Quality Tipping Paper CTP Application Experience

Quality Tipping Paper CTP application experience

 

1. How to ensure the smooth implementation of CTP system

The structure principle of the CTP platemaking machine is similar to that of the phototypesetter is no longer an obstacle to the development of CTP.

One of the reasons why it could not develop rapidly earlier is that the corresponding process could not meet the needs in the past period of time.

Digital proofing, automatic plate is the only way to CTP system application, if these technologies are not really solved, CTP system is not to speak of development. In other words, the development of CTP system is not the CTP platemaking machine itself, but the process. A complete digital process from typography to output control is the foundation of the CTP system. The key to the successful implementation of CTP system is:

 

1). More than two years of experience with the PostScript electronic prepress system will ensure that the prepress technician is familiar with basic file handling and troubleshooting, and can quickly find and resolve font problems, defective images, poorly constructed documents, etc.

 

2). More than half of the work is in PostScript or PostScript format compatible files.

 

3). Sufficient print consumption: The implementation of a CTP system requires a certain amount of money. A printing house must consume a certain number of plates to get a return on its investment.

 

4). High quality plate operation: The printing plant must ensure the continuity of plate quality.

 

5). The main work is not more than 4 colors, and the printed cable is less than 175lpi.

 

6). 6-12 months of digital proofing experience: Digital proofing is one of the most controversial techniques in the CTP workflow because of the impact it has on both the customer and the print shop. Need to train customers and print operators in various digital proofing techniques. In addition, the success of printing is also related to the technical personnel of the company. Their technical level and learning ability directly affect the speed of the introduction of CTP. The company needs to conduct necessary training for such technical personnel. And when the server to handle the work task is very heavy, in order to ensure that the server and the network can run properly, it is very important to add a system manager. Because the CTP system affects the entire printing company, it requires a series of adjustments and training for all departments involved.

 

Platemaking machine:

From the platemaking equipment, after several years of development, manufacturers launched a mature technology, can automatically on the version, can deal with different specifications and different types of plate, plate speed greatly improved a variety of direct platemaking system.

 

Thousands of direct computer machines, such as the prestigious Quansheng 3244 series, have been successfully operated throughout the country. It uses a new 20-watt thermal laser head and unique SQUARESPOT square photosensitive imaging technology. Awarded five times by the American Printing Technology Foundation GATF Technology Award, the company enjoys a reputation in the field of computer direct platemaking and has rapidly expanded into the field of digital offset printing. A built-in laser cooling system and a debris collection unit for ablative no-wash plates feature a time-tested external drum design that rotates at a constant rate during exposure to ensure consistent imaging. In order to accurately register, a unique temperature compensation system is used. During the imaging process, it can adjust and compensate the plate thermal expansion and cold contraction caused by the change of ambient temperature, so as to ensure that the same machine can accurately register at different times, even different plates, and the exposure is stable, consistent and repeatable.

 

CTP plate:

The key point of computer direct plate making technology is to match the plate and imaging system. Silver salt plate material: high sensitivity, high resolution, high printing resistance, must be operated under the safety lamp, and in the process of silver salt exclusion must be properly handled. Photosensitive resin plate: similar to ordinary plate, must be treated in water - based chemical composition. But compared with the silver salt version, sensitive resin version of the speed, resolution, and printing resistance is very low. The use of new high sensitivity resin emulsion, can ensure the consistency of the product and the stability of the text - this is the most important consideration when choosing the plate. Mixed plate: A low sensitivity silver halide mask is added to an ordinary photographic emulsion during the exposure process, so that the advantages of the two substances can be compromised. The mixture, however, requires a long platemaking line and two waste removal channels, as well as a more complex manufacturing process. Thermal plate: can be operated under the sun, high resolution replication, accurate imaging, has the potential to simplify the process, plate, film, proofing can be on the same instrument imaging. However, the thermal sensitive technology is not as mature as the visible laser system, so the thermal sensitive selection is very limited, and the thermal sensitive technology still has the potential to exploit.

