Pressure regulation of flexographic printing presses
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Pressure regulation of flexographic printing presses plays a key role in product quality, especially for fine dot printing. Let's take the COMCO flexo press as an example to introduce the pressure regulation of printed film materials.
How to adjust the pressure of the flexographic printing press
There are 3 printing zones on the flexo press, and the pressure adjustment of each press zone will affect the quality of the flexo product.
1, ink pressure
The ink pressure refers to the pressure between the ink reel and the anilox roller. It controls the amount of ink transferred and ensures the uniformity of the output ink. The ink volume is high and the amount of ink is small; on the contrary, the amount of ink is large.
If the ink pressure is too large, the amount of ink carried by the anilox roller is small, and the reproduction effect of fine lines, characters, and dots is good, but the print lacks gloss and the hue is not saturated enough. If the ink pressure is too small (ie, zero pressure), the effect of the ink metering will not be achieved, and the quality of the printed product will be significantly reduced.
The ink pressure should be determined according to the number of screens of the printed product and the anilox roller. Under normal circumstances, the ink pressure can be slightly larger when printing dot, small text, and line version; when printing color block and full version, the ink pressure can be smaller; when the printing material has strong ink absorption, the ink pressure can be small. Some, on the contrary, larger; when the printing area is large, the ink pressure can be slightly smaller, and vice versa.
2, ink pressure
Inking pressure refers to the pressure between the anilox roller and the printing plate. Its function is to transfer the ink on the anilox roll onto the printing plate to form the desired ink layer on the graphic of the printing plate. Ink pressure is closely related to dot gain. If the pressure is too large, the dot gain will increase severely. The mesh point of the high-profile part will increase to 20%, the tone level will become darker and deeper, and more than 60% of the dots will appear ghost or become solid. If the pressure is too small, the desired ink layer cannot be formed on the printing plate, and the printing effect cannot be achieved.
3, printing pressure
Printing pressure refers to the pressure between the printing plate and the impression cylinder. It transfers the ink from the plate to the substrate. The printing pressure is large, the dot is enlarged obviously, and the middle color is light, the surrounding color is deep, the level is not obvious, and the dark tone part is easy to paste. The printing pressure is too small, and the dots and small characters are easily lost. When adjusting, care should be taken to ensure that the pressure at both ends of the plate cylinder and the impression cylinder is appropriate, so that the two are in line contact.