In the increasingly strict environmental protection policy and depressed market environment, the soft bag industry is facing great survival and development pressure. The rising cost of raw materials calls for technological innovation constantly. How to break through the original technical bottleneck, improve the printing quality and efficiency, and improve the competitive strength of enterprises are the topics of common concern.

According to the 13th five year plan of China, China has become a world printing power with international influence, which needs to lay a solid foundation for building a world printing power. It is emphasized that, focusing on the industrial development trend of digitalization, informatization, networking and intelligence, we should promote the integration of modern science and technology in printing and brush industry, and realize the overall transformation to digitalization.

I. quality problems encountered in soft packaging industry
At present, the competition in soft packaging industry is fierce. How to reduce labor and improve production efficiency is a big trend. In this context, to speed up the printing speed, increase the printing width, and improve the quality requirements of printing products often lead to a higher rate of waste products in the production process, and more difficult to control the production quality. How to better manage the production quality has become an important problem encountered in the development of the industry.

At present, the profit of soft packaging printing industry is very small. The average level of the industry is about 30% of gross profit and 10% of net profit. The main reasons are as follows:
1. The competition is fierce, and customers purchase several companies to reduce the price;
2. The customer requirements are increasingly strict, and the scrap rate is increasing.

The current printing process includes printing, compounding, cutting and rewinding. The speed of each process is very fast. In the production process, the human eye cannot accurately identify the defects, and the standards of quality control of different processes cannot be unified. The waste products of the previous process cause the waste of the next process, and the waste products flow to the end customer is more serious, which means rework or order loss.

Figure 1 common printing defects

The conventional quality control methods are to irradiate the printing products with strobe lights, to observe the printing defects by naked eyes and to detect the printing defects by sampling with testing equipment.

Fig. 2 printing defects of strobe light and still picture observation

These two quality control methods lead to a large number of defective products missing inspection, because:
1. These two detection methods belong to the nature of sampling inspection, which can only detect continuous defects, resulting in missed detection;
2. Relying on manual inspection, it is easy to produce visual fatigue, resulting in defects missing inspection;
3. The printing speed is faster and faster, these two detection methods can not achieve 100% comprehensive detection, resulting in the defect missed detection leading to the defect missed detection;
4. Simple defect detection, lack of defect classification and analysis, unable to judge the defect.
There are a lot of product waste caused by missed inspection and customer complaints. Here are two cases to share.
Case 1:
The annual output value of a composite membrane product is 30 million, with a gross profit of 35% and a net profit of 10%. Most of the orders are large orders with a length of more than 60000 meters. They are printed in 7 colors and coated with aluminum film. The cutting width is more than 40 cm. The yield of the product is 95.3%, and the cost loss caused by waste products is about 1 million yuan.

Fig. 3 waste sample of soft bag printing factory

Case 2:
A major customer of a well-known printing factory complained that after a batch of 5-ton film bags were loaded with products, obvious defects such as ink block, ink strip and printing blur / wrinkle caused by printing oil rejection were found. The customer thought that the appearance was poor and it was difficult to read, so all of them were manually removed and repacked As a result of the final discussion, the printing factory shall bear all the losses caused thereby.
2. Necessity and perfect scheme of automatic quality
Marriott company in-depth study of the quality problems encountered, studied a set of high-speed photo taking using optical camera, high-speed computer processing image data, 100% quality full inspection detection scheme, and according to the personalized needs of different customers, provided a series of solutions.
1. Online detection solution

Figure 4 online detection system

The camera is installed on the flexographer or gravure printing machine. If any problem is found, it will give an alarm in time to prevent material waste. It can effectively reduce the rate of production waste, adjust the production volume according to the order quantity, ensure the delivery and reduce waste at the same time.


However, after the defects are detected, the printing machine can not directly stop to deal with the defects, so we have two options: one is to label the defects, and the other is to transfer the detection data to the rewinder through the Internet, so as to achieve online detection and offline elimination.
2. Online detection offline waste removal solution

Figure 5 online detection offline elimination solution案

This solution solves the problem of on-line detection of a large number of data transmission, as well as the problem of difficult to find the defect downtime caused by the film pull-up, and can improve the following problems in the soft package printing production process:
(1) there is no need to rewind the printing roll without defects to improve the production efficiency;
(2) detect printing defects and realize the function of eliminating defects while reminding;
(3) preserve defect data to provide basis for improving printing quality in the future.

3. Printing quality offline detection solution

Figure 6 offline detection system

The off-line detection system can eliminate the defective products in the last process of soft package printing, no matter what the printing quality is, to ensure the quality and provide customers with high-quality products.