Paper Gift Bags With Flat Paper Handles. Paper Gift Bags With Flat Paper Handles

Paper Gift Bags With Flat Paper Handles. Paper gift bags with flat paper handles

 

Printing and Packaging Principle - Process - Technology: How to determine the mouth edge when loading plate? How to determine the width of the mouth of the plate when loading? What is a print positioning system... The following to introduce to you the packaging offset printing in the common problems and solutions. The following content is organized by Xiaobian, to provide your reference.

 

Packaging offset printing common problems and solutions

 

When loading, how to determine the mouth edge?

 

Which side of the original version is chosen as the mouth edge should be considered from the needs of printing and post-press processing.

 

(1) Considering the specifications and positioning accuracy of the printing press, the long side of the original rectangular version should be used as the mouth edge.

 

(2) From the perspective of overprinting accuracy, due to the small deformation of the paper on the mouth side, the large deformation of the paper on the drag edge, so the side with high overprinting requirements on the original should be used as the mouth side.

 

(3) From the perspective of saving paper, because the position of 1cm wide mouth edge is not printed, sometimes the paper format is very tight, we need to make full use of this part of the white edge, so we should use the white edge of the finished product or the paper tongue edge of the paste box as the mouth edge.

 

(4) From the point of view of post-press processing, the choice of mouth edge should be conducive to die cutting processing.

 

How to determine the width of the mouth of the plate when loading?

When loading, the distance between the original image and the mouth of the printing plate is required within a certain range. Set the distance between the image on the original edition and the edge of the printing plate as c, the distance between the image on the original edition and the edge of the paper as a, and the distance between the edge of the paper and the edge of the printing plate as b, then c=a+b. The size of b is determined by the position of the plate drum relative to the impression drum and the amount of paper in the teeth of the front gauge. The influence of the adjustment of the front gauge on b is very small. Different machines have different adjustment amount of the plate drum relative to the impression drum, which is generally about 5cm.

 

The good printing plate, that is, c has been determined, adjust the size of b, can change the printing image on the paper before and after the position, commonly known as "borrow roller". But if printing needs to rely on "borrow drum" to adjust the position of the image on the paper, obviously will affect the production efficiency. a more reasonable approach is to select a roughly medium b0 value for a certain type of printing press. If you want the image to be printed on the paper with a distance from the mouth edge, then determine the distance c from the image to the mouth edge of the printing plate according to c=a ten b0. Each time in this way to determine the printing plate when the original relative to the plate mouth edge position, printing does not need to "borrow drum". If there is a corner line on the original version, it is usually the corner line as a reference to determine the original distance from the printing plate mouth edge.

 

What is a print positioning system?

 

From the original manuscript to print, to go through color separation, Mosaic, copy. Printing, printing and other production processes. In order to ensure that the color separation image in each process of production can be the fastest way to achieve the accuracy of overprinting, can use the positioning pin and positioning hole coordination, through a series of operations to achieve the purpose, this system is called printing positioning system. As the desktop system is now widely used for layout production, it can automatically output and overprint accurate color separation negatives, so the positioning system is mainly used in the process of printing and printing.

 

What does the positioning system consist of?

 

Positioning system mainly by the plate. Composed of a negative punch, a locating pin and a locating pin on a plate cylinder.

 

What are the benefits of using a positioning system?

① greatly shorten the loading and adjustment of the time. If you can reasonably arrange the position of the original relative to the printing plate. And the correct use of positioning system, so the printing press between different color groups basically do not need to adjust the plate can achieve the purpose of alignment, so that the production efficiency is greatly improved.

 

(2) The printing plate no longer needs to be pulled repeatedly, which reduces the misprinting caused by the tensile deformation of the printing plate and improves the printing quality of the product.

 

How to use the positioning system correctly?

At present, multi-color printing and positioning system is adopted in China. The correct use method is as follows:

 

(1) Cut the polyester sheet base, the width should be less than the distance between the original image on the edge of the mouth and the edge of the printing plate, and punch holes for the polyester sheet base.

 

(2) The perforated edge of the polyester sheet base is used as the reference of the mouth edge of the printing plate, and the circular hole in the middle of the polyester sheet base is used as the center line of the printing plate. The negative of the first color plate is fixed on the plate base. Note that the film base should be attached to the non-drug film surface of the negative.

