Cast vs. Blown Stretch Wrap Films
You may have heard the terms stretch wrap, cast stretch film and blown stretch film but probably don’t know the difference, uses and advantages. Most of us may have even used these, and here’s an overview talking about all the how’s and why’s of stretch film.
Stretch Film is an extremely stretchable plastic film made from Linear Low Density Polyethylene (LLDPE). It is generally used to wrap around products as the high elasticity keeps them securely in place.
Using a stretch film to wrap products helps minimize products loss, reduces the risk of product tampering, and highly negates worker injury. A stretch film can be obtained in different types, widths and thicknesses. There are two common ways of stretch film extrusion- Cast Stretch Film and Blown Stretch Film. Both these manufacturing processes have their own distinct pros and cons.
Cast Stretch Wrap Film
A cast extrusion process is used to manufacture this type of stretch film. During the process, a thermo-plastic material is brought to molten state and then extruded using a flat die on a roller. The molten material is quenched and re-solidified at this step. This process results in great clarity and needs less force for stretching. It also enhances the tear resistance and powerful cling feature. Cast stretch film can be obtained by machine as well as hand.
- Clear and Glossy
- Quiet unwind
- Great strength in the machine direction
- Consistent machinability
- Forgiving application
- Low cost of manufacturing, thus less expensive
- Enhanced clarity
- Double sided cling
- Lesser load holding power.
- Lower tear resistance compared to blown stretch film.
Blown Stretch Wrap Film
A blown extrusion process is used to manufacture this type of stretch film. Molten plastic is extruded using an annular slit die to obtain a thin walled tube. Air is then passed through a small hole in the middle of the die to blow up the tube. Air is blown on the top to hasten the cooling process. It makes the film tough and highly resilient. The load holding capacity is also extremely high.
- Cloudy until stretched
- Slightly “Noisy” unwind
- Great puncture resistance
- Bi-directional tear resistance
- Excellent for “C” loads
- High quality, stretch and load holding power
- Maximized security for products
- High tear resistance, even for sharp edged products
- The advanced manufacturing process increases the cost
- Poor clarity
This is a basic overview on the differences between two types of stretch films. Depending on individual needs and requirements, we have the best pallet wrapping films available for your specific application.