Offset printing is currently the main printing method for printing companies. However, due to the failure of the paper-feeding system, offset printing is inaccurate, the ink color is uneven, and even the printing cannot be carried out. This is the main reason for the delay in delivery. This is one of the more thorny issues that printers most often encounter.
One, two or more sheets of paper failure 1, paper is not flat, the edge of upturned. When the airflow blown by the paper blowing nozzle touches the edge of the paper, the edge of the paper curls up into a circular arc angle, and the air blowing is divided into two parts. A portion of the airflow lifts the paper upwards, while the other portion of the airflow pushes the paper down so that the paper cannot be separated and the baffle brush loses its effect, resulting in double or multiple sheets, or even large stacks entering the paperboard. The general approach is to remove the paper and perform an anti-knock paper process to make the paper flat and conducive to separation.
2. The loading height exceeds the allowable height of paper teeth. According to previous printing experience, the height of general paper loading should be less than about 5mm. If the adjustment is not appropriate and exceeds the allowable range, two or more sheets of incoming cardboard will be produced. The usual method of handling is to use a cork wedge to control so that the paper stays on the same plane. If there is a regulator model, you can use the regulator to reduce the height of the paper to solve.
3, hair pressure and stop paper brush too little into the paper edge. According to the previous operation experience, the general blocking brush extends into the edge of the paper about 8mm, and the blowing foot extends into the edge of the paper about 10mm~15mm. If it is improperly adjusted or the cutting of the paper is uneven, double or multiple sheets may appear. Zhang. Generally, the whole of the feeder will be adjusted to make the separation nozzle approximately 5mm away from the edge of the paper. Adjust the blocking brush and the presser foot to solve the problem.
4. When the paper is too thin, the air volume is adjusted improperly. When printing 70g/m2 thin paper, if the air volume is not properly adjusted, it is easy to produce double or multiple sheets. The general processing method has the following points: (1) Adjust the blowing foot downwards, increase the distance between the paper stack and the paper suction nozzle; (2) Adjust the air volume appropriately; (3) Reduce the paper suction nozzle The rubber band or transparent glue is used to reduce the wind force; (4) Press the baffle downwards and increase the pressure to control it.
5. The paper is not loose or sticky. Generally when the paper is cut, the cutting edge is bonded, or when the full version of the semi-finished product is printed on the ground, water stains and ink stains cause sticking, thereby forming two or more sheets. Therefore, before the paper is printed, that is, when the paper is loaded into the unit, it must be shaken and shuffled, and the semi-finished products must be stacked and fluffed loosely. When the machine is on the machine, it should be installed less to avoid adhesion due to heavy pressure. .
6, blow pressure foot wear. When the presser foot is used for a period of time, it will wear out. When it presses down on the paper, the paper will make an oblique angle, the force will change direction, the paper will move forward, and the paper brush will lose. The role of the paper suction nozzle down when the suction paper suction on the edge of the paper, and the formation of double or multiple. Generally, new hair pressure presser foot treatment is adopted. If the wear is not serious enough, welding copper sheets can be used, and then the boring tool can be used to solve the problem.
Second, the uneven product color ink products Inhomogeneous ink causes are: (1) water transfer, transfer ink, even ink and ink by the version of the cylindricity of the rubber roller wear poor, wear bearing shaft wear, rubber roller skin Aging, decline in the ability to transfer ink, etc.; (2) string water roll layer peeling, cylindricity wear is poor, the surface has a thin layer of ink, two parts of the ink grow out part of the ribbon, resulting in roller uneven beat ink; ( 3) Support the locks of the printing water and ink roller, and the swinging bracket is worn badly, causing the roller to jump when the plate is pressed, causing the pressure of the plate to be unstable, resulting in unbalanced ink and ink, uneven ink, dry printing, ink bars, and old ink. Version (relying on the pressure of the platen roller) and other phenomena; (4) aging or poor quality of the water roller pile causes the water transfer capacity to decline; (5) there is no regular check of the pressure of the ink roller and the plate cylinder and the printing ink roller; (6) If the roller drive gear wears out badly, a regular “gear roller†with the same spacing as the gear appears.
