How to crack the quality problem of wireless rubber binding books
Wireless glue binding is the most commonly used type of book binding process at present. The process is to use hot melt adhesive as adhesive, the process flow is the slotting of the page→ milling back→ slotting→ the last glue backing→ the upper side glue→ the second adhesive backing→ the upper cover→ primary molding→ secondary molding→ cooling→ three-sided cutting of books and periodicals, the process is relatively simple, the production efficiency is high, but the wireless glue binding process is very easy to cause quality problems such as exposed glue roots and loose pages due to raw materials or improper operation, affecting the beauty and use performance of the book. Therefore, we need to take effective measures to ensure the quality of wireless glue-bound books. In this article, the author analyzes the causes of exposed roots and loose pages and talks about the corresponding solutions.
Selection of hot melt adhesives and raw materials
First of all, the quality of hot melt adhesive and raw materials is the key, which is the basis for ensuring the quality of glue-bound books. The quality of the hot melt adhesive is related to the bonding fastness of the book pages, in addition to choosing the hot melt adhesive with stable quality and excellent comprehensive performance, it is also necessary to correctly choose the appropriate hot melt adhesive according to the performance of the paper.
The hot melt adhesive used in coated paper, offset paper and other ordinary papers is different, and cannot be used incorrectly or mixed. In addition, according to the performance of the hot melt adhesive, it should be operated in strict accordance with the temperature parameters provided by the supplier, and the use temperature should not be easily changed. The use temperature of hot melt adhesive should not be too high or too low, the temperature is too high, although the fluidity, wettability and permeability of the glue have increased, but the bonding strength will decrease, easy to produce bubbles, loosen the glue, and will also cause the glue to age easily and become brittle, affecting the tensile strength of the glue; On the contrary, if the temperature is too low, although the viscosity of the glue increases, it will reduce the fluidity of the glue, and the decrease in the wettability and permeability of the book core will also affect the adhesive strength of the glue, and even the phenomenon that the hot melt glue and the book core margin will not stick at all, resulting in the phenomenon of exposed glue roots and loose pages.
The treatment of the back of the book in the offset binding process
01
Milling back process requirements
Adjust the milling back amount as required, the milling back of the bookcase of tri-fold is 1~2mm, and the milling back of four-fold is 2~3mm. Ensure that the milling cutter is sharp, so that the pages with rings behind the book milling are all milled into a single page, and the back ridge is straight and flat from head to toe, clean and flat, and the front and back pages are milled in the same amount.
The height adjustment of the back milling cutter requires a gap of 0.2mm between the back milling cutter and the extrusion wheel, and the position of the back of the milling back is on the same plane as the cleat inside the bookclip, and the distance between the tip of the back milling cutter is 0.2mm. If the position of the milling back is deviated, the gap between the milling back cutter and the extrusion wheel is too large, and the milling cutter becomes dull and worn, there will be uneven milling back or unclean milling backing, and there will be paper scraps residual, and then the upper glue backing will be uneven, hollow, exposed rubber roots, and loose pages.
02
Grooving process requirements
The groove depth is 1~1.5mm, and the groove spacing is 5~7mm. After milling the back of the groove, the groove depth and groove spacing can reach the standard and symmetrical, the front and back pages are consistent, and the back of the book is clean and there is no paper lint residue.
Adjust the groove depth and groove distance according to the parameters to ensure that the grooving knife and groove backer are intact, and the groove of the groove backer is consistent with the shape of the grooving knife, so that all the grooving knives pass smoothly in one turn and the gap between the grooving knife and the groove is less than 0.2mm. The position of the slotted backer should be on the same plane as the cleat inside the bookcase, the paper brush is complete, and all the paper dust pulled down is removed by the brush. If the groove is worn or the position is off, it will cause the depth of the groove on the front and back pages to be inconsistent, and the paper wool will remain, causing the glue to not penetrate into the groove. In addition, the paper brush is also very important, but we often overlook that the brush can not only clean the paper hair in the notch, but also completely expose the fibers of different lengths after the paper is grooved, so that the glue can be fully contacted and penetrate into the groove to enhance the bonding fastness of the pages.
03
Adhesive gluing process requirements
Ensure the thickness and uniformity of the adhesive layer of the book backing adhesive, ensure that the glue filling in the groove is full and non-permeable, and the thickness of the adhesive layer is 0.8~1.2mm.
The thickness and uniformity of the adhesive layer on the back of the book are directly related to the fastness and quality of the book, and must be operated in a standardized manner. The adjustment of the gluing wheel is very important, not only to ensure that the glue fills the groove hole, meets the thickness requirements of the glue layer, but also does not penetrate too much into the page. First of all, ensure that the back of the book is in parallel contact with the rubber wheel, and secondly, adjust the height of the rubber wheel and the rubber stick correctly.
