Types of pallet wrappers, and what they mean for your film

What moves: four basic types

Type	How it works	Typical use
Turntable	The pallet stands on a rotating table; the film carriage moves up and down a mast.	The most common type for regular loads.
Rotating arm	The pallet stands still; an arm carries the film carriage around it.	Heavy, tall or unstable loads that should not be spun.
Ring wrapper	A ring carrying the film carriage rotates around the pallet and moves up and down.	High-throughput automatic lines.
Orbital wrapper	The film is wrapped through the product, around a horizontal axis.	Long products, coils and profiles rather than pallets.

Many lines add automatic film cutting, top sheets, and roping (gathering the film into a rope on part of the pattern to tie the load to the pallet).

The film carriage decides the film use

Brake carriage

The film is held back by a brake while the rotating load pulls it. The stretch comes from the load itself. That puts a lot of force on the corners of the load, and the film usually stays at low pre-stretch, often well under 100 %. Film use per pallet is high.

Powered pre-stretch carriage

The film runs through two rollers, the second turning faster than the first. The film is stretched between them before it reaches the load, typically to 200–300 %. The stretch no longer depends on the load pulling the film, so the film can be run near its rating with less force on the corners.

Within powered carriages, the film path differs between designs (for example S- and W-shaped paths through the rollers). More contact with the rollers helps keep the film from slipping.

Rectangular and off-centre loads

A square pallet centred on a turntable pulls film at a fairly even speed. A rectangular pallet, or a load that is not centred, pulls film fast at the corners and slow along the sides, and the difference grows the further the load is off-centre. A good carriage adjusts its speed through every turn. If it cannot, the film is over-stretched at the corners and under-stretched along the sides, which shows up as tears or as loose film.

What this means when you test film

• Know the carriage. A film that is designed for 300 % will not show its value on a brake carriage.
• Check the real pre-stretch. The setting on the panel is not what reaches the pallet. Film can slip on the rollers, and rollers wear and collect dirt. See the right pre-stretch.
• Test on the same wrapper and load. Compare grams of film per pallet for the current film and the new one, then check that the load still holds.

Palletseal records the wrapper and its settings with every test, together with photos, so the report shows the conditions the saving was measured under.