Guide to Blown Film Extrusion Machines
Blown Film Process Explained
The process to produce the film is similar to blowing bubbles. The blown film machine virtually replicates the blowing process on its tower-like production line except it uses polymers (plastic materials) to replace soap water and nip the continuously blown bubble into an extremely thin film. The tower structure ranges several stages high. After the film is formed, it is wound into rolls and later distributed for final applications. As one of the leading blown film extrusion machine manufacturers with over 50-year-experience in Taiwan, now CHYI YANG is going to break down the process into details and discuss how blown film extrusion works.
When the plastic polymer is fed into the machine, it enters the extruder first. The extruder is responsible for heating the raw material and mixing additives (anti-statics, adhesives, UV stabilizers, etc.) into it. The extruder is a barrel that contains a screw. The screw rotates to extrude the molten polymer to the next station. In a blown film process, there can be multiple polymers (more than one raw material). After the polymer is thoroughly molten and mixed with additives, it exits the extruder to the next station, the blown film die head.
Blown Film Die Head/Air Ring
The blown film die head is set right next to the extruder. It is configured as an annular ring so that when the molten polymer passes through the die, pressurized air is introduced to the polymer extrudate to form the tubular bubble. There are also some machines like high speed twin die blown film machines that are designed as one extruder provides two dies to get bigger capacity and less space.
The blown film die head and the air ring are vertically set for the bubble to inflate and expand upward, and hence the machine has a tower structure.
The bubble cage is a frame structure that surrounds the blown film bubble. This structure is important because it ensures the stability of the bubble inflation. Some blown film machines feature an internal bubble cooling (IBC) system (optional). The IBC system helps accelerate the cooling process and improve product quality and productivity. The molten polymer turns from liquid to solid at this stage. The blown film bubble is then ready for nipping after it reaches the ultimate stability.
Tube Collapsing Frame/Nip Rollers
The tube collapsing frame and nip rolls are implemented on the top of the blown film machine. The collapsing frame directs the bubble to the nip rolls to compress it into the film. The film will then enter the winder for collection.
▲ The red circle is the tube collapsing frame and nip rollers.
The winder is a master roll that collects the film band. The rolling speed of the winder must coordinate with the nipping rollers so that it does not result in an unwanted stretch of the band. This way of collecting the film is convenient not only for collection but also for distribution. Some machines are equipped with automatic winders which save operation time, such as CHYI YANG’s LDPE/LLDPE blown film machine. With the winder, the film is prepped into rolls and ready for transportation or end applications.
In this article, we have learned the process of extrusion and its mechanical components. Taken together, blown film machines are an important tool for the production of high-quality blown films. Blown film extruder machines are used for producing films with different properties, such as barrier, strength, and appearance. They find applications in food packaging, medical packaging, agricultural films, construction films, and more.
These machines allow for precise control over the thickness, composition, and properties of each layer, resulting in films with superior strength, flexibility, and barrier properties. There are various kinds of blown film machines, therefore selecting the right machine could be a demanding task. It is recommended to consult an experienced manufacturer like CHYI YANG.
CHYI YANG is a highly experienced and reputable manufacturer of blown film extruders and machines, with a wide range of products that meet various film extrusion needs. Our machinery is easy to operate, flexible, economical, high-performance, and energy efficient. Established in 1965, we are committed to providing efficient and reliable equipment to our clients for the production of blown films. We are confident in our products and services are a great fit for your projects.
Interested in learning more about blown film extrusion machines? Looking for a blown film solution? Get in touch with our knowledgeable team today!