Discussing the best printing pressure

The optimal printing pressure is also called the ideal printing pressure. That is, under the condition that the printed surface is compressively deformed, the minimum pressure used for making the print sufficiently strong and uniform. To achieve the best printing pressure must also be achieved: complete imprinting, smooth, clean, distinct, colorful, minimal deformation. This article analyzes the factors related to achieving the best printing pressure in order to discuss with everyone.

First, the conditions for achieving optimal printing pressure

There are many factors involved in achieving optimal printing pressure. In addition, the optimal pressure is not fixed, but should be adjusted according to various objective printing conditions under the premise of favorable print quality. All the following factors must be in the best state of fit.

1. From the aspect of the printing machine's roller parts, it is theoretically necessary to make the roller reach the centerline of the drum when printing; the pitch circle of the gear is tangential; the actual radius of the roller is equal; the linear speed of each roller surface is the same.

2. From a paper point of view, the amount of compression between the different paper, blanket cylinder and impression cylinder is different, the amount of compression needed for coated paper is small, and the amount of compression required for offset paper is large. Because the surface roughness of offset paper is large and does not increase the amount of compression, it may not be printed in some places. However, the surface roughness of coated paper is small, the amount of compression is large, and the deformation of the imprint is increased more quickly. It is easy to paste the plate. .

3. From the perspective of ink-water balance, ink-water balance is the guarantee of printing quality. As the pressure of printing changes, the balance of ink and water also changes. The printing pressure is too large, and the imprinting is easy to spread. This leads to a vicious cycle of “water, ink, and ink” and destroys the ink and water balance.

4. The hydrophilicity of the printing plate, printing color sequence, environmental temperature and humidity changes and other factors must achieve the best fitness in order to achieve the best printing pressure.

5. Due to a variety of factors, the best printing pressure adjustment method is: the gear in the standard mesh state, by changing the thickness of the liner, to achieve the best printability. In addition, when printing thicker paper, the best printing pressure adjustment method is: 1 reduce the thickness of the liner under the blanket cylinder. 2 Increase the liner thickness under the plate cylinder. 3 Minor difference can be compensated by changes in center distance.

Second, the common factors that undermine the best printing pressure

Although the best pressure is recognized by everyone, it is not all very important or can be achieved. In addition to not complying with the above-mentioned operation to achieve optimal pressure, in the production, the phenomenon of inappropriate pressure due to ideological and technical problems is often caused, and care should be taken to prevent and correct it. It is particularly prone to excessive pressure (because the pressure is too small to be noticeable). The consequences are very serious. Common factors are as follows:

1. The problem of imprint transfer occurred in production. There was no comprehensive analysis of the causes. Blindly changing the center distance of the rollers or adding spacers not only failed to achieve the best printing effect, but also undermined the normal operation of the rollers and accelerated the gears and bearings. Wear.

2. Blanket, plate, or underlay measurement is inaccurate and destroys the best printing pressure. Some operators do not measure the thickness of the printing plate. When the blanket is installed, the measurement is inaccurate. Especially for new blankets and new linings, it is easy to measure and inaccurate, which inevitably results in improper gaskets and severely destroys the optimal printing pressure.

3. Due to various reasons, such as poor flatness of the blanket and low surface ink-absorbing capacity, it is mistakenly thought that the pressure is insufficient and the liner is increased, resulting in excessive pressure.

4. Due to the poor contact between the ink roller and the printing plate, the ink may not be transferred normally, which is often mistaken for the lack of roller pressure to increase the pad, resulting in excessive pressure.

5 due to a variety of reasons caused by uneven ink distribution, caused by imprinted dark ink uneven, it is often very easy to be mistaken for pressure, and increase printing pressure.