Beginners should master the basic knowledge of the printing roller (below)

In order to make the ink and water evenly spread on the printing plate, the surface of the rubber roller must be straight, that is, the diameter of the rubber roller at any point in the axial direction should be the same, such as the small middle two large, so-called: "bellied", or the middle small two large The so-called "waist", "taper", "wave" and so on are not allowed. Unless certain special designs, such as slender rollers require "medium height", to compensate for the deformation of the shaft.

Second, printing failure and rubber roller

Because the color lithography technology is relatively complicated, the cause of the printing failure is not easy to judge, and the printing roller can often be "defective." In fact, most of the printing failures are not related to the roller. As far as the problem of the ink roller itself is concerned, the following situations may occur.

1, the ink roller is too hard

If the ink roller is too hard (usually >HS50°), it is easy to produce “bars”, which are more obvious when the roller is hit.

2, the water roller is too hard

The rollers are too hard and may cause difficulty in diverting water or unstable water supply. When intermittently supplying water, there may be a runout of the rollers, causing a "bar" on the printed product.

3, ink roller with water

Ink roller with water, usually not the ink roller itself, but caused by improper adjustment of water and ink balance.

4, water roller stick ink

The water roller sticking ink may also be caused by the imbalance of ink and water, or the hydrophilicity of the water roller rubber itself, or the "dirty" surface of the water roller. If there is no problem with the new roll, it should not be the reason for the glue.

5, the roller unexpectedly damaged

In normal working conditions, the rubber roller has a critical breakage life. If it breaks before it is "unexpected". The possible cause is the failure of the rubber roller bearing to “stick”, the rubber roller being subjected to excessive friction and damage, or other mechanical reasons, such as a string of hard rollers breaking the skin, and a “glitches” on the surface of the chrome-plated iron roller with water. "Beating" or the like will cause the roller to withstand "unusual" friction resulting in unintended breakage of the roller.

There is also a situation that will lead to unexpected damage, that is, the so-called "dry grinding", that is, the ink roller without ink, the water roller is running without water, because the roller does not have the lubrication and cooling effect of ink and water. At this time, the rubber roller will be quickly worn. This situation often occurs. First, some masters do not understand the machine. First, because of negligence. If only a part of the color machine is used, the unused ones will be idle at the same time without any protection. Cream and so on.

Third, UV ink and UV roller

UV rubber roller instructions

At present, there are two types of UV ink roller, both UV-specific and UV / common dual-use roller, used by a large number of customers, the effect is good. However, some users are not familiar with the characteristics of UV ink because of the initial UV ink printing. They do not understand the selection and maintenance of the printing roller and blanket, resulting in many problems and even failure to produce. In view of this, we hereby specify that we expect customers to worry and reduce losses.

1, rubber roller and blanket selection

Because the chemical properties of UV inks are different from ordinary inks, the rollers and blankets used for common inks are not suitable for UV inks. Dry ink, swelling, deformation, or even embrittlement on the surface may occur, and normal printing cannot be performed.

Therefore, the use of UV ink, you must choose a special blanket and roller, be sure to consult the supplier at the time of purchase to avoid mistakes.

2, rubber roller and blanket maintenance

Even with special rubber rollers and blankets, pay attention to maintenance issues. In particular, we must pay attention to the washing machine that we must use every day! No matter what kind of washing machine water, it will damage the rubber roller and blanket, but the degree is different.

At present, there are many kinds of UV washing machines sold on the market, and the chemical properties are very different. There are many products that are freely deployed by underground workshops. The quality is not guaranteed, and there is a great toxicity. At the same time, it is also the killer of rubber rollers and rubber blankets. Using this kind of product will not only save money, but it will take more money to compensate for the damage it has caused.

3, UV ink special roller

The roller is not suitable for ordinary inks.

4, UV and ordinary ink dual purpose roller

Because many customers produce the same machine, sometimes use ordinary ink, and sometimes use UV ink. If the roller is replaced frequently, it will be annoying. Therefore, UV and common dual-purpose rubber rollers are used to avoid being bothered. Welcome, but please pay attention to the following points when using:

(1) The rubber roller is used for ordinary ink printing, and it is the same as ordinary ordinary rubber roller. It can be directly replaced.

(2) The following matters should be noted for UV inks:

a. If the whole roller of the printing press (ie, one color) is replaced with a new roller at the same time, UV varnish must be used first in order to adapt the roller to UV ink. The usage is as follows:

Put the UV varnish into the ink tank, and start the machine with the same ink as the normal ink, so that the varnish fills all the surface of the rubber roller. After 4-6 hours of operation, the formal printing can be started.

b. If you insert a few new rolls in the center, there is no serious problem. You can apply UV ink directly.

In recent years, the rise of UV ink printing has developed rapidly. UV inks are UV light-curable inks. The ink can be instantaneously dried under ultraviolet light (UV light). The quality of printed ink is better than ordinary ink. Because the UV ink is very different from the ordinary ink, the rubber roller and the rubber cloth have to be changed accordingly. Usually, special rubber rollers and blankets are used. For details, refer to the UV Cots User's Manual.

The hardness, elasticity and other properties of the adhesive layer directly affect the ink transfer effect and dot reproduction effect, so it also has higher requirements. Different manufacturers of offset presses may have different requirements for the hardness of the roller. The range is as large as between 30 to 40 Shore Shore hardness.