Stretch wrapper settings: are you wasting film?

Nobody wrote that down, and nobody priced it. But if your wrapper is set up wrongly, you can be using 20% more film than you need, or you can be putting on thin film that has been stretched so far it barely holds. Either way, the settings are where the money goes.

What should a stretch wrapper actually be doing?

The job isn't to cover the pallet in plastic. It's to hold the load tight enough that it survives the process. Lantech, a stretch wrapping equipment maker, calls that containment force.

Containment force is the wrap force multiplied by the number of revolutions. It's how hard the film squeezes the load, not how much film is on it. That's why a pallet with plenty of film can still be loose, and a pallet with less can be tight.

How do you measure containment force?

Lantech says to measure it at the top, the middle and the bottom of the load. Every point needs to meet your target, not just the average.

Do it at least once per shift. A pallet that's solid in the middle and slack at the top is the one that leans in the lorry.

It takes a few minutes. Write the three readings on the load specification for that product, with the date, the shift and the initials of whoever measured. The next person to adjust the machine will know what good looks like.

How much should film stretch?

Pre-stretch is how far the machine pulls the film before it reaches the load. Pre-stretch of 150 to 300% is common, according to Lantech.

More stretch means more length from each roll, which is why people chase it. But Lantech also warns that over-stretching thin film makes it break. When that happens, operators turn the force down to stop the snapping and then add layers to compensate.

You end up using more film, not less. The machine looks efficient on the settings screen and costs you more on the stores report.

What does 20% too much film cost?

Let's work an illustrative example. A pallet takes 50 metres of film. Tune the settings and the same pallet holds with 40 metres. That's 10 metres saved, or 20% less film.

Say you wrap 1,000 pallets a week, 52 weeks a year. That's 52,000 pallets and 520,000 metres less film a year. On 500mm film at 20 micron, a metre weighs about 9.2g, which comes to roughly 4.8 tonnes.

At an illustrative £2.50 a kilo, that's about £12,000 a year. Your film, your width and your price will differ, so treat it as a way of seeing the scale, not a quote.

Not sure what yours are costing you? We'll check them with you on site.

The reverse also happens. Settings that save film but leave pallets loose cost you damaged loads and rewraps. The goal is the lowest film that still passes the containment check.

Is your film thinner than the label says?

Sometimes it is. On one site we visited, hand wrap sold as 17 micron and 300 metres measured 14 micron. The roll weighed 1,746g on a 350g core and was 500mm wide, and working back from the film weight, it held about 216 metres.

You can do the same sum yourself. Film length equals net film weight divided by density times width times thickness. For this kind of polyethylene film, use a density of 0.92. And always weigh the empty core, because it's easy to forget.

Here's an illustrative case. A 500mm, 20 micron roll with 2.5kg of net film is about 272 metres. If that 2.5kg includes a 0.6kg core, you have 1.9kg of film, or about 207 metres. That's about 24% less film than you thought you were buying.

How do you keep the wrapper settings under control?

Set up a weekly check routine. It takes 15 minutes and looks like this.

Once a shift, measure containment force top, middle and bottom on one pallet of your tallest product. Once a week, weigh a full roll, weigh the core, and work out the length. Record the number of rolls used against pallets wrapped.

Then divide. Film per pallet, in metres or grams, is the figure that tells you whether anything has drifted. If it creeps up 10% in a month, someone has changed a setting or added a layer.

Make one person responsible, usually the shift supervisor or warehouse manager, and write their name on the sheet. If the film is bought by one team and used by another, this is the figure that connects them.

Run it for a month before you judge it. The first week usually turns up the surprise, such as one product that eats twice the film of the rest, or one shift that wraps differently from the others. Those are the cheapest savings you'll find, because they cost nothing to fix once you can see them.

Frequently asked questions

What is a good pre-stretch setting?

Pre-stretch of 150 to 300% is common. The right figure depends on the film and the machine, so check what the film maker recommends and prove it with a containment check.

How often should I check wrapper settings?

Lantech says to check containment force at least once per shift. We'd add a film-per-pallet check every week.

Why do operators add extra layers?

Often because over-stretched film is breaking, so they lower the force and add turns to compensate. That raises film use without making the load safer.

How do I check how much film is on a roll?

Weigh the roll, subtract the empty core, then divide by density times width times thickness. Weigh the core every time.

We'll check your wrapper

We'll check your wrapper settings and film use per pallet on site, with your operations team, and show you the figure in metres and in pounds.

It sits inside our free site check. We walk the site with the operations team for about 30 minutes and send a written report. No contract. Where measuring a roll is needed, we arrange the testing.

We compare cost per use, not price per roll. We test what you buy, lock the spec and never swap without your approval.

Email sales@kptrading.uk or call 020 4576 5500.

Sources

Lantech, check your containment force: https://www.lantech.com/check-your-containment-force/

Lantech, how much does stretch wrap stretch: https://www.lantech.com/how-much-does-stretch-wrap-stretch-is-more-better/

KB Packaging, blown vs cast stretch wrap film: https://kbpackaging.com/blown-vs-cast-stretch-wrap-film/

Illustrative figures are labelled in the text. Images are illustrative.