Before the stretch wrapping process can begin a load must first be assembled on a pallet. Once the load is on the pallet, the whole ensemble (pallet and load) is stretch wrapped together.
Assembling the load on the pallet is an important step. Load placement on the pallet is key. The load should not overhang the sides of the pallet or be more than four inches inboard. The pallet itself also plays a role and should be in good condition.
It is important when stretch wrapping not to skip steps that secure the load the pallet. One options is to wrap all the way down to the bottom of the pallet. However, this runs the risk of film punctures from forklifts or pallet jacks when picking up the load. Such large punctures to the film can propagate up the load, causing a loss of containment force and increasing the risk for load failure.
The bottom few inches of the film web are automatically rolled into a tight cable at the end of the wrap cycle. The cable is driven down just below the top deck boards of the pallet. This strong cable locks the load to the pallet and leaves enough room to clear forks and avoid the puncture problem.
There are three ways to apply stretch wrap to a pallet of products: manual, semi-automatic stretch wrapper, or high speed automatic stretch wrapper.
Hand wrapping, as the name implies, relies on people to manually stretch wrap a load. A worker secures the film to the pallet and then walks the film around the load.
Pulling a heavy roll of film around a pallet is wrapping is physically demanding - especially if done right. Imagine the awful dizzy feeling in a hot warehouse. Hand wrapping generally has the highest material cost because there is no consistency of film usage and no substantial pre-stretch. It is also very difficult to wrap a safe-to-ship load consistently.
Semi-automatic stretch wrappers come in two different machine styles - turntable and straddle. The load is place on or in the stretch wrappers wrap zone and Stretch Film is applied. Turntable models will rotate the load on a turntable while straddle style models have a wrap arm that will move around the load and apply film.
High speed automated stretch wrappers are similar to semi-automatic styles in that a machine performs the actual stretch wrapping of a load. However, automatic stretch wrappers typically include infeed and exit conveyors to automatically cycle loads through the machine.
There are a number of features that can be added to semi-automatic machines that offer some increased automation. For instance, automatically cutting and clamping the film and a remote start lanyard allow fork truck operators to remain safely buckled in their seats on the trucks even while wrapping loads on a semi automatic machine.
For more help choosing the right level of automation and machine style check out our Stretch Wrapping Fundamentals pages. That's actually the critical factor to consider - how many loads/day may not capture the surges which often occur late in the day as shipments are picked up. So loads/hour is an important factor.
