featured in this issue - NZIFST - The New Zealand Institute of Food ...

glass hotter and using higher pressures, so it very accurately
reflects the mould.
A lighter bottle and reduced use of resources both make
good economic and ecological sense.
Leading edge technology
Much of the new furnace and plant has been built using O-I’s
own expertise.
The bottle making machine was built in the USA, using worldfirst
technology, with componentry sourced from around the
world. All steel work was carried out by local firms. O-I has
its own bottle-mould facility in China which supplies the Pacific
Region.
Black glass
O–I has ‘rediscovered’ black glass. Old, old
knowledge has been brought into the 21st
century and the company is guarding the
secret of its technology very closely.
First product to appear in black glass bottles
in New Zealand is Monteith’s new Single
Source brew. Monteith’s saw black glass
as delivering a very distinct image, reflecting
their unique brewing process with the added benefit that the
glass protects the beer flavour from damaging UV light.
O-I’s new black glass beer bottles are commercially available in
one design and two closure finishes. The bottles are 100% recyclable
and provide a number of functional benefits, including
superior light and UV protection.
Construction
Bottlemaking 101
First you make your glass ‘batch’. This consists of sand, limestone,
soda ash and cullet (recycled glass, around 60% of
the total weight) up to a total weight of around 1-1.5 tonne.
Where colour is required the appropriate metal oxide is used,
e.g. iron chromate for green glass. The batch is loaded into
the silo above the furnace and progressively ‘charged’ into
the furnace above the ‘glass line’. The temperature is around
1600°C in the airspace. The high temperature within in the
furnace is needed for the chemical process that converts the
silica in the sand into extremely hot liquid glass. The inflow
of raw material controls the rate of the outflow of glass which
controls the size of the glass gobs that drop into the blow
moulder, so the rate at which raw material is added to the
furnace is critical. The glass in the furnace is mixed by fluid
dynamics, the intensity of heating that is applied is used to
keep it moving as required.
Made glass exits the furnace through the ‘throat. The ‘throat’
is a tank behind the furnace and conditions the glass, ready
for making the bottles, by removing bubbles and ensuring
an even temperature for the bottle making machines. Liquid
glass at 1100-1200°C ‘drops’ into the new machine through
three orifices (triple gob). The weight of the gobs is adjusted
by setting the time the glass is allowed to flow before being
cut off and ‘shooting off’ into the moulds. There is some
form of alchemy, or instinct which seems to operate here to
ensure the correct weight drops every time.
Once the bottles have been shaped, they leave the moulds,
still glowing yellow and orange, and line up on the conveyer
belt (see cover image) which carries them through the primer
stage. The hot glass bottles are primed with an organic tin
coating which fills microscopic fissures and holes in the glass
surface.
At this point the bottles have cooled to about 500°C so they are
then passed through the annealing tunnel to reheat, then slowly
cool again which ensures any stresses in the glass, caused
by too rapid cooling are relieved. On exiting the annealing
tunnel, they are coated with a plastic emulsion (‘teflon’ for
glass bottles) which ensures they slide past each other on
production and filling lines.
Finished bottles are bulk palletised, each bottle individually
identified in the stack so that if, perhaps, one mould is found
to be producing a less than perfect bottle the sorting machine
can go through a pallet and ‘spit out’ every, say, 24th bottle.
Brand new technology, skilled operators and significant recycling
are features of any visit to the glassworks.
What makes a bottlemaker
Our host at O-I, national sales and marketing manager, Andrew
Sharp, reckons that bottlemakers are a unique breed.
The site has many long term employees among the 240 staff
on site, with even some third generation employees. Staff in
the production area are mostly highly skilled: a mix of mechanical
and chemical engineers and tradesmen.
Andrew has been with the glass company since finishing university
studies. “I have worked through many areas of the
business and find the process of creating product from sand
with a ‘little’ heat is fascinating and 22 years later every day is
still new. Glass making may have been around since the pharaohs
but the new technology, new products and new issues
keep you hooked.”
GLOBAL
LEADER IN
REUSABLE
PACKAGING
CHEP New Zealand congratulates
O-I Glass on the commissioning
of Furnace AK4
Phone (09) 279 2929
Freephone 0800 652 437
www.chep.com
CHEP – exclusive NZ pallet suppliers
to O-I Glass since 1982
April/May 2011
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