One article to help you solve the problem of printing ghosting!
Time:2022-12-01
Views:1379
1、Horizontal ghosting of printing ghosting
Transverse double shadow refers to the light shadow appears on the left and right side of the dot or line axis, its position is relatively fixed, the double shadow is light and heavy. Horizontal ghostliness is generally caused by the following three reasons:
（1）Double shadow caused by axial displacement of two rollers in operation
Offset press drum thrust bearing is to prevent the roller axial movement parts, if the thrust bearing wear or loose, there is a gap, under the action of the helical gear axial thrust, the roller serial movement and transverse ghosting, multi-color machine axial fine-tuning mechanism loose, bearing wear, will make the printing press under the normal working condition of the plate drum and rubber drum produce axial relative displacement, This results in horizontal ghosting.
Solution: Usually, we should pay attention to the maintenance of the printing press, and timely replacement of bearings with serious wear can be avoided.
（2）A double shadow made by peplum paper
Due to the longer edge of the flounce paper, under the action of the first color printing pressure, the paper squeezed to the trailing edge and gradually moved inward. When it enters the second color after the first color printing, the paper originally squeezed and closed by the first color is released again. This folding and releasing amount are random, which leads to the imprinting of the previous sheet of rubber cloth left in the next set and the current imprinting cannot completely overlap. This can cause a double image. This double shadow occurs mostly in the first color of the two corners of the trailing edge, not in the middle.
Solution: the paper for drying paper treatment, so that the paper becomes more flat after printing.
（3）Ghosting caused by axial paper errors
Transverse double shadow refers to the light shadow appears on the left and right side of the dot or line axis, its position is relatively fixed, the double shadow is light and heavy. Horizontal ghostliness is generally caused by the following three reasons:
（1）Double shadow caused by axial displacement of two rollers in operation
Offset press drum thrust bearing is to prevent the roller axial movement parts, if the thrust bearing wear or loose, there is a gap, under the action of the helical gear axial thrust, the roller serial movement and transverse ghosting, multi-color machine axial fine-tuning mechanism loose, bearing wear, will make the printing press under the normal working condition of the plate drum and rubber drum produce axial relative displacement, This results in horizontal ghosting.
Solution: Usually, we should pay attention to the maintenance of the printing press, and timely replacement of bearings with serious wear can be avoided.
（2）A double shadow made by peplum paper
Due to the longer edge of the flounce paper, under the action of the first color printing pressure, the paper squeezed to the trailing edge and gradually moved inward. When it enters the second color after the first color printing, the paper originally squeezed and closed by the first color is released again. This folding and releasing amount are random, which leads to the imprinting of the previous sheet of rubber cloth left in the next set and the current imprinting cannot completely overlap. This can cause a double image. This double shadow occurs mostly in the first color of the two corners of the trailing edge, not in the middle.
Solution: the paper for drying paper treatment, so that the paper becomes more flat after printing.
（3）Ghosting caused by axial paper errors
This kind of fault is generally due to the axial movement of the paper teeth shaft caused by the paper transmission is not allowed, and produce double shadow.
Solution: Adjust the gap between the tight ring at both ends of the drum and the end face of the sleeve.
2、The longitudinal ghosting of printed ghosting
Longitudinal double shadow refers to the light shadow appears in the dot or line after the axis forward, its position is fixed, there are light and heavy double shadow, branch and the whole page two kinds. It is generally believed that longitudinal ghosting is caused by the following three reasons:
（1）The blanket cannot be completely reset after each transfer
2、The longitudinal ghosting of printed ghosting
Longitudinal double shadow refers to the light shadow appears in the dot or line after the axis forward, its position is fixed, there are light and heavy double shadow, branch and the whole page two kinds. It is generally believed that longitudinal ghosting is caused by the following three reasons:
（1）The blanket cannot be completely reset after each transfer
The pressure between the rollers is too large or the radius of the rollers is improperly configured. Under the action of the friction force on the stamping surface, the rubber blanket has a large displacement. After each transfer, it can not be completely reset, resulting in double image.
Solution: reasonably adjust the lining data of the printing plate drum and rubber drum, so that they meet the requirements of synchronous rolling; Under the premise of ensuring ink transfer, reduce printing pressure.
（2）A double shadow caused by a loose blanket
（2）A double shadow caused by a loose blanket
The rubber cloth is not tight, the displacement in the rolling process is large, and can not rely on the tension force to reset, the rubber cloth is not tight there are two situations: one is the whole is not tight, causing a large area of double; Second, the rubber cloth is cut skewed or loaded with iron splint fashion is not good, resulting in local tension and local double. This type of ghostwork occurs in the trailing part, usually only in the first few dozen.
Solution: If the whole blanket is not tight, it can be tightened again; If the local tension is not tight, check whether the rubber cloth is cut crooked or not installed well, find out the reason and correct it.
（3）The irregular ghosting of printed ghosting
（3）The irregular ghosting of printed ghosting
Irregular ghosting refers to the imprinted ghosting (neither transverse nor longitudinal ghosting) that occurs in an offset press with multiple diameter under continuous operation. The irregular ghosting is caused by the printing press itself, but also by the printing process operation. The main reason for the machine is that the double diameter roller two pairs of teeth installation accuracy is not enough. The printing process operation problems are mainly caused by the wear and tear of the long-used dental pads and the decrease of accuracy. Usually pay more attention to the maintenance of the machine, so that the machine is in a good running state, the shadow will be controlled, the quality of printing will be improved.
Printing ghosting is often the devil that printing masters cannot drive away, but as long as we learn more printing technology and constantly sum up our experience, we will stay away from the devil and restore the true image!
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Anna Zhang