Talking about the risks in the prepress process control process

Although 93% of the surveyed printing companies used process control methods in the prepress process, the actual situation was not so satisfactory.

In the manufacturing industry, process control is a good thing to promote. It can effectively control the production process and can effectively use human resources. When the PIA/GATF surveyed its printer members in 2004, 93% of respondents said they used process control in the prepress process. However, when asked about substantive issues, respondents clearly stated that they rarely use process control in their daily affairs.

Why is there a difference? For many printers, "I am a craftsman and I apply my skills to the world's best print reproduction process." This feeling is their true portrayal.

To define a printer as a skilled craftsman, his craft is always under his own “control”. Comparing the new process with the traditional process, the process model of the printing company is always in control. He can always see what he wants to see, and don't worry about taking "emotional risks" to get a breakthrough. But for most printing company owners, this breakthrough is the only viable business model. With the old methods, it is impossible to achieve continuous improvement.

One of the products of this new business model will be integrated into the process control process -- not a "term" that speaks, but a real change in the workflow. At the R&E Council Digital Smart Factory Conference held last month, Barbara Pellow of Kodak Graphic Communications summed up this new paradigm: “The key is to automate the process of manufacturing prints. Integrate it to ensure the rationality of the workflow from customer ordering to shipping."

What is the required tool? There are five: 1) the implementation of the standard, 2) the overall workflow concept, 3) the color management, including the calibration of all process steps, 4) the implementation of control procedures to ensure the consistency of process steps, 5) the analysis of all process outputs, From design to completion. For printing companies, the biggest change is to consider these tools as the standard of daily work, rather than the experience of “craftsman”.

Where does the standard appear?

Today, all standards for the printing industry are published by the ISO TC 130 Graphic Technology Committee. Its most basic product is the newly revised standard. Mainly include: ISO 12647-2 graphics technology, process control of half-tone color separation products, proofing and product printing. Part 2: Offset lithography process.

In the United States, these standards are supplemented by the specifications issued by SWOP (web offset standard) and GRACoL (general requirements for commercial lithographic offset technology), and the IDE has adjusted this. In the currently published GRACoL specification, the solid ink density values ​​in KCMY (on paper type 1) are specified as 1.70, 1.40, 1.50, and 1.05, respectively. New specifications based on gray balance, tone values, and evenness will be published with GRACoL 7.0, and this version is currently being written.

Workflow solutions

Just setting a standard is not enough. You must define a standardized workflow that can achieve consistency. The workflow is not a new thing, people need it to handle the daily affairs.

The digital revolution not only made it possible to automate workflows (for the first time), but also a variety of workflows offered by different vendors. The workflow is not a product, not a hardware with size, performance specifications, product capacity, but the printing company must install a controllable workflow environment.

Workflow solutions must take into account JDF. JDF is the abbreviation of Job Definition Format. It is an open standard job entry language and provides the user with the foundation for building the next printing process. It builds on existing technologies such as the Print Production Format (PPF) developed by CIP4 (an international organization that integrates prepress, print and postpress processes).

EFI's JDF-compliant software conforms to this format: When it is ready for production, the MIS system informs the press through EFI's JDF connector to inform the press installation. If all or part of the job is digitized, the MIS system sends JDF data and content directly to EFI's Balance, Fiery and OneFlow workflow solutions.

However, not every device today can use JDF. In fact, older devices (about four or five years old) may not be compatible with JDF. The cost of updating is also difficult to implement. However, we have a technology tool that can make the device compatible with JDF in the print production workflow. This idea appeared at the recent TAGA meeting in Toronto. It can establish the connection between different processes, and these different processes are the biggest obstacle facing JDF at present.
CTP prepress plate making process

Pre-press process plan Computer-to-plate work plan Computer-to-plate work plan To shorten the distance between originals, proofs and prints, images can be processed with Heidelberg's Coloropen software. Coloropen works with the ICC profile to manipulate picture files in the largest color space, simulating different system colors and print modes. Once set, both the scan input and picture library images can be output on the digital proofer, and are close to it. Printing effect proofing,

The specific plan is as follows:

• Image scan output: Using ColorOpen software to set up the ICC profile ensures that scanned images can be output as requested by the customer. And suitable for different output devices.
• Image processing: High-resolution images are stored in the host, providing only low-resolution images for signastation. Before output, the page is sent to Preserver for RIP processing.

