INSIDE HP's SECRET INK-CARTRIDGE FACILITY IN IRELAND

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INSIDE HP’s SECRET INK-CARTRIDGE MANUFACTURING
FACILITY IN DUBLAND IRELAND
How an inkjet nozzle fires 36,000 times a
second
The precision needed for an inkjet nozzle to work is
like dropping a grape from a 30-storey building and hitting a bucket on
the pavement below. Now that’s accurate. But in the case of an inkjet
nozzle it’s also doing it 36,000 times a second, not bad for something
which is the third of a width of a human hair.The drops fall at a speed
of 50kmph – 35 million of them for every 6 x 4 photo you print.We took
the short hop over to Dublin, Ireland to check out HP’s DIMO (Dublin
Inkjet Manufacturing Operation) facility where it develops and
manufactures ink cartridges.

Each new ink takes three to five
years to develop and goes through thousands of different formulas.”Ink
is the hardest working part [of inkjet printing],” explains HP’s Thom
Brown. “One change or minor alteration could make a huge impact. It’s
wet but when you want it to be on the paper you want it to be dry,” he
explains.

HP came to Dublin in 1995, helped by IDA grants and has
established a massive, 200-acre site. Intel’s operation had already
been in the area for a few years. The site is a mix of R&D and some
low-level manufacturing.

How cartridges are made
At the
facility we saw tri-chamber cartridges being made with integrated print
heads. The early part of the manufacturing process involves putting a
filter then sponge into the cartridge. It’s essential that the right
material is used to deliver the correct amount of ink to the nozzles –
too much or not enough ink can result in the nozzles being starved or
clogged.

HP dimo
Everything about the process is designed so
no contaminants can get into the cartridge or that the different
chambers inside the cartridge can’t contaminate one another. The
cartridges itself flies around the facility on small conveyors.According
to our guide, they can always track back if something has gone awry in
the process – the cartridges all have an individual 16-digit ID laser
etched on them along with a date. The lid is placed on and sealed before
the cartridges are filled and everything is tested to stop
leakage.Attaching the print head is also a delicate process. Adhesive is
applied on the area where the head will go, while the Tab Head Assembly
(the flexible print head) is attached precisely. Any problem here and
the head won’t line up inside the printer. The THA is made with
specifications at single-digit micron levels using a microscopic welding
process.

HP dimo
The chip wafers are manufactured elsewhere.
The so-called banner material is drilled using sand or laser in a
process that creates the minute channels for ink to flow through. The
material is laid across the wafer, but as it is UV curable, it needs to
be kept away from UV, hence the lab we saw was bathed in yellow light.
Another layer, the plating, has the holes through which the ink is
actually forced and the different layers are then bonded and connected
to each other.

Filling and testing
Then we move on to the
filling process. This is the “Wet Loop.” What about the toxicity of
inks, we ask – is it possible to have non-toxic inks? “We use the lowest
amount of toxicity versus effectiveness” says our guide.Four cartridges
are filled at any one time, taking four to five seconds to fill each of
them in a vacuum.A high pressure is used to fill the cartridges from
1,000 litre tanks which are rolled around the facility. A huge ink
splodge on the ceiling is the result of a time when the pressure got a
little too much.After the cartridges are filled, the nozzles are fired
to test them. A vent in the top of the cartridge enables air to replace
the ink as it’s used, though access is via a labyrinth channel to
prevent ink evaporation.After a test print, the nozzles are sealed by
the tape that you remove when you install them in your printer.Finally,
the cartridges are sealed and loaded into boxes and sent elsewhere to be
placed in their sale packaging.

HP dimo
The electrical
process is tested out at several stages throughout the process and
techniques such as X-rays are used to see inside the cartridge as it
prints in a special test area filled with tens of printers and old
machines. An autopsy area seeks out the causes of problem cartridges.
Long-life testing also takes place here.

HP dimo
“The physics
of what happens inside a printer is quite extraordinary,” says HP’s Pat
Harnett. “There’s mathematics, temperature, process and fluid dynamics.
It takes a lot of tuning to get it right on different papers.””It’s not
as simple as millilitres of ink – there’s a lot more behind that in
terms of the nozzle balance. And it’s not just about millilitres, it’s
about pages.”

HP dimo
But how much of the cartridge uses
recycled material? According to Harnett, it was 70 per cent in 2008.
“You want an HP cartridge that’s made of a recycled material but with
all the benefit of buying an original HP cartridge. There’s a mixture of
both using content and complete recycling,” he explains.”Virgin
material is much easier from a technologist’s point a view. In recycled
content there’s the possibility of interaction with the ink. We need to
get the wall thicknesses correct for example. A lot of research has to
go into it. The difference between 70 per cent and 80 per cent [is] a
lot of effort.”

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December 1, 2009 at 11:53 AM