Causes of failures due to poor dampening and how to deal with them

The use of oil and water compatibility rules is the basic principle of the lithographic process. Therefore, the layout text and the blank part are almost on the same plane. To achieve normal printing, ink and water balance control is an important cup. Due to operational technology, equipment, and other reasons, printing quality failures caused by poor dampening occur. This article analyzes and discusses some fault phenomena in the daily production process.

First, the water phenomenon and its cause

The so-called water bar mark refers to the printing bar or field version of the product, in the transverse direction of the print is one or more, its position is not fixed or fixed, the spacing is equal or unequal whitish strip marks, people used to call the water mark . The main causes are:

1. When the shaft head or bearing of the watering roller is worn out, the water roller will inevitably generate a jumping or sliding phenomenon during the rolling process, which will cause a water lever failure, and the worn shaft head or the damaged bearing should be repaired. The shaft head of the water roller or the damaged bearing is repaired so that the water roller maintains uniform rolling and evenly contacts the printing plate.

2 water roller and plate pressure caused by the water bar. When the contact pressure between the water roller and the printing plate is too light, and the water roller and the printing plate have poor contact, it is not only easy to make the plate dirty, but also causes the phenomenon of the water bar. Therefore, the water roller and the printing plate should be adjusted. The pressure keeps them in uniform contact.

3. When the contact pressure between the water roller and the string water roller is too large, it will inevitably cause the water roller to transfer water or uneven rolling due to the extrusion, and thus it is also prone to produce water bar phenomenon. It should be adjusted between them. Contact pressure.

4. When the surface area of ​​the water roller is more ink, it will also affect the normal and even transmission of the fountain solution, so it is easy to introduce the water bar phenomenon. Therefore, the water roller should be cleaned to keep the water even and prevent the water bar from spreading. The phenomenon occurs.

5. If the pH of the dampening solution is too large, it is prone to produce water bars. The PH value should be adjusted to reduce the acidity.

Second, dirty version, paste version, pattern phenomenon and its causes

1. Dirty version. The contact pressure between the ink roller and the printing plate is too small, so that the water transfer is not smooth and uneven, and the dirty ink on the layout ink is small, and the contact pressure between them should be adjusted; the pressure between the water roller and the string water roller is too tight. The fountain solution will be squeezed to stay on the water roller and the string water roller, so that the water supply is not normal and the dirty plate is generated. The pressure between them should be adjusted; when the water pile cover is installed, the ends and the middle are not uniform. Flattening, tightening and sewing, resulting in uneven thickness affect the normal dampening; flocking pile wear bad, water absorption, poor water transfer performance, water supply is not a normal source of dirty version, should be re-quilted pile of water The thickness is even and uniform, and the worn fleece sleeve should be replaced in time; the appropriate contact pressure between the water transfer roller and the water roller and the string water roller ensures normal water supply to prevent dirty plate.

2. paste version. The pressure between the roller and the plate is too small or too large; the pressure between the roller and the roller is not suitable, and the pad will be caused due to insufficient and uneven water supply. The appropriate pressure between them should be adjusted; water roller Oil contamination on the surface will affect the normal transfer of water also paste version, should scrub bucket roller; transfer roller and roller roller and string water roller pressure is too small, so that the fountain solution does not come out, resulting in paste version, should be adjusted Good pressure between them. In addition, the water roller's fleece sleeve is severely worn, and the water bucket roll angle is small or the rotation speed is too slow, etc., and the paste version may also be caused due to insufficient water supply. Therefore, a new water pile cover should be replaced, and the rotation angle of the water bucket roller should be increased to increase the rotation speed.

3. Flower version. The pressure between the water roller and the printing plate is too high, which intensifies the gravitational damage to the plate mask layer. This should adjust the pressure; the plate fountain solution supply volume is too large to cause the flower plate, which should be turned by turning the small water roller. Angle or reduce the water roller speed, to prevent the situation of the flower version; dampener fluid too much acid will destroy the printing plate surface caused by failure, should be washed fresh water solution concentration, lower its PH value. General PS version of the PH value between 5-5.5 is appropriate.

Third, the water roller fault phenomenon and its treatment

1. The water roller cannot be pressed together. The position of the screw on the clutch is uncomfortable, and the position of the screw should be adjusted; the lack of oil expansion of the rotary shaft and the abnormal state of the spring work, so that the water roller cannot be pressed together, the problem should be checked to see that part, and deal with accordingly; The slide keys in the shaft are stuck, manual pressure is not on, and the lock lever cannot be pushed in. The position of the slide keys should be inspected and adjusted. The connecting rod components are damaged so that the water roller can press water to repair damaged parts.

2. The water roller is not watered. The position of the water roller is uncomfortable, and the contact position between the water roller and the printing plate should be adjusted; the bearings at both ends of the water roller head should be damaged, and the new bearing should be replaced; the aging of the water roller cover and the adhesion of the ink dyeing affect water absorption. The water transfer performance should be replaced with a new fleece jacket or clean the dirty water roller.

3. Water transfer roller is not uniform. Roller bearing damage caused by uneven rotation or stuck phenomenon, should replace the new bearing; water transfer shaft and water roller roller and string water roller contact position is not suitable, should adjust the contact position between them; string water roller string momentum uncomfortable, should Adjust the amount of stringing; when the pile is dirty or worn and aging conditions exist, cleaning or replacing the pile jacket should be performed to avoid the phenomenon of water transfer.

In summary, the poor quality of the dampening system causes the breakdown of the quality of the linked product to be varied. As long as you are good at conscientious analysis and research, and carefully observe the characteristics of the fault phenomenon, you can quickly and quasi eliminate the fault phenomenon caused by various factors. Ensure product printing quality.