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one. Excessive sheet folding when designing layout or imposition
When the pages are folded, the more the number of errors, the greater the error, and the greater the number of overlaps, the greater the possibility of wrinkling. This is due to the fact that the air in the overlapping signatures does not release the air resulting in wrinkling. . For a long period of time, up to four percent discounts have been stipulated, and air has been broken. However, in the past, the weight of the book block paper used was generally about 52 g/m2 letterpress paper or newsprint. Now, the book core paper is mainly composed of 65 g/m2 offset paper or 80 g/m2 bond paper. As the weight of the book block paper is increased and the thickness is increased, if the four-fold or three-fold reduction is still carried out according to the original regulations when using thin paper, problems will certainly arise. In this regard, the departments engaged in the design of publishing houses and printing houses must pay attention and can no longer operate according to the old regulations, nor should they think that the number of people involved in the dismantling is more than that. In fact, this does not take into account the quality of the processed products. Because there is no quality, there is no output. The relationship between quantity and quality must be made clear. This will never change.
Based on these circumstances and the fact that the weight of paper has increased, the revised national industry standard CY/T27-1999.3 clearly states in 3.1.2 that 59g/m2 or less of paper should be folded at a maximum of 40%; 60-8Og/m2 Up to 30% off paper; up to 20% off paper above 81g/m2. This provision guarantees that the pages of the bound book will be free from or less wrinkled. However, according to the understanding of printing factories across the country, many units still do not pay attention to this issue, and some are blindly pursuing production and are not implementing national industry standards. As a result, books are bound more folds, dead folds, and products are not. The serious consequences of the pass.
two. Manual folding is not broken
CY/T27-1999. 3 of 3. 1. 1 It is also stipulated that tri-fold (referring to paper of more than 60g/m2) and signatures of more than 30% should be marked to exclude air. This is also to ensure that the folds are not wrinkled. Books that have been folded by four packs (59g/m2 and below) or tri-folded by hand (60-80g/m2 sheets) should be cracked at the penultimate fold of the signature to eliminate air in the signature. But to prevent wrinkles from appearing, there are now many units who know that they should break when they fold the pages manually. However, blindly pursuing output is not to break. Finally, after the books are bound, the folds are extremely serious and cannot be remedied. This practice is extremely undesirable. The factory should seriously implement the national standard and it should not be ignored.
three. Machine folding is not equipped with a broken knife
The folded folding roller of the folding machine is now equipped with a book-folding slit breaking knife device, which breaks the fold of the signature into a regular pattern through the transmission of the sheet and the rotation of the folding roller. The small mouth, in order to discharge the air inside the book, to prevent the book from processing due to stress caused by dead folds. However, it is understood that there are a large number of folding machines in factories across the country. When using a folding machine, because of fear of inaccurate cutting of the broken knife (not accurately marked on the crease line), the broken knife device will be unloaded. If you don't use it, this is extremely bad. Breaking the knife is not allowed to adjust and master the technical problem of the folding machine. It is not necessary to remove the breaking device because the technology is not convenient. As a result, all the signatures inevitably appear to be wrinkled. The technical management department of the factory must take this phenomenon seriously, otherwise it cannot guarantee the product quality of the unit.
Now commonly used H660-type four-fold bar-knife hybrid folding machine, in the third fold no break device (folio four fold) should be modified to solve the four-fold book without a broken knife caused There are wrinkled quality problems.
four. Humidity affects sheet creases
Paper contains a certain amount of moisture, which can ensure the flexibility and peace of the paper. Approximately 7% of the water content is reasonable, and if this is exceeded, the paper may become brittle, damp or deformed. Now that the quality of book paper is getting better, the grammage is getting higher and higher. If the production shop does not pay attention to the specification of humidity, it will cause serious losses. There are now more than 100,000 bookbinding factories in China, and the conditions are good (only about 1/10). The temperature and relative temperature of the production workshop can also be guaranteed (generally about 50%), but the conditions are not guaranteed. Some processing plants do not pay attention to scientific management, and pile up book pages, signatures and semi-manufactured book blocks. Some pile up on the wall, some on the ground (without paper table), and some rely on the heating. Once these paper products are wet or dry, the moisture inside the paper is destroyed and the pages are deformed. The pages are often flat, and the whole book core appears to have a hill-like wrinkle after being bound. The publishing house is dissatisfied with this. These are all due to management problems. Therefore, management personnel must take seriously, strengthen scientific process management, re-arrange facilities, rational layout, ensure the reasonable temperature and relative humidity in the workshop, and prevent the paper from being damaged.
Fives. Improper process processing
In addition to the above reasons, it is also important that the process is reasonable. Bound books or volumes are bound to be adhesives. Nowadays binding binders are more water-soluble. These binders contain a lot of water inside, especially cold glue, which are almost all water-soluble. Water smears on the paper and has a certain effect on the paper. Some pages are wrinkled and deformed after being glued, so the viscosity of the glue must be reasonable and appropriate. Some factories use binders that are not sufficiently cooked to make up for them with multiple amounts of water, causing the pages to become soaked with water that the paper is distorted and wrinkled. Under normal circumstances, the adhesive should be used in the most appropriate low limit, the amount is less and both are accurate, so as to ensure that the book is firmly bonded, but also can make the book less water and ensure the flatness of the book . Which type of adhesive should be used should also be taken care not to be used indiscriminately. Because many types of adhesives are available today, some are suitable and some are not applicable, and the selection must be based on the texture of the adherend and the required viscosity.
Why book pages appear after bookbinding?
After the binding of books, the crumpling of the quality of the characters has become a problem that has become extremely common in various printing and packaging plants. It has become a difficult problem in bookbinding and processing, and has rigorously affected the overall quality of books, especially in recent years, reflecting even more serious problems. Relevant departments have also studied and created favorable conditions for many times, but so far it has not been well resolved due to various reasons. Let's talk about the causes and solutions of the wrinkles and hilly wrinkles that appear after the books are bound.