cartridge paper, tracing paper

grid paper uses

scale drawings, quick sketches

cartridge paper uses

drawings, pencil, charcoal, paintings

tracing paper uses

copying, tracing

3 types of board

corrugated card, solid white board, inkjet card

corrugated card uses

packaging and boxes

solid white board uses

high quality packaging, printing, book covers

inkjet card uses

high quality photographs

types of timber

hardwoods, softwoods, man-made

hardwood definition

come from a broad-leafed deciduous tree that loses its leaves over winter

3 hardwood examples

oak, maple, willow

softwood definition

come from conifers: evergreen trees that keep their needles all year round

3 softwood examples

pine, cedar, spruce

man-made board definition

sheets of timber made by gluing either wood fibres or wood layers together

3 man made board examples

MDF, plywood, block board

types of metals

ferrous, non-ferrous, alloys

ferrous properties

contains iron, almost always magnetic

ferrous examples

carbon steel, cast iron, wrought iron

non-ferrous properties

do not contain iron, not magnetic

non-ferrous examples

copper, aluminium, tin

alloy properties

metals that have been mixed together, combined properties

3 steps of converting raw metals into products

mining/extraction, forming, recycling

mining/extraction

metals extracted from the earth are often mixed with others. these are separated by chemical reactions at heat to get the desired metal

forming

after extraction, the metal is melted down and cast/formed into the desired product

recycling

at the end of its usable life, metal can be recycled by melting it down and reforming it. this reduces the amount of new metal needed

types of polymers

thermoforming, thermosetting

thermoforming definition

they contain no cross linkage molecules: can be easily melted, moulded, and reformed. they are recyclable

thermoforming polymer examples

PLA, ABS, acrylic

thermosetting definition

undergo a chemical change when formed: permanently rigid, resistant to heat, not recyclable

thermosetting polymer examples

epoxy resin, melanin formaldehyde, polyester resin

types of fibres

natural fibres, synthetic fibres, mixed fibres

natural fibres definition

come from biological sources. renewable and biodegradable

natural fibres examples

silk (lightweight), cotton (soft)

synthetic fibres definition

made from chemical sources/fossil fuels. Not sustainable/biodegradable

synthetic fibres examples

polyester (durable), nylon (non-absorbent)polyester (durable), nylon (non-absorbent)polyester (durable), nylon (non-absorbent)

mixed fibres definition

2 or more fibres spun together to produce yarn. combines different fibres with desirable properties

mixed fibres examples

polycotton (durable), terrywool (elasticity)

fabric structures

woven, non-woven, knitted

woven

interlocking two sets of yarn at 90 degrees. fabrics tend to be very strong. used in clothes

non-woven

fibres are bonded by mechanical, chemical, or thermal method. used in disposable cloths

knitted

interlocking loops of yarn together. used in clothes

knitted fabric types

weft knit, warp knit

weft knit

stretchy and warm, can unravel

weft saying

‘weft can go left‘

warp knit

less stretchy, unlikely to unravel

technical textiles

engineered for performance, not aesthetics

nomex properties

heat and flame resistant

nomex uses

racing drivers, fire people, astronauts, oven gloves

kevlar properties

resistant to abrasion and damage by sharp/pointed objects

kevlar uses

stab/bullet resistant vests for police, car/motorcycle tyres

coolmax properties

wicks water away from body, improves breathability

coolmax uses

bedding, sportswear, uniforms, underwear

modern materials examples

polymorph, flexi ply, teflon

polymorph

can be moulded/remoulded at 60 degrees in water

polymorph uses

modelling, rapid prototyping

flexi ply

plywood that is very flexible, easily bent

flexi ply uses

furniture

teflon uses

non-stick pans

smart materials

respond to external stimuli

smart material examples

SMA, thermochromics pigment, photochromic material

SMA uses

glasses, springs

thermochromics pigment uses

colour changing mugs

photochromic material uses

car windshields, glasses

composite materials

kevlar (bullet proof vests), glass reinforces plastic (boats)