Causes and countermeasures of eight common film gravure failures
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This article comprehensively organizes the causes and countermeasures of the eight kinds of faults commonly seen in the film gravure printing process, so that you can check when you encounter problems.
Elimination of eight plastic film gravure printing failures
1, the color is not allowed
(1) The film tension is varied to change the longitudinal printing color.
Each tension control device should be adjusted, such as adjusting the drum brake of the unwinding device; setting the rotation speed of the roller reasonably; increasing the frictional force of the roller surface; adjusting the winding tension of the winder.
(2) The printing cylinder has a diameter difference, and the diameters of the first, second and third color plate cylinders are sequentially thickened or thinned, causing the longitudinal printing color to change.
Should be re-plate.
(3) The rule line density is insufficient, and the printing color is longitudinally offset.
The sensitivity of the photocell should be adjusted and the paste of the plate should be eliminated.
(4) The guide rollers are not parallel, the printing pressure is unbalanced, and the taper of the plate cylinder and the impression cylinder causes problems such as lateral vibration of the film and slack on one side, causing unstable lateral color registration.
Targeted adjustments should be made.
(5) The adjustment screw at the shaft end of the plate cylinder is loose, causing the lateral color to be unstable.
The tightness of the screws should be readjusted.
(6) If the contact pressure of the rubber roller and the flower roller is too large, the printed pattern will produce a double pattern.
The contact pressure should be adjusted to make the printed pattern clear.
2, the printed surface is spotted
(1) The viscosity of the ink is too low or the flow is poor.
The viscosity of the ink should be appropriately adjusted so that the viscosity of the ink is moderate and the fluidity is good.
(2) The plate depth is too deep or the blade angle is not properly adjusted.
The blade angle should be adjusted appropriately or re-plated.
(3) Improper printing pressure control.
Should be adjusted appropriately.
(4) The surface of the printed matter is too static.
Static electricity should be eliminated.
(5) Poor ink drying.
Drying should be strengthened, such as improved ventilation and drying conditions.
3, printing surface foaming
(1) If the surface of the ink has been crusted and the internal ink is not dry, once the crust is broken, a crater-like cell is formed, which is mainly caused by rapid drying.
A low temperature-high temperature-low temperature drying process should be used, and a slow drying ink should be used as much as possible.
(2) During the printing process, a large amount of air bubbles are generated in the ink hopper, and the air bubbles adhere to the printing roller, so that the dots of the printed pattern partially disappear or the pattern is blurred.
The ink should be kept at the proper viscosity, the ink drop should be minimized, and a circulation pump should be used to prevent air bubbles from entering the ink.
4, the printed surface has a pear skin pattern
If the underprint ink is dissolved and partially mixed with the second color ink when overprinted on the dried printing surface, a printed pattern will be produced on the printed surface.
One is to properly adjust the viscosity of the ink; the second is to properly control the drying speed; the third is to determine the depth of the plate reasonably.
5, poor ink absorption
When the surface of the product film is multi-color printed, when the ink of the second color is printed on the coating film of one color, if the absorption is poor, the dots after the transfer of the ink are made into independent states, and the color of the dots is deep. The unevenness of the other parts is lighter. This has nothing to do with the amount of ink transfer or non-harmonization, and is mainly related to the diffusion of the dot ink after transfer.
In this regard, one is to use a hysteresis solvent in the second color ink; the second is to move the second ink blade position as close as possible to the printing direction; the third is that the ink after the second color should be lightly pressed as much as possible; The second color is deep; the fifth is to use a reducing agent in the ground color ink; the sixth is to appropriately increase the printing speed.
6, the printing roller wears too fast
(1) The scraper is too thick.
Thinner blades should be used instead.
(2) The contact pressure between the scraper and the printing roller is too large.
The contact pressure between the two should be properly adjusted.
7, the blade wears too fast
(1) The blade is too thin.
Thicker blades should be used instead.
(2) The contact pressure between the blade and the printing roller is too large.
The contact pressure between the two should be properly adjusted.
8, the network is blocked
(1) During the printing process, as the solvent evaporates a lot, the viscosity of the ink increases, causing the ink inside the wire to be clogged.
The dry ink should be removed regularly.
(2) When the position of the scraper is far from the printing roller, the diameter of the plate roller is large or the depth of the plate roller entering the ink tank is insufficient, the hot air blown from the machine affects the ink on the surface of the plate roller, which is likely to cause serious blockage.
Targeted adjustments should be made.
(3) The ink is mixed with impurities to cause blocking.
Impurities and filter inks should be removed.
(4) During the printing process, the operating temperature is too high, causing the solvent in the plate roll wire to evaporate too quickly, causing the plate to become clogged.
Try to reduce the operating temperature.
(5) The etching depth of the roll network is not suitable.
Should be re-plate.