The printing roller is the main component
of the offset printing ink inking system. Its function is to transfer
and apply ink to the printing plate. Its quality directly affects the quality
of the product. The correct use and maintenance of the rubber roller will not
only ensure the product quality, but also extend the life of the rubber roller.
1. Use of rubber roller
(1) Roller pressure
When working, the rubber roller should
maintain a good contact state and proper pressure, including the pressure
between the equidistant ink roller, between the stencil roller and the ink
roller, and between the squeezing roller and the printing plate. In the inking
system, the contact pressure generally has the following rules:
F1 - Pressure between the impression cylinder and the blanket cylinder
F2 - Pressure between blanket and plate
F3 - Pressure between Plate Roller and
F4 - Pressure between Plate Roller and
F5 - Pressure between the squeegee rollers
If the pressure between the platen roller
and the plate cylinder is too high, it will cause the printing plate to produce
bars, dirty plates and floral plates, which will reduce the printing plate's
resistance to printing force; if the pressure is too small, the ink will be
transferred poorly, causing the printing plate graphic. Not true or incomplete.
If the pressure between the printing roller
and the ink roller is too large, it is difficult to lift the plate by the plate
in the process of clutch pressure, and the friction force is large, which can
easily soften the roller heat, accelerate the aging of the roller, and even
cause the roller to deteriorate. The rollers grind badly and cause equipment
accidents; if the pressure is too small, not only is the ink transmission bad,
but also the problem of ˇ°jumpingˇ± of the rubber roller during printing.
(2) Balance of ink and wash
In the offset
printing operation, ink emulsification is normal, but it is also
necessary, but the ink emulsification produced due to the ˇ°great ink and large
inkˇ± will form a hydrophilic base on the smooth rubber roller, deinking the
rubber roller, and fountain solution. Corrosion rubber surface. Therefore, the
fountain solution should be as small as possible without stickiness.ˇˇˇˇ
2. Use caution
(1) After the printing is finished, clean
the ink on the roller. Cleaning ink should choose special cleaning agent, and
check whether there is still paper on the rubber roller, paper powder has not
been washed off, paper hair, paper powder generally stay on the uniform ink roller,
need to take a cloth to wipe.
(2) Machines with powder spraying device,
dusting will return to the rubber roller with the offset paper or secondary
printing. After cleaning the rubber roller, clean the dust on the rubber
(3) A hardened film of ink is formed on the
surface of the rubber roller, that is, when the plastic surface is vitrified,
pumice powder is used to grind it off.
(4) When cracks appear on the surface of
the rubber roller, remove it as early as possible.
(5) When the machine is stopped, the platen
roller and the plate cylinder should be disengaged in time to remove the load
to prevent static pressure deformation.
(6) When installing and disassembling, they
should be handled with care, not touching the roll neck and the rubber surface,
so as to avoid damage, bending or damage to the rubber surface of the roll
body. The roll neck and the bearing must be tightly fitted. If the looseness
should be promptly repaired repair.
3. Storage of rubber rollers
The purpose of keeping the rubber roller is
to maintain its stable mechanical properties, chemical properties and
printability, and to extend its service life.
(1) Cots should be stored in a cool, dry,
ventilated place, and be vertical or horizontal.
(2) Store horizontally on a shelf. It is
strictly forbidden to stack and squeeze each other on the plastic surface to
prevent deformation and adhesion of the plastic surface.
(3) Avoid storage with acids, alkalis, oils
and sharp hard materials to avoid corrosion and damage to the rubber roller.
(4) After the rubber roller is stored for 2
to 3 months, it should be changed in the direction to avoid bending and
deformation in a long-term direction, and to prevent rust on the shaft head.
(5) It is necessary to make backup rubber
rollers, but it should not be used for too long, because spare rollers will
naturally age and occupy funds. Storage should be prevented from causing
excessive aging, cracking, and rust on the shaft.
(6) Long-term preservation of the rubber
roller, before use, should be polished or pumice powder wipes the surface of
4. The influence of the aging of the roller
on the quality of the printed matter
surface of the rubber roller is subject to physical damage or occurrence of
cracking and other aging phenomena. The influence on the product quality is
easy to observe and judge; when the vitrification phenomenon occurs on the
surface of the rubber roller, the impact on the product quality is not easily
found. When the surface of the hardened film with the ink produced on the
surface of the rubber roller is vitrified, the surface of the rubber roller
becomes very smooth, the ink roller on the surface looks uniform, but the
performance of adsorption and transfer of ink is weakened, and the ink supply
is insufficient, which may cause the printing plate to receive ink. Unevenness,
the mouth is dark in ink, and the mouth is light in ink. At this time, the ink
roller should be ground or rubbed with pumice powder, and the rubber surface
should not be slippery.