Since waterless offset printing does not use fountain solution, it greatly reduces the discharge of volatile organic solvents. It is an environmentally friendly printing method.
1. Dirty back
The main reason for the backside to be dirty is that the amount of ink is too large, insufficient powder spraying and uneven powder spraying.
Solution:
Adjust the printing status to the best and reduce the amount of ink if allowed;
Choose powders with proper particle diameter and distribution density. Generally, the distribution density standard for powders with a diameter of 20 μm or more is 5-10 pieces / mm2.
2. Uneven paper collection
The reason for the uneven paper delivery is static electricity in the delivery section.
Solving methods:
Stick carbon cloth on the take-up roller;
Install an anti-static fan or an electrostatic rod in the delivery section;
Install a humidifier, if there is a humidifier, then enhance its humidification function;
Install an anti-static bar at the last transfer drum, and often clean the dust on the static bar, and replace it in time if it is aging.
3. Mopi
Ink skin is mainly caused by paper powder, ink skin impurities and so on.
Solving methods:
When there is ink skin on the watermarked version, the operator can just scrape it away, and the silicone layer of the waterless version is very easy to be scratched, and there will be scratches if you do n’t pay attention, resulting in the scrapping of the entire version and waterless offset printing Nor can the water roller with the function of removing ink skin be used. Therefore, in order to prevent the ink skin from getting onto the printing plate, the ink roller can be installed at the first inking roller;
Replace the rubber roller with poor ink absorption;
Dry a solid strip at the mouth of the printing plate, so that the ink skin is attached to the solid strip;
The non-graphic part is added with solid ribbon, but it should be noted that the back is sticky and dirty;
Thoroughly clean the ink roller and ink fountain, and replace the aging ink roller;
Use the deinking tool for waterless offset printing.
4. Missing ink and graphic parts
The main reason for the lack of ink stacking and graphics is that the viscosity of the waterless offset printing ink is too high or the surface strength of the paper is too low.
Solving methods:
Choose waterless offset printing ink with lower ink viscosity;
The temperature of the printing paper should not be too low, and the paper should be sent to the printing workshop as early as possible to adjust the paper to a suitable temperature;
Reduce printing speed (necessary emergency countermeasures);
Wash the blanket and use the old paper that is not prone to problems to distribute the ink at the beginning of printing.
5. Scratching
Scratches are mainly caused by flapping caused by static electricity on the paper.
Solving methods:
Put anti-static tape on the take-up roller to reduce static electricity caused by friction between the rollers and prevent ink from sticking to the take-up roller;
Install a static remover on the take-up roller.
6. Ghost
Ghosts are mainly caused by poor ink flow. For some special patterns, it is difficult to completely remove ghosts.
Solving methods:
Add color blocks outside the graphic to increase the fluidity of the ink;
Pay attention to the aging of the ink roller and confirm that the pressure of the ink roller is within the appropriate range;
To avoid the ink layer being too thick, adjust the printing pressure and the plate surface temperature to a suitable state;
When imposition printing is adopted, if there is room for the printing layout, try to evenly distribute the graphic positions;
In the case of not getting dirty, allow a certain amount of series movement by the ink roller.
7. Dirty
Smearing is caused by a drop in ink viscosity caused by an increase in printer temperature.
Solving methods:
When printing more than 10,000 jobs, the temperature of the printing machine continues to rise due to high-speed operation, and the dirt will slowly appear on the gripper of the printed sheet. For this situation, it can be eliminated by lowering the set temperature of the cooling machine Dirty, of course, it takes some time. The temperature of the cooler can be set separately according to the long and short jobs. For example, when printing long jobs, after printing thousands of sheets, you can follow the long jobs. The temperature standard lowers the temperature of the chiller, but this is not conducive to stabilizing the temperature of the printing shop;
Reduce the temperature of the printing press, such as lowering the cooling temperature of the ink circulation part of the printing equipment , increase the fluidity of the air around the printing press by increasing the number of fans, and reduce the heat retention of the printing press;
Increase air-conditioning refrigeration capacity;
Reduce printing speed (necessary emergency countermeasures).
8. Color difference
There is a slight difference between the color of the printed product printed with waterless offset printing and the one printed with waterless printing, so it is necessary to follow the color.
Solving methods:
When waterless offset printing is used for reprinting and reprinting, if the color of the reprinting and reprinting is inconsistent with the printed product with water printing (the publication curve of the water printing may change), first confirm that the water printing Publishing curve , and then adjust the publishing curve of waterless offset printing accordingly (pre-made several publishing curves of waterless offset printing).
9
Poor field smoothness
The poor smoothness of the field is mainly caused by the low pressure between the printing plate and the rubber cylinder, the ink viscosity is too high, the ink on the printing machine is dry, and the pressure of the inking roller is too low.
Solving methods:
Confirm whether the pressure between the printing plate and the rubber cylinder is appropriate;
Replace the rubber cloth with good smoothness;
Confirm the plate surface temperature, use the appropriate type of ink, and set the appropriate cooling temperature;
Confirm if the ink on the printing machine is dry, clean the ink roller or spray anti-drying agent if necessary
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