A complete guide to printing plates and baking plates, solving common problems in one article!

A complete guide to printing plates and baking plates, solving common problems in one article!

In the printing process, whether it is single-color printing or multi-color printing, printing operators and managers hope that the printing plate can maximize the plate usage capacity during the printing process, thereby maximizing the overall production efficiency and reducing production costs. However, in actual production, various factors such as equipment pressure, paper, ink, and dampening fluid pH in the plate-making process and printing process will directly or indirectly affect the print resistance rate of printing plates to varying degrees. Therefore, reinforcing the graphics and texts through the baking process to improve the printability of the printing plate has become an effective solution with lower cost. After baking plate treatment, the printing plate print resistance rate will be significantly improved.

Preparation before baking

Before baking the plate, the plate needs to be effectively cleaned to ensure that the surface of the plate is clean and free of stains; After cleaning, an appropriate amount of baking plate protection liquid should be coated, usually the amount of hand-applied baking liquid for each plate is about 20ml.

The function of baking fluid is to seal and protect the blank part of the printing plate, preventing the oxide film micropores after sealing from opening and reactivating in a high-temperature environment, so as to avoid ink absorption and dirt. Under the condition of high temperature and heating, the inside of the plate of the coating baking liquid will undergo thermal modification, and the structure of the plate will change greatly, which can not only enhance the stability and corrosion resistance of the graphic part of the printing plate, but also improve the mechanical strength of the printing plate. It should be noted that when applying baking liquid by hand, try to avoid water dregs on the layout.

As the last key process before printing on the printing plate, the importance of baking plates is self-evident. Below, the author analyzes the problems that are prone to occur in the process of baking.

Problems and countermeasures that are easy to occur in the process of baking

01/ After baking, the graphic part is dark brown or dark red

When the temperature of the baking plate is too high or the baking time is too long, carbonization will occur inside the graphic part, resulting in dark brown or dark red color of the layout and text. At this time, the printing plate will be obviously bent and deformed, accompanied by obvious softening phenomenon, and the mechanical strength is weakened, which in turn leads to the problem of plate dropping during the printing process. In such cases, the baking temperature or baking time should be reduced immediately.

02/ After baking, the graphic part is dark green

Contrary to the above situation, when the plate stays in the plate machine for too short a time or the temperature of the plate is too low, the resin component in the plate cannot be completely cured, which will make the layout graphics appear dark green. In this case, the baked plate does not achieve the expected effect, and the printing plate has low print resistance. When encountering this problem, the uncontaminated plate needs to be put back into the baking machine, and the second baking plate is baked by extending the baking time or increasing the baking plate temperature until the plate color meets the standard requirements.

03/ Dirty plates due to contamination of the layout

If the plate is not thoroughly treated before baking, dust, impurities, protective glue and stain remover will remain on the plate, and after high-temperature baking, these pollutants will be firmly attached to the surface of the plate, causing dirt on the plate layout. In this regard, when cleaning the layout, it is necessary to wipe it carefully with a sponge or wet towel to ensure that the layout is clean. If pollution has occurred, local pollution with small dirty spots or uncovered graphics can be solved by dedirty treatment; If the dirty area is too large, the plate needs to be remade.

In addition, it is necessary to pay attention to the link of the developer rubbing the baking plate glue, the printing plate will have been wiped with the baking plate glue after being transmitted from the developer, so it is required that the rubber rollers, circulation pipelines, glue containers, glue tanks and other components in contact with the printing plate must be kept clean and dirt-free, which is a prerequisite for the machine to apply baking plate glue. The operator needs to operate in strict accordance with the specifications, regularly clean and maintain each rubber roller, circulation pipeline and related components, and must not be sloppy.

04/ Baking liquid crystallization or uneven rubbing causes stains

Some baking liquid may precipitate during long-term storage, and if the upper liquid is used directly, it will not be able to effectively protect the layout due to the relatively thin composition, resulting in dirt on the printing plate. Therefore, the operator needs to shake the baking liquid with slight precipitation evenly before use, and wipe the plate evenly; If the baking liquid crystallization is serious, it needs to be replaced in time.

For the machine coating of baking glue, it is necessary to check whether there is hardening of the glue layer or scratches and damage on the surface of the glue roller, which will directly affect the uniformity of the baking plate glue coating.

The best working condition of the baking machine

The working state of the baking machine directly affects the baking effect, and its optimal working condition must meet the following conditions:

(1) The outside of the baked plate chassis and the surrounding environment (including the ground) should be kept clean;

(2) The various lines of the baking machine are firmly connected, there is no looseness, and the working condition of various electrical parts is maintained well;

(3) The temperature display of the baking machine can normally reflect the temperature during operation, and the numerical change range is not large, and it is relatively stable.

(4) The heating pipe inside the equipment is in good working condition and the motor is running normally;

(5) In the process of pushing and pulling, the slide is smooth, the bearing rotates flexibly, and there is no heaviness;

(6) The clamping device is moderately tensioned, and the screws of the suspension hook are not loose;

(7) The insulation layer of the baked plate box and push-pull body is not extrusion, deformation, damage, etc.

Cleaning precautions for plate baking machines

Since plate baking machines are usually placed in relatively open spaces, their hygiene is particularly important, and the following points should be noted:

(1) External cleaning and maintenance: In order to avoid a lot of dust outside the machine, the operator should regularly wipe the outside of the equipment;

(2) Top item placement specifications: the baking machine should not be placed on the top of the plate machine when the temperature is high, especially paper and other flammable items are prohibited to prevent accidents;

(3) Internal cleaning requirements: The internal cleaning of the baking plate box should focus on cleaning up iron chips, dust and other debris caused by the friction of metal parts in the box.

Due to the working characteristics of the plate baking machine, it is also necessary to remind: whether cleaning the outside or the inside of the box, the power supply must be turned off in advance, and the machine push-pull body should be turned on to dissipate heat first, and then cleaned; When cleaning, the wipe should not be too wet, and the residual moisture in the inner and outer boxes should be evaporated before closing the electric gate.