The production of composite flexible packaging materials must go through multiple processes such as design, plate making, printing, compounding, slitting, and bag making. Each process has key quality control points. In order to obtain continuous and stable quality flexible packaging products, in addition to conventional control methods The influence of changes in processing factors on quality cannot be ignored. The following briefly discusses the effects of changes in processing factors on the quality stability of composite flexible packaging materials .
I. Processing elements of composite flexible packaging materials
"Processing factors" as the name implies are all important factors that have an impact on the processing of composite flexible packaging materials, which can be divided into "static factors" and "dynamic factors". Static factors include: manuscripts, standards, quality standards, operating specifications and other documentary items that have a reference or production guidance role; dynamic elements include operators, materials used, process methods and processing parameters, processing environment, equipment use and time cycle, etc. . Processing element control is a comprehensive control method of the system, covering the control of various problem points.
The production process of flexible packaging composite film includes preliminary preparation, formal production and post-processing until the finished product is put into storage. Each stage has corresponding influencing factors, such as: the customer's graphic design draft is the element of plate making, the printed color standard is the basis for comparing colors when printing, the work instruction for each process is the instruction file during operation, and the processing parameter settings Be sure to refer to process data, confirm the first product during trial production, and check according to quality standards and test specifications. These documents can also be considered as the "management elements" of processing. Different teams can produce the same product on the same machine, and the same team can also produce the same product on different machines. To produce the same type of products, the same raw materials from different suppliers can be used, or the same raw materials can be used by different teams. Production of the same product, processing on different machines, the processing parameters of the two machines are not necessarily the same. Similarly, in different processing environments, other processing elements must be changed accordingly to ensure stable product quality. These variable influence factors can also be considered as "process elements".
"Management elements" and "process elements" are two major aspects of the stable quality of composite flexible packaging materials. Analyzing the resulting quality problems can be targeted prevention, and control nodes for certain types of quality problems can also be found.
Second, common changes in processing elements
The printing process is the source of the flexible packaging composite film production. Now, the printing process is taken as an example to explain the changes of the elements under normal circumstances.
1. Customers change design samples. Before printing and making plates, it is very common to change the design manuscript, such as adding and modifying text content, adjusting pattern layout, and so on.
2. According to the processing adaptability requirements, the technical draft of the sample before plate making is technically modified, for example, the line is thickened, and the direction of the text or bar code is adjusted.
3. Due to customer revision, single or multiple plate rollers are modified or remade.
4. Re-sign or replace the color standards.
5. According to the layout and specific production conditions, the processing technology sheet has been modified, especially the changes in process parameters.
6. Documentary instructions for a certain problem point during printing were added, such as the provisions on the proportion of remaining ink used, the requirements for controlling the number of joints or post-processes, and the requirements for the number of meters of printed semi-finished products.
7. Changes in raw materials (including films , inks, solvents) and auxiliary equipment (including squeegee blades, pressure rollers, ink circulation pumps, ink dispersion rollers, winding paper tubes, etc.).
8. Changes in equipment functions, such as tension system, air pressure, temperature control system, air supply and exhaust system, cooling device, overprint system fluctuation or sudden abnormality, etc.
9, production temperature and humidity environment changes, such as the difference between winter and summer, the difference between day and night, the difference between sunny and rainy, the difference between wind and no wind.
10. The production team changes, different captains, experience, skills and grasp of quality standards will be different, sometimes it may be very different, the speed of processing issues is also different, so the change of the team will directly affect the consistency of product quality.
11. Changes in the production cycle, the same product, the same material, the same shift, the same machine, the same set of processing technology, even in a constant temperature and humidity production environment, once a weekly production and monthly production orders are possible Different quality problems occurred.
12, add ink, ink viscosity changes.
13, printing plate, scraper wear, pressure roller deformation.
14. Change the material and pass the raw material joint.
15. Stop and start during the process.
16. The processing quality is abnormal during startup.
17. The personnel in the production process temporarily leave the post.
18. Illegal operations.
The above is a common situation of changes in the processing conditions of the printing process.The following processes have similar changes in the processing conditions such as compounding, slitting, and bag making. If all the processing factors are constant, the product quality will be stable, but these changes will occur at any time. Directly or indirectly affect the stability of product quality.
