section 3 Flashcards
fusibility
ability to be converted through heat into liquid and combined with another material before being cooled again
elasticity
the ability to return to its original shape after being compressed or stretched
toughness
the resistance to fracturing of a material
how are most paper and boards made
they are made from wood pulp and converted at a paper mill
what is paper measured in and common papers
gsm - grams per square metre
bleed proof paper - 70gsm, coated to stop solvent based markers staining the page
cartridge paper - 120-150gsm, total opaque and thick for drawing
grid paper - 80gsm, thin blue lines for diagrams
layout paper - 40-60 gsm semi translucent for tracing
tracing paper - 40 -120gsm , translucent for tracing
what is boards measured in and common boards
microns - thickness measurement, 1000 microns = 1mm
corrugated cardboard- 1000-1500 microns. lightweight with rigid perpendicular corrugations used for packaging
foil lined board - 200-400 gsm, white card lined with foil for heat oil and moisture resistance to hold food
inkjet card - 120-350 gsm, thick brilliant white card on which ink dries to create deep colours and high quality photography
hard wood vs softwood
it refers to the cell structure of the tree and not the strength
hardwoods come from deciduous trees which are broad leafed and drop leaves in winter
softwood comes from coniferous trees, with needs or cones that are evergreen
felling
the process of cutting down trees, done with a chainsaw and machinery today
hardwood characteristics
hardwoods are denser and less porous
this makes them harder wearing and less prone to rot|
they take longer to grow so are more expensive and have deeper and darker aesthetic Thant softwood
hardwood types
oak - brown with cool grain tough durable and hard used for furniture also
beech - light pink hue used for toys and furniture
ash - brown/cream and tough/shock resistant used for handles
mahogany - rich red brown and durable used for high end furniture
balsa - white and soft used for modelling
softwood characteristics
more porous cell structure so if left exposed to elements can absorb moisture and rot
some softwoods like cedar contain oils that protect them
it has less colour available than hardwood so is often stained
more cheaply available than hardwood
softwood types
larch - pale to red brown with good water resistance used for flooring
pine- pale yellow to brain with attractive grain that ages nicely. easy to work and used in interior construction
spruce - whit cream with high stiffness to weight ratio, used for furniture and instruments
manufactured boards
boards made from low quality and grade recycled wood. they are cheapened typically covered with veneer to have a high quality look
types of manufactured board
MDF - light brown with smooth finish available but very absorbent. used for flatpack furniture
plywood - thin layers of natural timber stuck at 90 degrees. strong in all directions and used for shelf.
chipboard - pale ugly mismatch board covered with laminate. good compressive strength so good for furniture with veneer on it
why is carbon mixed with iron
it adds hardness to it and makes it less readily oxidise
common ferrous material
low carbon/mild steel - 0.05%-0.3% carbon content. bright grey and smooth used for construction components and is easy to weld but rusts fast if not protected
high carbon steel- 0.6 - 1.5% carbon content. doesn’t rust as readily but Is hard to construct with as it is harder but it also keeps edges better so good for knives
cast iron - 2.4 - 4% carbon content. dull colour and very hard so used for machinery like vices and less prone to rust
non ferrous materials like copper
they do not rust, but oxidise. copper oxidises into a deep turquoise colour called verdigris. the layer of copper oxide is called patina
common non ferrous metals
aluminium - high strength to weight and doesn’t oxidise used for cans
copper - brown colour but oxidises to green. high conductivity and ductility makes it good for wires
tin - silver metal plated onto ferrous materials to protect it
zinc - silver material used for galvanising to prevent rusting
alloys with examples
two or elements with atleadst one metal mixed together to achieve desired properties
brass - copper zinc used for bells \
stainless steel - made with chromium and carbon and resists rust well so good for cutlery
high sped steel - alloyed with many metals like vanadium tungsten cobalt to withstand high temperatures. used for drill bits
polymers and plastics
materials made from Long chains of polymers like plastics
plastics are made from petrochemical usually but can also be made from natural material like vegetable starch
thermosetting vs thermoforming
thermoforming - more flexible when heatedd because they have no crosslinks so the chains can move over one another. this makes the remouldable and therefore recyclable for a greater range of applications
thermosetting - cannot be reformed after set because they have crosslinks between them so when heated they will char. They have more hardness and brittleness and are great insulators
thermoforming plastics examples
high density polyethylene - opaque and hard. used for hard hats
low density polythylene - light’flexible’‘tough . used for shopping bags
polyvinyl chloride - flexible and easily shapable. used for pipes
High impact polystyrene - made in coloured sheet used for vacuum forming products like yoghurt [otds
common thermosetting plastics
polyester resin - same as epoxy and used to encapsulate artefacts
epoxy resin-made of a resin and catalyst that harden and set together. hight strength to weight ratio makes it useful for lamination and water proofing
urea formaldehyde- smooth white finish and highly insulate . used for electrical buttons
melanin formaldehyde -moulded into food safe and colourful products so useful for kitchenware
natural fibres
cotton - plant based fibre that is soft, warm and absorbent. used of towels and shirts
silk - animal based derived from worms and spiders. it has a shine and is very soft and fine so used for luxury wear
wool - derived from animal fleece, it is warm and used in coats
synthetic fibres
polyester - tough strong and non absorbent used for all types of clothes and furniture
polyamide(nylon) - also strong and non absorbent used for clothing g
elastane(lycra) - elastic and stretchable used for sportswear to Hug body for aerodynamics
polycotton - blend of polyester and cotton for durability and cheapness.
woven textiles terms
warp thread is the thread that goes through the weft threads, which covers the width of the fabric and goes from selvedge to selvedge
felting and bonding
bonding - web of fabrics are held together using heat or adhesive. used for disposable product as they have low strength and durability
felting - matting together fabrics using heat, adhesive, pressure and moisture to mesh together. it has no elisiticty and is used for hats
knitting , weft and warp knitting
a process of interlocking yarn loops for strength and aesthetic.
weft knitting. a single yarn is interlocked across the width of the fabric. more stretchy. trap more air,but lose shape more easily
warp knitting - yarns are interlocked vertically so less stretchy but less likely to ladder or come apart
