Common problems and solutions in corrugated carton ink printing process
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There are currently four ways to use water-based ink printing equipment in the corrugated box industry, and their characteristics vary. The first is the chain-type single-machine printing method. This printing method can only be printed without slotting and die-cutting. The second is the commonly used production method of printing slotting and round die cutting. This method uses upper ink printing. After slotting or die cutting, it can be formed by only bonding (nail box). The third is to use the production method of automatic printing trough and folding bonding (nail box). This machine adopts the lower inking printing system for folding forming, and belongs to the one-time molding machine. The fourth type is the more advanced printing and round die cutting method. It is characterized by multi-color printing, high precision equipment, and printed products can achieve color printing effects, especially for color carton sales. package. In the above several ways, the common feature is the use of ink printing. The printing principle and equipment structure are basically the same, but the printing color, the number of mesh lines and the process equipment are different. The printing process is affected and restricted by many aspects and factors. Many problems can be solved without simple adjustments by the operator. Only through various aspects of cooperation, to minimize and avoid some unnecessary problems in production.
Slotting knife and longitudinal pressure line are not accurate, resulting in inaccurate printing position
Cause Analysis:
Since the slotting and pressing lines are not adjusted according to the size required by the process drawings, the length or width of the paperboard is deviated, which ultimately affects the printing position.
Solution:
Firstly, the groove or the wire size should be adjusted according to the manufacturing dimensions of the drawing. The position is required to be accurate, and then the plate position is re-adjusted according to the exact size position, and the deviation caused by the wear of the groove or the pressure roller is checked.
The position of the printing plate is not allowed, causing the plate to be re-adjusted
Cause Analysis:
Since the color registration and the position of the partial printing plate are not clear, the error in the typesetting is large, and the printing position is obviously deviated in actual production. The current printing equipment is basically drum printing, and the typesetting is on the plane, which will inevitably produce a longitudinal position error, and the shrinkage rate problem arises due to the size of the printing pressure.
Solution:
First, when making a 1:1 ink map, it should be drawn at the normal percentage reduction rate. When printing, strictly adjust the printing plate according to the ink position. When the color registration accuracy is very high, the "cross line" typesetting method should be used, and the cross line of the printing plate and the ink pattern should be aligned, and if necessary, the magnifying glass can be used to check the deviation.
Printing ghosting and whiteout problems
Original group analysis:
These two problems are common in the production process. The ghosting around the printed pattern or text is caused by the excessive pressure of the anilox roller and the printing plate; the ghosting of the front edge of the printing is caused by the excessive pressure between the printing cylinder and the platen roller. Large-area printing through the bottom, whitening is caused by insufficient pressure of the printing roller and the embossing roller. These two problems are caused by the opposite pressure.
Solution:
Printing ghosting problems should adjust the gap and pressure between the web, the roller and the plate roll, commonly known as the upper pressure. The ghosting is because the upper pressure is too large, and the anilox roll squeezing the printing plate (referred to as a flexographic plate) is deformed, so the gap between the two rolls is increased to reduce the pressure accordingly. The problem of printing leakage should adjust the gap and pressure between the plate roller and the platen roller, commonly known as the downforce. Due to the excessive gap between the plate roll and the platen roll, it is not possible to print in a large area, which requires an increase in the downforce. In addition, the unevenness of the printing plate, the quality of the plate lining and the hardness of the printing plate will affect the above problems, and local adjustment should be made.
Multi-color printing overprint is not allowed
Cause Analysis:
The problem of overprinting is common in the printing industry. Because it is composed of many factors, it is not easy to solve it. First of all, the accuracy of the position and accuracy of the multi-color printing slot machine itself is a direct factor. Followed by the adjustment of the paper feed roller, the traction roller, the use of the traction belt, the arrangement of the printing plate; the accuracy, and the problem of the warpage of the cardboard will cause the problem of overprinting.