· Imposition: Use low-resolution images for imposition in Signastation. Preserver for RIP processing. High-resolution images are placed into the layout before being output, and a single page can be replaced without having to re-ripify the entire layout.
• Proofing: The Epson stylus PRO9000 can output color proofs.
· Version: Heidelberg CREO Trendsetter controls the output of printable plates via the Delta tower.

3-2 Performance Parameters The CTP performance parameters are as follows:

· Production software supported by the system: Adobe photoshop, Adobe Pagemaker, Adobe Illustrator, CorelDraw, Freehand, QuarkXpress, etc. are available on Mac/PC workstations.

Fonts: Most PS fonts and all True type fonts; Full English fonts, 100 Hanyi fonts. 87 Arphic, 88 Founder and some special fonts.

·CTP output: Maximum size: 749×1030mm Resolution: 2400dpi/1600dpi/1200dpi dot type: FM network 21um, circular net, circular net, square net, elliptical net, etc. Exposure speed: 4min (2400dpi) Plate material: Off : 770×1030 mm0.3mm Four-opening: 605×745 mm 0.3mm Eight-opening: 400×510 mm0.15mm Proofing: Maximum size: Width 1090mm, Unlimited length Resolution: 360dpi (blue paper), 720dpi paper: Epson only Matte Photo Paper, High-gloss Photo Paper Thermal Plate: The plate is extremely stable: no sunlight is used for full sunlight operation, and the quality of the plate is stable for a long time. The mesh is more accurate: the light spot is similar to the binary image. High resistance to print force: 200,000 impressions without baking, and one million impressions after baking. Accurate registration: The repeatability of the printing plate ±5um (eight plates with the same machine exposure) Absolute accuracy <20um (plates with different machine exposures) Registration accuracy ±15um (image and plate edge). Heidelberg Drum Plate Maker Advantages: Auto focus, drum speed 150 rpm. Similar to the printing roller structure, the light path is short, there is no vibration, and the thermal and mechanical properties are stable. Square laser dot technology: The edge of the dot is very sharp and can accurately duplicate 1%-99% dot. The printing density is extremely high, C-1.9D, M-2.0D, Y-1.5D, K-2.75D. FM network output is very easy. Delicate levels perfectly displayed.

The output settings of the 3-3 platesetter color separation plate output settings are as follows:

• If the user's publication includes a PageMaker component that traps (that is, trapped), select the Utility - No leak option. Click “Enable trapping for publications” to set trap options and click OK.

· Choose File - Print.

• Select a PSD for the platesetter for the user's printer type.

· Click "Color" and then click "Print Separation."

· The following is the determination of the screen angle and screen number for each color. The general rules are briefly described as follows:

a) For spot colors, the screen angle specified for “custom color” in PPD is usually printed, typically 45°.

b) For the primary color, select the name of the primary color, and then verify its value on the PPD "Optimization" screen. It is recommended to use the optimized screen settings.

6) Select the name of each color you want to print, and click "Print This Color." Alternatively, the user can hit the name of each color that you want to print. To select the color you are using, click Print All Skins.

7) Select the "Mirror" and "Plate" options as needed.

8) Click "Paper" to check that the user's publication is adjusted to the selected paper size, and select the printer mark and page information.

9) Click "Print". 3-4 Output Plate Quality Check General inspection method. This method is commonly used in output centers and design companies. Its main equipment is the viewing table and density meter. Densitometer is a key equipment for testing printing plates. Its basic function is to read out the halftone percentage of the halftones, so as to judge whether the size of the halftone dot generated by the platesetter is correct. For example, at the 40% tone in the original image, whether the measured density on the printing plate is 40%.

The following are the main inspection aspects of the general inspection and their meanings:
a) Test the web ladder attached to the printing plate so as to judge whether the adjustment of the printing plate is correct. It mainly examines the process of stencil printing and its parameters (such as the development speed, temperature and time, and the developer concentration, and may also include the problems of the plate making machine itself, such as the quality of linearization.

b) Observe the quality of the plate: Include whether the exposure is even and check the plate for scratches.

c) Check Postscript error: Used to check whether the interpretation of the file by the Postscript interpreter misses the content. The main observation is whether the content on each plate has no output. For the separation sheet, besides the single observation, the four color separation sheets should also be observed whether the tone and concentration of the image are normal and whether the registration is correct. 2. Proofing system check. Now the CTP output center generally uses color digital proofing before the printing plate. If problems are found, modify the electronic file. The color samples after successful proofing will become standard proofs for color printing. This is different from the traditional film production and proofing of the printing plate. It is also a problem to be solved and improved by the CTP.

Source: PACK.CN