Analysis of Function of Automatic Fault Detection System for Flexographic Printing

In the flexographic printing process, spots, streaks, ghosts, misprints, inconsistent ink colors, and other problems often occur, all of which are detrimental to production. Therefore, in the high-speed printing process, whether the print register system works stably and how the printing quality is, these are all situations that the operator must clearly understand at any time, and must actively take measures to control it so as to ensure the smooth progress of production and product quality. improve. The automatic fault detection system is such a new kind of auxiliary equipment, which can reduce the reject rate and reduce the downtime, thereby saving the production cost, increasing the production efficiency and the profit rate. It can be said that it is the operator's eyes to observe the operation of the machine.
With the development of economy and the improvement of living standards, people's demands for product quality are getting higher and higher. In order for a printing company to gain a firm foothold in the increasingly fierce market competition, it is imperative to shorten the production cycle while improving the quality of printed matter. under these circumstances. The automatic fault detection system has fully exerted its own advantages and functions, and has been greatly favored by people. It has become an important part of the flexographic printing press. The core purpose of an automatic fault detection system is "prevention and prevention," and the goal is no waste. In order to achieve the desired satisfactory results, an automatic fault detection system can emerge and point out possible problems before a noticeable and perceptible fault is formed on the printed matter. In this way, material waste can be greatly reduced, especially for the printing of flexible films that are expensive and have poor printability, such as printing on substrates such as plastics, transparent films, and metal foils. . Therefore, the automatic fault detection system can help printers to increase production efficiency, reduce waste of raw materials, reduce production costs and obtain satisfactory products.
First, the automatic fault detection system detection process in the printing machine behind the last color group to install a CCD camera, through a certain method, the lens captured print images stored in the computer's memory, the operator can clearly on the screen See the printing effect of color and overprint details, the image of the refresh rate, magnification, vertical and horizontal automatic scanning, etc. are automatically controlled by the computer to complete. In general, the fault detection sequence is from left to old, the operator only needs to input the circumference of the impression cylinder, and select the appropriate magnification to be able to clearly observe the image, and then the system can automatically store the image. In the computer memory, as the main image. Once the main image is stored, the system will automatically compare the later printed series of images with the main image as a reference. If the deviation is relatively large, it may cause malfunctions, produce rejects and defective products, and the automatic fault detection system will issue a warning. Some fault detection system monitors also have a multi-window (picture-in-picture) function. The advantage of “picture-in-picture” is that the operator can discharge the current printed image together with the main image or the image printed several days ago. For comparison, the effect is more obvious and it is more convenient to work.
Some fault detection systems also use two monitors, one for "failure analysis" and the other as a "real-time image monitor." The two monitors work in tandem and track any suspicious events such as squeegee blade lines, color misalignment, or tiny dust particles that can lead to printing failures and waste defects. occur. Usually, people cannot observe these problems with the naked eye until they have printed a large number of prints and apparently have appeared waste products before they can be observed. This will inevitably cause huge waste.
There are also more advanced and more advanced devices that have a warning alert function that can promptly warn the operator. This kind of system can analyze and classify the data. When the situation on the printing press changes, the system notifies the press operator of any problems that may occur, and clearly shows the corresponding failure phenomenon on the monitor. If you want to observe more clearly and more closely, the operator can also enlarge the corresponding part, or call up the main image for comparison.
two. Auxiliary function printing is an important part of the copying process. In order to improve the overall management level of the printed matter detection and printing process, many automatic fault detection systems are equipped with auxiliary function modules or other tools for improving production efficiency. One of the application areas of these auxiliary tools is cold-sealing inspection and gloss inspection. In flexo printing, the application of cold-sealing liquid adhesives and coating oils is becoming more and more common, and the quality requirements for prints are also increasing. .
There are two main problems in the cold seal fault detection process. First, the adhesive is a transparent material that is difficult to see with the naked eye, especially when it is used on white opaque film materials. Second, when the adhesive is applied to the back of the roll substrate material, the automatic failure detection system does not work. There is no doubt that if overprinting problems cannot be detected during the printing process, the quality of the final product will be affected and the customer will refuse to accept the product.
In terms of fault detection, if a quality data collection and reporting tool is used, process control can be greatly facilitated. A typical report will show on the screen the printing speed, the specific location of the fault on the drum, and the type of the fault. Based on this information, the press operator can easily follow and observe when the fault has occurred. , where the fault occurred, and the degree of failure of the printed matter. Some software also provides a "drum record" function that allows the press operator to take the impression cylinder to the rewind position and cut it off from the point of failure. With this tool, flexible packaging printers can estimate the reject rate of the printed product and make necessary adjustments to reduce the scrap rate and increase the profitability in the future printing process. This tool also contributes to the implementation of the quality assurance system.
III. Detection of Bar Codes Many of the jobs that were rejected or returned by customers were caused by unacceptable bar code printing. The control of bar codes has become a major issue in quality control. In fact, we cannot ask the print operator to test every bar code printed one by one to check whether it can be identified or read. Therefore, printers need an auxiliary tool for detecting barcodes to automatically identify and locate the barcode signals. The bar code detection system can check the size, quality, contrast, and "decoding performance" of the bar code, thereby improving the overall quality level of the printed matter.
The automatic fault detection system enables flexographic printing to be greatly improved, allowing the printing quality to reach a higher level and enter the market that has been occupied by gravure printing. The combined automatic fault detection system has achieved considerable success in flexographic and gravure printing. Since this technology is suitable for any web material printing process, other printing methods will realize this and learn from it.