In the publishing and printing process of books, quality control is a very important link. Readers are indispensable for the selection and use of books and the quality control of the contents, design, editing and editing of books, and the printing process. Quality management in the printing process is an important part of book publishing.
The book quality includes the content quality of the book, the design quality of the binding and the quality of the printing. With the improvement of people's living standards, readers have not only paid attention to the content of the book to buy books, but the design and printing quality of the books has also become a very important criterion for them to measure the quality of books. The high-quality design and printing level can attract people's attention and enhance their trust in the contents of the books. They are eventually loved and purchased by readers.
The quality of book printing is also an indispensable factor in evaluating book quality. Content and form (appearance) are two major elements of the book. The printing of books belongs to the appearance of books. A good appearance can better express the content and promote the expression of the content. On the contrary, the bad appearance not only fails to express the content well, but also has a negative impact on the content.
1 Quality control in publishing
The quality control in the publishing sector mainly includes graphic design and production. In the prepress production process, the input, edit, output, post-process process design, and framing design are all important factors affecting the quality of books.
1) Scan input of picture
The scanning and processing quality of the image is an important prerequisite for ensuring the final color and tone reproduction of the image. Accurate and high-quality processing of the image is performed, and the image information such as tone, level, contrast, and saturation on the original is retained as much as possible. The basic standard of image quality.
Today's books usually have many illustrations. During the inspection of the illustrations provided by the author (including color pictures, black-and-white images, line drawings, etc.), attention should be paid to the quality of illustrations: color and black and white drawings must be clear and hierarchical. Strong sense, in which the color of the color map is bright, and the lines of the line drawing are clear and full. When scanning and scaling a picture, the characteristics of the different types of manuscripts such as photographs, prints, hand-painted prints, positive prints, negative prints, etc. shall be distinguished and accurate standards shall be determined. When scanning originals with rich layers, high saturation, and strong contrast, it is necessary to restore originals as accurately as possible. If the quality of the original is not very good, there is a color cast or saturation is low, and adjustments should be made accordingly. The resulting image is brighter and more realistic than the original.
The scanning resolution must meet the publishing requirements. The scanning resolution of print images is generally set to 1.5 to 2 times the dot lines. Usually, the scanning resolution of color books is 300 dpi, the dot line number is 150 lpi, and the scanning resolution of fine pictures is adopted. For 350dpi, the number of printing dot lines is generally 175~200lpi. During the scan, we must also reasonably select the appropriate color separation parameters for printing paper and printing equipment, determine the calibration parameters for black and white fields, and make appropriate adjustments to the image tones.
2) Processing of pictures
At present, the popularity of digital cameras has led to the increasing use of digital cameras and other digital images. This also imposes higher requirements on image processing, not only to meet the characteristics of the printing process, but also to consider targeted processing of digital images. .
In dealing with the picture, it is necessary to adjust the location of the original color, poor tone, usually using professional software such as Adobe's Photoshop software for morphological transformation, color conversion, layer correction, image modification, special effects design Other processing methods, such as color accuracy, tone balance, at the same time for a lot of line drawing generally have to use a corresponding graphics processing software (such as Freehand, CorelDRAW, etc.) to re-draw, if the map saves unnecessary requirements to the illustration The printing stage will inevitably affect the quality of printing. Internet download photos have fewer layers, excessive sharpening, inaccurate colors, and low number of pixels. After printing and copying, the effect is not good. Use less and use caution.
On the other hand, when dealing with pictures, we must consider the requirements of the printing process, adjust the pictures through software, stretch the middle tone, and concentrate the main layers in the visually sensitive area of 10% to 60% to ensure high light and darkness. To adjust the level and quality of the parts, and to compress the layers within the effective range of the printing, so that the gradation of the original document corresponds to the gradation that the printing can reproduce to the maximum extent, so that the image is clear and real.
The types and levels of manuscripts vary from one manuscript to the next, and the contents and colors vary greatly. Copying photos with consistent styles and satisfying printing requirements is a central task in scanning and processing. The basic principle of this work is: faithful to the original, higher than the original and strive for uniform style.
3) Matching book design and printing process
Publishers should work with printing companies to select reasonable printing processes to achieve the best effect of book printing.
1 open and print selection
Sometimes, in order to highlight the diversity and novelty of books, publishing society chooses some special-shaped copies. However, in the printing process of printing companies, due to the inconsistency between the profiled opening size and the normal open format, the difficulty of printing production will be increased and the cycle will be extended. This leads to an increase in costs, so when choosing a draft, it is best to choose a normal copy and choose a vertical copy. When determining the printed sheets, it is best not to print zero sheets such as 0.125 sheets or 0.875 sheets because the zero sheets will also lead to increased printing processes, longer cycle times, and higher production costs.
