general Flashcards
examples of sensors
moisture sensors
temperature sensors
push to make (PTM) - doorbells, keyboards
reed switch - controlled by magnetic fields
examples of processes
ICs and microcontrollers
output examples
LEDs, buzzers, lamps, loudspeakers, motors
environmental controls of circuitry
RoHS - restriction of hazardous substances in electrical equipment such as lead, mercury
WEEE - waste electrical and electronic equipment, ensures safe disposal of obsolete circuitry eg batteries
surface treatments of paper and board
additives - to help ink dry, speeds up rate of printing so mass printing
embossing - gives texture through rollers
varnish - top coat of thin varnish such as UV varnish
surface treatments of timber and board
seasoning - wood is full of moisture so it is sliced and dried
tanalising - outdoor wood is dipped in preservative so it wont rot and is susceptible to insect attack
varnish - smooths and protects, wax/paint
polymer surface treatments
UV stabilising chemical can be added to reduce UV degradation
vinyl decals can be added to protect
metal surface treatments
annealing - heating a metal and allowing it to cool slowly so its ductile and easy to bend
dipcoating - heating metal and dipping in plastic granules which melt to make a smooth, conductive handle
powder coating - high pressure powder sprayed on
galvanising - ferrous metals rust, so coated ina protective layer of zinc
textile surface finishes
flame retardant
dye and ink
flame proof fibres
antistain additives
electronic surface finishes
photosensitive CB board has surface anodised with aluminium to improve hardness
laquer lubricates PCB to avoid damage from moisture
what is wastage
where material is cut away to form a shape
die cutting
cutting a shape by pressing a die cut shape through the material, sharp metal blade. cuts metal and polymers
perforation
line of cuts through thin material making easily ripped lines such as for cheques
lathes
material spins and tools shape it and shave layers off
milling
thin layer of metal removed each turn at a carefully measured depth and speed. can cut horizontally and vertically
saws
tenon, jigsaw, scroll, coping
shearing
like scissors but for metal
what is addition
where materials are added to form shapes
brazing
heats joints using brass/zinc to fill holes. uses spelter stick to fill the holes
welding
melts and fuses metal parts using a filler. can use electricity
soldering
joining using solder (an alloy) of tin and lead with a hot iron.
vaccum forming process
put mould on platform
thermoplastic heated
pulled over mould
vacuum sucks air
takes mould’s shape
drape moulding
shape the thermoforming polymers by heating sheet plastic until it is soft enough to drape over a mould and then sets
quality checks for paper, board, and fabric printing
registration marks to check print rollers and plates are in place - cross in circle
quality checks go/no go
method of checking whether parts fit within limits
quality checks depth stops
pillar drills adjustable length
types of boards
chipboard - wood chips and sawdust compacted with glue
MDF - processed pulp, flattened and dried
plywood - thin layers of timber cut and glued at 90 degrees
4 scales of production
continuous
mass
batch
one off
quality checks x4
depth stops
laser cutters
ink in printer measured
exposure in PCBs
clothing sampled
what is a cooperative
groups of people such as employees who share ownership of the business and work together to ensure fairtrade
how are companies more ethically friendly
dyson - vacuum cleaner has interhangable parts which are easy to repair
fair trade fabrics
fake fur to stop killing animals
more factories reshored to stop transport and emissions
what is planned obsolescence
how long products are expected to last until they are obsolete and of no use.
how to shape paper
cutting - scissors, guillotine, lasercutter maybe even metal die
creasing and scoring -
perforating - dies or lasercutter
how to shape timber
cutting - saw
drilling - pillar/power drill
chiselling - electric routers
sanding - sandpaper, filing
planing - planer or power planer
how to shape metal
cutting - shears, guillotine, saw
drilling - pillar/power drill
milling
casting - molten metal in mould
HYDRAULIC PRESS - kitchen sinks, car parts
how to shape polymers
cutting
drilling
casting
forming (vaccum)
printing
joining - liquid solvent cement
alloys examples
brass = brass + zinc
used in decorative metal such as candles sticks
pewter = tin +antimony + copper
used in jewellery, cutlery
what metals can be forged by hand
iron and steel, hammered to form shapes such as gates, swords, horseshoes
sand casting metal process
moulds created with an oiled sand with an entrance (runner), and an exit (riser). cooled and then remoulded then trimmed. only used once
die casting
water cooled mould has molten metal injected into it then cooled. can be used repeatedly
pros of being renewable
after set up, energy supply is free
energy source is infinite
deforestation cons.
