How does the blowing process of a bubble film machine operate?

Bubble film machine is a type of anti pressure, moisture-proof, and shockproof chemical product machine used for packaging and filling. Its products are applied to the outer packaging of electronic instruments, household appliances, handicrafts, glass products, handicrafts, bicycles, and other items. But some production packaging problems may occur, resulting in unusable packaging. So what are the reasons for this?
1. The low extrusion temperature results in poor resin plasticization, resulting in poor transparency of the bubble film after machine blow molding. The solution is to increase the extrusion temperature appropriately to ensure that the resin can be uniformly plasticized;
2. In order to solve the problem of unstable film bubbles caused by the large blowing expansion ratio of the product, which can swing back and forth from left to right and easily cause wrinkles, it is necessary to appropriately reduce the blowing expansion ratio of the bubble film machine;
3. Adjusting the cooling device to ensure uniform air flow at the air outlet can achieve uniform film thickness. Therefore, when the air supply volume around the cooling air ring is inconsistent, resulting in uneven cooling effect, adjustment is necessary.

How does the blowing process of a bubble film machine operate?
The bubble film machine has a very important process, which is film blowing. This article explains how the film blowing process of the bubble film machine is operated. During the blowing process, low-density polyethylene (LDPE) is in a molten state when extruded from the mold mouth, with good transparency. After leaving the mold mouth, the expansion area of the film bubble needs to be cooled by a cooling air ring. When the cooling air blows towards the plastic film bubble just extruded from the machine head at a certain angle and speed, the high-temperature film bubble comes into contact with the cooling air, and the heat of the film bubble is taken away by the cold air. Its temperature will significantly drop below the viscous flow temperature of low-density polyethylene (LDPE), causing it to cool, solidify, and become blurry. On the blown film bubble, we can see a boundary between transparency and blurriness, which is the dew point (or frost line). During the blowing process of the film blowing machine, the dew point has a certain impact on the film performance. If the dew point is high and located above the blown film bubble, the blown expansion of the film is carried out in the liquid state. The blown expansion only thins the film, and the molecules are not subjected to stretching orientation. At this time, the blown expansion film performance is similar to that of the cast film. On the contrary, if the dew point is relatively low, the blowing process is carried out in the solid state. At this time, the plastic is in a high elastic state, and the blowing process is like horizontal stretching, causing the molecules to undergo orientation, thus making the performance of the blown film close to that of the oriented film. Extruder temperature: When blowing low density polyethylene (LDPE) film, the extrusion temperature is generally controlled between 160 ℃ and 170 ℃, and it is necessary to ensure uniform head temperature. If the extrusion temperature is too high, the resin is prone to decomposition, and the film becomes brittle, especially causing a significant decrease in longitudinal tensile strength; If the temperature is too low, the resin will have poor plasticization and cannot be smoothly expanded and stretched. The tensile strength of the film is low, and the surface gloss and transparency are poor. There may even be patterns like wood rings and unmelted crystal nuclei (fish eyes). Blowing ratio: Blowing ratio is one of the key control points in the production process of blown film, which refers to the ratio between the diameter of the film bubble after blowing and the diameter of the pipe ring that has not been blown. The blowing expansion ratio is the lateral expansion ratio of the film, which actually involves stretching the film horizontally. Stretching will have a certain degree of orientation effect on plastic molecules, and the blowing expansion ratio increases, thereby improving the lateral strength of the film. However, the blowing ratio should not be too large, otherwise it can easily cause unstable film bubbles and the film is prone to wrinkling. Therefore, the expansion ratio should be appropriately combined with the traction ratio. Generally speaking, the expansion ratio of low-density polyethylene (LDPE) films should be controlled between 2.5 and 3.0. Traction ratio: Traction ratio refers to the ratio between the traction speed of the film and the extrusion speed of the pipe ring. The traction ratio is the longitudinal stretching ratio, which enables the film to have a directional effect in the direction of extraction. As the traction ratio increases, the longitudinal strength will also increase, and the thickness of the film will become thinner. However, if the traction ratio is too large, the thickness of the film is difficult to control, and it may even break the film, causing film breakage. The traction ratio of low density polyethylene (LDPE) film is generally controlled between 4 and 6. Dew point: Dew point, also known as frost line, refers to the boundary between the viscous flow state of plastic and the high elastic state.