2 Use of special processes
Book printing generally uses lithographic printing. There are no special requirements in the process of printing the inside text. For the binding production of the front cover, the publishing house often uses some special processes such as laminating (light film, matte film), bronzing, and UV coating. , embossing, special printing, etc. When using these special techniques in the framing design, it is necessary to consider the different conditions of the paper or material being printed. Some materials do not have good bronzing effect, they are not easily hot, and they are prone to blooming. Not only do they increase the loss, they also increase the cost of printing. It does not achieve the desired effect, but also leads to an extension of the cycle.
3 book spine
There are several ways to determine the width of the spine. A better method is to use the same paper size and a certain number of printed sheets to determine the spine thickness. However, considering the thickness of the paper when the book is reprinted Change, different batches of the same paper will be different circumstances, the design of the spine should have a certain margin, and the spine should not use as much as possible with the seal, seal four different colors of the color or ribbon, in the cover, cover four and the spine Do not design the wireframe. The spine word should not be too big or too full compared to the width of the book. This design not only facilitates the production of the printing plant, but also improves the product quality and reduces the quality problems.
4 layout design
In order to pursue results, some designers will design some small words (below 5th), especially those with relatively thin strokes or some thin lines, to design them as four-color or anti-white characters. This design will greatly increase the difficulty of printing and binding. If you use offset paper printing, it is easy to produce overprinting, gluing, leaking and other quality problems.
When printing neutral gray, the color is not easily grasped, and it is often easy to cause color cast. This is particularly prominent for reprinted books. Therefore, in the prepress production process, it is recommended that some grays formed by four-color overlays be made into special ones. The color is better, and the color gamut expressed by the spot color is wider than the color gamut of the four-color printing performance, and the color that the CMYK four-color printing ink cannot display can be realized.
5 bookbinding process design
Binding is a commonly used binding process, but a book with a thin spine or a particularly thick book is not suitable for binding. Because the hot melt adhesive used in glue binding has poor tensile strength, poor anti-aging, and poor durability, it can cause the middle of the book block to be opened and inconvenient for books that need to be stored for a long time, and may cause intermediate opening. The quality of the page drop problem, so it is not suitable for the use of wireless glue binding method, but must use the lock line and then plastic package process. The extremely thin spine book (generally less than 3mm) is also not suitable for processing equipment processing parameters, because the spine is too thin, it is easy to cause spine round back and spine word skew quality problems.
Although the binding process is in the final process, the position of the core should be considered during the early stage of the layout, and the position of the offset milling hole should be reserved in advance. For the slightly thicker saddle-stitched books, the inner pages are likely to produce the core. The phenomenon of “remove” is to correct the “outward shift” of the inner page. It is necessary to adjust the amount of shifting of the printing plate. At this time, the position of the printing plate should be considered in order to ensure the entire book. Uniform visual experience.
For cross-page graphic design, the requirements for different binding methods are different and should be treated separately. Bookbinding products must not only consider the reserved 2~3mm milling amount, but also consider the position of the encapsulated side glue of 5~8mm reserved for the bond between the cover and the book block. Otherwise, cross-page images may be disconnected, misplaced, missing text, and the content is being milled. If the book whose cover is film-covered does not have a mouthpiece, the cover will have a large amount of curling, the inner core will be dirty, and the appearance will not be beautiful.
2 Quality control in printing
The elements of print quality control are: the authenticity of the dots, the color reproduction, and the stability of the printing process. The mesh value (the dot size) of the overprint area is the most important control element. Of course, there are other factors affecting the printing quality such as ring-shaped white spots, stencils, dirt, overprinting, and so on. For customers, the reason for their dissatisfaction is that there is a color difference between the original and the printed pattern.
1) Film quality control
The density of the black solid on the film should reach 3.5. Below this value, the dots will transmit light during the printing, causing the exposure of the photosensitive layer, resulting in the dots on the printing plate is not solid, the density is low when printing, and the dot is easy Dropped, resulting in dropped calls.
A strict inspection of the quality of the film before printing can identify the problem at the first time and remove the major hidden dangers in the later printing. Otherwise, it will not be discovered until the printing process or after the printing is completed. It will bring great problems. loss.
2) copy control
When printing, it is necessary to strictly control the exposure according to the requirements, if the exposure time is too long, it will cause the printing plate Internet point is not solid or even lost, off screen when printing. When printing, it is necessary to ensure that 3% of the small outlets are not lost and 95% of the outlets are not affixed. In this way, the perfect reproduction of levels and tonality in the printing process can be guaranteed.
