With a growing focus on efficiency and sustainability, many business owners are moving away from traditional blown film packaging and opting for cast film instead. Currently, cast film is used by around 70-80% of the packaging industry worldwide, a shift driven not just by popularity but also by its unique advantages.
While cast film’s popularity alone may tempt you to make the switch, understanding the distinct production processes and characteristics of each type can help you make a truly informed decision.
Understanding Cast and Blown Film: The Key Differences
The primary difference between cast and blown film lies in how they’re made, which directly impacts their physical properties and ideal uses.
Blown Film
Blown film production follows a traditional method where heated resin is extruded through a circular die, creating a bubble that rises many feet into the air. This height allows the film to cool slowly before being collapsed and rolled flat. Due to the stretching involved in this process, blown film naturally has a high level of pre-stretch and an adjustable thickness based on the tube’s diameter.
Cast Film
Cast film, on the other hand, is produced by extruding heated resin through a flat die, then cooling it immediately on large, chilling rollers. Unlike blown film, cast film undergoes minimal pre-stretching, giving it enhanced depth for applications like thermoforming. By adjusting the cooling rate, manufacturers can alter the film’s properties, and it can even be thinned further by increasing the roller speed.
Choosing Between Cast and Blown Film
When deciding on the best type of film for your packaging needs, several factors come into play, including environmental conditions, storage and shipping methods, and the degree of pre-stretch required. Here’s a breakdown of the benefits and limitations of each option.
Blown Film: Key Benefits
- Higher Puncture Resistance: Ideal for heavy, sharp-edged items such as construction materials, where durability is crucial.
- Less Clarity: Due to crystallization in the production process, blown film may have a hazy appearance, which can be a drawback for barcode scanning.
- High Cling Level: This can be beneficial for certain applications but might require more effort to handle in some cases.
Cast Film: Key Benefits
- Ease of Use: Cast film unrolls smoothly and quietly, making it easier to work with in busy environments.
- High Clarity: The transparency of cast film allows for easy barcode scanning, making it popular for products stacked on pallets.
- Requires Less Force to Stretch: This property can reduce material usage and make cast film a more sustainable option.
- High Tear Resistance: Despite being thinner in some cases, cast film provides excellent tear resistance, suitable for lighter items.
In Summary
Choosing between cast and blown film depends on your specific packaging needs. Blown film is well-suited for heavy-duty, sharp-edged items, whereas cast film is a great choice for items requiring clarity, ease of application, and a lighter touch. Both types offer distinct advantages, but with industry trends leaning towards cast film, it’s clear that this option is increasingly meeting the needs of modern packaging demands.