Adjustment and solution of the hottest printing ma

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Adjustment and solution of printing press

the structure, control system, wetting system and configuration of different printing presses are different, and the adjustment method is difficult to unify. Using alcohol free fountain solution has more stringent requirements on equipment than using IPA fountain solution, so some problems that can be covered up when using IPA fountain solution will appear. It is suggested to reduce the use of alcohol to about 8%. If there are still problems, it indicates that IPA does cover up some noteworthy problems

the key to ensure the success of non fermentative printing is to correctly select the hardness of the water roller of the wetting device and adjust the roll gap. When alcohol free printing is used, the hardness of the metering roller is slightly lower than that when alcohol fountain solution is used. Generally, the hardness of the metering roll is (25 ~ 30) shore, which will harden after being used on the machine

when using alcohol free fountain solution, it is recommended to reduce the hardness of the metering roll to (8 ~ 22) shore, because the soft roll is easy to absorb water, and the roll gap between the metering roll and the chromium roll can be increased, but the printing pressure is not increased, so that the adjustment range of the operator is more relaxed. Another problem encountered when using the standard hardness measuring roll is that the water forms stripes on the hall roll and the measuring roll (measure the length and cross-sectional area after fracture or ridge water marks), and also causes printing stripes within the week. Using soft metering rollers to increase the roll gap can often flatten the water film on the chromium roller. Another reason for the formation of ridge water marks is the speed difference between the two rollers

when using Di alcohol fountain solution, you also need to adjust the gap between the winding roller and the fountain roller. When IPA fountain solution is used, the roll gap is generally (8 ~ 10) mm wide, while when alcohol free fountain solution is used, the roll gap should be reduced to (3 ~ 5) mm. In a typical IPA wetting device, the metering roller and chromium roller are driven by gears through separate motors, while the printing plate ink roller is driven by the printer

if the plate inking roller starts to drive the chromium roller, the speed of the chromium roller increases and the wetting control is lost. When the roller acceleration of the wetting system exceeds the normal state, water often accumulates at both ends of the roller, causing splash; If the speed of the roller is too fast, the motor of the wetting system will be improperly stressed, resulting in open circuit and motor failure

the adjustment of metering roller speed is also a key problem. In order to measure alcohol free fountain solution, it is often necessary to rotate the fountain roller at a higher speed, and reaching the conditions will lead to inaccurate ejection and control range

the metering roller of some printing machines will be designed into a spindle type, so that the fountain solution can be evenly distributed on the printing plate. For some non fermenting fountain solutions, it is best to use a spindle to align the metering roller. If the middle part of the plate roller is too wet and both ends are too dry, the metering roller must usually be adjusted; If there is not enough fountain solution in the center of the plate roller, make the metering roller parallel to the chromium roller

the best angle of deviation adjustment varies with the alcohol substitutes used, which should be determined through experiments. By observing that domestic material suppliers have been able to produce few materials that meet the requirements of aviation performance for a long time, the dirty line formed at the bend of the printing plate can determine whether the ink and water balance is good, and the dirty line can be evaluated by stopping the printing machine after the printing machine enters a stable state. When the ink balance is ideal, thin and uniform dirt lines will be produced on the full width of the printing plate. If the printing plate is too dry in a certain part, the width of the dirty line increases, and if it is too wet, the dirty line disappears

possible problems

using alcohol free fountain solution is likely to encounter some unprecedented problems

Problems caused by

may include: the metering roller absorbs ink

alcohol substitutes can make the metering roller sensitive to ink. The ink is first adhered to the accessory chrome Wong and then transferred to the metering roller. The solution is to contact the printer manufacturer or use a specially prepared mixture to corrode the roller. The hydrophilicity of the metering roll is maintained by coating with cloth gum or paint. Some institutions believe that the sensitivity of the metering roller is caused by the contamination of the fountain solution, because as long as the metering roller is stained with 1% of the blanket cleaning agent, it is enough to destroy the satisfactory fountain solution

ridge watermarks

as mentioned above, when alcohol substitutes are used, if the hardness of the metering roller is (25 ~ 30) shore, ridge watermarks can appear, which will affect the quality of printed matter. The solution is to use softer measuring Wong. Some manufacturers also propose that metering rollers with long fiber surface are more hydrophilic

maintain the correct concentration

it is very important to determine the correct concentration of fountain solution, especially in the initial preparation. Most alcohol substitutes will slowly express from the plate solution. Since there is no method to accurately adjust and determine the concentration of alcohol substitutes, the use of unleavened fountain solution needs to be replaced at least once a week

speed up the upgrading of plastic granulator technology to make the fountain solution too cool. When increasing the printing machine speed, cooling is very important, but operators sometimes make the fountain solution too cool. This will increase the viscosity of the ink and cause the problems of paper roughening and ink stacking. The correct temperature pair first depends on the conditions of the printing workshop. At the same time, the cooling unit of the fountain solution should be adjusted to (10 ~ 13) ℃. Or as recommended by the supplier

organic matter breeding

if organic matter breeding occurs in the fountain solution circulation system, the circulation system, including the discharge bucket, should be cleaned at least once every "industry 4.0" week that emphasizes intelligent manufacturing, network manufacturing and digital manufacturing. Wash with ordinary water; Mold eliminators are also used to prevent organic matter from breeding; You can also wash the circulating system with an aqueous solution containing (1 ~ 5)% bleach during the week of work, but before refilling the fountain solution, make sure that the circulating system has been cleaned and no detergent remains

inking roller deinking

using different alcohol free fountain solutions without thoroughly cleaning the circulation system, inking roller deinking may occur. At this time, the practice of copper plating the ink roller can be used for the old printing machine with steel ink roller

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