The operator should determine different exposures under different conditions according to the situation and the test strip. The printing environment should be standardized, clean, and the original plate and printing glass should be cleaned before printing, so as not to cause the uneven drawing of tiny foreign matter, and the picture and text will be made empty. Second, the control of the development process is also an important factor in the quality of the printing plate. The developer concentration must be strictly prepared according to the requirements and control the development speed so as to avoid the loss of small dots due to the high concentration of the developer, high temperature or high speed, or the dirty version due to the low concentration of developer, slow speed or low temperature. Paste phenomenon.
3) Dot size control
The dot size is a decisive factor in determining the printing quality. The process of plate making and offset printing will change the dot. Therefore, the dot enlargement, sharpening, deformation, and ghosting of each process must be strictly controlled. We can use print control strips and magnifiers to monitor the changes in outlets. In the offset printing process, dot enlargement will occur. This requires continuous monitoring of product quality during the printing process, detection of problems, and timely adjustment of equipment.
4) Color difference control
Chromatic aberration refers to the difference between the color of the printed product and the original. Only when it is controlled within a certain tolerance, the printed product is qualified. The spectrophotometer is used to measure the CIELAB value and the color difference value of the print and the original, and then the obtained color difference value and the allowable range of the color difference are plotted on the coordinate chart to obtain the color difference allowable graph, which can be used to estimate the degree of product passing or not. . Under normal circumstances, the eligibility of printed products is determined on the basis of a person's visual experience and the customer's satisfaction or rejection of the printed product.
5) Ink thickness
The thickness of the printed ink layer has a great influence on the quality of the printed product. The thickness of the printed ink layer is related to the viscosity and fluidity of the ink. The viscosity of the ink is too large and the ink layer is thick. When printing, the phenomenon of detachment of paper hair occurs. On the contrary, the ink layer is thin, and the ink roller is easy to slip and lead to the ink bar, so that the dot is enlarged, the image is distorted, and the surface of the printed product is glossy. Degree difference. Under normal circumstances, under the premise of no back stain, the ink layer is printed as thick as possible. When the printing speed is faster, the ink layer can be thickened properly to achieve the desired ink color. In addition, when the printed paper surface is rough When the ink absorption is strong, the ink layer should also be properly thickened, and the layout is not easy to send flowers.
6) Stability of the printing process
To maintain the stability of the printing process, the printing equipment needs to be checked regularly. As the seasons change, the machine will continue to run for a long time. The pressure between the printing cylinders and the pressure between the rollers between the rollers will change slightly. These changes will affect the printing quality. Important. Machines and maintenance personnel must check the rubber roller pressure and roller pressure once every two months and find that the problems are adjusted and resolved at any time.
Strengthen the graphic and text inspection work, especially in the pre-press process, the film should be tested, timely detection of problems and quality risks, eliminate unnecessary waste. The inspection in printing is indispensable, and it is one of the effective means to control quality. The focus of the inspection in printing should be on the control of print quality, such as checking whether the print sample, plate-off sample, plate change sample are the same as the original sample, check the page number sequence and image quality, and check if there is a word drop, etc. Control the quality of printing to prevent the occurrence of various quality accidents.
7) Paper Selection and Control
The surface strength of the paper is too low, and it easily causes the phenomenon of pulling and de-powdering on the surface of the paper due to the adhesion of the ink during the printing process, and the printing quality is poor. Use paper with high surface strength to obtain better print quality. In order to ensure good printing quality, paper with higher surface strength is used, or the printing pressure is appropriately reduced, or the ink viscosity is appropriately adjusted. Therefore, it is necessary to put forward specific requirements in the paper related standards. For example, in the national standard GB/T18359-2001, it is stipulated that the surface strength of coated white paperboards such as A, B, etc. and C, etc. shall be 2.8m / s or more in order, 1.6 More than m / s and 1.0m / s or more, as a basis for use, should also be based on different styles, different grades of the correct choice of paper to ensure print quality.
When the moisture content of the paper is too high, the paper becomes soft, expands, the tensile strength decreases, the plasticity increases, the imprinting cannot be dried in time during the printing process, or the moisture content is too low, the paper is brittle, shrinks, is easily broken and fractured, and is easy to produce. Static electricity affects the normal printing process. The expansion and contraction of the paper caused misprints. The moisture content of paper is affected not only by the ambient temperature and humidity, but also by the nature and materials of the paper. In general, under the same temperature and humidity conditions, the greater the tightness of the paper, the greater the amount of sizing, the more long fibers in the slurry, the lower the moisture content. In the storage and printing of paper, controlling the proper moisture content is the key. For example, in order to control the moisture content of the paper at 4 to 8%, the ambient temperature should be controlled at 18 to 24°C and relative humidity at 40 to 55% RH.
White material cutting is often an important aspect that is easily overlooked in quality control. The size and quality of the cutting directly affect the rules and quality of the printing. When the cutting is performed improperly, it will cause the wrong size.
