Why does my machine stretch film keep breaking?

Its so frustrating, Dave in the warehouse is a good fella though, and will always come up with a solution and simply get on with the job.

But that quick fix always has associated consequences, and they often don’t reveal themselves immediately. It may be that he reduces the amount of secondary tension in order to stop the film breaking, but that means the pallet isn’t tight enough and possibly not safe. So now you have another problem for Dave to solve, and he’ll probably do that by layering on rotation after rotation of film until the pallet doesn’t move. Good job, it’s a safe pallet again! But now you’re getting through a full roll of film just to wrap one pallet and its going to cost you a fortune!

If this sounds familiar, the first thing you need to do is find out why the film is breaking.  

And here are a few useful things to bear in mind when trying to get to the root of the problem.

“How is it breaking Dave?”

Observe how the film is breaking. It can give you really good clues as to why it’s happening.

Top Edge Break

                                                             Bottom Edge Break     

Edge breaks can occur for a few reasons, roll damage for starters. If they aren’t handled with care machine film rolls can easily suffer damage on the edges, scuffs and nicks in the film will often lead to breakages, make sure you’re not unduly rough with the rolls in storage or when loading the machines. If all the edges are damaged it could be a winding problem, if the winding has been uneven then the edges can sometimes overlap causing breakage.

Centre Break

Central breaks can occur due to a dink in the film just like edge breaks, damage doesn’t have to have actually pierced the film for it to break on application. Once again check for any obvious signs of a scuff or dink on the central part of the roll.

“Have you cleaned your rollers Dave?”

Check your power stretch rollers. Sticky rollers will pick up debris and a little bit of grit on a roller will just do enough to make your stretch film break as it’s applied to the pallet. Also sticky rollers can mess up the stretch ratios, if your film is sticking to the roller it can and will tear it. Most bog standard films are going to break if they are sticking to the rollers, not all the time, but enough times to make you want to fling the film across the warehouse. Just get Dave to clean the rollers regularly.

 "And while you are at it Dave, is that film threaded properly?”

Most modern stretch films are manufactured with the cling on the inside. Most modern machinery will come with some kind of threading guide. Make sure you thread the film as per the machine guide and (as a rule of thumb) so that the side of the film with the cling on it goes directly against the pallet you are wrapping. You don’t want your pallets sticking together on the back of the trailer.

If the film isn’t threaded properly, missing one of the rollers for example, it may not stretch efficiently, which means it wont be as economical as it should be or in certain circumstances secure your pallet as well as it should. And don’t just shout at Dave for threading it wrong, he may be missing the rollers for a reason, and its probably because when threaded correctly the film keeps breaking!!

Which leads us nicely on to –

Tension break

If the break appears as a straight line from top to bottom then it could be a tension break.

Tension breaks occur when the film is being overstretched. Stretch films are manufactured to be able to cope with a certain amount of even stretching being applied to them. Different films have different stretch capabilities. The grade of film you need for your machine is dictated by the what kind of machine you have and, if it’s a power stretch model, by what gear ratios it has.

The simple rule of thumb is that you must match the film to the machine. So if you have a 250% fixed gear semi-automatic stretch wrapper, then you need a film that can cope with being stretched that far. If you were to put a 150% grade stretch film on to this machine it will break as per our illustration above. Its not the films fault, it was made that way and is perfectly adequate for a non ps or 150% stretch machine.

Don’t forget though, on a power stretch machine you have two stretching process’, the mechanical stretch in between the rollers, and then the secondary lay on stretch when the film is applied to the pallet itself. So be aware that the secondary stretch needs to be taken into account when selecting a film.

And don’t forget you may just have a bloody awful pallet!

This one has the stretch film killer of an inboard load, its no surprise that when wrapped under a decent tension this pallet will break most stretch films, as will sharp pointy bits sticking out of your load.

See if there is any way you can re-stack your pallets to avoid any nasty sharp bits or pallet corners. If you can’t, then there are products on the market that are much better at coping with these problems than the more traditional films, they generally cost a bit more per kilo or roll but they don’t break when your pallets smile at them.

If all else fails get a stretch film expert in! Somebody with plenty of experience of different machines and different films, get them to help you diagnose the problem and provide a solution.

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