Product quality inspection system commonly used in Cigarette Boxes printing
Feb 16, 2022
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Product quality inspection system commonly used in Cigarette Boxes printing
In the printing process of Cigarette Boxes, gravure printing is mainly used, and offset printing is supplemented. Because the tobacco factory has extremely high requirements for packaging quality, its quality control methods are also constantly being developed and improved.
In the printing of Cigarette Boxes, a large number of gold and silver cardboard, plain laser paper, and light beam laser paper are used. In the surface layer process, there are bump varnish, silk screen varnish, laser film, C-square laser transfer, etc. At the same time, embossing, Local processes such as embossing and die-cutting are also essential, and many processes are integrated together, which requires high quality control methods.
A prepress process
In the pre-press link, cigarette pack companies have less product types, less workload for proofreading PDF plate-making files and documents after CTPRIP, and the latest manufacturing processes such as CIP3/CIP4 are rarely popularized. With the continuous increase of product types, the "electronic document matching system" can be introduced to solve the pre-press risks such as file format conversion, imposition errors, and RIP errors.
B printing online inspection process
At the online inspection process end of cigarette label printing, there is currently the latest high-precision online inspection system for gravure, which can perform high-precision inspection of gravure below 0.1mm knife wire, overprinting and missing printing. Developed a "hyperspectral color measurement system" that can measure the color of the printing results of light beam laser paper, plain laser paper, and gold and silver cardboard. For white cardboard, the same color difference measurement results as the XRite spectrophotometer can be obtained. Paper, a hyperspectral color measurement system for stable, consistent color measurements in the event that XRite doesn't work properly. The measurement accuracy can reach 0.05ΔEab.
For the printing process of the offset press, the main problems are the color difference, dry water, ink marks and other printing defects caused by the balance of ink and water. The focus is on the control of color difference and the quality control of some printing defects. The visual quality solutions are mainly the online detection + color measurement system installed on the offset printing machine, implementing 100% defect detection and real-time color measurement of key ink key areas; due to the online detection + color measurement system of the offset printing machine, it is necessary to Structural modification is carried out on the offset printing machine to realize the system installation. If the waste rejection of the offset printing line is to be realized, a large equipment modification action is required. Printing companies generally have doubts about the transformation of offset presses. Therefore, an offline measurement system independent of the offset printing machine is also derived. It can be placed next to the offset printing machine and equipped with a balcony. The workers can directly complete the offline scanning of the sampled products during the sampling process. The vision system also gives 100% printing Defect detection results, and color measurements in critical ink areas.
With the continuous improvement of quality requirements, manufacturers of offset printing machines will be deeply aware of the value of online quality inspection, and can carry out the transformation of the structure of the offset printing machine before the new equipment leaves the factory, including reserving space for the installation of the image system and independent waste products. Warehouse and its control system, etc., the offset printing online will be greatly promoted and applied.
C process quality control process
The cigarette pack printing process technology, as shown in Figure 1, includes several variants. The main body is divided into roll material technology and single-sheet technology, including roll-to-roll hot stamping, roll-to-roll die-cutting, single-sheet hot stamping, single-sheet silk screen printing, Sheet die-cutting, etc., also includes part of the C-square (Cast&Cure) varnish process. During the process, a large number of waste products will also be generated, such as bronzing waste products, varnish waste products, die-cutting waste products, etc. Therefore, it is also necessary to carry out automatic quality control of the printing process of Cigarette Boxes, which are mainly divided into three types of process control visual inspection equipment:
1) Hot stamping online detection system;
Regardless of whether it is a round or flat stamping machine, the pressure and temperature of the stamping plate and the quality of the stamping anodized aluminum will cause quality defects such as poor bronzing transfer and lack of bronzing, and the cost of bronzing anodized aluminum is relatively high. Detection can greatly improve the yield and reduce costs, and is of great value.
At present, due to the narrow chain space on the domestic flat stamping hot stamping machine, it is still impossible to install the full-width detection system; there is more installation space on the roll-to-roll hot stamping machine, and the online detection system can be transformed. At present, domestic enterprises such as Jiujiu Color Printing, Qiaotong Color Printing, Zhiyuan Color Printing and other enterprises have taken the lead in introducing the hot stamping online detection system to control the quality of hot stamping.
2) On-line inspection system for die-cutting embossing
With the hot stamping online detection system, a detection system is installed on the die-cutting machine (if the embossing and bronzing are completed in the same process, the embossing online detection can be realized on the hot stamping machine), which can realize the quality inspection of indentation, embossing and die-cutting . Under normal circumstances, the embossing quality is difficult to control and is the focus of process inspection.
3) Independent large leaflet offline quality inspection system
In order to shorten the overall process chain, there are many users at home and abroad. Before die-cutting, an independent large-sheet offline quality inspection system is used to test the large-sheet before die-cutting. Due to the high yield of die-cutting, the genuine products after the inspection of large sheets can be directly shipped after die-cutting, without the need for final inspection. Machine, or manual inspection, and then delivered to the factory.
With this process control method, if the scrap rate is higher than 20% (large sheet scrap ratio), or the number of imposition sheets for a large sheet is relatively small, the overall production efficiency is low. And because the quality of genuine products must be guaranteed to be 100%, the precision configuration of the image system for the large single 1020mm format is relatively high, and the one-time cost investment is relatively high.
D Factory final inspection process
When most domestic users configure the visual quality inspection system, they first introduce the equipment from the last link, the final inspection of the factory, which is basically in the state of "head and foot pain doctor". However, the final inspection process at the factory is a necessary equipment. First, it is necessary to ensure that the products delivered to customers cannot be defective. Therefore, final inspection equipment develops the fastest in China and has the highest technical maturity. The final inspection vision system for cigarette pack printing quality is divided into two types: rewinding inspection machine and single-sheet inspection machine.
1) Rewinding inspection machine
The rewinding inspection machine is a final inspection quality control system that is finally delivered to the cigarette factory in the form of a whole roll during the printing of Cigarette Boxes. It is mainly aimed at soft pack products. "Mainly. In order to improve the efficiency of packing cigarettes, cigarette factories are constantly transforming the cigarette packing machines and introducing new ones, which will eventually become a major process reform trend. With the delivery method of the curled soft pack, it is basically impossible to use the single cigarette label method for random inspection. The rewinding product inspection machine solution must be used to conduct high-speed inspection of the coiled products, and screen the defects after the inspection. Finally, according to the requirements of the cigarette factory, a There are no more than 3 joints in the large plate, and the platter is shipped and delivered. At present, Yunnan Jiujiu Color Printing, Qiaotong Color Printing, Yuxi Tongying, etc. have maturely used this process, and the detection efficiency is greatly improved compared with manual work.
2) Single-sheet inspection machine
The single-sheet inspection machine is the first to be promoted in China and has the highest utilization rate. The single-sheet inspection machine for cigarette labels can adapt to the 100% quality inspection of products such as cigarette labels in hard boxes, small sheets, soft packs, and bars. Its maximum detection speed has exceeded 100,000/hour (generally stable detection speed of 60,000/hour), and the number of CCD cameras configured has been expanded from 1 to 4 to 5 cameras for joint detection.