Analysis and treatment of common faults in the mos

2022-08-07
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Analysis and treatment of common faults of sheet fed offset printing (serial III)

fault 12 low printing plate resistance

reasons: 1. The water roller has too much force on the printing plate; 2. When printing, the force between the printing plate and the blanket is too large; 3. The blanket was not scrubbed in time after stacking the plates; 4. Too much paper powder in the printing paper; 5. Paper pH value is too high or too low; 6. Improper pH value of fountain solution; 7. The metal composition of the plate base does not meet the requirements of the printing plate; 8. There is sand or sand in the printing paper; 9. The printing plate is not anodized, and no solid and dense aluminum oxide film is formed on the surface; 10. Rubber inverted; 11. The printing plate is improperly stored and exposed to strong light, resulting in slight or complete exposure; 12. Excessive development during plate making; 13. Rubber blanket aging; 14. Ink viscosity is too high; 15. Insufficient film density when printing; 16. Printing plate storage time is too long, its photosensitive resin film has undergone qualitative change; 17. The amount of water used to wipe the remaining plate repair paste (agent) after plate repair is too small and it is not rubbed to non graphic places, resulting in the thinning of the printing plate resin film; 18. The water roll sleeve is too aged; 19. The action force of the plate inking roller on the printing plate is too large and the printing speed is too fast, resulting in easy damage to the printing nip; 20. Printing plate photosensitive resin film thickness; 21. The printing plate sand mesh is too coarse; 22. When the printing plate is not inked, the water roller acts on the printing plate, and the machine idles for too long; 23. Use wetting powder to wipe the plate for too long and with too much force; 24. There is too much ink hanging on the water roller and the ink hardens on the water roller; 25. There is dirt on the back of the printing plate at the time of the previous version, resulting in too high protrusion of the printing plate after the previous version; 26. The paper is easy to lose powder and the amount of liquid used in printing is too small, which is easy to stack plates frequently; 27. Too much ink dirt is accumulated on both sides of the blanket and at the tail; 28. The cylinder sleeve of the printing machine is seriously worn, resulting in the increase of the impact force on the printing plate during printing; 29. The hardness of the blanket pad is too high, which is easy to wear the printing plate; 30. Excessive baking; 31. The quality of the printing plate resin film is too poor, and the sand mesh of the printing plate is too sharp; 32. The ink roller on the plate is aging, and the printing plate is seriously collided during printing; 33. The rubber blanket is too loose; 34. The ink used is too aging; 35. The blanket was not cleaned when it should be cleaned and used continuously; 36. The blanket liner or backing paper is uneven; 37. The amount of ink used in printing is too small and the printing speed is fast; 38. The force between the printing plate and the rubber is too large, or the force between the rubber and the impression is too large, so that the blanket is easy to stretch and stretch, which is easy to wear the printing plate; 39. Paper powder is easy to accumulate at the slight wrinkle of the paper; 40. The pressure difference between the two ends of the printing plate and the rubber is large, or the pressure difference between the two ends of the rubber and the impression is large; 41. There is dirt on the printing plate pad, which is caused by the high bulge of some parts of the printing plate; 42. Dirt is stuck on the rubber pad, which is caused by excessive bulge of some parts after the rubber is installed; 43. The tightness of both ends of the blanket is different, one end is too tight, and the other end is too loose; 44. The rubbing gauze is too old and the printing plate resin film is operated during rubbing; 45. The axial movement of the printing machine drum is serious; 46. The printing plate liner is too thick or the rubber liner is too thick

