Stretch Film Types

There are different types of stretch films, intended to facilitate different packaging applications. The primary purpose of a stretch film is to contain loads, usually on pallets. The purpose of the existence of different types is to ensure easier management of different kinds of loads.

All stretch films fall into two categories: blown stretch film and cast stretch film. Both stretch films are manufactured using different methods. Both of these films have different characteristics. In this article, we will discuss both briefly.

Blown Stretch Film

The stretch film made through the process of blown extrusion is known as the blown stretch film. This process uses a vertical die that forms a thin tube by extruding the plastic melt. Then a blow of air into the tube results in the formation of an air bubble with the film. The width of the film is determined by the amount of air blown into the tube. The film rotates during the process for an even distribution of the blown air. The thickness of the film depends on the speed of the film rotation and the speed of the film when it is pulled upward.

During its journey upward, the stretch film cools down. The bubble collapses to form a flat tube when it hits the roller. The film moves to another set of rollers from the first roller. That set of rollers cuts the flat tube into two layers. One side of the flat tube can be slit to form a wider stretch film.

Blown stretch film comes with an improved capacity to manage loads. That is why it is considered one of the best films for load containment. Due to better memory, the blown stretch film remains tighter to contain heavy loads. It is also tear-resistant, which makes it a more suitable option to secure loads with sharp edges.

The most significant pitfall of this film is its higher manufacturing cost. Moreover, it doesn’t offer much clarity. This lack of clarity is due to the formation of crystals in the composition of this film.

Cast Stretch Film

The film manufactured using the cast extrusion process is known as the cast stretch film. The cast extraction process utilizes a horizontal die. The manufacturers move the melt through the horizontal die. The flat slit in the die results in the formation of a flat film shape. The thickness of the film depends on the size of the slit in the die.

After the film exits the die, it moves to the chilled nip rollers that trim the film to create the desired width of the film. It then moves to more chilled rollers that cool the film. At the end of the rollers is a core that rotates to roll the film over itself. The film is cut when a significant amount of it rolls over the core.

The most significant advantage of the cast stretch film is its cost. It is cheaper than the blown stretch film. The performance of this film is also satisfactory for some types of loads. Due to the formation of fewer crystals in its composition, this film offers better clarity.

Although it can contain loads, it is not as good as blown stretch film. If you want to contain heavier loads, you may need to use blown stretch film.