Quality Management of Packaging and Printing--Quality Control Experience (II)

Plate review

Printing plates are the basis of printing. Once the plates have problems, serious quality accidents will occur. The printing of books and periodicals is mostly based on texts, and the meaning of words and phrases between the contexts is integrated. Individual words appear to be illegible or typo, and the impact is not too great. Therefore, the state regulations allow a certain error rate. However, packaging and printing is not the case. The text is concise and simple, and the contents are compulsorily stipulated by the national standards. The required text is 100% correct. Therefore, the information provided by the customer must first be reviewed, for example, the trademark standard drawing, bar code, and product implementation standards. Such as clear and clear and then transferred to the next process, and the structure of the packaging product is also very different, in the printing plate shows the unfolded floor plan, and in order to save paper often have to fight spells, prone to a Variety of errors, so to To ensure that the printing plate is completely correct, three levels must be strictly controlled.

(1) Review of customer data.
(2) Print film review.
(3) Die-cutting knife layout review.
Each check must design a checklist, list the detailed inspection items one by one, ensure that more than three people are to be audited, and use the registration form for records to be checked.

Quality inspection of raw materials

The main substrates for non-packaged printing are thin papers such as offset paper, coated paper, sub-paper, writing paper, etc. The thickness is generally 0.18mm or less and the material is single. The main substrates for packaging and printing are thick paper, such as: whiteboard, white cardboard, PVC, gold (silver) cardboard, etc. The thickness is generally more than 0.25mm, the material is more complicated, and each material has different printing. Fitness. For example, gold (silver) cardboard is a non-absorbent material. The ink cannot penetrate on the surface and can only be dried by the natural evaporation and internal fixation of the ink itself. The drying time is longer and the surface is prone to be scratched during printing. Dirty back.

The bad quality of paper not only affects the printing, but also directly affects the post-printing process. The focus of raw material quality inspection is first on the surface strength and thickness of the paper. These two indicators have a greater impact on printing. The surface strength of the paper is poor. In the printing process, hair loss and powder fall occur, resulting in frequent cleaning of the blanket. The number of shutdowns increases and the ink is unstable. The paper thickness should be uniform and the tightness meets the standard.

We know that pressure is one of the basics of printing. If the thickness of the paper is inconsistent or the tightness is not enough, it will directly lead to constant changes in the printing pressure. As a result, the printing outlets will be imaginary, and the ink will be disorderly and disorganized. The second thing to notice is the paper's quantification, stiffness and deformation. They have a greater impact on post-press processing, and the lack of quantification and stiffness will directly affect the strength and formability of the packaging product. The amount of deformation of the paper is large, but it affects printing overprinting, and it affects the accuracy of hot stamping, embossing and embossing of the printing process, and even affects the position of die cutting.

Print quality control

Printing is the key process of packaging products. Due to the design features of packaging products, packaging printing is more difficult, mainly in the following aspects.

1. Graphic design

Non-packaged printing graphic design is relatively simple, books and magazines are mostly text plus four-color pictures, even if there is a field, flat screen or gradient, but due to the smaller size, it is easier to print. The packaging printing pursuit is the appearance of the display effect, a large area of ​​the field, flat net is more common, printing is more difficult. When printing, we must pay attention to quality issues such as ink bars, water bars, front and back light, front and rear light weights, and different sticky inks on both sides. Printing ink in the field is large. Pay attention to proper amount of dusting and avoid too low.

2. Printing batch

There are few printing batches of books and periodicals, especially periodical printing. In general, only one batch is printed, and there are few opportunities for multiple batch printing. The packaging prints are often printed in multiple batches, even for several years. And require the same color before and after, otherwise it will cause consumers' doubts. Packaging products require a consistent appearance, which determines that the packaging and printing must be faithful to the original, and that the ink color of multiple batches should be consistent. This requires:

(1) The whiteness of the paper should be the same. Try to use the same type of paper as the same manufacturer.

(2) The seal must be accurate, especially the original sample of the printed sign, must be kept sealed. In order to prevent discoloration for a long time, the main position should be cut and sealed in a plastic bag. If the film is covered with a film, it is still necessary to leave a film-like pattern, especially in the light-colored position. After the film is coated, the color of the ink changes greatly. Therefore, care should be taken when printing. When signing, you should consider the change of ink after the film is covered.

(3) Carefully record the process, the ratio of spot color inks, and the brand and amount of ink.

Due to its special use, packaging and printing products have certain requirements for the abrasion resistance and light resistance of inks. If the product is not covered or over-oiled, adding too much detackifying agent to the ink will greatly reduce the friction resistance of the ink. It is recommended that the surface be treated with a varnish plus 5% anti-friction agent or a friction-resistant oil. Ordinary inks have a certain degree of light resistance, but they are made of white ink; after the lighter agents, discoloration is likely to occur, so white ink should be avoided as a lighter agent.

Before and after the process of mutual cooperation

The post-press processing of non-packaged printed matter is relatively simple, and it is generally bound directly into a booklet. A few products will be stamped, coated, and embossed on the cover. The packaging prints are often processed through multiple processes, including hot stamping, laminating, embossing, creasing, die-cutting, and gluing. The process of finishing the carton is even more numerous and there is a lot of manual work.

When the post-processing is different, the previous process needs more attention to some problems.

(1) Any procedure must pay attention to the production of rules and regulations, and disorderly rules will lead to serious quality problems and inefficiency.
(2) Too thick a layer of printing ink may cause misprinting or reverse pulling.
(3) Printing and dusting too much will cause the film to grow, and it may also cause the screen printing not to be printed on ink or printed off.
(4) Large amount of printing water is the main cause of paper deformation, which can cause a series of quality problems such as hot stamping, inaccurate positioning of embossing and embossing.
(5) When the film is stretched, the film is pulled too tightly, which can cause the paper to bend and increase the difficulty of post-processing.
(6) When screen-printed varnishes are required, the film must be specially processed. It is best to batch after the trial. (7) The amount of glue when picking up paper is large, which can cause the paper to bend and deform.

This article takes the overall quality management as the leading ideology and focuses on the analysis of the production process. It should be noted that although the content of on-site quality management in packaging and printing production is less involved, it is also an important link in quality management. Many seniors and peers have already written articles to explain in detail, so they will not be repeated here.

Author: Zhengzhou gorgeous color printing paper Limited Cui Xiaoming Liu Jing Yang Source: "packaging and decoration printing," 2005, 10 (packaging and decoration printing)