Pre-Stretch Ratio: How Much Film Your Wrapper Should Actually Use

Pre-stretch means the film is stretched before it reaches the load. Each extra percent of stretch means less film on every pallet, which is why it is the first place many operations look when film spend climbs. It is also the place where a small change can cause a large problem.

What limits how far you can stretch

Three things set the ceiling. The first is the film itself. Each film has a maximum stretch its manufacturer rates for, and pushing past it causes thin spots, tears and holes that can open during transit. The second is the machine. Carriage rollers and drive settings must run the film at the rated speed without slipping. The third is the load. A load that shifts or sags under tension will lose containment even when the film never breaks.

A simple test to find your setting

1. Pick three representative loads: a light one, a typical one, and your heaviest.
2. Wrap each at your current setting, then at one step higher, and inspect the film after each.
3. Check for thin spots, tears, and any film that pulls away from the corners.
4. Shake or push each load gently. Note any shift in the top layers.
5. Set the highest value that passes every check on all three loads, then recheck it each time you change film.

Record the setting on the machine or near it, along with the film lot. Film varies from one supplier and lot to the next, and a setting that worked last quarter may need adjusting after a supplier change.

Where the savings really come from

Film is one part of the cost of wrapping. Hand wrapping or a poorly set machine usually costs more in damaged loads and labor than it saves in film. Use pre-stretch to trim film spend once the load is contained reliably, not as a way to reduce wraps below what the load needs.