hardwoods grow slowly so cant be replaced in a lifetime
more carbon emissions
less carbon offsetting
damages watercycle - flooding
less wildlife habitats
mining and drilling cons.
loss of habitat
deforestation
noise and light pollution
water run off of chemicals
unsustainable
farming cons.
more space needed so more deforestation and less offsetting
6rs hierarchy
refuse
rethink
reduce
reuse
repair
recycle
levels of recycling
primary - reusing without modification
secondary - modifying for different purpose
tertiary - reprocessing to make new material
dynamic loads stress
static load force < dynamic load force
FORCE =
FORCE = MASS X ACCELERATION
what is shear
opposite directions of horizontal force = vertical force
example of a logging concern agency
FSC - forest stewardship council tries to stop illegal logging and desertification
how can timber be processed
PAR - planed all round or rough sawn
how to make veneers mass production
rotational veneer production : the wood spins on a wheel thing and a sharp tool takes a thin strip off
advantages of using a board
large numbers so sheets with no faults/defects
aesthetic flaws such as knots can be eliminated
little finish needed
made of wood that would otherwise go to landfill
available in a vast range of surface finishes
disadv of boards
adhesives toxic
traditional joints mat be less effective
edges hard to finish
prone to absorption of water
adv to stock froms
cost efficiency - minimises waste
structural reliability - up to code
time-saving - less cutting
joints
butt
dowelled
mitre
housing
mortise + tenon
how to bend wood easily
soaked in water - more malleable
hot steam box
commercial cutting
saw drill milling
commercial turning
CNC lathe
smelting process
lava lamp
/ input \
/ waste gas \
\ slag /
\ molten iron/
ore of alumium
bauxite ore
chemically refined using electrolysis
what is pig iron
like the beskar things where they pour it out of a crucible into moulds
THE INGOTS ARE THE PIG IRON
what is duralumin
lightweight. aluminium alloy w copper magnesium and manganese
used in aircrafts, car panels
what is pitch
the thichness of the thread on scres etc
types of rivets
pop rivets/cold formed rivets
adv of pop rivets
stronger than welding, only needs one side’s access
cold formed rivets explain
they snap on with access to both sides
what is knurling
the lattice engraving on a torch eg for aesthetics or grip
what is the melted stick called in brazinf and welding
the spelter
what is work hardening
working a piece of metal makes it harder but also more brittle
what is annealing
heating the metal and cooling it to make it more malleable and to relieve internal stresses
makes soldering stronger as it is more receptive
what is blanking
where the die is on the botto and the punch goes down on it and cuts the metal into x shape
what is temperign
the workpiece is reheated again and left to cool in the air which tempers it making it more tough and less brittle
what is hardening
the metal is heated to a temmperature then rapidly quenched in water/oil
finsihes on metal:
plastic dipcoating - insulation, ergonomics, aesthetics
powder coating - electrostatically applied then cured
zinc galvanising
electroplating - other coat of metal on top
sand blasting - sand/lead shot under pressure
types of polymers and examples
natural - latex/amber
bioplastics - biopol soya, PLA corn
synthetic - nylon, EPS for packaging
why are plastics good
good strength : weight ratio
versatile
raw materials cheap
less processing energy
easily mass produced
less transport costs
why are plastics bad
use crude oil - finite
pollution of CFCs and CO2
requies energy
carcinogenic toxins in PVC
unbiodegradable
low cost -> throwaway
plasticisers leach toxins
plastic additives
stabilisers - stop UV damage
pigments
plasticisers - more flexible
fragrances
antibacterial
