Glossary of Terms: Key Vocabulary in Blown Film and Polybag Manufacturing

Blown film and polybag manufacturing can feel full of technical jargon. For clients, new employees, or anyone entering the industry, it helps to have a clear guide to the words used every day. This glossary explains key terms in simple language, making it easier to understand how the process works and how different parts fit together.

Key Terms in Blown Film

Extruder
The extruder is the machine that melts plastic pellets and pushes the molten material through a die. It is the first step in the blown film process. For more details, see How the Blown Film Process is Done Efficiently and Sustainably.

Die
The die forms the molten plastic into a narrow tube, which is then expanded with air to create film. Different die designs change film quality and thickness.

Bubble
Once the plastic exits the die, air is introduced to inflate the tube into a bubble. The bubble’s stability and size play a key role in film strength and consistency.

Frost Line
The frost line is the point where the hot, molten plastic cools and solidifies into film. Its position is important for film clarity and thickness control.

Nip Rollers
These rollers flatten the bubble at the top and guide it into the next stage. The rollers also control film thickness and line speed. Swallow’s Turning Bar & Idler systems are a good example of equipment that supports smooth handling.

Key Terms in Polybag Manufacturing

Gusset
A gusset is a fold pressed into the side or bottom of a bag. It allows the bag to expand, giving it more volume and strength.

Sealing
This is the process of joining layers of film together to form a finished bag. Seals can be made using heat, pressure, or adhesives.

Cutting
Cutting shapes the bags from rolls of film. In high-speed production, cutting and sealing often happen at the same time.

Perforation
A line of tiny holes that makes bags easier to tear from a roll or open when in use.

Handle Cut
In some cases, polybags are designed with a built-in handle cut-out, making them easier to carry.

Technical and Process Terms

Gauge
A measure of film thickness. In packaging, gauge is often expressed in microns. The right gauge balances cost, strength, and flexibility.

Tensile Strength
Strong tensile properties are essential for making bags that last. High tensile strength is key for durable bags.

Barrier Properties
Barrier properties describe how well a film blocks gases, moisture, or light. Films with effective barrier qualities are commonly chosen for food storage and packaging.

Web Guiding
A system that keeps film aligned as it moves through the line. By keeping film aligned, precise web guiding leads to better results and less material loss. For more on this, see Why Blown Film Needs Precise Web Guiding.

Winders
Machines that roll the finished film onto cores for storage or later use. Advanced winders allow smooth rolls with even tension. Swallow offers a full range of film winders designed for efficiency and reliability.

Why This Glossary Matters

For new employees, learning the language of blown film and bag making speeds up training and builds confidence. For clients, understanding these terms makes conversations with suppliers clearer and more productive. It also helps in choosing the right products for a given application.

Swallow offers a wide range of blown film equipment and handling solutions, including turning bars and idlers, web guiding systems, and winders. Knowing the right vocabulary makes it easier to see how these components fit into the full process. You can explore more in the Swallow Knowledge Base.

Final Thoughts

Blown film and polybag manufacturing use a lot of technical terms, but they don’t have to be confusing. With a simple glossary, both staff and clients can feel more confident in understanding how film is made and how bags are produced. To talk to an expert, reach out to us today.