XJ128 and XJ128 Plus Printhead
XJ128 Guide to Operation
Xaar Document no: D031010302 Version A
Page 45
One way of avoiding such a re-warming period is to ensure that the ink is of the correct operational
temperature prior to entering the printhead.
8.3.2 Vacuum purge
The vacuum purge maintenance technique achieves the same two functions as pressure purge,
however ink is pulled through the printhead and out of the nozzles by applying a vacuum to the
nozzles and nozzle plate area.
Figure 8.2 - Vacuum purge details
In order for this maintenance technique to be successful, a good seal must be created
around the nozzle plate before applying the vacuum to the nozzle plate face. This
should be done only with a soft compliant material that will not damage or scratch the
nozzle plate surface.
8.3.3 Wiping
Wiping can only be used with the X128/200 Plus printhead, as this printhead utilises
the wetting nozzle plate. Wiping must not be used with the XJ128/200 and XJ128/300
printheads as these use a non-wetting coating on the nozzle plate.
Wiping usually consists of the movement of a flexible blade (SH <40) across the nozzle plate.
Wiping will often remove fibres that are partially lodged in a nozzle and have resisted purging. It can
however re-deposit contamination in another nozzle. Wiping should be carried out in one direction
only as debris tends to collect on one side of the nozzle plate. Wiping in both directions would re-
deposit this debris on the nozzle plate.
It is preferable to wipe at right angles to the line of nozzles to prevent re-contamination, although the
stiffness of the blade makes this difficult. A compromise is to wipe with a blade at an angle.
The wiper should itself be cleaned after each wiping operation by passing it over a replaceable
absorbent non-shedding pad. To prevent the wiper from scratching the surface of the nozzle plate,
wiping must not be carried out on a dry nozzle plate. Normally a purge is performed prior to wiping.
Pressure at
nozzle plate
-0.1kPa to
–
0.5kPa
8
-20kPa to
–
50kPa
8
0 kPa
2 - 4
sec
Time