Q: Our factory is a cup-making factory. When printing with a wide-format flexo printing machine, there are sometimes ambiguous phenomenon of unclear printing and graphic arts. A: There are two situations to explain:
If it is a large area stencil, there may be ink drying speed is too fast, the printing pressure is not enough or the pressure at both ends of the roller is inconsistent, the line number of the plain roller is too high or there is serious wear, resulting in reduced ink transfer, ink pressure or printing Too much pressure. There should be a corresponding solution: adjust the ink, reduce the drying speed; reasonably adjust the printing pressure; replace the anilox roller; reasonably adjust the ink pressure and the printing pressure.
If it is a partial stencil, it may be that the layout is uneven and the amount of ink is not uniform. The improper cleaning of the anilox roller partially reduces the volume of the local mesh. Then it should be trimmed or patched; it should be checked and thoroughly cleaned.
Q: In the narrow-width label printing, there are strip marks on the printed product that are parallel to the axial direction of the roller. What are the reasons?
A: According to the different reasons for the production of ink sticks, there are mainly three types of ink bars, both tooth-shaped ink bars and roller-ink bars and vibrating ink bars.
If it is a gear-type ink stick, the cause of the failure is mainly manifested in the defective roller and anilox roller driving gear, such as: gear, bearing wear; excessive error of the drive gear; gear tooth surface foreign body; poor lubrication. It is also possible that the installation is incorrect.
If it is a roller-type ink stick, it is because the accuracy of the anilox roller itself is not high or it is easily installed. Mainly in:
1, the anilox roller geometry error is too large.
2. The anilox roll is poorly installed and there is a large radial runout.
3, bearing installation in three aspects.
Vibrational ink bars are more complex and are mostly related to the performance of the machine and the maintenance and maintenance of the equipment. It is often caused by vibrations at the relevant site. For example, the vibration caused by the wear of the bearing, the vibration caused by poor printing and pasting, the vibration caused by the steady loss of the printing pressure, and the vibration caused by the poor smoothness of the drive motor.
It should be pointed out that once the above-mentioned failures occur, it is necessary to immediately stop the test and check thoroughly to find out the root cause of the failure and eliminate it.
Q: In the printing process, the paper fiber and the filling material are peeled off or pulled off. What causes this phenomenon and how to eliminate it?
A: What you are referring to is the phenomenon of pulling hair. The fundamental reason for the generation of pulling hair is that the ink viscosity and the surface strength of the paper are out of balance, that is, the viscosity of the ink is higher than the surface strength of the paper.
The solution is:
1. Composition and Viscosity of Ink: Adding the varnish and thinner, pay attention to the amount of diluent should not be too much, the lowest is appropriate.
2, the paper's performance: appropriate to improve the smoothness of the paper to reduce the paper's ink absorption performance.
3, printing pressure: adjust the ideal printing pressure, not only meet the basic requirements of the minimum printing pressure.
4, a reasonable choice of printing speed.
Q: How to control the tension between the yoke and the traction roller?
A: The printing material has a certain speed due to the action of the pulling roller. The tension is pulled from the yoke axis and fed into the printing section. The tension on this section is greater than the tension on the printing section. The tension is usually controlled by a brake attached to the feed shaft. As we all know, the winding diameter of the work gradually becomes smaller. Due to the high speed, the use of materials is diversified, and the coil diameter changes greatly. Therefore, the use of manual mechanical brakes is impossible to obtain high-quality prints. Now choose the automatic control method, use the tension measurement table with data management. Its detection methods are spring-rolled roller type and micro-displacement type detection. Mechanical brakes have been used since very early, and they are inexpensive, but they are inaccurate. So gradually there are other forms. Magnetic powder brakes use magnetic powder as a friction medium to generate braking force through current, because of its direct-current nature of torque-current characteristics. Pneumatic brakes, although some printing machines are used in large quantities, are due to the non-linear torque characteristics and the large wear factor. Also gradually replaced by large-capacity magnetic powder brakes.
Q: What are the conditions for gravure ink printing?
A: Gravure ink printing is prepared from three aspects: printing plate uses electronic engraving gravure or laser engraving gravure, the depth of the network hole is 15 ~ 25μm, shallow solvent ink gravure. This is because the ink is produced using tap water. The boiling point of water is higher than that of the solvent. Therefore, the ink is not easy to evaporate, and the shallow version can increase the printing speed and avoid water ripples. If solvent inks are used for printing, the depth of the plate's cell is 35 to 40μm, which is likely to cause water ripples. However, when using ink printing, the depth of the plate at 25μm or more, there will be water ripple phenomenon, so choose the right one. Plates are crucial.
Good drying equipment: drying temperature should be based on the different substrates, the size of the printing area. Such as aluminum foil label printing, drying temperature above 100 °C; plastic film printing, drying temperature of 50 ~ 60 °C is appropriate. The wind power should be stronger than using solvent inks because hot air can quickly dry the ink after it has been transferred to the substrate.
Surface treatment: In addition to aluminum foil, vacuum aluminized film, paper, all plastic film before the ink printing needs to be EDM, so that the surface tension of 0.04N / m or more. The ink produced by using water as the main solvent has a surface tension of 0.072N/m or so, which shows that the surface tension of the ink is greatly different from the surface tension of the film, which will affect the adhesion of the ink on the substrate and improve the plastic film. The surface tension can improve the adhesion of the printed slug on the film.