Third, the impact of changes in processing factors on product quality
In the production process of composite flexible packaging materials, changes in processing elements exist objectively. Analyzing their impact on product quality stability can reduce the occurrence of quality problems. It can reduce the possibility of personnel, equipment, materials, process technology or operating procedures, production environment, etc. Periodic or temporary changes that occur are subject to planned controls to avoid adversely affecting product quality.
1. Management elements
Changes in management elements, including personnel structure, data, and communication methods, among which the accuracy, speed, and place of information transmission are the most important. After these changes, the most basic requirement is that the carrier of information and the communication method must not be in error. For example, the revision of printing, the revision information is sent from the customer, and the pattern and text changes must be achieved by modifying the printing plate. Compared with the old layout, there have been changes here. If the changed information is not transmitted to the workshop manager and operator level, If the old version is not dealt with accordingly, the printed product may still be the old version. Such quality accidents are often in large quantities and costly.
Furthermore, quality standards and testing methods, which are important management elements, are often considered to be standardized and will not change easily, but in actual operation, this will often change. For example, the internal quality standard of a flexible packaging company as a management element is usually higher than the customer standard or the national standard for insurance purposes. In fact, after the product is made, one or some indicators are not qualified according to the internal standard, which is just slightly higher. For customer standards, in order to avoid losses, internal standards are often lowered to be checked and accepted according to customer standards. The change of the quality standard here has also changed the "unqualified" products into "qualified products".
There is also this situation: a certain index of packaging materials is very important for customer use, and strict control is required during inspection. At this time, the sampling plan must be changed, the sampling ratio should be increased, and the batch of products passed under the original sampling plan. After strict sampling, it may become "nonconforming product". Similar changes in this kind of management element have no substantial impact on the quality of the finished product itself, but it plays a decisive role in determining whether the product quality is qualified.
The management elements can not only guide the production of correct and stable products, but also influence the quality level of the products. They can even turn unqualified products into qualified products, and they can also turn qualified products into unqualified products.
High-quality products are designed and manufactured, not tested. If you only understand product quality control from this perspective, "process elements" can play a decisive role in product quality. These changes must be closely monitored by the operator. So as to correct immediately when an abnormality occurs, or use other changes in conditions to compensate for changes that could not be corrected before, so as to play a balancing role.
Changes in process elements, in addition to the five major factors of "human, machine, material, environment, and law" that affect quality, are also changes in the time period. In the practice of flexible packaging processing and production, when analyzing and finding the cause of quality problems, the captain often complains that this condition is the same as the last production, the environment has not changed, the machine has not changed, and the process parameters have not changed. Why is there a problem with the same batch of materials? This kind of complaint is more common when there are problems with abnormal batch characteristics. Every condition the captain has called hasn't changed, it's just a superficial condition. In fact, it must be a certain factor that affects the quality of the product. For example, operations that cannot be quantified, and equipment parameters affected by abnormal materials. For example, when mixing two-component glue, after the main agent, curing agent, and solvent are added in proportion, they should be stirred uniformly. What is considered uniform? Standard enterprises will require the use of a pneumatic stirrer to stir for ten or five minutes. Minutes, there is no time requirement, the operator often according to experience, which increases the randomness. Although it is considered that the stirring is uniform, in fact, unevenness may cause the abnormality of intermittent curing of the composite film.
Changes in process elements are often linked. Changes in one factor will bring changes in other factors. Here we must pay attention to control. For example, in the bag making process, if the machine is in normal production and all parameters remain stable, a film joint is passed during the film passing process. After this joint is recognized by the electric eye, the position of the heat seal pattern may be changed, and the joint is pressed by the sealing knife. After that, the balance of the sealing knife is affected, and the insulation cloth may be broken. After these changes occur, it will directly affect the heat sealing effect of the film behind the joint. After the chain changes, it must be properly corrected to restore the original balance. To ensure stable quality.
From the above analysis, it can be seen that "management elements" and "process elements" are indispensable for stabilizing and ensuring the quality of flexible packaging products. Their changes will affect product quality and require equal attention.
