Printing roller use and maintenance
03-29-2018 16:42:50

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>F2>F3>F4>F5, where:
F1 - Pressure between the impression cylinder and the blanket cylinder

F2 - Pressure between blanket and plate cylinders

F3 - Pressure between Plate Roller and Cross Roller

F4 - Pressure between Plate Roller and Plate Roller

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 “jumping�?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 “great ink and large ink�?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.  

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 roller.

(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 the roller.

4. The influence of the aging of the roller on the quality of the printed matter

The 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.

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