How to distinguish between paste and drag in gravure
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Gravure often encounters paste and dragging faults. The two faults show different phenomena, the causes and solutions are different, but many people, including some articles published in printing professional magazines, put this The two types of faults are confused, which makes it easy to mislead people who have just touched the gravure.
1, the phenomenon is different
Dragging is a gradual change from a certain part of the graphic, gradually disappearing, shaped like an animal, often referred to as tailing.
The paste version is different. It is a graphic in which the edge of the graphic overflows substantially the width of the graphic, the ink color is lighter than the graphic, and the shape is indefinite.
2, the reasons for the difference
The cause of the drag is the presence of impurities between the blade and the plate and extends to the back of the blade. When the scraper scrapes through the graphic part of the printing plate, the impurities are in contact with the ink, and when the scraping blade scrapes out the force producing part, the impurity lags behind the blade and contacts the printing plate to drag the graphic.
The paste plate is mainly due to the arc-shaped contact between the scraper and the printing plate, that is to say, the knife is tight and the air pressure is also large. When the scraper scrapes through the graphic part of the printing plate, the long-pressed blade has a tendency to straighten, which is in the elastic range. Internal is allowed. When the scraper moves out of the graphic part, the blade touches the shoulder of the net, and it will rebound like the ball hits the wall. Therefore, when the blade moves out of the graphic part of the printing plate, the part of the scraper that comes into contact with the graphic will be sideways. The plate is scraped clean, and under the action of the printing pressure, the ink will overflow the graphic part, resulting in a paste.
3, the solution is different
In the production, you encounter the problem of dragging the picture and text, usually just scrape it with bamboo chopsticks.
In case of a paste problem, it needs to be solved by loosening the knife and reducing the air pressure.
4, the common point of the two faults
When the viscosity of the ink is relatively low, both drag and paste failure are easy to occur. Therefore, appropriately increasing the viscosity of the ink plays a significant role in preventing the occurrence of the above two types of failures.
Rotary printing press changing die cutting machine
A rotary stencil printing machine in the printing factory can be converted into a die-cutting machine. The modified die-cutting machine has accurate overprinting, uniform pressure, fast die-cutting speed, simple operation and low labor intensity. It can be used for die-cutting of 450g/m square. Printed. The machine can also be used to press the concave protrusion, which also has the advantages of accurate overprinting, high pressure and high speed.
The specific modification steps are as follows:
First, the ink fountain assembly is removed as a whole. In order to ensure the safety of the modified equipment, another glass cover can be used to cover the plate. The shield should be designed to be openable for easy loading and other operations.
The impression cylinder was then removed and wrapped in stainless steel with a thickness of about 0.50 mm. Depending on the thickness of the print, the PS plate, polyester base or paper can be padded under the steel to ensure that the total thickness of the press liner is not more than 1.20 mm.
Then, with the die-cutting plate, a circular flat die-cutting machine was successfully modified.
Corrugation and molding quality of corrugated boxes
In the production of corrugated boxes, in addition to some high requirements for molding quality, to the high-speed automatic packaging production line outside the carton, the basics are to cut, indentation, open the corner, molding, nail box process route. The indentation plays a key role in the forming quality of the corrugated box.
The role of the indentation is to enable the corrugated board to be folded into a box as designed. Corrugated cardboard has different structure from ordinary care cardboard. Therefore, in order to ensure the trace line after indentation is clear and does not damage the cardboard, it is easy to fold and form, and the corners are sharp after folding. The twist line is straight and the box is regular, whether it is in the indentation knife. The arrangement of the line is still very particular about the selection of the indentation line. Especially for thick corrugated board, indentation quality, box size and indentation position have a great relationship.
For vertical, for the makeup, when the indentation line falls on the peak or valley of the corrugated core paper, the quality of the indentation is generally better, and the forming size of the carton is also easily guaranteed. However, if the indentation line falls between the peak and the valley, that is, at the half waist, the quality of the indentation is difficult to ensure, and the forming size of the carton tends to be deviated.