Difference between ink roller and water roller of printing press machine and cause of wear
The rubber rollers of printing press machine play an important role in the printing process, but in actual production, many printing companies will soon need to replace the original rubber rollers. Due to insufficient cleaning and maintenance of the rubber rollers by most manufacturers, the original rubber rollers are prematurely aged, causing printing failures and cost loss.
Ink roller refers to the rubber roller in all ink supply systems. The role of the ink roller is to quantify and uniformly transfer the printing ink to the printing plate, which can be divided into three types: ink, ink transfer, and printing plate.
The ink is used to extract a fixed amount of ink from the ink fountain and then transfer it to the transfer roller. The ink transfer roller receives these inks and distributes them evenly to form a uniform ink film. It is then passed to the platen roller, which is responsible for distributing the incoming ink on the printing plate. At this point, the task of the ink roller is completed.
In offset presses, rubber rollers and hard rollers are always spaced apart to form a soft-hard alternate arrangement. This arrangement is more conducive to ink transfer and uniform distribution. The function of the ink roller can further strengthen the axial distribution of the ink. When it is working, it also rotates in the axial direction and performs a series of axial translation. Therefore, it is called an ink roller.
The ink roller is used to transfer ink, so the rubber must be ink-friendly. Due to the long-term contact between the adhesive layer and the ink, it must have certain resistance to ink corrosion. At the same time, the speed of the offset press is very high, and the speed of the ink roller is also very high, which causes serious heat generation of the adhesive layer, thereby accelerating the aging of the rubber. Therefore, to make the rubber roller durable, the requirements on the rubber material are also very high.
The water roller is a rubber roller in the water supply system, similar to the ink roller, and its function is to uniformly transport water to the printing plate. Water rollers also have water, water, and plate. At present, there are two types of water supply methods for water rollers. One is the continuous water supply method. The water supply amount is achieved by adjusting the speed of the bucket roller, which is suitable for high-speed printing. The other is intermittent. The platen roller is covered with a fleece cover, and the water roller swings back and forth to supply water.
The water roller is used to transfer water, so it must be hydrophilic and resistant to water corrosion, and its hardness is usually lower than that of the ink roller.Ink rollers and water rollers of offset printing presses traditionally use nitrile rubber, but they have their own emphasis on the formula of rubber compounds. Of course, other materials can also be used as long as they meet the requirements for use.
Causes of Rubber Roller Wear
1. Improper pressure adjustment of the ink roller will cause wear of the ink roller, especially if the pressure is heavy on one side and light on the other, it will easily cause damage to the rubber roller.
2. Forgetting to close the handles on both ends of the water bucket roller will cause the colloid of the metering roller to tear and damage. If one end is not closed or the other end is not in place, the metering roller and the plate-type water roller will be worn.
3. During the plate loading process, the PS plate is not installed properly, the bite of the PS plate and the tension screw at the end of the plate are not tightened. The PS plate will wear out the rubber roller due to the untensioned part and the protruding protrusions; The plate is too tight or the top plate is too powerful, which causes the plate to deform or rupture and damage the ink roller, especially because the plate water roller has low rubber hardness and its damage is also * obvious.
4. In the printing process, when printing a long order, the running conditions of the two ends and the middle are different, which will cause the two ends of the ink roller to wear.
5. Poorly printed film. The powder and sand particles falling off the film will cause the ink roller and copper roller to wear.
6. Use a sharp tool to draw a gauge line or make other marks on the printing plate, resulting in damage to the ink roller.
7. During the printing process, due to the poor local water quality and high hardness, and the printing plant did not install a proper water treatment device, the surface of the ink roller accumulated calcium compounds, which increased the rubber hardness and increased friction. This problem not only causes wear of the ink roller, but also causes serious print quality problems.
8. The ink roller is not regularly maintained and recycled.
9. The ink on the surface of the metering roller will not cause abrasion if it is not washed for a long time.
10. Special processes, such as printing gold and silver cardboard, stickers or films, require special inks and special additives, which will accelerate the cracking and aging of rubber rollers.
11. The roughness of ink particles, especially the roughness of UV ink, has a direct impact on the wear of rubber rollers.
12. The speed of wear of rubber rollers in different parts is different. Such as the ink transfer roller, because its action is stationary → high speed → stationary continuously reciprocating, its wear degree is faster than ordinary.
13. When the rubber roller is stationary for a long time when it is stopped for a long time, the rubber diameter of the rubber roller is uneven, and the rotation and deformation of the rubber roller are different, which exacerbates the wear of the rubber roller.
14. The temperature control of the working environment is not good. It exceeds the physical properties of the rubber roller and increases the wear of the rubber roller.