Common Problems and Solutions in the Application of CTP Technology

The maturity and development of CTP technology brings different production benefits to the manufacturers who use it. In the face of new technologies and new processes, due to the operator's experience or pre-production documents and other reasons, there are often problems that require our attention in practical work.

First, the issue of document production

1. Dimensional issues (1) The size of the created document does not match the actual required size.
(2) The required amount of bleeding was not taken into account when making the document.
(3) The text or image is too close to the finished cutting line.

Solution:
(1) Define "Document Settings"/"Page Size" as the finished product size.
(2) The amount of bleeding on the page should be taken into consideration when making the document, which is generally 3mm.
(3) The distance from the text or image to the finished cutting line is at least 5mm, preferably more than 8mm.

2. Image Problems (1) Color images or graphics use the RGB color mode.
(2) The image accuracy does not meet the basic printing requirements, such as the resolution is too low.
(3) Images compressed in JPEG format have lost information on levels and details.
(4) The electrical points or unretouched images after scanning will leave dirty spots on the images.
(5) An error occurred while linking or re-imaging the image.

Solution:

(1) It requires that the design and production staff have the most basic understanding of conventional printing knowledge and have certain aesthetic knowledge.
(2) To achieve standardized management of the CTP system and standardized processes, and to clarify the requirements of each process.
Recommended practices:
(1) There are basic requirements for color separation image quality.
(2) The CMYK color mode is generally used in printing.
(3) The image must have sufficient accuracy. For large images, the resolution of a color image is usually 300 dpi or 350 dpi, and the resolution of a Bitmap image is usually 1200 dpi and at least 800 dpi in order to avoid jaggies.
(4) The time-sharing setting should be accurate. The document should faithfully reproduce the original, with high definition, rich details and good levels.
(5) After the electricity is divided, it is required to rectify the color when processing the color to avoid leaving dirty spots.
(6) Do not compress images as much as possible, especially images compressed into JPEG format cannot be used for printing.
(7) Regulate the naming of documents and avoid the appearance of documents of the same name. Be careful when relinking images. Once errors are fatal, don’t take it lightly to avoid major losses.

Second, the font problem

For fonts not available in PS fonts, especially Chinese fonts, TrueType fonts are generally used for download, but it is easy to generate missing words or word shifts.
Solution:
(1) Purchase the corresponding PS font or CID font.
(2) Install commonly used fonts for CTP systems and require customers to use the fonts of the corresponding fonts.
(3) For the missing fonts, you can consult with the customer to use an approximate font, but pay attention to the word shift; you can also ask the customer to provide fonts, especially foreign language.
(4) The font is converted to a curve by software such as Illustrator, FreeHand, or CorelDraw, and stored as an EPS file format as image processing.
(5) For K100 fonts, traps are generally required.

Third, fight the big issue

1. For a book with a smaller size, a double-joint copy or a multi-joint print is generally used, but if the text is arranged in a double-joint or multi-column book, the cover or backing paper is arranged in a single copy, it is easy to make a large version. Make a mistake and increase the workload for binding.
Solution: The book (including the text, cover, and backing paper, etc.) is arranged in a double-joint or multi-joint book, and the gap between them must be consistent.

2. For printed products, printing properties are not taken into account, and printing requirements are not met. For example, work items with large differences in color are printed together.
Solution: Place as many prints of similar colors as possible in the same ink path.

3. For a series of packaging boxes of the same size, when there are two or more packaging, it often happens that each large version has to be used as a die cutter because of different gaps.

Solution:

(1) Use CAD software to make knife mold lines, and then apply them in accordance with the knife mold line to make sure that the knife molds are shared.
(2) The different versions of the large version have different influences on the quality and efficiency of printing and binding. The optimal solution can enable the completion of the post process, and the failed spelling can bring unforeseen problems to the post process. Unable to complete or even have to rework. Therefore, the operators of the imposition version must be familiar with the prepress, printing, and post-printing processes. It is advisable to have special personnel to conduct quality checks.

