Products move inside the box because the pack occupies space rather than restraining the item. Loose fill settles and migrates during a journey, so the void that was filled at the bench reappears in transit. The fix is a component that physically holds the product - a fitted fitment, a partition or a cut foam cavity.
Filling a space is not the same as holding something still
This is the distinction that resolves most movement problems. Void fill occupies the space around a product at the moment of packing. It does not fix the product in position.
Over a journey involving conveyors, chutes, vibration and repeated handling, loose material compacts and migrates - typically downward and into corners. The product then has room to move, and keeps moving for the rest of the journey.
Why adding more fill does not solve it
More fill delays the point at which the void reappears; it does not prevent it. It also has side effects that can make things worse.
- An over-filled carton bulges, which weakens the stack and can press on the product.
- More fill is more material cost and more bench time on every order.
- Loose material can itself abrade a polished or coated surface.
- It makes the pack larger, which raises volumetric carriage.
What actually holds a product still
| Method | How it works | Best for |
|---|---|---|
| Fitted corrugated fitment | Product sits in a shaped board structure | Most goods; recycles with the carton |
| Cut foam cavity | Product sits in a profiled recess | Fragile, heavy or finely finished items |
| Multi-cavity partition | Each item has its own compartment | Glassware, bottles, multi-item orders |
| Moulded pulp fitment | Shaped recess in moulded fibre | Consumer goods where recyclability matters |
| Correctly sized carton | No space to move into | The cheapest restraint of all, where it is achievable |
Restraint options.
The last row is worth emphasising: the cheapest way to stop a product moving is frequently a carton that fits it. See bespoke carton manufacture.
Diagnosing it properly
- Check whether the box arrives intact. If it does and the product is damaged, it moved.
- Shake a packed carton - gently, next to your ear. If you can hear or feel movement, so can the journey.
- Open a returned pack and look at where the fill has ended up. Migration is usually obvious.
- Measure the fill ratio. Below two thirds, the box is the problem rather than the fill.
The fix usually costs less, not more
This is the part that surprises people. Replacing loose fill with a fitted component typically reduces cost per order: one component instead of several handfuls, less bench time, and a smaller pack because the fitment uses space efficiently.
Add the reduction in damage and it is rarely a close comparison. See protective packaging and foam packaging.
Multi-item orders need separation, not just filling
Where several items travel in one pack, the failure is usually items knocking against each other rather than against the carton.
Fill between them helps temporarily and migrates like any other loose material. A partitioned insert that gives each item its own compartment is the structural answer - see packaging materials.
The short version
- Filling a space is not the same as holding something still.
- Loose fill compacts and migrates during a journey.
- More fill delays the problem and adds cost and pack size.
- The cheapest restraint is often a carton that actually fits.
- Shake a packed carton - if you can feel movement, so can the journey.
Frequently asked questions
Why does our void fill not stop the product moving?
Because it settles and migrates during a journey. The void you filled at the bench reappears in transit, and the product regains room to move.
Should we just use more fill?
It delays rather than prevents the problem, and it adds material cost, bench time and pack size. Restraint is the structural answer.
What is the cheapest way to stop movement?
Often a carton that actually fits the product. Where that is not achievable, a fitted fitment or cut foam cavity.
How do we test for movement before despatching?
Shake a packed carton next to your ear. If you can hear or feel movement, the journey will find it too.
Do fitted inserts slow packing down?
Usually the opposite - a product that drops into a cavity is faster and more consistent than a judgement about how much fill is enough.