Adhesive Quality Problems (2)

2. Milling back, improper slotting cause quality problems.

1 milling back process is an important part of quality control glue binding process. Only when the book is affixed to the “ridge” of the fold line, the hot melt glue penetrates into each page to ensure that no loose pages, page breaks, etc. will occur. From this point of view, it seems that the more milling back capacity, the better the insurance coverage quality is, and it is not. Because once the milling back load is too high, on the one hand it will increase the resistance to the milling back knife and slotting knife, which will make the knife edge dull, which will lead to the back deformation and milling back, so that the back of the book “eats glue” and affects the adhesive fastness. On the other hand, milling too much back and easy to mill the book stickers mouth position. Therefore, under the condition that the back of the book is required to be as tidy as possible, the amount of back-to-back milling should be based on the principle of being able to mill the off-page book.

2 Should the back of the book be milled, whether the inclination of the milling cutter bowl is adjusted well and whether the milling back knife is directly affected whether the milling back is smooth or not, and the milling back unevenness will directly affect the quality of the book, such as slanting back, empty back and so on.

3 Improper adjustment of groove depth, width, and spacing will affect the contact area between the adhesive and the page, reduce the bond strength, and cause loose pages and page breaks.

4 The paper shavings produced by milling back and slotting are not thoroughly cleaned. As the paper dander on the back of the book and in the groove hinders the penetration and infiltration of the glue, some of the books are not firmly bonded and the book block breaks. Leaflet.

Third, the package cover process quality problems

1. The gap between the glue stick and the back of the book should be adjusted properly. Under normal circumstances, the gap between the glue stick and the back of the book is 1 to 1.5 mm, so that the adhesive layer in the back of the book and the groove can be uniformly coated to avoid occurrence of phenomena such as empty back and loose leaf.

2. Sizing thickness is generally required between 0.8 ~ 1.5mm. Whether or not the glue book can be bonded firmly depends on whether the hot melt glue adheres firmly to the back paper fibers. If the hot melt adhesive does not bond well to the paper, the thicker adhesive layer will not work. Many companies are pursuing low-priced hot-melt adhesives on the one hand and over-sizing on the other, which can neither guarantee the quality of glued books or waste of resources. In fact, the use of good quality hot melt adhesives, adhesive layer does not need to be too thick, the cost of hot melt adhesives spread in a single book may be lower. 0.8 ~ 1.5mm thickness of the glue layer can fully meet the requirements of 15mm thickness glue book, and does not appear book back broken and so on. Of course, for books over 15mm in thickness, it is necessary to appropriately increase the thickness of the sizing, but it is better to use staple gluing or sub-enveloping, otherwise it is easy to have quality problems.

3. The width of the side glue should be in the range of 3.0 to 7.0 mm. If the side glue is too narrow, the cover is not bonded tightly, and the side glue is too wide, it will cause wild glue or sticking images (this is a serious quality problem). Should always check whether the side rubber wheel is working properly, absolutely no unevenness of the side glue, or even serious quality problems with no side glue.

4. The back of the book should be straight and without wrinkles. Whether the book is straight or not, whether there is an arc-shaped book back, one end is flat and one end is arched, the back of the book is wrinkled, and the post line is not good. The key lies in whether the book block is pressed, flattened, enclosed and horizontally clamped. The pressure and adjustment status are appropriate, whether the position of the cover indentation line is correct, and whether the pressure of the book clip is normal (for different thicknesses of the book block, the pressure of the book holder needs to be adjusted), and other aspects need to be standardized. In addition, at present, the arc-shaped skateboard from the book end of the disc machine is relatively easy to be deformed when the book is relatively thick. Therefore, it is necessary to pick up the book by hand during the process of dropping the book, and then gently place it on the conveyor belt so as not to deform the back of the book.

5. Adhesive viscosity should be appropriate, the right time hot melt adhesive. At present, in the quality inspection, it is often found that the side glue has been coated but not on the cover. This is because the ambient temperature is too low (especially in winter), the working temperature of the side glue is too low, and the cover is too thick. Or edge plastic curing time is not suitable due to other reasons. To make the hot melt adhesive not spill onto the cover or book back, the key is to need a larger cover. Now many publishers or users design cover shorter than the length of the book block. When the cover is wrapped, it often causes the back of the book or the cover to be glued. This requires the operator to clear the overflowing hot melt adhesive and glue thread frequently to ensure the back of the book. The cover is tidy.

The quality problem of bookbinding is not just a binding issue. It involves all aspects. To improve the quality of bookbinding, it is necessary not only to solve the problem of the production and use of hot melt adhesives, but also to solve its own technical level. The production personnel, processes, equipment and environment are all hands-on, solving problems effectively and efficiently.