 

③ The fixed number of the first color plate of polyester film base on the positioning pin, the second color plate and the first color plate of the negative. At the same time, the second polyester film base is set on the positioning pin, in the case of the second and first color plate plate, the second color plate plate and the second polyester film base is fixed together. Process the rest of the plate in the same way as the second plate.

 

④ Punch holes for each plate to be printed, align the negatives of various color plates and the positioning holes of printing plates with positioning pins, and then print.

 

⑤ When installing the plate, first of all, the plate drum in the mouth of the plate clip back to the same base position, the two U-shaped holes on the plate hanging on the positioning pin, so that the U-shaped hole and the positioning pin close. Then tighten the version of the edge of the drag, and then tighten the version of the edge of the mouth.

 

What are the requirements of exposure light source for PS version?

 

The spectrum of the light source of the printing machine should be consistent with the photosensitive spectrum of the photosensitive agent of the PS version. The photosensitive spectrum of PS version is about 350-450nm, requiring the light source to have high energy peak in this wavelength segment, in order to shorten the exposure time, and achieve good exposure effect.

 

The illuminance of the light source should be uniform. The illuminance meter can detect the illuminance of the middle and surrounding points of the printing platform, and the illuminance of the points of the layout is less than 1 5%.

 

③ The power of the light source should be about 3000W, and the voltage fluctuation should be less than 10%. Before exposure, the light source should be preheated to ensure stable light intensity during exposure.

 

How to determine the exposure time of PS version?

The exposure time of PS plate mainly depends on the photosensitive range of PS plate. Sensitivity and spectral characteristics of light source, strength of light source and other factors. Therefore, every time you change different brands of PS version or replace the light source, you need to use the measurement and control strip to PS version for a series of tests, in order to determine the correct exposure time.

 

The test method is as follows: Select a transmission gray ladder scale with a continuous density difference of 0.15 and Brunard or other similar test strips with positive small dots and thin lines. Use the two test strips to gradually increase the exposure time on the PS plate for exposure, record the corresponding exposure time of each piece, observe with a magnifying glass after development, and check each test strip. The exposure time corresponding to the test bar that meets the conditions can be used as the normal printing time. When sunning ordinary mesh products, the first 4 levels of the grey ladder scale are required to be sunned; 6% of the dot out, 2% of the dot out; Fine lines 11μm wide are retained, and fine lines 8μm wide are sun-dried.

 

How to adjust the exposure time of PS version according to specific conditions?

① No dot, only thicker text. Lines and field of the original, can increase the exposure time, the small dirty points and dirty marks out of the sun, to reduce the time to remove dirty.

 

(2) negatives are stored for too long, the blank part is yellow, or after manual plate, there are two or three layers of blank film base superimposed together, can slightly increase the exposure time; Part of the field density is not high enough to reduce the exposure time of the original.

 

③ The pressure of the press is less than that of the printing press, so the increase of the proofing dot is less than the increase of the printing dot, so the exposure time of the proofing plate should be less than the exposure time of the printing plate. Drying proofing version generally do 0.5% of the dot out, 1% of the dot retained.

 

Strictly speaking, for the level of manuscript color separation plate. The difference in dot growth in various cases should be taken into account and compensated when determining the step replication curve. In fact, the standardization of this process in China is not very good, so it should be based on the production conditions of their printing plants. Adjust the exposure time. If the factory printing in the process of network increase rate. Can increase exposure time. According to the different substrate to be printed, the exposure time of printing offset paper plate should be longer than that of printing coated paper plate.

 

Why do you need to pump air when printing and exposing?

Take the production of positive PS version as an example, when printing, the film surface of the negative if there is no PS version of the sensitive coating close. There is a gap in the middle, and the light will be slanted from the blank part of the negative to the photosensitive coating just below the picture and text part, resulting in the light decomposition of the picture and text part of the edge. Bleach the image. Dots get smaller, small dots and thin lines are lost.

 

Because one side of the print frame is transparent glass, the other side is a rubber pad. When the vacuum pump will print the air out of the frame, the air pressure inside is low, the rubber pad in the external atmospheric pressure, will PS version. The original negatives were pressed together against the glass.