Crosslinked film manufacturer - heat shrinkable packaging -4
Shrinkage packing method
Shrink packaging has two ways: manual thermal shrinkage and mechanical thermal shrinkage packaging.
Manual heat shrinkage is usually done by hand wrapping the wrapped items, and then hot air spray guns and other tools are used to blow the hot air of the package and finish the heat shrinkable packaging. This method is simple and quick mainly for the heat shrinkable packaging of the products that are not suitable for mechanical packaging, such as the products of large pallet assembly or the large volume single piece products, with the heat power of 1.5 * 108J/h of the heat power, and the packaging of a 2M2 product with a heat contraction of only about 2min. Only one LPG can be used except the spray gun. This method is convenient and economical, and is worth promoting in China.
The working procedure of mechanical heat shrinkable packaging is usually carried out in two steps. First, the product and the package are pre wrapped in mechanical way, that is, the shrinkable film, such as the crosslinking film, the POF crosslinking film is packed up, the necessary mouth and seams are hot sealed, then the heat contraction is then heated, and the pre wrapped product is heated in the heat shrinkable equipment. This method is most commonly used by us, so it is also our main content. In the heat shrinkable packaging, the wrapping film of heat shrinkable film is wrapped in three forms, such as cylindrical membrane, flat film and folding film. The folding film can be cut by cylindrical membrane and can be made with flat film. Wrapping the goods with cylindrical membrane, making bags and sealing seams less, but the mechanical wrapping efficiency is low and the structure is complex.
1. when pre wrapping is done, the size of the film should be 10% to 20% larger than the commodity size. If the size is too small, the filling material is inconvenient and the shrinkage tension is too large. It may tear the film. If the size is too large, the shrinkage tension is not enough, and the package is not tight or uneven. The thickness of the shrinkable film can be determined according to the size and weight of the goods and the required shrinkage tension. The commonly used heat shrinkable packaging methods are as follows: (1) open ends of the two ends: when the cylindrical membrane is used, the opening of the tube film should be expanded and the articles are sent to the cylindrical membrane with the aid of the slideway. The size of the tube film is about 10% larger than that of the item. This method is more suitable for the packaging of cylindrical objects such as batteries, paper rolls and bottles. The advantages of cylindrical film packaging are reduced 1~2 seams, beautiful appearance, shortcomings are not suitable for the variety of products, usually used in the packaging of a single variety of large quantities of products. With flat film wrapped goods, there are two ways: single flat film and double flat film wrapping. The film should be wider than the article, wrapped with a single flat film wrapped in the elbow, first unfolded the flat film, and will be wrapped in the middle of the flat film, forming a horseshoe wrapped package, then folded into a closed sleeve, and sealed by hot melt. Double flat wrap wrap, that is, two thin films are used up and down, after the first package is cut off, the two film is sealed up, then the product is pushed to the upright film by machine or hand, then the cutting mechanism is in place, the other side of the product is sealed and cut off at the same time after heat contraction. The contraction is shaped to form an oval opening, and the flat film is not restricted by the variety of the product variety. The flat film is mostly used for the packaging of a single or multiple product of the shape square, such as multiple cartons. (2) four side seal: wrap the product around (flat film) or both ends (when cylinder membrane is used). It is used for packing products with good sealing performance. If wrapped with a cylindrical membrane, it is only necessary to seal and pierce holes at the same time when the cylindrical membrane is cut off, and then heat shrink. If the folding film is used, the L type seal can be used. This way is to use the drum to fold the film, pull the film out of a certain length and put it in a horizontal position, use the mechanism or hand to open the open end and push the product to the joint. Before this, the last heat seal is cut and a transverse joint is left, and the joint two joints are not required to be sealed again. Then, a "L" type cutter is used to press down the rear part of the product and connect with the thin film, then heat cut and cut, and complete a longitudinal seam at one time. Easy operation, manual or semi-automatic. It is suitable for the products with different shapes and sizes. The occipital bag can be used with a single roll of flat film. This way is to use a single roll flat film, first seal the longitudinal seam to form a cylinder, wrap the product in it, then seal the transverse joint and cut it into pillow type packaging. Its principle is similar to the packing and packing of bag making. After sealing the four face seals, the internal residual air will expand during the heat contraction, which makes the film difficult to shrink and affects the quality of the packaging. So the needle is often installed beside the sealing device, and the puncture needle is spiny on the film when the heat seal is sealed. Small holes in sealing joints after thermal shrinkage often close by themselves. (3) one end open package: one end open shrink packaging, stacking items on pallets for transport packaging. Most of its process methods use the shrinkable packaging film (tubular membrane or flat film) and prefabricate the bag with the bag (the size of the packing bag is about 15% to 20%). When wrapping the bag, the packing bag is opened first, then the tray and the accumulations are put into the bag. When there is no special sealing requirement, the lower end is open and unsealed, and then the tray is heated to shrink. The use of pallet shrink packaging is a fast development method in transportation packaging. The main feature is that the product can be firmly bundled up in a certain number of units, and it will not be loose in transportation and can be stacked in the open air.
2. heat shrinkable operation is used in heat shrinkable packaging, which is packed with heat shrinkable film materials such as crosslinked POF, and the crosslinking film is wrapped in the package to be transported to the heat shrinkable device. The heat shrinkage device is called the heat shrinkable channel (also called the heat shrinkage tunnel), which is composed of a conveyor belt, a heater and a cooling device.
.jpg)
.jpg)