How to choose jumbo rolls for stretch film rewinding

Why the jumbo roll matters

A rewinding machine changes the length, weight, core and width of the roll. It does not change the film itself. Thickness, strength, cling and colour all come with the jumbo roll, so the quality of your finished rolls can only be as good as the jumbo rolls you buy.

1. Make sure it fits the machine

The most common jumbo width is 50 cm. Wider jumbo rolls on the SM-1300 models can be slit into several narrower rolls; see rewinding vs slitting.

2. Thickness and length

Thickness decides how many metres you get from each kilogram, and therefore how many finished rolls you get from each jumbo roll. Ask for the nominal thickness and its tolerance, and the length on each jumbo roll. Longer jumbo rolls also mean fewer jumbo changes per shift. See stretch film thickness.

3. Cast or blown

Cast film is clear and quiet; blown film is tougher and more puncture-resistant. Most hand and machine rolls are made from cast film. See cast vs blown stretch film.

4. Layers and performance

Modern cast film is co-extruded in several layers, so that the outer layers can be designed for cling and the inner layers for strength. The number of layers on its own is no guarantee of quality. Ask the supplier for the film's performance data, such as how far it stretches, how well it resists punctures and tears, and how it is recommended to be used.

5. Cling

• One-sided or two-sided: some films cling on one side only, so that wrapped pallets do not stick to each other. Know which one your customers expect.
• Cling develops over time: the cling agent (often polyisobutylene, PIB) moves to the film surface after production, so cling keeps building for some time. Published research found that cling forces reach their maximum about two weeks after production, and that warmth speeds the process up. Very fresh film can therefore cling less than it will later.
• Consistency: cling that varies from one jumbo roll or batch to the next makes tension harder to set. Rewinders with independent servo control, such as the SM-1300 2S and SM-1300 2S PRO, let the operator adjust tension from the touchscreen for each jumbo roll.

6. Jumbo rolls for pre-stretched film

A standard jumbo roll can be pre-stretched, but to a lower ratio. For high ratios such as 500% on the SP-1400, you need a jumbo roll made for pre-stretching. See standard or special jumbo roll?

7. Colour and additives

Colour and additives such as UV stabilisers are added when the film is made, so they are already in the jumbo roll. Order them by name in your specification. See black and coloured stretch film.

8. Check every delivery

• Labels: width, thickness, length or weight, and a batch number on every jumbo roll.
• Edges: straight and undamaged, with no nicks. A small nick at the edge can start a tear on every roll you make from it.
• Shape: no telescoping (layers pushed out to one side), flat spots or crushed areas.
• Film: no holes, gels or streaks when you unwind the first metres.
• Weight: weigh the jumbo roll and compare it with the stated length, width and thickness, using the formula in roll length and weight.

Keep a sample and a photo of each batch, so you can trace a complaint back to its jumbo roll.

9. Run a trial

Before you order in volume, rewind a sample jumbo roll on your own machine. Check how the film runs at your normal speed, how much tension it needs, and how the finished rolls look, cling and stretch. If you can, let a customer test them too.

10. Store them well

Film makers typically recommend storing stretch film indoors, out of sunlight and moisture, at about 10–30 °C and 25–60% relative humidity, using it within a year, and letting it adapt to the room for about 24 hours before processing. Stack jumbo rolls so their edges are not pressed or damaged.