GLASS pt 2 Flashcards
name two methods for shaping glass
blow-and-blow
press-and-blow
why do we blow twice in the blow-and-blow method?
temperature differences in the glass require a second blow to ensure that the structure of the bottle is uniform
what is the benefit of the press-and-blow method?
using the plunger ensures a uniform thickness; it’s also faster
which shaping method uses more energy?
press and blow
benefits offered by ionomer resin?
- acid/solvent resistant
- transparent with low haze
- high tensile strength
- improves fill speed
- no labelling adhesive needed
- can protect from UV
describe annealing
removes internal stresses caused by heat
heat to 500-700C and cool slowly to prevent stresses from re-forming
why heat to 500-700C in annealing?
each compound has different transition temps - hotter temp = softer gob. annealing occurs at this temp to retain the shape of the container but still enabling the molecules to “relax”
what kind of properties are tested during inspection
- internal pressure breakage
- vertical load strength
- impact strength
- resistance to abrasion and scratching
- thermal shock breakage
what’s one way you can increase the strength of a bottle?
increase the amount of glass to make it thicker
thicker bottles are more/less thermally stable
less
what are the 3 types of defects?
critical (hazardous), major (function loss), and minor (inconvenient)
what specifications are present on a finished container?
- description of container finish
- dimensions
- plant
- company mark (OI)
- year
what’s a finish?
the part where the bottle closes (screw cap or cork opening)
what do the numbers mean in the 2-number system?
first #: millimeter diameter across the inside of the cap’s opening or the outside of the bottle’s threads
second #: thread style
t dimension
outside diameter of the thread. determines the cap chosen
