CTP plate packaging

Failure Analysis: This is due to the printing plate being scratched by a hard object. May be ink, paper containing fine sand, or the environment of the workshop is poor, dust, sand and other impurities fall onto the ink roller or ink fountain, and adhere to the printing roller on the printing roller with the operation of the machine, under the effect of printing pressure Scratch base, and scratches continue to deepen, resulting in the blank part of the printing plate in the middle of the hydrophilic layer damage, decreased hydrophilic capacity, enhanced lipophilic properties, resulting in the formation of redundant lines.

Solution: Close the doors and windows, clean the workshop environment, clean the water roller, ink roller, replace the ink, remove the soft rubber roller, and remove the sand particles (especially the plate roller) that are embedded on the roller.

If the scratches only appear in the blank part of the plate, you can use a small amount of wetting powder to grind the scratches to restore the hydrophilic properties of the plate blank. When grinding, be careful not to grind to the printing plate basis, so as not to damage the graphic.

Fault 2

Symptoms: When printing a batch of bills on a Y-structure double-color offset printer, only 30,000 sheets were printed. The color saturation (purity) of the printed artwork changes, and the blanks slightly float. The color saturation of the ink on the ink fountain and the ink roller did not change. Stopped the printing plate inspection and found that another printing plate appeared in the blank space of the printing plate.

Failure analysis: When the number of printed products is small, the blank part of the printing plate has excess fat-sensitive text. It may be that the blank part of the printing plate has a thin hydrophilic layer, the metal surface is relatively smooth, and the sand holes are small, resulting in water storage on the printing plate surface. Poor ability, blank part of the low hydrophilic performance, due to strong sense of fat. If the roller pressure, the pressure of the water roller and the ink roller is large, the wear of the printing plate sand will be accelerated during the printing process, and the hydrophilicity of the printing plate will be reduced.

Since the drum arrangement of the two-color offset offset printing press adopts a Y-shaped structure, that is, two printing plate cylinders work together on one blanket cylinder, and the graphics are respectively transferred from the printing plate to the blanket, and then transferred to the paper via the embossing cylinder. on. Due to this special structure, when the hydrophilicity of one of the blank portions of the printing plate is reduced, a sense of grease image at the corresponding position on the other printing plate will appear on the plate due to the effect of the roller pressure, thereby adsorbing the ink. The ink transferred from the blanket to the paper is mixed with the two inks before and after, resulting in a change in the color saturation of the ink.

Solution: Check the drum pressure, ctp price/quote, water roller, ink roller pressure is reasonable, if not reasonable, re-adjust the pressure between the various systems, without affecting the printing quality, minimize the water roller, ink roller Relief pressure and the pressure between the plate cylinder and the blanket cylinder. At the same time, try to make the drum liner reasonable. The offset offset press should use a rubber blanket with good plasticity, and should be lined with a neutral liner; and keep the surface of each roller and the ink roller and water roller at the same linear speed to reduce the speed difference; control the ink viscosity and ink layer thickness.

For excess floating and fat-sensitive images on the printing plate, use a cleaning paste and gum arabic (commonly known as peach gum) to wipe the coating. Add appropriate amount of gum arabic solution to the fountain fountain solution to remove dirt from the layout immediately. Restores the hydrophilicity and oil resistance of the blank part of the layout, improving the clarity of the layout graphics.