Discussion on the quality management of the hottes

2022-08-12
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On the quality management of packaging and printing

review of printing plates

printing plates are the basis of printing. Once there are problems with printing plates, serious quality accidents will occur. The printing of books and periodicals is mostly text-based, and the meaning of words is integrated between contexts. The meaning of words is often not mistaken in individual words, and the impact is not too great. Therefore, the national regulations allow a certain error rate. However, packaging and printing are not. The words are concise and comprehensive, and many contents are mandatory by national standards, requiring the words to be 100% correct. Therefore, first of all, the data provided by customers should be reviewed one by one, such as trademark standard drawings, bar code numbers, product implementation standards, etc. after being clear, they should be transferred to the next process. Moreover, the structure of packaged products is also very different, and the expanded plan is displayed on the printing plate, And in order to save paper, it often needs to be spliced, which is prone to various errors. Therefore, to ensure that the printing plate is completely correct, we must strictly control the three checks

(1) customer data review

Degradable plastics have been greatly developed

(2) review of printing film

(3) check the structure of die-cutting blade

each level should design a checklist, list detailed inspection items, check them one by one, ensure that more than three people review, and record with the rising raw material cost and energy cost pressure registration form for verification

quality inspection of raw materials

the main substrate of non packaging printing is thin paper, such as offset paper, coated paper, sub powder paper, writing paper, etc. the thickness is generally less than 0.18mm, and the material is single. The main substrate of packaging and printing is thick paper, such as white board paper, white cardboard, PVC, gold (silver) cardboard, etc. the thickness is generally more than 0.25mm, and the material is complex. Each material has different printing suitability. For example, gold (silver) paperboard is a non absorbent material. The ink on its surface cannot be penetrated by the conventional electronic universal material testing machine. It can only be dried by the natural volatilization and internal fixation of the ink itself. The drying time is long, and the surface is easy to be scratched and the back is easy to be scratched during the printing process

the deterioration of paper quality not only affects printing, but also directly affects the post press process. The focus of raw material quality inspection is first of all the surface strength and thickness of paper, which have a great impact on printing. The surface strength of the paper is poor, and there will be depilation and powder loss during the printing process, resulting in frequent cleaning of the blanket, increased downtime, and unstable ink color. The thickness of the paper should be uniform and the tightness should meet the standard

we know that pressure is one of the foundations of printing. If the paper thickness is inconsistent or the tightness is poor, it will directly lead to the continuous change of printing pressure, and the result is that the printing points are false and the ink color is disordered. Second, we should pay attention to the paper's weight, stiffness and deformation, which have a great impact on post press processing. Insufficient weight and stiffness directly affect the strength and molding of packaged products. The deformation of paper is large, which may affect the printing overprint, the accuracy of hot stamping and embossing in the post press process, and even the positioning of die cutting

printing quality control

printing is the key process of packaging products. Due to the design characteristics of packaging products, it is difficult to package and print, mainly in the following aspects

1. graphic design

the graphic design of non packaging printing is relatively simple. The printing of books and periodicals is mostly text plus four-color pictures. Even if there is field, flat or gradual change, it is relatively easy to print because of its small size. While the packaging printing pursues the appearance display effect, large-scale field and flat are more common, and the printing is more difficult. When printing, we must pay attention to the quality problems such as ink bar, water bar, heavy front and light rear, light front and heavy rear, and different ink colors on both sides. The ink volume of field printing is large. Pay attention to the proper amount of powder spraying to avoid too low

2。 Printing batch

there are few printing batches of books and periodicals, especially periodical printing. Generally, only one batch is printed, and there are few opportunities for multi batch printing. And the packaging printed matter is often printed in multiple batches, or even unchanged for several years, and the ink color is required to be consistent, otherwise it will cause consumers' doubts. Packaging products require appearance consistency, which determines that packaging and printing must be faithful to the original, and the ink color of multiple batches of products must be consistent. This requires:

(1) the whiteness of the paper should be consistent, and try to choose the same manufacturer and the same model of paper

(2) the sealed sample should be accurate, especially the original sample of the printed signature sample, which must be kept in the sealed file. In order to prevent discoloration after a long time, the main positions should be cut and sealed with plastic bags for storage. If the printed matter is covered with film, it is also necessary to retain the film covering sample, especially the light color position. The ink color changes greatly after the film covering, so you should be extra careful when printing. When signing the sample, the change of ink color after coating should be considered

(3) carefully record the process, the proportion of spot color ink, the brand and dosage of ink

packaging and printing products have certain requirements for the friction resistance and sun fastness of inks due to their special uses. If the device of the electronic universal testing machine should pay attention to the precautions that the product is not covered with film or over oiled, adding too much debonding agent to the ink will greatly reduce the friction resistance of the ink. It is recommended to use inking oil plus 5% friction resistant additives or apply friction resistant oil for surface treatment. Ordinary inks have certain sun fastness, but they are made with white ink; It is easy to fade after medium light agent, so white ink should be avoided as medium light agent

the cooperation between the front and rear processes

the post press processing of non packaging printed matter is relatively simple, which is generally directly bound into a book, and a few products will be subject to simple processing such as hot stamping, film coating, embossing, etc. on the cover. Packaging and printing products are often processed through multiple post processes, including hot stamping, film covering, embossing, paper mounting, die cutting, box pasting, etc. There are more processes for hardcover cartons, and there are a lot of manual operations

when the post-processing is different, the pre-processing needs to pay more attention to some problems

(1) pay attention to the stability of production rules in any process. Disordered rules will lead to serious quality problems and low efficiency

(2) too thick printing ink layer may lead to inaccurate hot stamping or reverse drawing

(3) if the printing powder is too large, it will cause the film to be scratched, and it may also cause the ink not to be printed during printing or the ink to drop after printing

(4) large amount of printing water is the main reason for paper deformation, which will cause a series of quality problems such as hot stamping, inaccurate position of pressing concave convex, etc

(5) when laminating, the film is pulled too tightly, which will cause paper bending and increase the difficulty of post-processing

(6) when printing varnish is required on the film, special treatment must be carried out on the film. It is best to batch it after trial.

(7) when mounting paper, there is a large amount of glue, which will cause paper bending and deformation

this paper takes total quality management as the leading idea, and focuses on the analysis of production technology. It should be noted that although the content of on-site quality management of packaging and printing production is less involved, it is also an important link in quality management. Many predecessors and peers have written articles to explain it in great detail, so it will not be repeated here one by one

Author: Zhengzhou Huamei Color Printing Paper Co., Ltd. Cui Xiaoming, Liu Jingyang

source: packaging and upholstery printing 2005, 10 (packaging and upholstery printing)

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