When it comes to stretch wrap films, the choice between blown film and cast stretch film often depends on their manufacturing processes, usability, and cost. Understanding these differences can help you choose the right film for your application, saving time and money while improving efficiency.
How Blown Stretch Film Is Made
Blown film is created by feeding resin beads through a heated machine equipped with a circular die. The molten resin is forced through the die and blown vertically into a bubble. This bubble is then cooled by surrounding air and transformed into rolls of stretch film. Blown film generally costs more to produce due to its slower manufacturing process. However, it offers unique properties that make it ideal for specific applications.
How Cast Stretch Film Is Made
The cast process starts similarly to the blown process, with resin beads fed into a heated barrel. The resin is then forced through a narrow-slotted die to create a sheet of film. This sheet is cooled as it passes along a rolling path, solidifying the film before wound into rolls. This method is much faster and more cost-effective than blown film production, making cast stretch film a common choice for machine stretch wrap applications.
7 Key Differences Between Blown and Cast Stretch Films
| Feature | Blown Stretch Film | Cast Stretch Film |
|---|
| 1. Load Retention | Higher holding power; doesn’t re-stretch once applied | Stretches easily, even after application, causing shifts |
| 2. Film Memory | Excellent ability to shrink back to original size | Minimal ability to revert to original state after stretching |
| 3. Film Yield | Stretches further, covering more pallets with less film | Additional stretching easier with lower micron options |
| 4. Puncture Resistance | Stronger resistance to tearing under stress | Standard tearing can occur under significant stress |
| 5. Cling | One-sided cling ideal for higher load retention | Naturally clingy on both sides, causing pallets to stick |
| 6. Visual Clarity | Lower clarity; reduces glare but makes scanning harder | Crystal clear; great for reading and scanning but reflective |
| 7. Noise on Unwind | Loud when unwinding | Quiet when unwound |
Which Stretch Film Is Right for You?
Selecting the right stretch film is vital to optimizing your operations. Blow stretch film is your best bet if you need superior load retention and durability under stress. Cast stretch film is the way to go for cost-effective solutions with excellent clarity and quiet application. Ready to take your production efficiency to the next level? Discover how purging compounds can dramatically reduce scrap rates, improve machine performance, and save money. Contact our experts today to learn more and request your free sample!