The first rubber wheel is called the rubber wheel, its main function is to fill the groove with glue, generally adjust the gap between the first rubber wheel and the book core to 0~0.5mm, so that the glue carried by the rubber wheel can be injected into the book slot with a large extrusion force, so as to fill the notch, and there will be no squeezing deformation of the back of the book. So according to the different paper, we adjust the height of the rubber wheel is also different, for coated paper and 80g paper we will adjust the gap a little smaller, generally adjusted to 0~0.2mm, for 60g softer paper, adjust the gap a little larger, generally adjusted to 0.2~0.5mm.
The second rubber wheel we call the rubber filling wheel, which is a supplement to the lack of gluing of the first rubber wheel, which can control the thickness of the glue film and make it uniform, and the generally adjusted gap is 0.5~1mm. The gap between the uniform glue stick of the first glue pot should not be too large, because there is also the rubber wheel of the second glue pot to supplement the book glue, so the general adjustment gap is 0.2~0.5mm. If the gap is too large, the tape of the first glue pot will be brought into the second glue pot, and there will be more and more glue in the second glue pot, and the main function of the rubber wheel of the second glue pot is to supplement the thickness of the book film.
04
Requirements for the process of gluing side gluing
The width of the side adhesive should be controlled at 5~7mm, and the thickness should generally be controlled within the range of 0.3~0.5mm. The side glue should not be too narrow or too thin, as it will easily expose the rubber roots; It should not be too wide or too thick, as there will be glue seepage.
05
Cover indentation process requirements
Four indentation lines are determined according to the thickness of the book, namely the wrap line and the flipbook line. It is required that there are two indentation lines in the middle of the cover, which should be consistent with the thickness of the book, and the distance between the two wrapping lines in the middle and the two flip lines on the outside is adjusted to 6~8mm. The flip line should be as heavy as possible, so as not to fracture or burst the cover, so as to avoid the phenomenon of exposing the rubber roots on the first or last page of the book core when opening the cover of the book. The error of the indentation line should be controlled to be less than 1mm.
06
Process requirements for sealing wheels
The upper sealing wheel is to paste the cover to the back of the book that has been glued for positioning, and when adjusting, first turn the adjustment handwheel counterclockwise to lower the upper sealing wheel, and the jogging machine turns a good glued book to the upper sealing wheel, at this time the cover is under the book, after the hot melt glue is cured, adjust the handwheel clockwise, so that the upper sealing wheel just touches the back of the book. At this time, pull out the cover with your hands, subject to a little force. The upper sealing wheel is too low, the cover bonding is unstable, and the cover positioning is inaccurate. On the contrary, if the upper sealing wheel is too high, the book core will be squeezed and deformed, resulting in quality problems such as high back, crooked back, and hollowness.
07
Molding process requirements
The forming table has two forces for book forming, support force and clamping force. The tablet is in full contact with the back of the book, and the tablet is in a horizontal state, and the head and foot of the back of the book are in full contact at the same time. The clamping force is slightly less than the thickness of the book by 1mm between the two forming knives, and the inner forming knife should be on the same plane as the inner splint when clamping, if it is not on the same plane, there may be a phenomenon of exposed rubber roots. The gap between the holding plate and the forming knife should be less than 0.2mm. The clamping force and support force of the second forming table can be a little greater than that of the first forming table. The books wrapped in this way will have a flat back and clear edges. If the support force of the forming table is too small, there will be a round back, hollow, and the glue layer is not full; On the contrary, if the support force is too large, there will be quality problems such as high backs, crooked backs, and post lines.
In addition to the above two main factors, the difference in weight between the cover paper and the core paper is also one of the reasons for the problem of exposed roots and loose pages, which should also be avoided as much as possible in decoration design.
There are many reasons for the problem of exposed rubber roots and loose pages, such as equipment accuracy, production environment temperature and humidity, processing speed, etc. These factors are both related and independent, and it is difficult to find a one-and-done way to completely solve this quality problem. In the process of operation, we can only analyze specific problems, think in multiple dimensions, and start from multiple aspects. Control all process links, conduct frequent random inspections, find problems, analyze problems, solve problems, and summarize experience in a timely manner.
With the craftsman spirit of "dedication, leanness, focus, and innovation", we focus on each component and every parameter, focus on each process, study and analyze the internal connection between various factors, innovate problem-solving methods, try to avoid the occurrence of quality problems such as exposed rubber roots and loose pages, improve the quality of book binding, and bring readers a pleasant reading experience.