Third, overprint failure 1, the impact of printing plate deformation on overprint. The metal plate has a certain degree of extensibility. Under the action of the tensile force, it will cause the deformation of the extension, and the tensile deformation of the zinc plate will be more obvious. Under normal circumstances, we found that overprinting was inaccurate when printing. Most of them were adjusted by printing plates. The greater the tensile force, the greater the tensile deformation of the layout, and the uneven distribution of the tensile deformation, the greatest force is exerted on the crotch edge and the crest side of the plate. The tensile deformation is also large, the internal force is small, and the tensile deformation is also small. small. Therefore try to use as little as possible to solve the problem of overprinting.
2. The effect of the increase or decrease of cylinder liner on overprint. In the printing process, due to the paper stretching caused by inaccurate overprint, the method of increasing or decreasing the thickness of the drum liner can be used to solve the problem of misalignment between the radial paths. The increase or decrease of the printing plate liner affects the plate's tensile deformation. The thicker the printing plate gasket is, the larger the size of the printing plate is. When the pad of the printing plate is reduced and the pad of the rubber roller is increased, the tensile deformation of the looming gray fabric increases, and the radial deformation of the pattern increases. Another is to reduce the thickness of the blanket cylinder, while increasing the thickness of the printing plate liner, the deformation of the blanket extrusion deformation is reduced, the latter commonly used.
3, blanket stretchability of the graphics overprint. The blanket is stretchable, and the tighter the blanket is stretched on the drum, the smaller the elongation is, and the pattern change is small. (1) Choose a blanket with a small elongation. (2) In the process of overprinting, try to keep the tightness of the blanket unchanged.
Overprinting is not allowed. In addition to the above-mentioned reasons, it is also necessary to pay attention to mechanical, adjustment, and paper issues. In short, overprinting is not always done at the instant of high-speed printing, and is caused by a slight accumulation of changes. It is difficult to observe directly. Therefore, as long as we pay adequate attention to printing, analyze the reasons, and take the most appropriate measures, we can avoid or reduce the occurrence of overprint errors. ("China Packaging News")
One, two or more sheets of paper failure 1, paper is not flat, the edge of upturned. When the airflow blown by the paper blowing nozzle touches the edge of the paper, the edge of the paper curls up into a circular arc angle, and the air blowing is divided into two parts. A portion of the airflow lifts the paper upwards, while the other portion of the airflow pushes the paper down so that the paper cannot be separated and the baffle brush loses its effect, resulting in double or multiple sheets, or even large stacks entering the paperboard. The general approach is to remove the paper and perform an anti-knock paper process to make the paper flat and conducive to separation.
2. The loading height exceeds the allowable height of paper teeth. According to previous printing experience, the height of general paper loading should be less than about 5mm. If the adjustment is not appropriate and exceeds the allowable range, two or more sheets of incoming cardboard will be produced. The usual method of handling is to use a cork wedge to control so that the paper stays on the same plane. If there is a regulator model, you can use the regulator to reduce the height of the paper to solve.
3, hair pressure and stop paper brush too little into the paper edge. According to the previous operation experience, the general blocking brush extends into the edge of the paper about 8mm, and the blowing foot extends into the edge of the paper about 10mm~15mm. If it is improperly adjusted or the cutting of the paper is uneven, double or multiple sheets may appear. Zhang. Generally, the whole of the feeder will be adjusted to make the separation nozzle approximately 5mm away from the edge of the paper. Adjust the blocking brush and the presser foot to solve the problem.
4. When the paper is too thin, the air volume is adjusted improperly. When printing 70g/m2 thin paper, if the air volume is not properly adjusted, it is easy to produce double or multiple sheets. The general processing method has the following points: (1) Adjust the blowing foot downwards, increase the distance between the paper stack and the paper suction nozzle; (2) Adjust the air volume appropriately; (3) Reduce the paper suction nozzle The rubber band or transparent glue is used to reduce the wind force; (4) Press the baffle downwards and increase the pressure to control it.
