How Stretch Wrap is Produced
Most businesses that ship freight are no strangers to using stretch wrap to secure their loads before loading them into their trucks. After all, the last thing you want is to have your product damaged or tampered with in transit. Everyone knows what stretch wrap is, but do you know how stretch wrap is made? There are two standard types of stretch wrap—cast and blown—named after the processes used to create them. Let’s examine each one:
Cast Stretch Wrap:
As you probably gathered from its name, cast stretch wrap is formed through a cast extrusion process. Thermoplastic material is melted down into a resin and extruded through a flat die onto a chilled roll, where it re-solidifies and forms into a thin sheet. This type of stretch wrap allows for greater film clarity, requires less force to stretch, and offers great tear resistance, quiet unwinding, and superior cling. Cast stretch wrap comes in both machine grade and hand grade to ensure your company’s needs are met.
Cast stretch wrap is less expensive than blown stretch wrap, which often leads to it being the preferred option by customers, however, it does not offer the same holding power than blown stretch wrap, causing it to have less memory and tear more easily.
Blown Stretch Wrap:
This type of stretch wrap is created through a blown extrusion process. The resin is extruded through an annular slit die, usually vertically, to form a thin tube. Air is then blown through an opening in the center of the die to blow a giant bubble. An air ring is then blown on top of the tube to cool it, resulting in a resilient and robust film.
As a more premium type of film, blown stretch wrap offers a higher load and stretch capacity than its cast counterparts, but is more expensive to produce, resulting in a higher cost for the end user. It is not as clear as cast stretch wrap and is also generally noisy to unwind.
Whether you decide to use cast or blown stretch wrap, know you’ll be shipping with peace of mind!