The correct printing pressure is the key for the book printing quality. Especially the screen printing of halftone dots. And line printing has higher requirements for printing pressure. Only the correct printing pressure can print exquisite and high-quality products.
1. The pressure of the ink distribution device
This pressure belt refers to the pressure between the ink distribution roller and the anilox roller. And its main function is to control the size and uniformity of ink transfer. The pressure between the two rollers is large (small gap). The ink volume on the surface of the anilox roller is small, and vice versa.
They relate the size of the printing pressure to the size of the printing area. Generally speaking, the pressure with a larger printing area can be lighter to increase the ink volume. Then to increase the thickness and vividness of the ink layer. The printing area is smaller and more delicate than text patterns. The pressure should be a little higher. To reduce the amount of ink to improve the clarity of small text. The principle of the pressure is depend on the characteristics of the product. When printing dots, the pressure is a little higher. The pressure of small text lines can be a little higher. And the large characters and large solid products can be small.
2. The pressure of the ink transfer device
The function of the pressure between the anilox roller and the printing plate roller of the ink transfer device. It is to transfer the ink on the anilox roller to the printing plate. Whether this pressure is correct. Or not have a great relationship with the definition of printing.
The anilox roller puts a lot of pressure on the plate roller. And the printed text patterns become thicker, double shadows, reverse white. And we will print the flexographic dots with serious image enlargement. Which will darken and change the tone level. Deep, poor image definition, and excessive pressure will reduce the printing durability of the printing plate. And it will be easy to pile up ink. Resulting in “irregular fatness” deformation defects during printing. If the embossing force is too light. The ink from the anilox roller cannot transfer to the printing plate. And we cannot perform printing. The best printing pressure should be the horizontal contact between the anilox roller and the printing plate.
3. The pressure of the imprinting device
This pressure refers to the printing pressure of the plate roller. And the impression roller on the cardboard. The effect of this pressure is to transfer the ink layer on the printing plate to the cardboard. In the book printing process, this is the last key. The pressure is too high.
The printed flexo has a spread-like dot, with a light middle color and a deep circle around it. Which has an enormous influence on the image level. The text line version spreads the imprint on both sides. Small fonts are easy to blur, and there is a clear sense of depression when touched by hand. The correct pressure is when the printed surface (protruding part) is in contact with the cardboard.
The dot enlargement is the smallest, the word line is simple. We spread no double printing; we print all the text images, and no leakage is the best. The depth of the press into the cardboard should not exceed 0.3mm. And during the printing process, we should adjust it at any time. According to the specific printing conditions, to keep it in the best condition.