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Although it is not often clearly stated, all anilox volumes are given as a
theoretical volume as there are so many variables that can and will affect the
final volume of ink or coating that is released from each cell. The volume that
you will be given by all manufacturers is a mathematical calculation based on
the cell opening, depth and base of the cell and is usually an average of a
group of cells, the exact number of which depends on the method of measurement
and equipment used.
Now this number will be quite accurate, but as mentioned, it is the other variables
on press that really affect the final volume of ink or coating that will be
transferred. For most modern ceramic anilox this can be as much as 85% or more
but due to the surface energy between the anilox, metering roll, printing plate
and finally the substrate the final amount will and does vary. This variance
can be quite dramatic particularly when an ink metering roll is used, which can
actually lead to a greater amount of ink being transferred than has been quoted
due to the hydraulic forces between the anilox and metering roll and the
limited ability to sheer the excess ink or coating from the surface of the
anilox.
In some instances where extra coat weight or density is desirable, this
can be beneficial but if you are wanting to maintain consistent densities and
coat weights then a doctor blade is always going to give you more consistent
results and better volume control. The actual chemistry, viscosity,
temperature, substrate, plate material, press speed, and drying system also all
have a bearing on how much volume can and will be transferred.
Finally, how
well you keep your anilox clean will also have a dramatic affect on any anilox
cell’s volume carrying capacity, which is why good house keeping and cleaning of
the anilox is so vital from day one that you put it on the press. The use of
the right cleaning solutions, stainless brushes (for ceramic) and cleaning
systems such as ultrasonics are all essential if you want to sustain any
anilox’s volume carrying capabilities. Of course if you change any of the other
factors previously mentioned the volume transfer will change as well so maintaining
good records and being aware of these variables is vital if you want to get the
maximum ink or coating to be released from each engraved cell.
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