5. The paper is not loose or sticky. Generally when the paper is cut, the cutting edge is bonded, or when the full version of the semi-finished product is printed on the ground, water stains and ink stains cause sticking, thereby forming two or more sheets. Therefore, before the paper is printed, that is, when the paper is loaded into the unit, it must be shaken and shuffled, and the semi-finished products must be stacked and fluffed loosely. When the machine is on the machine, it should be installed less to avoid adhesion due to heavy pressure. .
6, blow pressure foot wear. When the presser foot is used for a period of time, it will wear out. When it presses down on the paper, the paper will make an oblique angle, the force will change direction, the paper will move forward, and the paper brush will lose. The role of the paper suction nozzle down when the suction paper suction on the edge of the paper, and the formation of double or multiple. Generally, new hair pressure presser foot treatment is adopted. If the wear is not serious enough, welding copper sheets can be used, and then the boring tool can be used to solve the problem.
Second, the uneven product color ink products Inhomogeneous ink causes are: (1) water transfer, transfer ink, even ink and ink by the version of the cylindricity of the rubber roller wear poor, wear bearing shaft wear, rubber roller skin Aging, decline in the ability to transfer ink, etc.; (2) string water roll layer peeling, cylindricity wear is poor, the surface has a thin layer of ink, two parts of the ink grow out part of the ribbon, resulting in roller uneven beat ink; ( 3) Support the locks of the printing water and ink roller, and the swinging bracket is worn badly, causing the roller to jump when the plate is pressed, causing the pressure of the plate to be unstable, resulting in unbalanced ink and ink, uneven ink, dry printing, ink bars, and old ink. Version (relying on the pressure of the platen roller) and other phenomena; (4) aging or poor quality of the water roller pile causes the water transfer capacity to decline; (5) there is no regular check of the pressure of the ink roller and the plate cylinder and the printing ink roller; (6) If the roller drive gear wears out badly, a regular “gear roller†with the same spacing as the gear appears.
Third, overprint failure 1, the impact of printing plate deformation on overprint. The metal plate has a certain degree of extensibility. Under the action of the tensile force, it will cause the deformation of the extension, and the tensile deformation of the zinc plate will be more obvious. Under normal circumstances, we found that overprinting was inaccurate when printing. Most of them were adjusted by printing plates. The greater the tensile force, the greater the tensile deformation of the layout, and the uneven distribution of the tensile deformation, the greatest force is exerted on the crotch edge and the crest side of the plate. The tensile deformation is also large, the internal force is small, and the tensile deformation is also small. small. Therefore try to use as little as possible to solve the problem of overprinting.
2. The effect of the increase or decrease of cylinder liner on overprint. In the printing process, due to the paper stretching caused by inaccurate overprint, the method of increasing or decreasing the thickness of the drum liner can be used to solve the problem of misalignment between the radial paths. The increase or decrease of the printing plate liner affects the plate's tensile deformation. The thicker the printing plate gasket is, the larger the size of the printing plate is. When the pad of the printing plate is reduced and the pad of the rubber roller is increased, the tensile deformation of the looming gray fabric increases, and the radial deformation of the pattern increases. Another is to reduce the thickness of the blanket cylinder, while increasing the thickness of the printing plate liner, the deformation of the blanket extrusion deformation is reduced, the latter commonly used.
3, blanket stretchability of the graphics overprint. The blanket is stretchable, and the tighter the blanket is stretched on the drum, the smaller the elongation is, and the pattern change is small. (1) Choose a blanket with a small elongation. (2) In the process of overprinting, try to keep the tightness of the blanket unchanged.
Overprinting is not allowed. In addition to the above-mentioned reasons, it is also necessary to pay attention to mechanical, adjustment, and paper issues. In short, overprinting is not always done at the instant of high-speed printing, and is caused by a slight accumulation of changes. It is difficult to observe directly. Therefore, as long as we pay adequate attention to printing, analyze the reasons, and take the most appropriate measures, we can avoid or reduce the occurrence of overprint errors. ("China Packaging News")
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