If it is a large area stencil, there may be ink drying speed is too fast, the printing pressure is not enough or the pressure at both ends of the roller is inconsistent, the line number of the plain roller is too high or there is serious wear, resulting in reduced ink transfer, ink pressure or printing Too much pressure. There should be a corresponding solution: adjust the ink, reduce the drying speed; reasonably adjust the printing pressure; replace the anilox roller; reasonably adjust the ink pressure and the printing pressure.
If it is a partial stencil, it may be that the layout is uneven and the amount of ink is not uniform. The improper cleaning of the anilox roller partially reduces the volume of the local mesh. Then it should be trimmed or patched; it should be checked and thoroughly cleaned.
Q: In the narrow-width label printing, there are strip marks on the printed product that are parallel to the axial direction of the roller. What are the reasons?
A: According to the different reasons for the production of ink sticks, there are mainly three types of ink bars, both tooth-shaped ink bars and roller-ink bars and vibrating ink bars.
If it is a gear-type ink stick, the cause of the failure is mainly manifested in the defective roller and anilox roller driving gear, such as: gear, bearing wear; excessive error of the drive gear; gear tooth surface foreign body; poor lubrication. It is also possible that the installation is incorrect.
If it is a roller-type ink stick, it is because the accuracy of the anilox roller itself is not high or it is easily installed. Mainly in:
1, the anilox roller geometry error is too large.
2. The anilox roll is poorly installed and there is a large radial runout.
3, bearing installation in three aspects.
Vibrational ink bars are more complex and are mostly related to the performance of the machine and the maintenance and maintenance of the equipment. It is often caused by vibrations at the relevant site. For example, the vibration caused by the wear of the bearing, the vibration caused by poor printing and pasting, the vibration caused by the steady loss of the printing pressure, and the vibration caused by the poor smoothness of the drive motor.
It should be pointed out that once the above-mentioned failures occur, it is necessary to immediately stop the test and check thoroughly to find out the root cause of the failure and eliminate it.
Q: In the printing process, the paper fiber and the filling material are peeled off or pulled off. What causes this phenomenon and how to eliminate it?
A: What you are referring to is the phenomenon of pulling hair. The fundamental reason for the generation of pulling hair is that the ink viscosity and the surface strength of the paper are out of balance, that is, the viscosity of the ink is higher than the surface strength of the paper.
The solution is:
1. Composition and Viscosity of Ink: Adding the varnish and thinner, pay attention to the amount of diluent should not be too much, the lowest is appropriate.
2, the paper's performance: appropriate to improve the smoothness of the paper to reduce the paper's ink absorption performance.
3, printing pressure: adjust the ideal printing pressure, not only meet the basic requirements of the minimum printing pressure.
4, a reasonable choice of printing speed.
Q: How to control the tension between the yoke and the traction roller?
A: The printing material has a certain speed due to the action of the pulling roller. The tension is pulled from the yoke axis and fed into the printing section. The tension on this section is greater than the tension on the printing section. The tension is usually controlled by a brake attached to the feed shaft. As we all know, the winding diameter of the work gradually becomes smaller. Due to the high speed, the use of materials is diversified, and the coil diameter changes greatly. Therefore, the use of manual mechanical brakes is impossible to obtain high-quality prints. Now choose the automatic control method, use the tension measurement table with data management. Its detection methods are spring-rolled roller type and micro-displacement type detection. Mechanical brakes have been used since very early, and they are inexpensive, but they are inaccurate. So gradually there are other forms. Magnetic powder brakes use magnetic powder as a friction medium to generate braking force through current, because of its direct-current nature of torque-current characteristics. Pneumatic brakes, although some printing machines are used in large quantities, are due to the non-linear torque characteristics and the large wear factor. Also gradually replaced by large-capacity magnetic powder brakes.
Q: What are the conditions for gravure ink printing?
A: Gravure ink printing is prepared from three aspects: printing plate uses electronic engraving gravure or laser engraving gravure, the depth of the network hole is 15 ~ 25μm, shallow solvent ink gravure. This is because the ink is produced using tap water. The boiling point of water is higher than that of the solvent. Therefore, the ink is not easy to evaporate, and the shallow version can increase the printing speed and avoid water ripples. If solvent inks are used for printing, the depth of the plate's cell is 35 to 40μm, which is likely to cause water ripples. However, when using ink printing, the depth of the plate at 25μm or more, there will be water ripple phenomenon, so choose the right one. Plates are crucial.
Good drying equipment: drying temperature should be based on the different substrates, the size of the printing area. Such as aluminum foil label printing, drying temperature above 100 °C; plastic film printing, drying temperature of 50 ~ 60 °C is appropriate. The wind power should be stronger than using solvent inks because hot air can quickly dry the ink after it has been transferred to the substrate.
Surface treatment: In addition to aluminum foil, vacuum aluminized film, paper, all plastic film before the ink printing needs to be EDM, so that the surface tension of 0.04N / m or more. The ink produced by using water as the main solvent has a surface tension of 0.072N/m or so, which shows that the surface tension of the ink is greatly different from the surface tension of the film, which will affect the adhesion of the ink on the substrate and improve the plastic film. The surface tension can improve the adhesion of the printed slug on the film.
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