INDUSTRY INFO

differences between blown & cast stretch films

BLOWN STRETCH FILM

MANUFACTURING PROCESS:
- Process: Created by melting resin and extruding it through a circular die. The film is then blown into a bubble, cooled by air, and collapsed into flat film.
- Cooling: Slower cooling process, leading to more crystalline structure.
- Orientation: Bi-axial orientation (primarily in the machine direction)
PROPERTIES:
- Clarity: Generally, less clear and glossy due to the slower cooling process.
- Strength: Higher puncture and tear resistance because of the crystalline structure.
- Elasticity: Better memory, meaning it retains its stretch and cling properties longer.
- Noise: Noisier to unwind due to the structure.
- Cost: Typically, more expensive due to the complex manufacturing process.
APPLICATIONS:
- Ideal for: Securing irregularly shaped loads, handling heavy-duty wrapping needs, and providing protection for long-term storage.
- Preferred for: Products requiring higher puncture resistance and better load retention over time.

CAST STRETCH FILM

MANUFACTURING PROCESS:
- Process: Produced by melting resin and extruding it through a slot die, then cooling it on chilled rollers.
- Cooling: Faster cooling process, resulting in a more uniform film.
- Orientation: Uni-axial orientation (primarily in the machine direction).
PROPERTIES:
- Clarity: Higher clarity and gloss, making it more transparent.
- Strength: Lower puncture resistance compared to blown film.
- Elasticity: Less memory, which means it can lose cling properties faster.
- Noise: Quieter to unwind because of the smoother surface.
- Cost: Generally, less expensive due to the simpler manufacturing process.
APPLICATIONS:
- Ideal for: Wrapping uniform loads, lighter-duty applications, and when high clarity is needed.
- Preferred for: Products requiring better visual inspection, quieter application, and lower cost.

SUMMARY TABLE:

FEATURE:	BLOWN STRETCH FILM	CAST STRETCH FILM
Manufacturing Process	Blown into a bubble, slow cooling	Extruded through a slot die, fast cooling
Clarity	Less clear	High clarity and glossy
Strength	HIgher puncture and tear resistance	Lower puncture resistance
Elasticity	Better memory	Less memory
Noise	Noisier to unwind	Quieter to unwind
Cost	More expensive	Less expensive
Ideal For	Irregular loads, heavy-duty, long term	Uniform loads, lighter-duty, high clarity needed
Preferred For	Higher puncture resistance, load retention	Visual inspection, quieter application cost

This comparison should help you understand the key differences between blown and cast stretch films and determine which type is best suited for your specific needs.