exma processes polymers Flashcards
injection moudlign step by steo
polymer granuels in hopper
fed into ehated barrel with screw
driven by motor
fed into controlled split
liquid injected into mould
water pumped aroudn to cool
mould opens and steel ejector pins force out
injection moudl diragam left to right
motor
feed hopper
heaters
screw
female moudl
male mould
where ejector pins in inj moulding
between male and female moulds
what is male moudl pushed by
hydralich ram
qc for inj mould
wall thcikness
ribs
avoid sharp corners
avoid blind holes
draft angle
removal of flash
adv of inj mould
3d shapes
high volumes
very fast
low laboru cost
low waste
no finsihing really
cosn of inj moudl
high inital set up costs
expensive moulds
materials for inj moulding
pp
abs
how extrusion work
same as inj mould
but just forced through die
into cross section
as psuhed out, itno water tank
on coveyor belt
to cool
then cut to size
cut to size
materials in extrussion
polyetehelene
nylonn
upvc
pvc
adv of extrusion
consitent profile
simpel dies needed
cons of extrusion
have to cut to shape
only suitabel for cotnuosu flow productio
blow moudling step by step
pre form (pariosn) injection moulded
parsion placed into the mould
air injected into the parisom
blwo moudl diragam
parison in between mould
mould sealed
compressed air blwos into the shit
moudl opens
shit released
what si the air that is blown in blwo moudling
hot
does extrusion shit go straight to blwo moudlign
yes
blwo moudling qc to rememeber
removal of flash
cooling system on outside
is blow moudling liely to be fully auto
yes
pros of blwo moudling
unfirom shaoe
fast
efficient
low or high scales
many palstics used
less expnesive than inj
cons of blow
limited to holllow parts
moulds can be expensive
only curved shapes really
cosnideratiosb for blwo moulding
accurate split mould
parison transfered to mould whilst still hot
thicker sections say for threaded parts
all polymer moudls should accoutn for what
shrinkage
rotational moudling step by step
graneuls placed in mould
mould clamped
moudl rotated in heated chamber
many spin
ensure even cotating
mould cooled
product removed
how polymer granels heated in rotational moulding
by spinny bit being in heated champed or oven
how polymer grnaels cooled for rotational moulding
air
or wtaer channells and shit
diagram for rotational moudling
mould has polymers in
sealed clsoed
spinny in heated chamber
spin
left to cool and set
removed
adv of rotational
hollw part made in one piece with no lines
npo waste material
diff products moudled togehter in oen machien
surface textures
low cost machienry and tooling
con of rotational moudlign
only hollow shapes produced
polymer needs to be precise amouts etc
long cycle times
polyemrs fo roational
polypropelene
pvc
PET
how comp mould word
compressed palstci powder is set between two moudl haves
mould heated and and pressure set
untilshape tkaes ould cavity and solidifies
what si top mould of comp moudl attatched to
hydralich ram
what materials used in comp moudlign
thermo setting palstics
once moudl caivty filled in comp moudl what happens
heaters turned off
moudl allwoed to cool
themroettign thing
cures and hardness
what is there at bottom of comp moudl, bottom mould
ejector pin
pros of comp mould
ideal for themro palstics
long rpodcution runs
low set up and moudl cost
little waste
ideal for creating solid parts with thick walls
no need for prew or runners
cons of comp mould
cycle tiem long
limtied size and compexity fo products
what si trabsfer moulding
comp moudling but
polymer shit in open pot at top
plunger forces shit into the moudl via sprue
thermo forming step by step
sheet palstic between two halves
palstci heated jist above melting point
moudls close togehter
vaccum applied
pros fo thermo forming
low cost
works wellcreatign smooth shit
that need soem extra detail
which side of moudl wil detail be on
upper
how vacc form work
quality former made
former palced on bed or palten of machien
platen lowered
thermo polymer clamped into position
heater heats polymer until soft
platen rise and in contact with palstic
heat removed
vaccum on
suck
material cooled air or water
moudl released
bosh
finishign on vacc formign
trimming
cutting
drilling
polishing
vaccum form diagram
heater ontop
plastic beteen clamps
platen with moudl ontop
air on shti to dispaly
pros of vacc formign
availabel in schools
simple process
moudls can be made inexpsnive
sutiabel for raneg of scales
cons of vacc formign
additional processing
draft angles needed
udercuts with certain moulds
depth of mould
webbing
not intricate details
when cna there by intriciate detail on vaccum formig
using a think sheet fo material l
where surcae added to moudl on surfcae
shit to be made w vacc formign
yoghurt pots
disposable cups
sandwich oacks
multi parts in single former
how doem blowign work
same as vacc form
but shaped ring ontop of polyer
air blwon up and polyer rises
how blwon dome set
cool air blwon
how calendaring work
melted thermpolymer fed into rolers
rolers heated just aboev softwening point fo palstic
plastic is pulled and forced through roller
the final roller cools material
then oen role winds up
adv of calendarign
cotnuous rolls
no joins
good for long flat sheets
can be combiend with pritnign and sht
cons of calendarign
sutiabel only on large scale
producst made in calendarign
floor coverings
shower curtains
signs and displays
tabel covers
how dip moudling work
moudl dipped into bath of moutlen liquid
mould removed after layer coated
moudl cooled
end product removed
adv of dip moulding
good for short run
quick
no split lines
cons of dip moulding
limtied to simpel shape
s
products made from dip moudlign
ballons
ssues w dip moudlign
can have drips and shit due to gravity when coolugn
qc for polymers
removal of flash
accruate measures
draft angles
cooling sytems
