XJ128 and XJ128 Plus Printhead
XJ128 Guide to Operation
Xaar Document no: D031010302 Version A
Page 42
With the printhead
‘
on
-edge
’
as shown in figure 7.5, the following procedure may be followed; Use
pressure, no greater than 0.5 bar, to fill the XJ128 printhead with ink. Ink will start to bleed from the
nozzles when the printhead is filled with ink. Continue to do this for an additional 5 or 6 seconds to
ensure that the air is then removed from the printhead.
If the printhead is in the
‘
down
-shooter
’
orientation as shown in figure 7.4, the ink must be pulsed
between 0.5 and 1.5 bar for periods of 5 seconds each, with ink purging through the printhead at
different pressures. This should be repeated for about 5 cycles.
A further
‘
vacuum purge
’
is also advised, following the pressure priming of the printhead. Each purge
should be 5 seconds in duration, and the process should be repeated about 10 times. The
‘
vacuum
purge
’
technique is described in section 8.3.2.
For best results, allow the printhead to
‘
rest
’
after filling for a minimum of 30 minutes. This allows any
diluted air to settle and rise to a free surface. This will ensure that small air bubbles are not in the
vicinity of the internal ink filter.
7.5.3 First Use
Prior to printing, a start-up maintenance cycle should be performed on the XJ128
printheads.
The XJ128 printheads that have NWC should be purged with a small amount of ink. The NWC action
of the printhead will
‘
self
’
clean the ink from the surface of nozzle
-plate and printing should not
commence until the surface is seen to be clean. Excessive ink can be removed from the edges of the
nozzle plate by one of the maintenance procedures.
The XJ128/200 Plus printhead also requires a small purge and then a full nozzle-plate wipe to
spread the ink into an even film over the entire surface of the nozzle-plate. The wetting nozzle-plate
may require several of these maintenance cycles prior to printing to allow the ink to take (wet) to the
nozzle-plate producing a uniform film. The amount of maintenance cycles required to achieve this is
ink dependant and so each printhead must be inspected for a consistent and uniform film of ink.
A thin uniform ink layer over the surface of the nozzle-plate is required for good
reliability and operation of the XJ128/200 Plus printhead.
The XJ128 printhead should then be correctly primed with ink and ready to start printing.
Purging, wiping and general maintenance procedures are detailed in
‘
Printhead Maintenance
’
section 8, of this document.