3 Binding quality control
Stapling is the last production process of a book into a book. It mainly consists of folds, pages, locks, envelopes, and finishes. The binding process is extremely complex and its complexity is unmatched by any one process. There are more than a dozen channels in the binding process, and most of them have no commonality. It is understood that many binding quality problems occur when the binding is completed or the book has been sent to the customer. Therefore, in the binding production process, prevention work must be done to prevent problems. Once quality problems occur, they should be dealt with promptly to avoid waste.
1) Effect of binding materials
There are hundreds of kinds of binding materials and styles. There are many kinds of materials involved in each kind of materials. For example, there are more than 10 kinds of cover materials and their textures are different. These different materials also involve the use of bonding materials, and the bonding materials The difference is also related to the firmness of the bonded object and the bond. The correct use of materials directly affects the firmness of books and their preservation life. At present, quality problems such as dropped pages, unbalanced books, broken cores, air bubbles, holes, and glue that appear in the wireless glue binding are directly related to the materials using EVA hot melt adhesives.
The cover paper material was improperly broken. Now the thickness of the cover is getting bigger and bigger. The paperboard or paper design above 200g / m2 has a crocheting process. When the creases break, the crease breaks and breaks the bottom, destroying the appearance quality of the book. In fact, if the front cover of 200g / m2 or more is to be folded, it will make the binding of the book very difficult and quality cannot be guaranteed.
Cover paper and book paper are very different in thickness. In order to improve the binding effect of books, there are many books nowadays with cover thicknesses that are different from the thickness of the book paper or the weight of the snow. This results in a difference in tension between the two. When the book is bound, the cover lifts the first page of the book block to expose the glue. At the end, resulting in substandard products. Such products can be solved by adding a one-gram-thick liner or lining between the cover and the first page of the book block. However, many publishers are reluctant to do so in order to reduce costs. Do not consider the processing effect.
2) Wireless Adhesive Milling and Back Quality Control
The wireless glue binding does not use iron wire and does not use wire, but uses an adhesive to bind the book block, and its process flow is roughly as follows: collation, feeding, bumping, milling back, pulling groove, adhesive on the back, adhesive on the top, bag cover, Forming, drying, slitting, cutting of finished products, stacking light, inspection of finished products, and tying.
In glue binding, milling and backing are the key steps. Milling back should be based on the thickness of the paper, the number of folds and the number of generally required to mill 2.5mm ~ 3mm, pull the depth of the groove required in the 1.0mm ~ 1.5mm. If the depth of the milling back and groove is not enough, the penetration of the glue will be affected, resulting in the quality defects of page breaking and loosening. If the book is not affixed, bound, or compacted before it is glued, it will be turned into milling and backing, which will cause the book page to be not opened, resulting in poor penetration of the glue, missing pages, loose sheets, and insufficient firmness. And other quality defects.
3) Effect of hot melt adhesive on book quality
Glue glue on the back and side of the book, back glue and side glue are also different from the hot melt glue, the performance of the two are also different, the use of temperature is also different, to grasp the right process parameters in order to ensure the quality of glue . The glue temperature is particularly important for the quality of glue binding. The high temperature of the melt glue will make the glue too thin and the viscosity will be insufficient. The temperature of the glue will be too low, making the glue too thick to be infiltrated and flowing, and some will be small. The granular block is attached to the ridge or side surface, making the cover wrinkle, empty ridges. According to different models, the general adhesive temperature is controlled between 160~180°C, and the temperature of the side glue is controlled between 145~165°C. Under normal circumstances, after the glue is applied, the spine glue can penetrate and fill the milling ditch. It is advisable to dry the gum with a thickness between 0.8 and 1.3 mm.
The finishing process is not only a complicated processing process but also an art processing process. Today's books are not only reading items, but also a kind of gifts, artworks, and valuable preservation products; it not only adds knowledge to human beings, but also brings Give people artistic enjoyment. In the past few decades, people engaged in the design of the publishing industry, especially the US-made snowballs, often contacted the technicians and the masters of the binding and processing plants to absorb the opinions of the binding workers in order to improve and improve the design of the binding design. Many problems were avoided in the selection of materials, dimensions and specifications, etc. to achieve the consistency between design expectations and product completion, and many high quality products were made. Therefore, there should be more exchanges between the publishing house and the printing factory, especially with the binding process. We learn from each other and designers can learn more about various binding processes in order to better design more excellent works.
To sum up, under the conditions of a market economy, publishers and printing houses are responsible for improving the quality of book printing. Publishing and printing should be a collaborative department for book printing quality management. In addition to the prepress production, strict management is also required for books printed by printing companies, and printing companies should also control the quality of books throughout the printing process. The publishing house and the printing factory should communicate with each other in a problem-solving manner. Each of them should bear the responsibility, work closely together, and work together in order to improve the quality of the book's printing and installation, and provide readers with excellent and unified books and contents.
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