How to prevent hidden quality hazards caused by changes in processing conditions
To manage changes in processing elements to prevent quality problems caused by changes in processing conditions, we can use "program management" and "data management". Because there are too many changing factors in the production process of composite flexible packaging materials, if effective management is not carried out, it will inevitably have an adverse effect on the stability of product quality. What is effective management is to statistically classify all changed elements and make procedures. Documents to minimize the adverse effects of actual or potential changes.
Everyone is familiar with procedure management. Similar to the procedure files in the quality management system, they can be classified and explained on a management system, clearly how to manage changes, determine the responsibilities of each department of change management, change classification, control methods, and quality risk assessment. Individual projects that do not need to be included in change management. In addition, it provides rules for processes, change applications, change approval, change implementation, change acceptance, and quality analysis before and after changes. In response to changes in one or several processing factors, a single item of management procedures can be done, and each related post is executed in accordance with the management procedures, which can prevent problems. For example, control programs for adjusting ink viscosity, composite glue configuration management program, joint management program, process adjustment management program, etc.
Data management: Based on this, you can analyze the magnitude of the impact of the change, in order to determine the entry point of the impact of the change, which need to be controlled or verified, and which do not. Through data management, especially major changes in equipment functions, new material trials, etc., it is necessary to find the regularity through statistical analysis of the data and evaluate the changed quality risks. Through improving change management measures, the goal of stabilizing product quality is finally achieved.
V. Handling of abnormal quality due to changes in processing conditions
Changes in processing conditions will bring hidden dangers to the product quality or directly cause poor quality. How to deal with this abnormality? In the case of changes in processing factors and without effective control, the product will inevitably have abnormal quality. The conventional processing method is to spot check the product, find the abnormal product isolation range, then remove the defective product or reprocess it to become a qualified product, analyze the cause of the accident synchronously or after rework processing, develop preventive measures, and subsequently verify the preventive measures. Implementation effect, further improvement, etc., similar to the "PDCA" cycle.
In addition to the above conventional methods, the analysis of quality factors should increase the content of change factor analysis, so that the point of change can be specifically identified, and targeted prevention can be done at this node. For example, for a batch of dry and complex products whose solvent residues exceed the standard quality accident, to find the place that has changed from normal production, first of all, whether there is any abnormality in the air intake and exhaust volume of the machine and equipment, and whether the set parameters are consistent with the actual operation. Whether the user has arbitrarily increased the machine speed, whether the ambient temperature is too low, whether the coating amount is too large, whether the solvent residue of the incoming printed film is high, and whether the curing temperature is lower than the process requirements. When the product quality is abnormal, the node that can change can always be found. This node is the focus to be controlled. Because a change in processing conditions will bring quality problems or hidden dangers, it is often possible to make up for possible problems by changing other conditions, such as the above example of solvent residues. If the ambient temperature is too low, such as in winter in the north, you can Through the workshop heating, increase the drying temperature, preheat the film, reduce the machine speed, etc. to compensate for the adverse effect of ambient temperature on the control of solvent residues.
We must be aware of the adverse effects of changes in processing conditions on product quality, and we can also use the changes in conditions to improve product quality. Because changes exist objectively, to find the cause of abnormal quality, based on stable product quality, one or more processing conditions can be changed to improve the quality level. For example, to increase the heat-sealing strength of the bag, the formula of the heat-sealing layer can be adjusted, the thickness of the heat-sealing layer can be appropriately increased, and the heat-sealing temperature or pressure can be increased. As the overall quality level increases, the chance of abnormality will be greatly reduced.
6. Concluding remarks
Changes in processing factors will affect the quality and stability of the composite flexible packaging materials. In the complex production process, especially the diversification of "dynamic elements", it is very difficult to grasp and control. Some changes are hidden, and it is difficult for the operator to find them directly. Therefore, sampling tests according to the sampling rules are necessary. Quality problems can be found in time by sampling and testing, so that the changing factors can be found in reverse, and adjustments and corrections can be made to avoid batch An exception occurred. In the dynamic processing process, changes are ubiquitous. Do not extravagant preventive measures can avoid all quality problems. What can be prevented is only changes that have been found with experience, and changes that are not foreseen are difficult to prevent. To ensure high-quality products, we need to have rich quality management experience, constantly explore the change factors, and have management measures for important changes, so that we can consider all aspects and multiple perspectives, do quality verification, and do our best Reduce quality issues.