 

2. Common problems and solutions when using CTP

The mature and development of CTP technology has brought different production benefits to the manufacturers using it. In the face of new technology, new process at the same time, due to the experience of operators or pre-production documents and other reasons, in the actual work often appear some problems that need to cause our attention.

 

1). Size problem

 

(1) The size of the produced file is inconsistent with the size actually required.

(2) The amount of blood loss required was not considered in the preparation of the document.

(3) The text or image is too close to the finished product cutting line.

 

Solution:

(1) Define "Document Settings"/" Page Size "as the finished product size.

(2) The amount of bleeding on the page should be considered when making files, generally 3mm.

(3) The distance between text or image and finished product cutting line should be at least 5mm, preferably more than 8mm.

 

2). Image problem

(1) Color images or graphics adopt RGB color mode.

(2) The image accuracy does not meet the basic requirements of printing, such as low resolution.

(3) Image compression in JPEG format, level, detail information loss.

(4) Electrical or scanning after no repair, leaving dirty spots on the image.

(5) An error occurs when linking or re-placing images.

 

Solution:

(1) Design and production personnel are required to have a basic understanding of the general knowledge of printing, and have a certain sense of aesthetics.

(2) Realize the management standardization of CTP system. Standardize the process and clarify the requirements of each process.

 

Recommended practices:

(1) The quality of color separation image should be the most basic requirements.

(2) The color mode of CMYK is generally adopted in printing.

(3) The image should have sufficient precision. For large images, resolution is usually 300dpi or 350dpi for color images and 1200dpi for Bitmap images, at least 800dpi to avoid jagging.

(4) electric time-sharing Settings should be accurate, files should be able to faithfully reproduce the original manuscript, high clarity, rich details, good level.

(5) It is required to revise the drawing when doing color correction processing after electrical separation, so as not to leave dirty points.

(6) Do not compress the image as much as possible, especially the image compressed into JPEG format can not be used for printing.

(7) Standardize file naming to avoid files with the same name. Re-link the image must be careful, once the error is fatal, so do not take it lightly to avoid major damage.

 

3). Font problem

For PS font does not have the font, especially the Chinese font, generally use Truetype font download, but easy to produce leakage or word shift.

Solution:

 

(1) Purchase the corresponding PS font or CID font.

(2) Install common font library for CTP system and ask customers to use fonts of corresponding font library.

(3) For the missing font, you can discuss with the customer to use a similar font instead, but pay attention to the word shift; You can also ask for fonts, especially in foreign languages.

(4) Through the Ⅲustrator, FreeHand or CoreIDraw software to turn the font into a curve, save into EPS file format, as image processing.

(5) For the font of K100, generally to do trapping.

 

4). Big questions

1. For the smaller size of the book, the general use of double or multi-copy printing, but if the text arranged in double or multi-copy, cover or lining paper arranged in a single book, it is easy to make mistakes when spelling a large version, to increase the workload of binding.

 

Solution: The whole book (including the text, cover and lining paper, etc.) should be arranged in double or multiple copies, and the gaps between them should be consistent.

 

2. For collated printing, the printing characteristics are not taken into account and do not meet the printing requirements, for example, the living parts with large color differences are printed together.

 

Solution: As far as possible will be similar color prints in the same ink line.

 

3. For a series of the same size of multiple packaging boxes, when two or more versions, often occur because of the gap is different and each large version must do the knife die.

 

Solution:

(1) Use CAD software to make tool die lines, and then unify the large version according to the tool die lines to ensure the tool die sharing.

 

(2) Different spellings of large plates have different impacts on the quality and efficiency of printing and binding. The optimal scheme can make the post process complete smoothly, while the failure of spellings will bring unpredictable troubles to the post process, resulting in the inability to complete, and even have to rework. Therefore, the operators of large plates should be familiar with the pre-press, printing and post-press procedures, and it is best to have special personnel for quality control.

 

5) Output problems

1. When printing PS files or PDF files, if the color separation mode is used, it will cause inconvenience to modify PDF files.

