It uses cylindrical or flat film to wrap the packaged material in a sleeve before conducting heat shrinkage operations. After packaging is completed, there is a shrinkage opening at both ends of the packaging.
1. When using a cylindrical membrane, first open the opening of the membrane, then use a chute to push the product into the membrane, and then cut off the membrane. As shown in Figure 1. This method is more suitable for wrapping cylindrical items, such as batteries, paper rolls, bottles and cans. The advantage of using cylindrical film packaging is that it reduces 1-2 sealing processes and has a beautiful appearance. The disadvantage is that it cannot meet the requirements of product diversification and is only suitable for mass production of a single product.
2. Wrapping items with flat film can be done in two ways: single film wrapping and double film wrapping. The film should be wider than the item and wrapped in two flat films, one on top and the other on the bottom. When the previous packaging is sealed and cut off, the two films are sealed together. Then, the product is pushed into an upright film by machine or hand, and the sealing and cutting mechanism drops when it is in place. The other side of the product is sealed and cut off. The product wrapped in the film shrinks after heat shrinkage, and both ends of the packaging shrink to form an elliptical opening. When using a single flat film, Firstly, unfold the flat film and feed the wrapped product towards the middle of the film to form a horseshoe shaped wrap. Then, heat seal the overlap seal.
Four sided sealed:
Wrap the product around with flat or cylindrical film, and use overlapping sealing at the seams. Used for product packaging that requires sealing.
1. The L-shaped sealing method can be used for folding the film in half, using a drum to fold the film in half. Pull out a certain length of the film and place it in a horizontal position. Use mechanical or manual support to open the open end and push the product to the folded seam.
2. A single flat film can be used for pillow shaped bag packaging. This method involves using a single flat film, first sealing the longitudinal seam into a cylindrical shape, pushing the product into it, and then sealing the transverse seam and cutting it into a pillow shaped packaging, or tying both ends into a cylindrical packaging.
3. The packaging with double flat film and four sided sealing is similar to the open end packaging, which only needs to be equipped with two side sealing devices on the machine to complete.
4. Wrapping with a cylindrical film only requires sealing, puncturing, and thermal shrinkage while the cylindrical film is cut off. There is often a needle next to the sealing device. During heat sealing, the needle pricks out the vent hole on the film, and the small hole often self seals after heat shrinkage.