treatment method: 1. The corresponding adjustment with a feeler gauge has not been published. During the adjustment, the printing plate can be reversed to avoid damaging the sand mesh of the printing plate. At the same time, the total pad of the printing plate should meet the requirements. The force of the water roller on the printing plate after adjustment is generally within the range of 0.2 ~ 0.5mm, but it should also be determined according to the specific situation. For example, the force of the new water roller sleeve should be slightly smaller than that of the printing plate during the adjustment, and it can be gradually adjusted with the use degree; The force of the old water roller on the printing plate should be moderate. Due to the small variability of the old water roller sleeve, the large force is also easier to rub the printing plate; 2. Use a micrometer for specific adjustment. Generally, the pressure is within the range of 0.10 ~ 0.15mm. Pay attention to the influence of different plate thickness on the printing pressure; 3. The blanket shall be scrubbed in time according to the paper condition, ink fluidity, picture and text condition and printing volume; 4. Try to use less paper with more paper powder. Even if you use it, you should always scrub the blanket and constantly add new ink; 5. It is best to avoid using it. Even if it is used, it should be used on low printing volume prints. During printing, the pH value of the bucket solution should be kept between 5 and 6; 6. The water bucket liquid shall be weakly acidic, and the water bucket shall be cleaned frequently to avoid the deterioration of the water bucket liquid; 7. Replace the printing plate. Even if it is used, it should be used in the printing products with low quality requirements and a small number of prints. Pay attention to the degree of use of the printing plate during the printing process to avoid affecting the product quality; 8. It shall not be used for printing; 9. It is used in live parts with low printing volume and low printing quality requirements; 10. Change the direction of the blanket. In order to avoid errors during installation, the best way is to hold the two ends of the blanket by hand and pull it. The direction of use is the one whose elongation is not obvious, or the direction of use can be determined by identifying the marks on the north side of the blanket; 11. Change the printing plate or use it in low printing volume; 12. During plate making, correct development shall be carried out according to the condition of the developer and the sensitivity of the printing plate. If the resin film is thinned due to improper development, the printing plate shall be replaced; 13. Replace the blanket; 14. Adjust the ink blending oil, adhesive remover, modifier, etc. properly, and determine the amount according to the printing conditions and ink categories; 15. Printing plate quality problems caused by insufficient density of plate printing film should be eliminated; 16. It is best to avoid using it. Even if it is used, it should be used in live parts with low printing volume and low printing quality requirements; 17. When wiping the revision paste (agent) after revision, it should be washed with a large amount of water while wiping to the non graphic area; 18. Replace the water roll sleeve; 19. Adjust the ink roller with a feeler gauge, and at the same time, pay attention to whether the total expanded thickness of the plate lining meets the requirements; 20. Change the printing plate; 21. It should be used in prints with low quality requirements and a small number of prints; 22. When the printing plate is not inked, the machine should not idle for too long when the water roller acts on the printing plate; 23. When using wetting powder to control the dirt on the printing plate, do not use too much force on the graphic part to avoid damaging the resin film of the printing plate; 24. Wash the water roller with detergent or gasoline. After washing, there shall be no residual detergent or gasoline on the water roller sleeve, and it shall be scraped off repeatedly; 25. When loading the plate, pay attention to check the back. If the back of the plate is raised due to careless inspection, remove the plate and place it on a flat surface. Press a thicker plate base from above the raised part of the front of the plate and flatten it with a smoother wood or bamboo board. During operation, pay attention not to make the plate base slide, and do not use too much force to avoid damaging the sand mesh; 26. For the printing products that are easy to lose powder on the paper, have low requirements on the quality of printing products and do not overprint, the amount of fountain solution can be slightly increased to make the ink have good transferability. The Vickers hardness test is especially suitable for the hardness measurement of thin parts, small parts, coatings, carburized and nitrided layers in precision instruments. At the same time, attention should be paid to the selection of inks with stronger water resistance and not easy to emulsify; 27. Both sides and the tail of the rubber are easy to get dirty, so it is advisable to often scrub the corresponding parts of the rubber and the impression cylinder; 28. Replace the corresponding accessories or repair them properly. If the accessories are not replaced, pay attention to the deceleration printing; 29. Do not use hard liners with higher hardness than normal ones, so as to avoid large vibration of the machine or serious wear of the printing plate; 30. After baking, if the layout is dark brown or more serious grayish black, it is generally not used; 31. Replace the printing plate or use it in the live parts with low printing volume; 32. If the ink roller is seriously aged, it should be replaced. If it is not serious, it can be cleaned with rubber cleaning reductant. The speed should not be too fast when printing; 33. If the rubber blanket is too loose, it shall be fastened. In particular, the newly replaced rubber and gasket are easy to be loosened after being used for a period of time, so it shall be fastened in time; 34. If the ink is used for a long time or mixed with more paper powder, the ink should be replaced; 35. After changing the version, pay attention to scrubbing the blanket, and do not use it continuously; 36. Flatten or replace the rubber lining or paper. The rubber lining caused by uneven lining shall be repaired or replaced in time; 37. During printing, the ink itself has a certain protective effect on the resin film of the printing plate, and it is easy to wear the printing plate if the amount of ink is too small; 38. Select the center distance of the drum and measure the pressure with a micrometer. Generally, the pressure is within the range of 0.10 ~ 0.15mm; 39. The blanket should be scrubbed frequently. When there is a large amount of paper powder in the slightly wrinkled area of the paper, local cleaning should be carried out to avoid easy wear of the printing plate; 40. Use a micrometer to adjust its pressure balance; 41. Remove the lower printing plate and the liner to remove the adhered sundries. If some parts of the printing plate are protruding, they shall be flattened with smooth wooden boards from the front tension sheet base; 42. Remove the blanket liner to remove obstacles. If the blanket or liner is damaged, it should be replaced or properly repaired; 43. Remove the blanket, cut off or cut off the original eyelet, measure the parallel dimension with a ruler and re punch; 44. Replace the version wiping gauze; 45. Tighten the roller shaft sleeve or replace the corresponding accessories; 46. Measure the required thickness with a micrometer

