Unitizing equipment stretches to meet demand
Stretch wrap: Is it time for lean packaging?
Users of end-of-line packaging machinery need units that can create high-quality, shipment-safe, secured loads of varying profiles at increased production speeds. They’re also paying particular attention to uptime, looking for equipment that requires minimal operator intervention to operate, reload and maintain.
In this article, Modern takes a look at some of the latest features in unitizing technology.
Stretch wrapper advancements improve load safety, quality
There’s been a big focus, directed particularly toward manufacturers of consumer goods, on improving the quality of stretch wrapped loads. “Billions of dollars of product waste occurs annually because loads are damaged on the way from the manufacturer to the retailer”
Stretch film tightly unitizes a load because it continuously attempts to contract back to its unstretched state. But, just because film is pre-stretched and applied to a load doesn’t mean the load won’t fail in shipment. Determining why loads fail, and how to stop them, is prompting shippers to develop and adhere to wrapping standards that minimize the risk of damage to product in transit.
“Just by consistently doing three things—ensuring the load has the minimum amount of containment force, locking the load to the pallet, and tucking the beginning and ending tails into the stretch film—shippers can have a massive impact on damage reduction.
“We encourage customers to look at their stretch wrapper not as the last machine at the end of the packaging line, but instead as the first and most critical machine at the beginning of their shipping and logistics process.
To help develop those wrap standards, suppliers of both automated and semi-automated stretch wrappers increasingly offer sophisticated test labs for load analysis. Lee’s company documents testing with high-speed photography showing how wrapped loads behave on shaker tables and acceleration/deceleration sleds.
“This helps determine the correct way to wrap specific loads. Research has shown that to wrap loads correctly, to ensure that they arrive at their final destination free from damage, that you must control film placement, containment force and prestretch levels.
The latest machines are capable of delivering multi-level, variable containment force as they wrap the film in a spiral up and down a load. “Once the failure points in a load are identified, we can recommend the type of film that should be used and the amount of containment force required; the correct film placement and the optimal pre-stretch level for each load; as well as set up multiple wrapping menus so a single machine can wrap multiple types of loads.
To determine the appropriate wrapping program for a given load, fully automated systems receive a signal from a palletizer, use a scanner to read load information with bar code, or are equipped with a sensor to detect load height or a scale to determine load weight. Alternately, semi-automated machines with human machine interfaces (HMIs) share graphical displays for easy wrap profile selection. Some even display the amount of containment force and prestretch applied to each layer of film.
In addition to accommodating multiple types of loads with multiple pre-programmed wrapping profiles, some of the latest stretch wrappers have multiple film carriages. A four-carriage machine, for example, can automatically switch between up to four different types of film.
“This feature allows one wrapper to service multiple production lines; alternately, it can be set up with four rolls of the same film for long, unattended production runs for labor and downtime savings. Film can be reloaded from the back of the machine without stopping its operation, keeping the operator completely out of an unsafe area.
That’s important for users who have recorded downtime as long as 5 minutes for film roll changeovers by experienced operators. Because of all the integrated safety devices they have to disable before entering the machine, and then reset after exiting.
Other ease-of-use enhancements include the engineering of lower profile automated equipment with ramps that allow single, double or triple walkie pallet jacks to load the stretch wrapper with any style of pallet.