 

Solution: Use composite color output.

2. For multi-language edition books, most of the K color plate is divided, and C, M, Y color plates shared, or four-color plates shared and spot color plate. In the actual operation process, it is easy to get confused.

 

Solution: In the drift mouth or ridge code, use text. ICONS or colors are used to identify different versions to avoid confusion.

 

3. File updates are the most common and deadly problem. If the modified application file is not updated in a timely manner on blue paper or large file, the old file is used in the direct platemaking process, and the old content will still be printed.

 

Solution: This belongs to the management standardization problem of CTP system. The key to solve this problem is to formulate reasonable and standard work flow of CTP system, strengthen the standardized operation of employees, and realize the barrier-free communication among employees.

 

6) Color management

Color management is the key and difficult point of CTP technology. ICC characteristic curve that can accurately reflect the characteristics of equipment determines the effect of color management. Therefore, the generation of ICC characteristic curve has become the top priority of color management. In the production practice, the author summarizes the following points to pay attention to:

 

1. Keep the printing as steady as possible. Enterprises should establish a set of effective printing standards, especially in the control of printing density and network increase, and require operators to resolutely implement in the printing process, the indicators control within the range of error.

2. Ensure that the digital proofing equipment is in normal condition. For example, Agfa Sharpa series can be tested and adjusted by QMS(Qualiy Management System) software so that the digital proofing equipment is always in normal condition and the printing effect is consistent.

 

3. The surface of IT8 used for measurement must be clean, free of oil and crease, which has an important impact on whether the ICC characteristic curve can accurately reflect the characteristics of the equipment.

 

4. Theoretically, different printing conditions correspond to different ICC characteristic curves. However, for common printing parts and the general visual perception of human eyes, three ICC characteristic curves reflecting their printing characteristics can be set respectively for three kinds of paper: coated paper, matte copper paper and offset paper.

 

5. With the continuous development of technology, color management software should be constantly upgraded. According to the feedback from the client, the ColorTune used with Agfa CTP system is upgraded to version 4.2, which can not only accurately simulate the printing effect, but also be very stable, and the effect of color management has been a qualitative leap.

 

7). Printing problems

The current CTP system is generally used by large and medium-sized printing enterprises, most of which have several units. A dozen or even dozens of presses of different types, like Heidelberg. Roland, Kobol, Mitsubishi, Beiren, etc., which have both single-side printing presses and double-side printing presses, as well as single-sheet printing presses and rotary printing presses. On the one hand, the size of the plate used by different models will be different, and the large plate mode of single-sided and double-sided printing presses will be different. On the other hand, for the CTP system, the blue paper once confirmed can be printed. In practice, a copy may be printed by a different press unless it is printed. In this way, not only can be prepared in advance, but also will not cause waste due to some reasons.

 

The plate of a double-sided press can be transferred to a single-sided press, but not vice versa. Large plates can be cut into smaller plates, and then printed on small format presses, and vice versa. Based on the above two points and the actual situation, considering the flexibility of production scheduling, it is necessary to pay attention to the following two points: if the paper is large enough, it should be made by double-sided printing press as far as possible; Can not determine the model used, it is best to make a large size plate, otherwise it will bring unnecessary trouble and loss to the production. In addition, pay great attention to the inspection of blue paper, most mistakes can be found from blue paper. As the CTP system management personnel and related practitioners, we must attach great importance to the inspection of blue paper, do multi-layer inspection, heavy checks, to minimize the error rate.

 

Today, the development of CTP technology is changing rapidly. We need to constantly learn and explore the process, specific analysis of the problem, there is no ready-made formula and rule can be copied. There are many techniques in the CTP technique, and learning and applying these techniques will greatly improve productivity. Operators engaged in CTP work should understand the process and technical requirements of the preceding and following processes, otherwise they cannot judge whether the work is correct or not; Managers engaged in CTP work should be proficient in technology, use a variety of management knowledge, overall overall situation in the complex work, master and control the work process, so that the work is carried out in an orderly manner.