Blown film extrusion plays a key role in producing plastic film.. From food packaging to agricultural films, it's used to create thin, flexible plastic that meets a wide range of needs. If you're new to the industry or want a simple overview, this guide will walk you through the basics.
What is Blown Film Extrusion?
Blown film extrusion is a method of making plastic film by melting polymer resin and forming it into a thin tube. The tube is inflated with air, cooled, and flattened into rolls of film. These rolls can then be cut, printed or converted depending on the end use.
The process is continuous, which makes it ideal for high-volume production with consistent quality.
Learn more about Swallow’s blown film equipment.
Key Components of a Blown Film Line
A typical blown film line includes the following:
- Extruder: This heats and melts the raw polymer. The molten plastic is forced through a specially shaped die.
- Die Head: This shapes the plastic into a thin circular tube. A common option is the spiral die, known for producing even film.
- Air Ring: This cools the bubble of plastic from the outside. Some systems also use internal bubble cooling for extra control.
- Haul-off and Nip Rollers: These flatten the bubble into a double layer of film.
- Winder: This collects the film into rolls, ready for the next stage.
You can read more about key components like blown film guiding and blown film handling in Swallow’s product range.
Materials Used
Polyethylene is the most common material in blown film extrusion. Variants like LDPE (low-density polyethylene), HDPE (high-density polyethylene) and LLDPE (linear low-density polyethylene) offer different levels of strength, clarity and flexibility.
Many manufacturers are now testing or switching to biodegradable and compostable materials. These alternatives help meet sustainability goals without a full equipment change.
Why Use Blown Film?
Blown film extrusion is popular for good reason. It offers:
- Strong mechanical properties
- Good film clarity
- High throughput rates
- Flexibility in film width and thickness
It’s suitable for many sectors, including food, agriculture, healthcare and retail.
Common Challenges for Beginners
New users often struggle with:
- Controlling the bubble size and shape
- Adjusting cooling settings
- Fine-tuning tension and film thickness
These challenges are normal. With proper setup and guidance, operators can learn to control these issues effectively.
Swallow offers full technical support and training, helping customers get the most from their machinery.
Final Thoughts
Blown film extrusion may seem complex at first, but once you understand the process, it becomes much more manageable. With the right equipment, training and materials, even a beginner can achieve great results.
If you're exploring blown film technology for the first time, get in touch with Swallow to learn how we can help you get started.
