Five printing experience
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First, clean ink bucket experience
Scrape the ink on a piece of scotch tape that is about the same width as 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 runs with an offset press, especially a small offset press.
Second, printing the field one method
I have undertaken a batch of printing business for spot color printing, using 80g/m2 coated paper. According to the routine, a solid PS plate printing should be done, but we used the waste PS plate to print out the solid printed products with good quality and fullness in the field, which was well received by customers. The specific method is: choose an old PS version with a flat surface and no lens bump and damage. When printing, the reverse side of the plate faces outward, faces inward, does not water, and only inks.
In the printing of coated paper, in order to prevent the reverse side from sticking, it is best to use a quick-drying ink. It is 8% gram adhesive and is very effective against offset. The addition of the gram adhesive to the ink not only prevents sticking, but also does not affect the color saturation, and the ink layer appears brighter and clearer, and is more convenient for post-press processing, such as calendering, laminating, bronzing, and the like.
Here, the gram adhesive can replace the anti-adhesive material such as dry oil.
Third, the rubber printing plate, paste version troubleshooting
Flower plate and paste plate are one of the most common failures in offset printing. Finding and solving it in time is an inevitable way to improve the quality of printed products and reduce the rate of scrap. The following causes the common causes of the flower and paste plates to be summarized, and propose corresponding solutions for your reference.
Flower version
(1) The amount of water supplied is too large;
It can be solved by reducing the angle of the bucket roller or reducing the speed of the bucket roller.
(2) too much water in the plastic velvet
The water roller is operated in a state of suspending the water to consume excessive moisture absorbed by the water rubber velvet, or scraping off excess water in the water velvet.
(3) serious ink emulsification
Try the replacement ink.
(4) The pressure between the water roller and the printing plate is too large
Reduce the pressure of the water roller.
(5) The pressure between the inking roller and the printing plate is too small
Increase the pressure of the ink roller.
(6) The printing time is too long
Problems from the plate must be completely resolved by replacing the plate.
2. Paste
(1) Insufficient water supply
The amount of water can be increased by increasing the angle of the bucket roller or increasing the speed.
(2) There is less water in the water bucket, resulting in insufficient water supply
This type of failure is most likely to occur when using manual watering. The solution is to add water to the bucket to ensure adequate water supply.
(3) The water transfer roller or the water roller has serious wear and tear, which causes the water to be bad. In this case, it is necessary to replace the water rubber.
(4) Oily impurities such as ink adhere to the surface of the bucket roller, and water is not repelled due to repelling of ink
Wipe the bucket roller clean.
(5) If there is too much ink on the surface of the water-soft velvet or water-feeding roller, the water will not pass and the water-soft velvet or water roller will be cleaned, and the problem will be solved.
(6) The pressure between the water rollers or the pressure between the water roller and the printing plate may be insufficient to try to adjust the pressure.
(7) The pressure between the inking roller and the printing plate is too large
Adjust the pressure.
(8) The amount of ink is too large
It is necessary to reduce the amount of ink supplied.
(9) The ink roller is too early to close
You should first get enough water and then apply ink.
(10) The surface of the plate is exposed, resulting in poor hydrophilicity and the plate must be replaced.
In the offset printing, the flower plate and the paste plate are not related to the printed version, but in the end, the ink is not balanced. Practice has proved that the best balance of offset ink and water balance is to use as little water as possible on the basis of not being dirty or dirty, except for waterless offset printing. Correctly mastering the balance of ink and water can print good products.
Fourth, the amount of ink on the CPC is very large, but the actual amount of ink is relatively small.
1. Cause of failure: The ink fountain film is used for too long, and the leaked ink is agglomerated under the ink fountain film, causing the ink discharge amount to decrease.
Remedy: Clean the ink on the cylinder eccentric (32 total), and remove the dirty sponge strip and replace it with a new ink fountain (the ink fountain has a service life of 36 hours).
2, the cause of the failure: control of the amount of ink on the motor thread has accumulated ink, so that the thread is not enough rotation or even stuck, resulting in no ink or uneven ink output.
Remedy: Disassemble the 32 blocks under the ink fountain (note: do not lose the hollow sleeve on the fastening thread), use the needle to remove the ink on the thread, and remove all the accumulated ink, and move the CPC to make each motor It is flexible to increase the amount of ink from the lowest amount of ink, and fill the tank with butter to maintain the ink discharge effect for a long time.
Fifth, Reasons for aging of blankets and ways to overcome them
The cause of aging of the blanket
1. In the daily production of blankets, due to the long-term contact with dampening solution, ink and gasoline, kerosene will be hard, the elasticity will be reduced, and the surface will be aging.
2. Fixed for a long time, tightened on the drum, and after being rolled by the drum, the blanket is stiff and loses balance and high elasticity.
3. The influence of external environmental conditions, such as the role of air, light, and heat, destroys the chemical structure of the blanket, changes its physical properties, and its mechanical properties are degraded, hardened, brittle, and cracks or hairs may occur when severe. Soft and sticky.
Method for preventing aging of blanket
1. When the machine is stopped for a long time, the ink of the blanket should be washed off and dried without leaving any residue, so as to prevent the surface rubber from being too smooth and hardened to improve aging. When there are many paper wool, powder and filler impurities on the surface of the leather cloth, it is necessary to insist on washing the blanket to keep the surface of the rubber cloth clean, to prevent the impurities from accumulating too thick, to harden into a solid, and to press the blanket. The rubber partially loses its elasticity.
2. After washing the blanket, you can take some talcum powder on the blanket to restore the elasticity of the blanket.
3. When the machine is not stopped for a long time, the blanket should be relaxed to restore its original elasticity. For the replaced blanket, it should be cleaned, patted with some talcum powder, and wrapped in opaque paper in a cool place.
4. Use organic solvent with fast evaporation and strong solubility as detergent for blanket. Our factory often uses light oil as detergent, while slow volcanic kerosene can easily make the blanket swell. In addition, pay attention to the printing pressure during printing. The paper should be preserved. There should be no sand and other debris. Do not use paper with wrinkles, adhesions or defects. At the same time, the blanket should be protected from high temperatures or low temperatures, away from electromagnetic, glare and chemicals.