Both cast and blown stretch films safely restrain and protect your goods on a pallet during packing, transit, and storage. However, there are varied performance, strengths, colours, clarity, and lengths that should be considered for your application. These specific characteristics will help determine whether cast or blown film is better suited to your needs.
Integrated Packaging’s specialist knowledge of film and equipment enables us to supply you the most effective and efficient film possible. Locally manufactured in Melbourne, Perth, and Auckland, our vast range of cast and blown stretch film has been developed throughout our 39-years of experience. This technical expertise ensures choosing the right film is a trouble-free experience for you.
Blown Manufacturing Processes
All blown films, whether mono (single layer) or co-extruded (two or more layers) have the granular resin and any additives fed by a heated screw barrel, forcing the molten resin into a circular die. The molten resin is then blown vertically upwards and outwards (commonly called a bubble). The bubble is gradually cooled by air as it ascends the tower. At the top of the tower the film is nipped together and drawn down to the slitting and winding stations via guide rollers.
Blown film is preferred to achieve higher load containment. The blown process uses high molecular weight polymers which have higher melt strength that enables the bubble to be formed. The higher molecular weight polymer give the blown stretch film higher tensile properties. These factors position blown film as the superior choice for load retention and tensile strength.
Cast Manufacturing Processes
Cast film also starts by having granular polymer fed into heated screws and barrel. The heated polymer is melted and pumped through a narrow slot die. The molten polymer exits the die onto a primary chill roll where the film is rapidly cooled and solidified. The film then passes over a secondary chill roller before being slit and wound. The rapid cooling creates a film of excellent optical properties giving the film inherent cling. The inherent cling therefore means no tackifier is required and the film is quiet to unwind. The film is then drawn through tension rollers to the slitting and winding stations.
Application Differences
Choosing between blown and cast film begins with understanding the needs of your product and the process. Cast film is appropriate for many applications. It’s clarity and quieter unwind are appreciated by customers. Blown film performs better with holding and protecting heavier loads.
Blown Film
- Higher load holding provides better suitability for heavy pallets
- Has a high resistance to puncture
Cast Film
- Comes off the roll easily and unwinds quieter
- Often used for lighter products, and loads stacked on pallets
- Excellent clarity/gloss making it easier to scan barcodes through the film
- Requires less force to stretch
Speak to the Experts
The Integrated Packaging philosophy is to produce premium quality film and sell it for what the product is worth. We can help determine just how much film you are using and how much it is costing you per application.
A higher quality film will use less material to achieve the same or better quality of wrap, at a similar or lower cost per unit, wrapped. You get much more out of a roll and use less to achieve the same job. This efficiency also means less waste will need to be recycled or discarded.
For more information on quality blown and cast stretch film, or have any other packaging queries, contact the team at Integrated Packaging.
