Printing is a process of mass reproduction. It is a kind of high-speed, continuous production. Its main purpose is to produce qualified and high-quality prints. Due to the large number of processes, there are many factors that affect the quality of the printed matter. The quality problem is often tens of thousands of scraps. In actual production, a large number of scrapped finished products or semi-finished products also occur from time to time.

Example 1: A printing house prints a product brochure for a special wire factory using a double-sided coated paper with a basis weight of 157 g/m2. Both front and back sides are in color printing, and the text description below one of the pictures should read “Paper Shell”. Delayed electric detonator line, because the proofreading error was printed as "paper shell expired electric detonator line", just contrary to the original intention, resulting in economic losses of nearly 100,000 yuan.

Example 2: When printing in the printing shop of a printing plant, mistakenly remove the outer border lines of a few lines of text on a black plate as film collage traces. This will only be discovered when some products of the previous printing process enter the next process. The problem has to be reworked, and the missed border lines will be reprinted. Fortunately, the overprinting does not affect the accuracy of the graphic and text, but the waste of manpower, material resources, and product consumption brought about by the overprinting of the border line is not small, and delays the printing of other products, which affects the normal production.

Example 3: A printing company prints the label of a food company's serial products. Due to the large number of varieties, different flavors are required to be distinguished by different ink colors, and the pictures are roughly the same, with only the difference between the characters “××”. As a result, the printing plate was not carefully inspected during the printing process, and the error in the machine loading caused the product to be scrapped. This not only caused economic loss, but also delayed the delivery date, which affected the normal use of the label by the food company.
Example 4: A certain ticket printing house prints a batch of bills, and uses kraft paper to wrap the cover. When the finished product is cut, it is tipped over and the knife is cut across the board. Dozens of bills become waste products. Because the bills were coded and the numbers couldn't be used without continuity, the scrapped parts had to be reprinted, and the entire production process was confusing because of the number problem.

There are many similar examples in actual production. Every link in the printing process is directly related to the final quality of the print, so no errors are allowed. From this we can see that the quality control of printed products is carried through to each process and it is of great significance to every operator.

To avoid the occurrence of printing quality accidents, the following measures can be taken: one is the self-check of each process during the copying process, and the other is the mutual inspection between the upper and lower related processes during the copying process. Specifically speaking, each operator is required to perform routine inspections, but it is also necessary to carefully inspect the quality of the previous process, eliminate all kinds of hidden accidents, identify problems as early as possible, and minimize losses.

Here are some of the key procedures to discuss the issues that should be noted when performing quality checks in daily work.

Proofreading

The basic responsibility of the proofreading is to be responsible for the manuscript. After the proofreading, the content on the proof meets the requirements of the manuscript and corrects all typographical errors. If any omissions or doubts are found in some places of the manuscript, the proofreader should give his opinion and be approved and corrected by the definite seal unit. You cannot modify the original on the proof. In short, the proofreading should be faithful to manuscripts, without neglecting any possible mistakes. “One-valued money” is not an exaggeration for proofreaders. Proof-reading is an important part of ensuring the accuracy of printed content.

Printing

Shaiban is the correct transfer of the image on the original plate to the printing plate. The original version is a graphic product made from the previous process, and it is a copy of the printing process. Therefore, the inspection of the original before printing is of utmost importance. Its inspection contents mainly include:

1. Whether the original name, content and craft list are consistent;
2. The original specification, quantity and process list are consistent;
3. whether the original yin and yang, positive and negative directions meet the printing process requirements;
4. The original quality and collage quality meet the printing requirements;
5. The necessary rules and various marks (such as the label, color, etc.) are complete;
6. Whether the chromatic registration is accurate or not;
7. Is the layout clean, with or without waste tape, dirt, etc.;
8. Is the layout smooth, with creases, scratches, etc.?

Checking the quality of printing plates after printing is an indispensable process. It can be said to be an important part of comprehensive quality control. Its purpose is to prevent unqualified printing plates from entering the printing process, causing unnecessary waste and rework. The main contents of the quality check of the plate:

1. Inspection of the appearance quality of the printing plate: It includes the flatness, cleanliness, and evenness of the printing plate.
2. Examination of plate layout specifications: It includes the layout size, the position of the text, the size of the mouth, the relationship between the folds, etc., and the comparison of the copying process sheet by item. Requires accurate plate size, the error is less than 0.5mm, the dimensional error between the chromatic printing plate is less than 0.1mm, and the image is no sun drying phenomenon.
3. Inspection of graphic content: Check whether the content of graphic and graphic content is complete, whether there are damaged words, defective characters, missing characters, etc., and check whether the color version is complete or not; The rules are complete and complete.
4. Check the quality of the outlets: Observe whether the outlets are full, clean, etc. with a magnifying glass.
5.Graphic and textual inspection: With the aid of magnifying glass and control strips, the reproducibility of bright, medium, and dark tone areas on the printing plate is checked separately according to the quality of the printing plate and the quality of the printing plate. Dark and shallow printing plates cannot be used. Printing on the machine.

Printing

Newly acquired printing plates often affect quality due to various factors (such as process operations, production environment, and the quality of workers) in the printing plate production process. Plates should be inspected before being placed on the machine, so that responsibilities can be separated and problems can be avoided between departments. Except for the smelting personnel and full-time personnel, the operator has the responsibility and obligation to review and inspect the printing plate quality. Only qualified plates can be used for loading. The contents of the inspection mainly include whether the colors are different, the shades of shades are dark, the network points are imaginary, whether the characters are in error, whether the lines are incomplete, and whether the plate format, cleanliness, and flatness meet the requirements.

In addition, in the printing production process, the “three-diligence” is implemented, diligent ink fountains are used, the layout surface moisture is read, and the proofs are diligently examined. “Sanqin” is an effective quality control measure in the printing process. Diligent ink fountain, diligently look at the layout of the surface moisture is an important work to maintain the consistency of the printed ink; diligently looking at the proofs requires the operator to always remove the just-printed printed sheets for inspection, mainly the accuracy of the printing position, image quality inspection. The shorter the inspection interval, the better. This can greatly reduce the scrap rate.

The above only listed several important aspects of the printing process and analyzed them. The occurrence of printing quality accidents must be conducted in many ways and with multiple channels. Each operator should have a high sense of responsibility for his work. Only the joint efforts of all staff members can improve the quality of printed matter and reduce the occurrence of quality accidents. Enterprises create higher profits.

Author: Cold phoenix

Reprinted from: Printing Technology