Complete Guide to Printing and Baking Plates—Solve Common Problems in One Article!

Complete Guide to Printing and Baking Plates-Solve Common Problems in One Article!

During the printing process, whether monochrome or multicolor, both operators and managers hope to maximize the plate's usability during printing, thereby maximizing overall production efficiency and reducing costs. However, in actual production, various factors such as plate making and printing equipment pressure, paper, ink, and the acidity or alkalinity of the dampening solution can directly or indirectly affect the printing plate's print resistance to varying degrees. Therefore, reinforcing graphics and text through the baking stage to improve printing durability becomes a cost-effective solution. After baking the plate, the printing plate's durability will be significantly improved.

Preparations before baking the plate

Before baking the printing plate, the surface must be thoroughly cleaned to ensure it is clean and free of stains; After cleaning, apply an appropriate amount of baking protection solution. Typically, about 20ml of the baking liquid is used per plate by hand.

The function of baking solution is to seal and protect the blank areas of the plate, preventing the micropores of the oxide film after sealing the holes from opening and reactivating under high temperatures, thereby avoiding ink absorption and dirt. Under high-temperature heating, thermal modification changes occur inside the plate coated with baking solution, significantly altering the plate structure. This not only enhances the stability and corrosion resistance of the graphic and text parts of the plate, but also improves the mechanical strength of the plate. Special attention should be paid to avoiding water stains on the board when applying baking liquid by hand.

As the final critical step before printing on the printing plate, the importance of baking the plate is self-evident. Below, I will analyze common issues that may arise during the baking process.

Common issues and countermeasures during the baking process

01/ After baking, the graphic and text parts appear dark brown or dark red

When the baking temperature is too high or the baking time is too long, carbonization will occur inside the graphic and text section, causing the images and text to appear dark brown or dark red. At this time, the printing plate will show obvious bending and deformation, accompanied by noticeable softening and reduced mechanical strength, which can easily cause plate drop during printing. If such situations occur, immediately lower the baking temperature or shorten the baking time.

02/ After baking, the graphic and text parts appear dark green

In contrast, when the printing plate stays too short in the baking machine or the baking temperature is too low, the resin components in the plate cannot fully cure, causing the images and text on the plate to appear dark green. In this case, the baking effect does not meet expectations, and the printing plate durability is low. When encountering this issue, uncontaminated printing plates should be put back into the baking machine, and a second baking process can be done by extending the baking time or raising the baking temperature until the color of the printing plate meets the standard requirements.

03/ Contamination of the layout causes dirt on the printing plate

If the plate is not thoroughly processed before baking, dust and impurities, protective adhesives, and stain removers remain on the plate. After high-temperature baking, these contaminants firmly adhere to the plate surface, causing dirt on the plate. To address this, when cleaning the panel, use a sponge or a damp towel to carefully wipe it to ensure the panel is clean. If contamination has already occurred, small areas of dirt or localized contamination not covered by graphics can be resolved by cleaning up; If the dirty area is too large, the plate must be remade.

In addition, special attention must be paid to the stage where the developer applies baking adhesive. After the plate is conveyed from the developer, the baking adhesive solution has already been applied. Therefore, components in contact with the plate, such as the glue roller, circulation pipeline, glue container, and glue tank that come into contact with the plate, must remain clean and dirt-free. This is a prerequisite for applying baking plate adhesive. Operators must strictly follow the standards, regularly and effectively clean and maintain all rubber rollers, circulation pipelines, and related components, without any negligence.

04/ Baking liquid crystallization or uneven wiping can cause dirt

Some baking liquid may accumulate during long-term storage. If the upper layer liquid is used directly, the relatively thin components cannot effectively protect the plate, resulting in dirty printing plates. Therefore, before use, the operator should evenly shake the baking liquid with slight sediment and evenly wipe the surface of the plate; If the baking liquid crystallizes severely, it should be replaced promptly.

For the machine's baking adhesive application, it is necessary to check whether the surface of the glue roller has hardened or surface scratches or damage. Such issues directly affect the uniformity of baking plate coating.

The baking machine's optimal working condition

The working state of the baking machine directly affects the baking performance. The optimal working state must meet the following conditions:

(1) The exterior of the baking machine enclosure and its surrounding environment (including the floor) must be kept clean;

(2) All types of wiring connections in the baking machine must be firm, with no looseness, and all electrical components must remain in good working condition;

(3) The temperature display of the baking machine can normally reflect the operating temperature, with minimal fluctuations and relative stability;

(4) The internal heating tubes of the equipment must be in good working condition, and the motor should run normally;

(5) During the push-pull drying process, the slide is smooth, the bearings rotate flexibly, and there is no sense of heaviness;

(6) The clamping device should be properly tightened, and the screws on the hanging hook should not be loose;

(7) The insulation layer of the baking box and sliding body must not be deformed or damaged by compression.

Cleaning precautions for the baking machine

Since baking machines are usually placed in relatively open spaces, hygiene is especially important. Please pay attention to the following points:

(1) External cleaning and maintenance: To avoid excessive dust accumulation on the machine's exterior, operators should regularly wipe the exterior of the equipment;

(2) Proper placement of items on top: When the baking machine operates at high temperatures, it is not suitable to place miscellaneous items on top, especially paper and other flammable items to prevent accidents;

(3) Internal cleaning requirements: Cleaning the inside of the baking oven should focus on removing iron filings, dust, and other debris generated by friction with metal parts inside the box.

Due to the working characteristics of the baking machine, a special reminder: whether cleaning the exterior or interior of the cabinet, be sure to turn off the power in advance and open the sliding body to cool off first, then clean afterwards; When cleaning, wipe with a cloth that should not be too wet, and only turn on the switch after residual moisture in the inner and outer cabinets has evaporated.