The first key point with all sleeves and mandrels is to keep
them absolutely clean.
Any ink, water, cleaning solution residue, tape or adhesive
that gets onto the surface of the mandrel or the inside of the sleeve will
cause removal problems of the sleeve from the mandrel.
Remember most sleeves only expand by a few
thousandths of an inch, so even the slightest amount of contamination on the
surface of the mandrel or the inside of the sleeve can and will cause major
Care should be taken not to damage the surface of the mandrel,
so any scratches or burrs should be polished to a smooth finish. Similar damage
to the inside of the sleeve will not only cause removal problems but may
actually cause it to split when put under pressure so even greater care should
be taken with the inside of the sleeve to prevent any form or scratching or
scoring of the sleeve.
If you are using a simple air mandrel with an inlet hole
through the journal or header and air holes drilled through the wall of the
core near the end of the core face and in the middle, great care should be taken
to ensure that your air that is pushed into it is free from any moisture or
oil. Even the slightest moisture whether it is in the form or oil or water will
cause major release issues if it gets between the inside of the sleeve and the
outer surface of the mandrel. In addition water moisture or vapor can and will
cause corrosion within the core itself which in turn can build up in the air
outlet holes and also cause further contamination between the sleeve and
mandrel face. In extreme instances it can even weaken the core structure which
could lead to catastrophic failure.
In my experience mandrels that have air piped to each
individual hole are far safer and in fact make the air mandrel no longer an air
vessel that would under normal circumstances be certified to be able to
withstand the air pressure used to lift the sleeve off the mandrel.
Having a small bevel on the end of the mandrel where the
sleeve is introduced will certainly help to push the sleeve onto the mandrel
instead of having to walk it on, which can cause cracking of the edge of the
Make sure that your sleeves are never dropped on their sides, as this will more than likely distort the sleeve making it oval instead of round
and the only solution is to replace it.
This is particularly pertinent with regard to the anilox
sleeve with its multi layer construction. If your anilox sleeve has an end ring
and you see a crack appear between the ring and the sleeve it should be glued
with a suitable epoxy resin to help reduce the complete failure rate of the
sleeve, but it is usually inevitable once this has occurred and is just a matter of
time before the sleeve becomes unusable.
Even spraying silicon or wax to the mandrel surface can
cause problems if it is allowed to build up on the mandrel surface.
If you mandrels are not fixed on press, you also need to
invest in a suitable jig to hold the journal of the mandrel so that the roll
can be held in the air to allow the removal of the sleeve from the opposite
The truth is parallel sleeves will always have some removal
issues at some point during its lifetime no matter how good your housekeeping