Solve the phenomenon caused by paper lint

Why does the paper fall off and lose hair when printed? What impact do they have on print quality?

In the printing of the cards, it often encounters dirty or scratched phenomenon, especially glossy paper or PVC cards. How to overcome such disadvantages has become an unavoidable problem for some high-end users. As a manufacturer of card printing presses, we are indispensable, and we should rush for users to find a solution.

First analyze the source of the problem:

one. Feeding process.

For all the paper feeding methods other than the vacuum suction upper feeding method, the above-mentioned smearing or scratching phenomenon exists. The main reasons are:

1. The paper feeding mode paper stack (card) has a certain pressure on the lowest card. The last printing card will go to the back of the previous card when the last printing ink in the printing cylinder has not been dried yet;

2. For the same reason as above, when printing a hard card such as PVC, if there is a burr behind the card, it will scratch the back of the previous card;

3. If there are any scratches or burrs on the platform of the paper feed path, back scratches will also be generated on the card being entered;

4. The double-feed limiter plate is too tight and the front card that is entering is scratched on the front and back;

5. If the edge of the feeder surface is not deburred, it may scratch the back of the card to be returned on the return journey.

two. Paper output process.

For the card machine without the characteristics of full-printing, the scratches generated between the card and the scraper are also a headache. First look at the reason:

1. The paperboard and rubber roller have too much adhesion;
2. The scraper is dirty or has burrs.

Based on the above analysis, the following methods are listed to eliminate or reduce the phenomenon of smearing:

(one). Feeding process.
1. Do not add too many cards to the cassette at one time, and try to reduce the pressure;
2. When printing hard cards such as PVC, first check and remove the card edge burrs;
3. Use fine sandpaper to remove any raised burrs on the platform;
4.Be sure to align the inlet gap of the double-feed limiter before printing;
5. Finely trim all burrs on the edge of the feeder with fine sandpaper.

(two). Paper output process.
1. Reduce ink viscosity (add appropriate amount of varnish; add appropriate amount of viscosity reducing agent; add appropriate amount of edible raw meal); avoid excessive printing pressure; reduce the number of manual transfer before printing; try to scrub the rubber roller as far as possible after shutdown; The amount of water should not be too large; when the color printing, the heavy ink version should be printed as far as possible; try to use non-glossy paper.
2. Clean the paper scraper frequently; use a fine sandpaper to remove the protruding burrs on the paper scraper.

Why should the blanket be cleaned? Why must the rollers be washed in the net when changing colors?

After printing for a period of time, there will be paper wool, paper powder, ink and other dirt on the blanket, which reduces the quality of the printed matter, so the blanket must be cleaned in time. Especially when printing paper with low surface strength, the accumulation of paper and paper powder is more serious, and therefore it is necessary to clean it more often. Washing the ink while changing color will not affect the purity of the newly printed ink if it is not cleaned. Pay special attention when changing from dark ink to light ink. If black ink is replaced by yellow ink, if the black ink is not cleaned, the yellow ink will be black, which greatly affects the quality of printed matter. Therefore, the ink roller must be cleaned when changing colors.

Does the printing speed affect the printing pressure?

The printing speed has a great influence on the printing pressure. When the printing speed is increased, the contact time between the plate and the blanket, the blanket and the printed sheet corresponding to each other is correspondingly reduced, which means that the degree of incomplete contact between the printed surfaces is increased, and the printing pressure is increased. It will be reduced; on the contrary, when the printing speed is reduced, the printing pressure will increase indefinitely. Therefore, in order to guarantee the quality of the printed matter, the printing pressure must be increased accordingly when the machine is operating at a high speed, and the printing pressure can be appropriately reduced when operating at a low speed.

Source: Starfire Design