Rollers in offset printing technology

In the production of offset printing rollers is rubber raw material that gives the rubber its fundamental characteristics. Vulcanizing agents are added to this by the subsequent vulcanization process.

Plasticizers (liquid oils) play an important role, because - along with the extenders and curing agents - to determine the next degree of hardness. Plasticizers are added again, the softer the rubber after the vulcanization process.

Shore-hardness Shore hardness of a roll of identifying with a meter of the coast indicates the resistance to penetration by a needle in the shape of a conic section (Shore A) or point (Shore D), is pressed with a force defined (1 kp) for a period of three seconds on the rubber surface. Soft wheels are measured by Shore A, and hard rolls Shore D.

Inking roller needs to be adjusted for foreign oil (or oleophilic). In a conventional ink inks, rollers Shore A hardness of between 30 ° and 35 ° are used. For UV inks, rollers with Shore A hardness of 25 ° and 40 ° and 45 ° are used. Dampening rollers should be water-friendly (hydrophilic). For alcohol damping systems, Shore A hardness of between 25 ° and 30 ° is adequate. Live damping systems, hard rubber wheels are used.

Maintenance roller

When it comes to clean the rollers are recommended:

1. Use a water-miscible wash to remove the top layer of particles of solvent soluble and water soluble from the nap of the roller.
2. Use a rubber roller no grain to remove insoluble particles.
3. Finally, wash a second time by using a water miscible wash to remove remaining soluble particles.

Glazzing

Over time, the rollers absorb particles from the ink, paper coating and cushioning agent that block pores. This contamination results in a smooth and shiny. Inappropriate detergents and hard water contributes to this effect. The flow of ink and dampening solution is markedly inhibited as a result of that.

Problems with uneven rolls

-A roller exhausted, a roller with damaged bearings, rollers set with too much pressure or roller that has not been cleaned efficiently, can cause:

* The color of the inconsistency
* Solid weak, or mottled
* Stripes
* Printing mud
* Gain abnormal point

Besides the obvious charges of low print quality, including waste paper and ink, poor or bad knee can cause press downtime abnormal, increased operating costs and lower roller life.

Roll storage

Whenever possible, do not expose rolls to direct sunlight or artificial.

• The special role of the rolls are delivered to the incoming light so avoid that helps save the characteristics of rubber. Because of this, remove the paper before applying the roller press.