First, the ink roller is too hard
If the ink roller is too hard (generally > HS 50 °), it is easy to produce "bars", especially when the solid bottom is hit, the reaction is more obvious.
Second, the water roller is too hard
The printing roller water roller is too hard, which may cause difficulty in water transfer of the printing machine or unstable water supply.
When the water supply is intermittently applied, the rubber roller may be beaten to cause a "bar" in the printed matter.
Third, the ink roller with water
Ink roller with water, in general, is not a problem with the ink roller itself, but is caused by improper adjustment of water and ink balance.
Fourth, the water roller sticky ink
The water roller sticks to the ink, which may be caused by water and ink imbalance, or the water roller compound itself is not hydrophilic enough, or the surface of the water roller is dirty (dust, etc.).
If there is no problem when the new roller is on the machine, it should not be the cause of the water roller compound.
Fifth. Unexpected damage to the printing rubber roller
In the normal working state of the printing rubber roller, in general, the rubber roller has a critical damage life. If it is damaged before this, it is "unexpected" damage.
The reason may be that the rubber roller bearing is “clamped”, the rubber roller is subjected to excessive friction, resulting in damage; or for other mechanical reasons, such as broken ink roller rupture,
The surface of the chrome-plated iron with water has “burr” or “pickup”, which will cause the rubber roller to undergo “unusual” friction and cause the rubber roller to be unintentionally damaged.