Heidelberg offset press common fault analysis and elimination (below)
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
Fault 5: The printing plate is easy to paste and greasy when printing
Cause of failure 1: The ink additive or varnish in the ink fountain is added too much, so that the ink is too thin, and the mouth of the mouth is greasy.
Remedy: First increase the amount of water in the entire layout, or clear it. Shut down again, scrub with moisturizing powder, hundreds of sheets before printing, and then repeated. Considering that Heidelberg high-speed machine has only one version of the rubber water roller, its water-carrying capacity and cleaning ability have no effect on the water roller with water-containing velvet sleeve. At this time, it should be printed with original ink, and special products need to be added with auxiliary materials. Be sure to be moderate. When it is found that the oil is dirty due to too thin ink, the original ink should be added to the ink fountain or the ink should be replaced.
Cause 2: The pressure of the plate water roller and the water roller are biased or light.
Remedy: If the pressure is heavy, the water on the plate water roller will be squeezed out by the water roller to cause the paste; and the pressure is too light, the ink on the ink roller can not be removed when it is printed. Observed below the water bucket, you can see traces of ink on the water roller, which also caused the paste. At this time, the metering roller can be removed, and the pressure is re-flattened with a 0.1 mm steel sheet. The width of the ink bar between the plate water roller and the water roller can also be checked. Generally, it is preferably adjusted to 3 to 4 mm.
Cause 3: The pressure between the metering roller and the plate water roller is too heavy or too light.
Remedy: If the pressure is too heavy, then when the machine is running, when the water roller is lowered, the water roller seat valve can be clearly seen to jump. When you see this phenomenon, you should stop immediately and re-adjust the pressure. Do not print it too much to avoid damage to the valve and damage to the water roller bearing and needle roller bearing. Generally, a white paper can be inserted between the metering roller and the water roller, and the water roller seat valve can be manually dropped. After lifting, the paper strip is taken out to view the width of the ink bar, and the width is adjusted to 5 to 6 mm.
Cause 4: The pressure between the plate roller and the plate is too heavy or too light.
Remedy: Excessive pressure between the plate water roller and the plate will also cause the water roller seat valve to jump. The specific adjustment method is as follows: point the plate cylinder to the appropriate position, manually drop the water roller seat valve, lift it up and then move it to the appropriate position to observe the width of the ink bar. Generally, the width of the ink bar is adjusted to 4~6mm. The pressure should be re-adjusted each time a new water roller is replaced. The pressure of the new water roller can be adjusted lightly. The water roller can be slightly heavier after using it for a long time, but the water roller valve does not jump to the maximum. .
Cause 5: It is caused by the unadjusted roller.
Remedy: This situation is mostly caused by the pressure of the latter two ink-receiving rollers being light, but the pressure is too large, and the hydrophilic layer of the printing plate is easily destroyed prematurely, and the printing plate is bright and the oil is dirty. The machine can be stopped to the appropriate position, manually lowered and pressed by the plate roller, and the width of the ink bar of the four ink rollers is observed. Generally, it is suitable to adjust to 3 to 5 mm.
Cause 6: The water from the bucket roller is uneven or the hose roller fastening screw is loose or broken.
Remedy: If the surface of the bucket roller is aging, replace it with a new bucket roller. In the usual cleaning of the water bucket roller, the rag that is clamped in will also cause partial depression, resulting in a large amount of water in the area, which increases the pressure between the entire metering roller and the water bucket roller, resulting in edge paste. If the injury is light, use a reducing agent to wipe it back. If it is not well adjusted, only replace the new water roller. However, if the metering roller and the plate water roller fastening screw are loose or broken, the paste or the plate may be caused by poor water supply, and special attention should be paid during the adjustment process.
Cause 7: The water tank is not working properly.
Remedy: (1) The water tank refrigeration device is damaged, causing the water temperature to be too high, so that the alcohol volatilization rate is too fast, the surface tension of the water is decreased, the dampening solution cleaning capacity is insufficient, resulting in a paste, so the refrigeration device is essential. Generally, the water temperature should be controlled between 3 and 5 °C.
(2) The alcohol concentration is too high or too low. Generally, it should be adjusted according to the amount of ink printed. The alcohol concentration should be controlled between 15% and 25%, and should not exceed 30%. Otherwise, the hydrophilic layer of the printing plate will be damaged due to excessive alcohol concentration.
Fault 6: Imprinted ink color is uneven
Cause of failure 1: This group caused ink emulsification due to large water and ink, and deinked.
Remedy: Check whether the ink color on the ink roller is dark, whether the particles are coarse, whether there is waterless ink in the ink fountain tank or whether the ink is emulsified; if the ink is emulsified seriously, use the shovel method to wash the ink roller and replace the ink in the ink fountain tank. The amount of water should be strictly controlled when printing ink.
Cause 2: The pressure between the platen roller and the squeegee roller is light or not leaning, causing the ink to accumulate on the ink roller from time to time.
Remedy: The ink roller can be removed, and the pressure between the two rollers is re-flated with a 0.1 mm steel sheet.
Cause 3: The intermediate roller is not properly adjusted.
Remedy: The pressure between the intermediate roller and the plate water roller or the first roller roller is too light or even in place, which will cause the ink to accumulate in the place. Stop the machine and open the rear cover with 0.1mm. The steel sheet is equal to the pressure between the intermediate roller and the water roller and the ink roller. Pay attention to the flat pressure when the hand feels when pulling out, generally there is a little resistance when pulling out. If the intermediate roller and the ink roller are too heavy, it will also cause extrusion of the ink, especially when printing gold or silver ink.
In addition, the intermediate roller does not collide or even bite and does not rotate, which may cause the ink to accumulate on the intermediate roller. It can be removed or clicked on the machine for observation. Generally caused by bearing damage or fueling is not timely.
Fault 7: Printed image on dirty
Cause of failure 1: The pressure of one of the ink roller and the ink roller is light, causing the unilateral or the entire layout to be darker when the printer is stopped after printing, and it is normal after printing hundreds of sheets.
Remedy: Re-adjust the pressure to the right.
Cause 2: The momentum of the ink roller is too small or does not cause the surface of the printed product to be a deep and light (longitudinal). Sometimes the position of the dark color corresponds to the position of the motor.
Remedy: If the amount of ink is too small, the drive surface cover can be removed (just loosen the two ¢19mm nuts), and jog the machine to the highest position of the ejector pin to release ¢ The 19mm fastening nut can increase the amount of ink. The amount of ink can be adjusted according to the disparity between the product surface and the amount of ink. The amount of ink with a large amount of ink can be adjusted larger, but it should be noted that the ink accumulated at both ends of the ink roller should be cleaned up when the amount of ink is suddenly increased. Anti-seize. The maximum ink quantity of the Heidelberg high speed machine can be adjusted to 35mm. If it is found that the ink roller does not work, it is likely that the rocker arm on the top of the ink roller is bitten or the other ink is partially bitten. It needs to be carefully checked and then printed.
Cause 3: The fastening nut of the plate roller is not locked.
Remedy: The general performance is that the two sides of the network cable are different in depth, sometimes accompanied by a slight network cable overlap (double shadow). In the normal startup state, it can be seen that the roller core of the ink roller is moving in series, and it needs to be fastened, or the roller core may not be pushed into place. The roller core should be flush with the seat, and the symptoms can be eliminated by generally adjusting to the normal working position.