Jump And Dwell Engraving, JADE, has two basic forms.
They are, Axial JADE and Circumferential JADE. ALE's
Multi Beam Anilox uses the Axial JADE method. This
method has two basic advantages:
Firstly high productivity can be achieved because time
is not wasted waiting for the roller to move to the next
cell to be engraved, instead the laser beam is moved
rapidly axially and circumferentially to the next
position for a cell to be engraved.
is that, as a
consequence of moving the beam axially, slower
rotational speed is required in order to achieve a given
productivity.Circumferential JADE uses a Dynamic Beam Tracking
technique in order to keep the laser beam in a constant
circumferential position while engraving an Anilox cell.
Circumferential JADE method has a number of key
Firstly long laser pulses can be used without creating a
elongated or elliptical cells, this is due to the
Dynamic Beam Tracking. Since the laser can track the
roller for up to 99% of the time available between two
anilox cells only 1% of the time is used for the laser
to move to the next cell position, this means there is a
very high utilisation of the available laser power.
Typical non JADE laser engraving systems have a laser
utilisation of around 25%. This means that around 75%
of potential productive laser power is just simply
wasted. For example a 200 watt laser could only be used
to deliver 50 watts!
Long laser pulses can give high volume engraving,
normally long pulses will elongate a cell but with
Dynamic Beam Tracking they do not. In addition longer
laser pulses mean that there is more time for the
ceramic to absorb the laser power.
Secondly, as a result of the longer exposure time, the
ceramic is more able to melt. For some ceramics in some
applications this factor may well improve roller life.
Circumferential JADE can produce engraving with the look
of an old CO2 type engraving. This is
because CO2 engravings would normally use a
longer laser pulse, which allows the ceramic to melt.
Circumferential JADE can do this by the Dynamic Beam
Tracking technique. This gives both ceramic melting,
and improved productivity. The Dynamic Beam Tracking
technique can be used to produce round anilox cells.
However if the tracking is allowed to "Slip", an
elongated or oval cell is produced. This is ideal when
engraving long hexagon cells. Furthermore the degree of
"Slip" controls the elongation or ovality of the anilox
cell, even though whether the cell be round or
elongated, 99% of the available laser power can be put
into the anilox cell. This is a different way of
thinking, appropriate to the Dynamic Beam Tracking
technique. ALE is developing a Custom Slip spreadsheet
application. This will allow cell elongation to be set;
zero percent being round, and higher percentages being
varying degrees of oval. In addition along the length
of the cell, relative depth can be set. This is
achieved by controlling the rate of change of Slip in up
to 64 different points along the cell length. This
Custom Slip system will allow cell profile to be
controlled, while using the maximum time available to
heat the ceramic.
The Dynamic Beam Tracking technique can also be used for
laser applications whereby, because of the laser type
being used, the laser is unable to be pulsed at a
varying rate. Some very short pulse lasers can only be
"free run", they pulse at a fixed rate, or an externally
controlled rate that can only be changed slowly, but the
Dynamic Beam Tracking technique can direct the laser
pulse to the correct position on a roller.