Application of Machine Vision Technology in Printing and Packaging Industry

Machine vision replaces the human eye with a video camera and replaces the human brain with a computer. The working principle of machine vision for printing and packaging quality inspection is also very simple. A camera captures (collects) the image of the product and compares it with the standard image (template) of the product in the computer. If a difference is detected and the set tolerance is exceeded The range, that is, it is determined to be a non-conforming product. Of course, the actual machine vision system is much more complicated.

1. Online detection and offline detection

The visual inspection system can be divided into an on-line inspection system and an off-line inspection system according to the carriers it installs.

The on-line inspection system is installed on printing equipment such as offset printing presses, gravure printing presses, flexographic printing presses, and code printing presses to detect print quality in real time. Prints can be either sheet or web. The visual inspection part of the on-line inspection system and off-line inspection system is basically the same in function, and the main difference lies in the processing method of defective products. When a defect is found, the online inspection system usually records the location of the defect (length: web, number of sheets: single sheet), or uses a printer, labeler, marking machine to mark the edge of the paper, number Check the record error number or the number of adjacent sheets.

Off-line inspection systems are usually installed on inspection machines or rewinders. In addition to the position detection and marking functions of the online inspection system, the inspection machine usually has a binning function and automatically assigns good and bad products to different bins based on the detection results.

2. Quality Analysis, Tracking and Management

The use of inspection equipment for quality inspection provides real-time alarms and detailed and complete analysis reports for the entire process. The on-site operator can adjust the problems in the work according to the real-time alarm and analysis report of the automatic detection equipment. The manager can follow the analysis report of the test results to track the production process, which is more conducive to the management of production technology. Because of the high-quality testing equipment required by customers, not only does it stop at the quality of the printed matter, but it also requires the ability to analyze afterwards. Some quality inspection equipment can not only improve the qualification rate of finished products, but also help manufacturers to improve the process and establish a quality management system to achieve a long-term stable quality standards.

3. What can machine vision bring us?

Obviously, although China is already a big printing country, China is not yet a printing power. We must go to the world, in addition to the use of advanced printing equipment and testing equipment, but also to improve the management level. Management is productivity, management needs efficiency, and management requires costs. Of course, all these must be guaranteed under the same quality and service. The installation of an automated visual inspection system requires a certain amount of investment in the early stages. However, the advantages of the inspection system in quality inspection will give companies long-term benefits in quality and labor costs.

The application of visual quality inspection in the printing and packaging industry can be prepress, during printing and after printing, but most of the current applications focus on post-print quality inspection. There are tens of thousands of printing companies in China, and few really use inspection systems. In addition to special industries such as banknote printing and ticketing, they are mainly in the packaging industry. The packaging industry has high requirements for printing, and the requirements for quality and color are rather special. Packaging and printing plants must have unique production advantages, technological advantages, and quality advantages to meet customer requirements for print volume, cycle, and quality. The emergence of cigarette printing companies that provide printing services specifically for the tobacco industry is an example.

To promote machine vision inspection, we must first make printing and packaging companies more aware of machine vision. Where it is installed, how it is installed, how best to achieve results, and what specific benefits it can bring, all of this needs to be continuously popularized and promoted. The practitioners of the printing and packaging industry have to put forward their own specific needs, learn and master the concept and operation of machine vision inspection; practitioners in the machine vision industry must understand the printing process, production process, operation methods and quality standards, only two closely In order to achieve the goal of improving quality, improving efficiency, and reducing costs, it is possible to have an automated visual inspection system that truly meets China's national conditions.