Causes and solutions for uneven trimming or fluffing of book printing
1. Influence of die cutter
In the processing process, with the increase of die-cutting time and the number of products, the die-cutting knife will gradually become not sharp enough. When the paper is not completely cut, the indentation will pull the paper and tear the paper apart to produce paper wool; When the steel knife is loose, it will also produce paper wool and paper dust on the cutting edge. When selecting a die-cutting knife, try to select a high-quality die-cutting knife, so that the blade is lubricated and easy to cut, reduce the paper wool generated during die-cutting and improve the durability of the knife line.
2. Influence of indentation steel wire or bottom formwork
The tension generated during indentation is an important factor leading to die-cutting fuzzing. Indentation steel wire and bottom die are the direct influencing factors of indentation tension. Therefore, the printers who provide printing service China need to improve the trimming fuzzing, on the one hand, the indentation tension can be reduced by reducing the height of the steel wire.On the other hand, the thickness of the bottom formwork can also be appropriately reduced without changing the height of the steel wire.
3. Influence of die-cutting adhesive strip
Die cutting adhesive strips play the role of elastic pressing paper in molding processing. On the one hand, they make the paper separate smoothly; On the other hand, the paper is pressed to reduce the impact of indentation on paper tension on die-cutting. In practical application, the adhesive strips with different hardness should be selected according to the different direction of paper fiber. Generally, the adhesive strips perpendicular to the paper fiber are harder than those parallel to the paper fiber, which plays a certain role in avoiding edge cutting and fuzzing. The die-cutting adhesive strip is generally pasted on both sides of the die-cutting knife, and the distance from the steel knife should be 2m (the minimum distance should not be less than 15mm). If the distance is too close, the adhesive strip will produce a lateral component when pressed, which is easy to damage the connection point of the paper or make the cutting edge hairy, affecting the die-cutting effect.
4. Influence of bottom formwork steel plate
Because the die-cutting processing of the product adopts the die-cutting method of "hard cutting", that is, by applying a certain pressure to make the die-cutting knife cut the paper directly on the steel base plate, over time, deeper and deeper knife grooves will appear on the steel base plate, resulting in the cutting edge of the die-cut product is not smooth or hairy. Even if the new knife is replaced, the problem of rough or hairy cutting edge is slightly improved, but it is difficult to eliminate. The printers who provide China printing service if want to solve such problems, the steel base plate must be polished and leveled before use, and the steel base plate shall be replaced if necessary. In addition, if the bottom die steel plate is not fixed firmly, or the middle bulge is not horizontal with the surrounding edges, it will lead to uneven stress of the steel plate and premature formation of knife groove and burr, which is more common in hand flattening and die-cutting.
5. Impact of paper
In the processing process, the paper itself also has a certain impact on die-cutting fuzzing. For paper with longer fiber, there is less chance of paper wool during die-cutting; For the paper with short fiber, it is easier to produce paper wool during die cutting. Therefore, in actual operation, the height of indentation steel wire should be appropriately reduced according to the characteristics of short paper fiber and brittle paper. In addition, for some coated cardboard (such as gold and silver cardboard, glass cardboard, etc.) used to enhance the appearance effect of packaging, it is easier to produce fuzzing during die-cutting. Good results can be achieved by using a straight grain high-edge knife with coating; At the same time, it can also be considered to separate the die-cutting indentation and concave convex embossing processing, so as to avoid the influence of concave convex embossing force on die-cutting, so as to reduce the probability of edge fuzzing.
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