Lec18 Flashcards
Inkjet printing if surface energy too low
print beads up
inkjet printing if surface energy too high
coffee staining occurs
Subtractive manufacturing
parts made by removing material in the form of chips from a bulk
Additive manufacture
parts made from small building blocks
adv of additive manufacture
zero waste
more design freedom
tailoring is much easier
disadv of additive manufacture
production rate is slow
expensive
strength in Z axis and overall strength of objects sometimes an issue
inkjet printing is
an additive technology
Injet printing adv
does not need masks or stamps to form a pattern
can switch rapidly between patterns automatically
does not generate wase
reduce costs
can be scaled up
How we build bring with injet
row of overlapping drops results in a line
an array of drops results in a film
Dot spacing inket printing
space between centre of two droplets - larger the dot spacing the less overlap
larger dot spacing can give narrower lines but also result in line breaks
Droplet evaporation leads to
coffee ring effect
conditions needed for coffee staining
a volatile and partially wetting solvent
a pinned contact line
evaporation occurring at the contact line
wetting meaning
perfect non wetability droplet will bead up and roll off
a wetting surface droplet will spread out and soak in
How to stop coffee staining
reduce edge evaporation; two solvent system
Two solvent system
combination of two solvent one high boiling point and low boiling point
