[Watch] The packaging machine has vertical and horizontal divisions. The vertical type has a continuous type (also called a roller type) and a batch type (also called a palm type). The bag has a three-side seal, a four-side seal, and a back seal. There is also a multi-column packaging equipment. There are many different types of packaging equipment, and the differences between the various equipments are also great. When actually using composite membrane coils, various problems will be encountered. This paper analyzes the causes of the six common problems in detail for reference.
First, the cursor problem
In the automatic packaging process of composite film coils, it is often necessary to perform positioning heat sealing and positioning cutting, and an electric eye cursor is required for positioning. There are certain differences in the size of the cursor and the different packaging opportunities. Generally, the width of the cursor is greater than 2 mm and the length is greater than 5 mm. The cursor generally uses a dark color with a large contrast with the background color, preferably black. Generally, the cursor cannot be used with red and yellow, nor can the color code of the same color as the photoelectric eye be used as the cursor color. For example, the light of the photoelectric eye is green. Light, you can not use the light green color as the color of the electric eye cursor, because the green photoelectric eye can not recognize the green color. If the background color is a darker color (such as black, dark blue, deep purple, etc.), then the cursor should be designed to hollow out the light white cursor.
The electric eye system of the general automatic packaging machine is a simple identification system, and cannot have the function of intelligent fixed length like the bag making machine. Therefore, in the longitudinal range of the electric eye cursor, the film film does not allow any disturbing characters and patterns, otherwise it will cause Identify errors. Of course, some of the more sensitive electric eyes, the black and white balance can be finely adjusted, for some light color interference signals can be removed by adjustment, but the color is similar to the cursor or darker pattern interference signal can not be removed.
The spacing between the cursors is used to lengthen, so the error between the actual spacing and the design value should not be too large, and generally only 0.5 mm error is allowed. For many automatic packaging equipment, the negative deviation is better than the positive deviation tracking, so it is recommended to design a negative deviation.
Aluminized or pure aluminum has a strong specular reflection, which will affect the recognition of the electric eye. It is recommended that the composite film cursor be printed on a white background. For a transparent composite film, it is also recommended that the cursor be printed with a white background due to the color of the item in contact with it, thereby reducing interference.
Second, the friction coefficient problem
The friction during the packaging process is often both drag and resistance, so the size should be controlled within the appropriate range. For automatic packaging coils, it is generally required to have a small inner layer friction coefficient and a suitable outer layer friction coefficient. The outer layer friction coefficient is too large, which may cause excessive resistance during the packaging process, causing tensile deformation of the material, if too small It will also cause the drag mechanism to slip, causing the tracking and cutting of the electric eye to be inaccurate. However, the inner layer friction coefficient can not be too small, and some packaging machines have too small friction coefficient in the inner layer, which will cause the stacking material to be unstable and misaligned when forming the bag. For the composite film for strip packaging, the inner layer friction coefficient Too small may also cause the tablet or capsule to be slipped to slip, resulting in inaccurate positioning of the blank. The inner layer friction coefficient of the composite film mainly depends on the content of the opening agent and the slip agent of the inner layer material, as well as the stiffness and smoothness of the film, the corona treatment surface during the production process, the curing temperature and time, etc., which also affect the product. The coefficient of friction. When studying the friction coefficient, special attention should be paid to the fact that the temperature has a great influence on the friction coefficient. Therefore, it is necessary to measure not only the friction coefficient of the packaging material at normal temperature, but also the friction coefficient at the actual use ambient temperature.
Third, the heat seal problem
The low-temperature heat-sealing property is mainly determined by the performance of the heat-sealing layer resin, and also related to the pressure. Generally, the extrusion temperature is higher when the extrusion compounding is performed, and the corona treatment is too strong or the film is left too long to reduce the low-temperature heat of the material. Seal performance. Hot tack is used to describe the strength of the heat seal layer's molten surface to resist external force peeling when the heat seal is not sufficiently cooled and cured. This external force often occurs in automatic filling and packaging machines. Therefore, the composite film coil for automatic packaging should be selected from heat-sealing materials with good hot tack. Anti-pollution heat sealability, also known as inclusion content heat sealability, refers to the ability to heat seal when the thermal cover adheres to contents or other contaminants. The composite film is selected according to different packaged materials, packaging machinery and different packaging conditions (temperature, speed, etc.) to select different heat-sealing resins, and a heat-sealing layer cannot be used uniformly. For packaging with poor heat resistance, a low temperature heat sealing material should be used. For heavy-duty packaging, heat-sealing materials with high heat-sealing strength, high mechanical strength and good impact performance should be used. For high-speed packaging machines, low-temperature heat-sealing and heat-sealing materials with high heat-bonding strength should be used. For products with strong pollution such as powders and liquids, heat-resistant materials with good anti-pollution should be used.
Fourth, heat sealing extrusion PE problem
During the heat sealing process of the composite film, PE will often be extruded and adhered to the heat sealing film, and the more accumulated the more the normal production, while the extruded PE oxidizes and emits odor on the heat sealing mold. Heat sealing and extruding PE can generally be solved to a certain extent by reducing the heat sealing temperature and pressure, adjusting the formulation of the heat sealing layer, modifying the heat sealing film to reduce the pressure at the edge portion thereof. However, it has been proven that the best solution is to use an extrusion compounding process to produce a composite film, or to increase the speed of the packaging machine so that the PE is not ready to be extruded onto the heat sealing film.
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