fault 13 is easy to paste the plate

reasons: 1. The amount of fountain solution is too small; 2. The printing pressure is too high, and the moistened version has more water transferred by the paper than under normal pressure, resulting in easy pasting; 3. Too much ink and too little water; 4. The water roller is seriously dirty; 5. The ink is too balanced and the fluidity is too large; 6. Ink drying too fast; 7. The ink is too thick; 8. The workshop temperature is too high; 9. Improper adjustment between the water splashing roll and the plate water roll or improper adjustment between the water transfer roll and the water outlet roll; 10. The force on the printing plate by the plate water roller is too small; 11. Poor base quality; 12. The printing plate is polluted by lubricating oil and grease; 13. There is no water content adjustment for different types of inks and different colors of inks; 14. Ink transfer amount is too large, ink is not easy to balance; 15. There are too many additives in the ink, such as adhesive remover, modifier, ink blending oil, etc; 16. The printing plate sand is damaged; 17. The printing plate was corroded by chemicals; 18. Printing plate creases are too serious; 19. The sand mesh of the layout is too coarse and easy to be damaged; 20. The water roll has rubber jumping; 21. The fountain solution is too acidic; 22. The paper is too acidic; 23. Incorrect selection of ink; 24. After the ink is cleaned, there is cleaning fluid left on the ink roller or gasoline or cleaning agent left on the water roller; 26. Too much oil is poured onto the paper and transferred to the ink; 27. The deteriorated and emulsified ink is reused; 28. The ink on the ink roller dries and crusts, and continues to be used after dilution; 29. Long downtime and failure to wipe or apply protective glue to the printing plate in time; 30. Due to the increase of the ink viscosity at the bottom of the workshop temperature, the ink fluidity increases due to the friction and heating of the ink roller due to the long printing time after the adjustment of the ink fluidity; 31. The water roller was not adjusted or replaced in time due to serious wear; 32. It is caused by different ink proportion when mixing ink; 33. After the hydrophilic layer of the printing plate is seriously damaged or the hydrophilic layer of the printing plate is slightly damaged, clean water is still used to moisten the plate; 34. Too much paper powder in the paper; 35. The fixed pin of water conveyance mechanism moves outward; 36. Too much dry oil is added to the ink; 37. Caused by temperature difference between winter and summer; 38. Use the frozen water moistened version and suddenly use the warm water moistened version

treatment methods: 1. Appropriate moisture should be given according to the law of large amount of ink, small amount of ink and small amount of water. The amount of fountain solution should not be too large or too small; 2. Print with the appropriate pressure, and pay attention to the moisture adjustment if the pressure needs to be increased; 3. The water depends on the amount of ink used. At the same time, pay attention to the changes of the water level in the bucket and the ambient temperature and humidity; 4. Catapult water

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