1. Little experience of cleaning ink fountain
Scrape the ink on a piece of transparent tape about the width of the ink fountain, pull out the tape and throw it away. This method can be used to quickly and conveniently clean the ink fountain when printing short-form jobs with an offset press, especially a small offset press.
Second, the printing field one method
Once undertook the printing business of a batch of spot color solid printing, using 80g / m2 coated paper. We should print a piece of field PS version as usual, but we used the waste PS version to print out good quality, full-on-the-spot, non-flowered field prints, which were well received by customers. The specific method is: choose a reassuring old PS plate with flat layout, no lens irregularities and damage. When printing, the reverse side of the version is facing outward, the front is facing inward, no water, only ink.
When printing on coated paper, it is best to use quick-drying ink in order to prevent the reverse side from sticking. It is 8% gram adhesive, which is very effective for preventing dirt. After adding the adhesive to the ink, it not only prevents sticking, but also does not affect the color saturation, and the ink layer appears brighter and clearer, and it is also more convenient for post-press processing, such as calendering, laminating, bronzing, etc.
Here, Glue can replace anti-sticking materials such as dry oil.
3. Trouble shooting for offset printing and paste printing
Pattern printing and paste printing are one of the most common faults in offset printing. Finding and solving them in time is an inevitable way to improve the quality of printing and reduce the scrap rate. The following is a summary of the common causes of the flower version and paste version, and proposes corresponding solutions for your reference.
1. Flower plate (1) The water supply is too large;
It can be solved by reducing the angle of the water bucket roller or the rotation speed of the water bucket roller.
(2) Excessive water accumulation in the water rubber fleece causes the water roller to operate in the suspended water supply state, so as to consume the excessive water absorbed by the water fleece, or use a scraper to scrape off the excessive water in the water fleece.
(3) If the ink is seriously emulsified, try the ink replacement.
(4) The pressure between the water roller and the printing plate is too large to reduce the pressure of the water roller.
(5) If the pressure between the inking roller and the printing plate is too small, increase the pressure of the inking roller.
(6) The printing time is too long. The problem from the printing plate can only be solved by replacing the printing plate.
2. Paste plate (1) If the water supply is insufficient, the water supply amount can be increased by increasing the angle of the water bucket roller or increasing the rotation speed.
(2) There is little water in the water bucket, resulting in insufficient water supply. This kind of failure is most likely to occur when manual water is used. The solution is to add water to the bucket to ensure sufficient water supply.
(3) The water rubber of the water transfer roller or water roller is seriously worn, and the water rubber should be replaced if this situation is poor.
(4) Oily impurities such as ink are attached to the surface of the water bucket roller, and the water bucket roller can be cleaned without water transmission due to the water and ink repelling.
(5) There is too much ink on the surface of the water rubber fleece or water roller, causing water to pass through. After cleaning the water rubber fleece or water roller, the problem will be solved.
(6) The pressure between the water roller or the pressure between the water roller and the printing plate is insufficient. Try adjusting the pressure.
(7) The pressure between the inking roller and the printing plate is too large to adjust the pressure.
(8) If the ink volume is too large, the ink supply volume should be reduced.
(9) If the inking roller is closed too early, you should apply the foot water before inking.
(10) The surface of the printing plate is exposed, resulting in poor hydrophilicity. The printing plate must be replaced.
In addition to being related to the printed version, the flower and paste versions in offset printing are, in the final analysis, still unbalanced. Practice has proved that the best state of offset ink-water balance is to use as little water as possible on the basis of not being dirty and not muddy, except for waterless offset printing. Only by correctly controlling the balance of water and ink can a good product be printed.
4. The amount of ink output on CPC is large, but the actual amount of ink output is relatively small
1. The cause of the failure: the ink fountain film has been used for a long time, and the leaked ink agglomerates under the ink fountain film, resulting in a drop in the ink output.
Removal method: clean the accumulated ink on the eccentric cylinder (a total of 32), and remove the dirty sponge strip, and replace it with a new ink fountain film (the service life of the ink fountain film is 36 hours).
2. Failure reason: There is ink accumulation on the thread of the motor that controls the ink output, which makes the thread rotation insufficient or even stuck, resulting in no ink output or uneven ink output.
Removal method: disassemble the 32 pieces of baffle under the ink fountain (note: the hollow sleeve on the fastening thread must not be lost), use the needle to remove the ink on the thread, and remove all the accumulated ink, move the CPC, make each motor Can flexibly hit from the lowest ink output to the highest ink output, and fill the tank with butter, you can maintain the ink output for a long time, the effect is very good after use.
5. The causes of aging of rubber blankets and ways to overcome them
Reasons for the aging of blankets 1. In daily production, blankets will harden with long-term contact with fountain solution, ink, gasoline, and kerosene, with reduced elasticity and aging surface glow.
2. Fixed for a long time, tightened on the roller, and after being rolled by the roller, the blanket is stiff and loses balance and high elasticity.
3. The influence of external environmental conditions, such as the effects of air, light, and heat, destroys the chemical structure of the blanket, changes its physical properties, and reduces its mechanical properties. It becomes hard, brittle, and cracks or hair can occur in severe cases. Soft and sticky.
Ways to prevent blanket aging
1. Every time when the machine is shut down for a long time, the ink of the blanket should be washed off and dried, leaving no traces, to prevent the surface rubber from being too smooth and hardening, and improving aging. When there are many impurities such as paper wool, powder and filler on the surface of the leather cloth, it is necessary to wash the blanket frequently and keep the surface of the blanket clean to prevent the accumulation of impurities from being too thick and harden into a solid. Press the blanket to make The rubber partially loses its elasticity.
2. After washing the blanket, you can shoot some talcum powder on the blanket to restore the elasticity of the blanket.
3. When printing for a long time without printing, the blanket should be relaxed to restore its original elasticity. The replacement blanket should be cleaned, patted with talc powder, and wrapped in opaque paper and placed in a cool place.
4. The organic solvent with fast volatility and strong solubility is used as the detergent for the blanket. Our factory often uses light oil as the detergent, while the volatile kerosene is easy to make the blanket swell. In addition, pay attention to the printing pressure when printing. The printing paper should be kept well. It should not contain sand and other debris. Do not use wrinkled, sticky, or torn paper. At the same time, the blanket must be protected from high or low temperatures, away from electromagnetics, strong light, and chemicals.
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