Cast Film Machine and Blown Film Machine are both equipment used to produce plastic films, but there are some significant differences in their working principles, production methods and properties of the films they produce. Here are their main differences:
1. Differences in production processes
Casting machine: A casting machine extrudes molten plastic and presses it directly into a film through a casting head. The molten plastic flows smoothly to form a film, which is then quickly cooled and solidified on a cooling roller to form a film. The process is a "flat drawing" form, where the film is stretched directly from the die to the cooling roll.
Film blowing machine: The film blowing machine extrudes the molten plastic through a ring die to form a film tube, and then blows it with gas (blowing film) to shape it. The film tube is stretched and expanded into a film shape. Finally solidified by cooling system. This process is a form of "blowing", where the film becomes thinner through the expansion of air.
2. Thin film structure and properties
Casting machine: Because the casting machine cools and shapes by flat drawing, the film produced is usually more uniform, smoother, and has higher transparency. The surface of cast film is smooth and delicate, and usually has no obvious bubble structure. Cast film is suitable for applications that require higher transparency and smoothness, such as food packaging, plastic wrap, etc.
Film blowing machine: The film produced by the film blowing machine usually has a more obvious bubble structure. The surface of the film may not be as smooth as the cast film, and the transparency is also slightly worse. Blown film is generally more stretchable and stronger, so it is widely used to make high-strength, durable packaging films (such as garbage bags, shopping bags, packaging bags, etc.). Blown film film thickness distribution may not be as uniform as cast film, but it can be improved by adjusting technical parameters.
3. Application areas
Casting machine: Because the film it produces has a smooth surface, high transparency, and good flatness, the casting machine is usually used for products that require higher transparency and appearance requirements, such as food packaging, transparent films, flexible packaging films, etc.
Film blowing machine: The film produced by the film blowing machine is suitable for most daily packaging applications, such as garbage bags, shopping bags, industrial packaging films, agricultural films, etc. due to its good stretchability and durability.
4. Production speed and efficiency
Casting machine: The production speed of the casting machine is usually fast, suitable for large-scale production, and can maintain high film quality and stability. However, due to different cooling methods, the thickness control of the film may be slightly complicated.
Film blowing machine: The production speed of the film blowing machine is relatively slow, and the thickness and strength control of the film may be complicated due to bubble expansion and film stretching.
5. Stretchability and strength of membrane
Casting machine: The stretchability of the cast film is relatively poor, but it has good transparency, smoothness and uniformity, and is suitable for products that have higher requirements on the surface of the film.
Blown film machine: The film produced by the blown film machine has better stretchability, higher strength and durability, so it is suitable for packaging applications that require strength and toughness.
6. Equipment complexity and cost
Casting machine: The structure of the casting machine is relatively complex, especially the design and adjustment of the cooling roller, which may increase the cost of the equipment. Due to its high equipment requirements, the initial investment of a tape casting machine is relatively high.
Film blowing machine: The film blowing machine equipment is relatively simple, the production process is more intuitive, and the cost of the equipment is low. Film blowing machines are suitable for a larger range of film production, and equipment maintenance is relatively simple.
Casting machines are suitable for producing films with high transparency and high uniformity, such as food packaging and packaging films with high requirements. It is characterized by a smooth film surface, high transparency, and is suitable for applications requiring finer film properties.
Film blowing machines are suitable for producing stronger and more durable films, such as garbage bags, shopping bags, etc. It is characterized by good film strength and stretchability, which is suitable for a wider range of applications, but the transparency and surface smoothness of the film are relatively low.
The two have their own strengths and weaknesses in applicable industries and products based on different needs.
