Why stretch film tears, breaks or does not cling, and how to fix it

Where breaks come from

Film breaks are the most common problem in stretch wrapping. Lantech, a maker of stretch wrapping machines, reports that on automatic high-speed wrappers film breaks about 3 to 7 times per roll on average, and names the load itself as the most likely cause. The usual suspects, in the order worth checking:

1. The load: sharp corners, edges and anything that sticks out.
2. The roll: nicks, damaged edges and flaws in the film.
3. The settings: too much wrap force or pre-stretch for the film.
4. Temperature: film that is too cold.

1. The load

• Sharp corners and edges: cartons with hard corners, metal parts, pallet boards that stick out. Use corner boards or edge protectors.
• Uneven layers: products set back from the pallet edge, or sticking out beyond it, put the film under uneven stress. Build square, even loads.
• Overhang: the load should not hang over the pallet edges.

2. The roll

• Damaged edges: a roll that has been dropped or knocked usually breaks at the edge. Keep rolls in their boxes until use, and do not drop or throw them.
• Flaws in the film: holes, gels or thin spots break under stretch. If breaks happen at the same point on several rolls of one batch, show them to your supplier.
• Folded edges help: reinforced, folded edges resist tears that start at the edge, especially on thin pre-stretched film.

3. The settings

• Too much force or pre-stretch: every film has a limit. If breaks start after a change of film or settings, go back one step.
• Threading: film threaded the wrong way through the carriage breaks easily; follow the threading diagram of your wrapper.
• Rollers: dirty, worn or damaged rollers on the wrapper mark and weaken the film.

4. Temperature

Film makers recommend storing stretch film at about 10–30 °C and letting it adapt to the room where it will be used for at least 24 hours. Packaging suppliers note that colder film becomes stiffer, stretches less and clings less. Film stored in direct sun or in a hot place can also behave differently, so keep it indoors and out of sunlight.

Why film does not cling

• Cold: cling drops at low temperatures; warm the film to room temperature first.
• Very fresh film: the cling agent (often polyisobutylene, PIB) moves to the surface after production. Published research found that cling forces reach their maximum about two weeks after production.
• Wrong side out: with one-sided cling film, the clinging side should face the load.
• Dust and moisture: a dusty or wet surface weakens cling between the layers.
• Old or badly stored film: film makers recommend using stretch film within about a year.

Problems on the rewinding side

Many problems users see on the pallet start earlier, at the rewinder:

• Uneven tension: rolls wound too tight or too loose stretch unevenly. Jumbo rolls with varying cling make this harder; independent servo control of unwinding and rewinding, as on the SM-1300 2S and SM-1300 2S PRO, lets the operator set tension from the touchscreen for each jumbo roll.
• Edge damage: nicks on the jumbo roll edges repeat on every finished roll. Inspect jumbo rolls on arrival; see how to choose jumbo rolls.
• Short or light rolls: a roll that runs out early is often shorter or thinner than its label says. See roll length and weight.

Quick checklist