Solution:
Since overprinting is composed of multi-color printing, it is inevitable that the position of the plate roller on each color printing slotting machine is relatively small; indeed, this requires the equipment department to adjust the printing position to ensure that the error is at a minimum. First, since the start of printing has an effect on the thickness of the paperboard, the plate roll of each color should be slightly larger than its previous pressure so that the pressure applied to all colors is equal. Secondly, there are paper feed rollers and traction rollers at the front and the back of each print. The adjustment of these two rollers is very important, especially when the width of the cardboard is too narrow, it should pay attention to adjust the gap and position. In case of partial color registration, two traction belts should be added at the edge of each printing plate to ensure the smoothness of the cardboard during the printing process. Moreover, due to the different degree of warpage of corrugated cardboard, it has an absolute influence on overprinting. If necessary, the cardboard should be replaced again, but it must be flat. [next]
Inconsistent printing colors
Cause Analysis:
Inconsistent printing color means that the whole board is unevenly printed along the machine longitudinal or horizontal direction after printing. The main reason for this problem is that the two sides of the horizontal printing are different in color, one side is shallow and one side is deep. There is also an unfavorable cycle of the inking system, insufficient ink flow, and uneven transfer of the transfer roller.
Solution:
The uneven horizontal color is caused by the difference in the gap between the rubber roller and the anilox roller, the anilox roller and the plate roller. Therefore, the gap between the three rollers should be adjusted, and both ends must be kept parallel. Since the printing grooving machine is centered, such as the production of narrower cardboard in the normal period, the rubber roller and the anilox roller will wear faster, and the wear at both ends will be less, and the result after printing will be different if the two ends are colored. Obviously inconsistent, you need to repair or replace a roller. The longitudinal color is not uniform because the ink flow rate is too small and the ink supply is insufficient. Therefore, it is necessary to increase the amount of ink, and the machine is idling, so that the amount of ink is fully circulated and then produced, which can reduce the occurrence of such problems.
Corrugating when feeding or printing
Cause Analysis:
This is caused by two aspects. First, the gap between the paper feed roller (referring to the printing slot machine) is too small, lower than the thickness of the original paperboard, and the corrugated sheet is crushed before printing; second, the printing roller pressure is too large during the printing process. , causing the corrugated part of the printing area to be crushed.
Solution:
The gap of the paper feed roller should be determined according to the thickness of the corrugated cardboard, which is basically 0.5 mm lower than the thickness of the original paperboard. If the gap is too small, the corrugation is destroyed, and the physical strength of the corrugated box will be affected after the molding; if the gap is too large, the cardboard can not travel at a constant speed, resulting in no printing position; Pay attention to adjusting the gap between the printing roller and the platen roller during printing. At present, most of the corrugated box printing uses a flexo plate, and the printing method uses light pressure, which is not only kiss-type printing, but the pressure must not be too large. If the pressure is too high, the corrugation at the printing site will be crushed and the performance of the carton will be affected. Therefore, the adjustment of the gap between the plate roller and the platen roller is very important, and the printed portion of the hand is not significantly recessed.
Corrugated carton manufacturing process should not destroy corrugated, it is different from the general carton sales package, because the force formed by corrugated is multi-faceted, this corrugation is meaningless once the UV type is destroyed.
In summary, these printing problems are only the most common problems. Others, such as blurred printwriting, distortion, excessive print marks after printing (commonly known as printing and hanging dirty), stripes appearing in stripes, and the ink color is not ideal, and so on. However, in addition to objective factors, such as plate material, plate liner, ink, and even the quality of corrugated cardboard, it directly affects the printing effect of corrugated boxes. Therefore, high quality raw materials should be used to ensure the high quality of printing. In order to solve various problems in the printing process, it is also necessary to rely on practical workers with practical experience. First, they must have a certain level of theoretical knowledge. For example, it is necessary to understand the principles and technical procedures of printing equipment and manufacturing processes, and fully grasp the printing system. The relationship between the middle rubber roller, the transfer roller (alloy roller), the plate roller and the embossing roller, how to be proficient when a problem occurs, and the corresponding position can be quickly solved. Secondly, it is necessary to summarize in the actual operation, under what circumstances to adjust which parts, and the requirements are accurate, which is not easy for general operators. As an excellent driver, you must be good at finding problems and solve problems in time so that productivity can be improved. All in all, the printing problems are inseparable from the various conditions described above, and as long as the printing principle is fully understood, the printing problems will be solved.