We’ve had a lot of enquiries recently about how pallet wrapping machines should be set up to optimise the usage of film and also give the best load stability. I thought I’d take the time to share some of the main points in a post, please read on if your role involves operating or managing packaging operations, or purchasing of packaging materials.
1. Clean the rollers
On the film carriage of the machine, give the rollers a visual check. Look for two things:
a.) labels / dirt built up around the rollers. This will impede the film application and will need to be cleaned off using rags and a suitable cleaning chemical. b.) score marks in the rubber of the rollers. This is caused when snapped film winds round the rollers and an operator uses a knife to cut it off. Cuts in the roller will cause further film snappages.
2. Check the de facto stretch %
Although all machines have a set stretch % ratio, this often comes out very differently when the film is applied to the pallet. To check this, mark a set distance on the roll of film and then wrap the pallet. Find your marks on the wrapped pallet and measure the new distance between them. If 10cm stretches to 30cm the machine is stretching to 300%.
3. Check that the film is threaded correctly
On each machine there is a diagram showing how the film should be threaded through the rollers. Check that the film is threaded as such. Bypassing the rollers often indicates that a poor quality film is being used and is snapping if threaded correctly, so the rollers are bypassed to reduce the stretch.
4. Check film carriage / turntable speed for overlap size
Wrap a pallet. Watch how much the film overlaps on each rotation. Aim for a 30-50% overlap on each turn of the film, any less than this could be detrimental to the pallet stability, any more is wasteful.
5. Check film type is suitable for the machine
There are two main types of machine, power pre-stretch machines and core brake machines. A power pre-stretch needs to be using standard unstretched film of a suitable stretch capacity for the specific machine. A core brake machine needs to be using pre-stretched film.
6. Check the containment force on pallet
This is to test the strength of the wrapped pallet. The simplest method is just to pull on the film at the top of the pallet and see if it ‘feels’ strong enough however a more scientific method should be used if possible. A pull test kit can be used to measure the containment force of the film in KG’s, or a fully digital load cell can be wrapped into the pallet to produce a graph measuring the pallet retention precisely and without human error. This is useful when comparing different types of film.
7. Check the weight of pallet wrap being applied
Check the weight of film used per pallet by cutting the film of a wrapped pallet and weighing it. As a rough guide, if it is any more than 200g then there is potential to save some good money – obviously this depends on a lot of factors such as the size of the pallet and weight / viscosity of goods being wrapped.
8. Ask the operators!
Lastly – ask the operators if they are having any problems with the machinery! They are the ones using it day-to-day and will be able to tell you if there is anything amiss!
how pallet wrapping machines should be set up to optimise the usage of film and also give the best load stability.