1. Sealed packaging
This kind of packaging is similar to shrink film packaging, the film is wrapped around the tray to completely wrap the tray, and then two heat grippers heat seal the film at both ends. This is the earliest form of use of stretch film, and thus developed more packaging forms
2. Full Width Packaging
This kind of packaging requires the film to be wide enough to cover the tray, and the shape of the tray is regular, so it is suitable for use with a film thickness of 17-35 μm
3. Manual packing
This kind of packaging is the simplest kind of stretch film packaging. The film is mounted on a rack or held by hand, and the tray is rotated or the film is rotated around the tray. It is mainly used for repacking after the packaged pallet is damaged, and for ordinary pallet packaging. This kind of packaging speed is slow, and the suitable film thickness is 15-20 μm;
4. Stretch film winding machine packaging
This is the most common and widest form of mechanical packaging. The tray rotates or the film rotates around the tray. The film is fixed on the bracket and can move up and down. This kind of packaging capacity is very large, about 15 to 18 plates per hour. The suitable film thickness is about 15-25 μm;
5. Horizontal mechanical packaging
Different from other packaging, the film is wrapped around the article, which is suitable for long cargo packaging, such as carpets, boards, fiberboards, shaped materials, etc.;
6. Packaging of paper tube
This is one of the newest uses of stretch film, and it is better than the old-fashioned paper tube packaging with stretch film. The suitable film thickness is 30-120μm;
7. Packaging of small items
This is the latest packaging form of stretch film, which can not only reduce material consumption, but also reduce the storage space of the pallet. In foreign countries, this kind of packaging was first introduced in 1984. Only one year later, many such packaging appeared on the market. This packaging format has huge potential. Suitable for film thickness 15 ~ 30μm;
8. Packaging of tubes and cables
This is an example of the application of stretch film in a special field. The packaging equipment is installed at the end of the production line. The fully automatic stretch film can not only replace the strap to bind the material, but also play a protective role. The applicable thickness is 15-30 μm.
9. Stretching form of pallet mechanism packaging
The packaging of stretch film must be stretched, and the stretching forms of pallet mechanical packaging include direct stretching and pre-stretching. There are two types of pre-stretching, one is roller pre-stretching, and the other is electric stretching.
Direct stretching is done between the tray and the film. This method has a low draw ratio (about 15% to 20%). If the draw ratio exceeds 55% to 60%, the original yield point of the film is exceeded, the film width is reduced, and the puncture performance is also lost. easy to break. And at a stretch rate of 60%, the tensile force is still very large. For light goods, it is likely to deform the goods.
Pre-stretching is done by two rollers. The two rollers of roller pre-stretching are connected together by a gear unit. The stretch ratio can be different according to the gear ratio. The tension is generated by the turntable. Since the stretch is generated in a short distance, the friction between the roller and the film It is also large, so the film width does not shrink, and the original puncture performance of the film is also maintained. No stretching occurs during actual winding, reducing breakage due to sharp edges or corners, and this pre-stretching can increase the stretching ratio to 110%.
The stretching mechanism of electric pre-stretching is the same as that of roller pre-stretching, the difference is that the two rollers are driven by electricity, and the stretching has nothing to do with the rotation of the pallet. Therefore, the adaptability is stronger, and it is suitable for light, heavy, and irregular goods. Due to the low tension during packaging, the pre-stretching ratio of this method is as high as 300%, which greatly saves materials and reduces costs. The suitable film thickness is 15-24μm.
