Analysis of product quality problems caused by the joint version

The joint version is a widely used technique in the printing industry. From the perspective of improving production efficiency and cost-effectiveness, the more versions you print together and the wider the format, the higher the productivity and output value. However, from the standpoint of equipment performance and process control, too many versions may not be beneficial. They can lead to issues such as misregistration, uneven ink coverage, paper wrinkling, and other problems that affect print quality.

For example, the "Taishan (AL)" cigarette small box printed by our company uses a 90g/m² coated paper with a 5-color offset printing process and water-based varnish. The printing process was smooth and trouble-free at first. However, the subsequent cold transfer process presented challenges. The cold transfer equipment used was domestically produced, and it had unstable paper feeding, delivery, and registration accuracy. To ensure proper alignment and improve yield, we initially opted for a smaller printing format with 9 spells. This significantly improved the performance of the cold transfer equipment and achieved satisfactory results.

Later, due to an increase in orders from the tobacco factory and tight delivery deadlines, we switched to a 15-spell printing format to boost efficiency and meet the schedule. However, the existing paper specifications were different from the original, and using 9-spell paper resulted in significant waste. Based on the available paper size, only the 15-spell format could be used. While the offset printing process remained stable, the cold transfer stage faced issues like paper feeding difficulties, wrinkling, and misregistration, leading to a sharp decline in yield and poor print quality.

As a result, many quality issues that appear to be related to paper quality are often caused by improper material selection or immature processes. It's crucial to analyze these problems carefully before making decisions.

When such quality issues occur, the following steps can be taken:

(1) Improve the stiffness of the paper through paper knocking to ensure flatness and stability during post-processing. (2) Increase the back coating process to reduce deformation caused by excessive surface tension, such as warping and bending. (3) Adjust the paper feeding direction by changing the plate layout so that the paper feeding direction during cold transfer is perpendicular to the winding direction of the printed sheet. This helps avoid issues like wavy edges, film adhesion, and pleating due to minor paper deformation.

In addition, due to the high volume of cigarette pack products later on, we made process adjustments and transitioned from offset printing to gravure printing through technical innovation. We also implemented a back coating process in the first color group to ensure the stability of the entire production flow.

The above content is reprinted from the official WeChat account "Printing Technology" (Printech1957), authorized by the company for publication. Copyright is reserved, and any unauthorized reproduction will be investigated!

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