Fourth, the output problem

1. When printing a PS file or a PDF file, if the separation mode is selected, it will cause the modification of the PDF file to be inconvenient.

Solution: Use composite color output.

2. For multi-language editions, most of them are K-color editions, while C, M, and Y editions are common, or four-color editions are shared and spot editions are divided. In the actual operation, it is prone to confusion.
Solution: At the flies or at the spine, text, icons, or colors can be used as different versions of the logo to avoid confusion.

3. File updates are the most common and most deadly problem. Modified application files, if they are not updated in blue paper or large version files in time, use the old files when printing directly, and the printed contents are still old.

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

V. Color management issues

Color management is the key and difficult point of CTP technology. The ICC characteristic curve that can accurately reflect the characteristics of the device determines the effect of color management. Therefore, creating the ICC characteristic curve becomes the most important task in color management. In the production practice, the author summarizes the following points that need attention:

1. To keep printing as stable as possible. Enterprises must establish a set of effective printing standards, especially in controlling the printing density and the increase of network points, and require the operator to resolutely execute the printing process, and control each index within the error range.

2. Make sure the digital proofing device is in normal condition. Such as Agfa's Sharpa series, QMS (Quality Management System) software can be used to detect and adjust the machine, so that the digital proofing device is always in a normal state, and to ensure consistent print results.

3. The IT8 used for measurement must have a clean, oil-free, and crease-free surface. This has an important effect on whether the ICC characteristic curve accurately reflects the characteristics of the equipment.

4. Theoretically speaking, different printing conditions correspond to different ICC characteristic curves. However, for the common impressions of the common prints and human eyes, three ICC characteristic curves reflecting the printing characteristics can be set for the three commonly used papers: coated paper, matte copper and offset paper.

5. With the continuous development of technology, color management software should also be continuously upgraded. From the information fed back by the client, the ColorTune used with the Agfa CTP system has been upgraded to version 4.2, which not only accurately simulates the printing effect, but also is very stable. The effect of color management has been a qualitative leap.

Sixth, printing problems

At present, CTP systems are generally used by large and medium-sized printing companies. Most of them have several, dozens, or even dozens of different types of printing presses, such as Heidelberg, Manroland, KBA, Mitsubishi, and North. People, including both single-sided printing presses and double-sided printing presses, as well as sheet-fed printing presses and rotary printing presses. On the one hand, the size of the plates used in different models will be different. The layout of single-sided and double-sided printing presses will also be different. On the other hand, for CTP systems, once the blue paper is confirmed, Plates can be output. In fact, unless the printing is completed, the print may be printed by different printers. In this way, it is possible to prepare for the release in advance, without causing waste for some reason.

The printing plate of a double-sided printing press can be printed on a single-sided printing press, and vice versa; a large-sized printing plate can be cut into smaller-sized printing plates and printed on a small-format printing press, but not vice versa. Based on the above two points and the actual situation, taking into account the flexibility of production scheduling, you need to pay attention to the following two points: If the paper is large enough, it should be as large as possible by the double-sided printing machine to fight the big version; can not determine the model used, the best out Large-size printing plates, otherwise it will bring unnecessary trouble and loss to production. In addition, we must attach great importance to the inspection of blue paper. Most of the errors can be found on blue paper. As a CTP system manager and related practitioners, we must attach great importance to the inspection of blue paper, so that multiple layers of inspection, check and control, to minimize the error rate.

Nowadays, the development of CTP technology is changing with each passing day. We need to analyze specific issues in the course of continuous learning and exploration, and there are no ready-made formulas and rules that can be copied. CTP technology has many skills. Learning and applying these skills will greatly improve work efficiency. Operators engaged in CTP work must understand the process and technical requirements of the processes before and after, otherwise they cannot judge whether the work is correct or not; engaged in CTP work