Stretch film, or stretch wrap, is a highly stretchable plastic film that is wrapped around items. It is frequently used to unitize pallet loads but also may be used for bundling smaller items.
Due to the rising demand for the light-weight material for industrial packaging, the global stretch and shrink film market is expected to witness a growth rate of around 5.50% during the period 2017-2021 and is forecasted to reach USD 18.46 billion by 2024.
That said, in the near future, stretch films can become one of the most commonly used products you find in the industrial markets. If you are new to stretch film, here are some terms and words that you should be familiar with.
Banding or bundling is the act of applying multiple wraps of stretch film to reinforce a certain area and/or to unitize multiple units.
Blown Stretch Film
Stretch films manufactured using the blown film extrusion process are blown films. They have greater puncture resistance, but on the other hand are hazier, duller, and noisier than cast film.
Cast films are stretch films manufactured using the cast extrusion process. Typical characteristics of cast films are superior transparency, glossy, greater tear resistance, and quiet unwind, as opposed to the blown films.
A test used to measure tear resistance of materials. This method initiates a tear in a sample material, and then measure the amount of force needed.
When using a stretch wrap machine, the speed at which stretch film is supplied to the load is called film feed. Film feed rate is rarely constant as it must be accelerated and decelerated as needed on load corners to maintain consistent film tension. If not, the film tension would increase at the corners and lead to potential damage or film breakage issues.
Hand Stretch Film
Hand stretch film (or hand wrap, hand stretch wrap) is the stretch film designed for manual use. In case you use stretch wrap machines, there is a different kind of stretch film (machine film). Typically, the hand film rolls are lighter and smaller. Also, hand wrap lacks certain stretching abilities of machine wrap.
When the film is stretched or pulled, there is a tendency for the film to lose its dispensing roll width/breadth and narrow down – think of bubble gums. This narrowing tendency of the stretch film is called neckdown. It reduces the coverage each wrap provides, therefore more wrap rotations and film will be required to wrap a pallet or load.
Pre-stretch is the process of stretching the film before applied to loads. At 250% pre-stretch, one foot of purchased film can yield 3-1/2 feet of usable film. Using pre-stretched film helps to increase film strength, produce excellent film cling, improve load clarity, eliminate edge damage, and save packaging costs.
Using a bar or roller to bunch the full width of the stretch film into a rope shape is called roping. Stretch film that has been roped is extremely strong and is used to start many loads or further secure a load.
Top sheeting, or overwrap, is the amount of stretch film put on the top of a load to protect the top from dust, dirt, moisture or other objects that might damage the load during storage and shipping.