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3
Introduction
3
User Manual
Ink Blockage Prevention
It is essential to use the correct solvent for the ink being used, i.e. the solvent used in the ink base: MEK
solvent for MEK based ink, ETHANOL solvent for ETHANOL based ink, etc.
The principle of continuous ink jet printing has proved to be the most effective means of printing with
an ink which is required to dry instantly, within a second, on almost any surface.
Blockages
If ink is required to dry on the product it will also have a tendency to dry in the printer, with a possibility
of causing a blockage. The continuous ink jet printer overcomes this problem by continuously producing
the print drops in operation. Although the ink is evaporating quickly during this process, it does not cause
a nozzle blockage, as there is a constant replacement of ink in the nozzle.
Automatic Cleaning at Shutdown
A potential problem arises on shutdown when ink is left in the nozzle; as it is fast drying it will soon dry
and clog up the nozzle. To overcome this, special procedures to clear the nozzle are necessary.
With EC-JET printers the clean up procedures at shutdown are achieved by an automatic flushing
system.
On shutdown, the ink is removed from the ink nozzle assembly by suction through a purge line. Just
prior to shutdown, a solvent flush system introduces solvent into the printhead, and runs solvent through
the nozzle and gutter, thus clearing ink from these vital components. This automatic procedure makes
it unnecessary to clean the printhead on shutdown.
Velocity of Drop
Ink velocity can impose a minor change in the mass of a drop, which will affect the final printing position
of the drop. However, precise placement of drops is more dependent on the speed of the drops as they
travel through the deflector plates.
For this reason, the velocity Of drop (VOD) is constantly monitored and compared with the optimum
(VOD reference) value printed on the printhead conduit. A “feedback loop” is used to increase or
decrease ink pressure, thus maintaining the correct speed of drops for accurate placement and
therefore quality of print.
The following illustrates this in principle:
Nozzle
Charge Electrode
Phase Sensor
Deflector Plates
VOD Sensor
Conduit
VOD
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