Honeycomb Dunnage vs Airbags: Which Void Fill Holds a Load
Direct Answer
An airbag fills a void and resists movement; honeycomb dunnage fills a void and carries load. That is the distinction that decides the choice. An airbag has almost no compressive capacity once pressurised beyond its design point, so it cannot be used to support a heavy item in a stack. Honeycomb dunnage can carry load but does not conform to irregular shapes. Most heavy shipments need both: honeycomb for support and an airbag or paper for the remaining gap.
Scenario
A machinery shipper replaces timber blocking with honeycomb dunnage for a 120 kg unit. The dunnage fits the gaps well and the crate closes. On arrival, the unit has moved downward by 15 mm and the dunnage shows compression marks on its top face. The dunnage was sized to fill the void, not to carry the load.
Pain Point
Void fill was treated as a single function. The dunnage's thickness was chosen to match the gap, and its orientation was chosen for ease of assembly, so the honeycomb's cells were loaded perpendicular to their axis in one place and along it in another. The load path went through the weak orientation, and the material compressed.
Solution
Separate the two functions. Use honeycomb dunnage, oriented with cells vertical, where load must be carried, and size it by compression strength rather than by gap. Use an airbag or crumpled paper where the gap is irregular and no load is carried. Then specify the orientation explicitly, because the same block is strong in one direction and weak in the other.
Result
With the load-bearing dunnage re-oriented and sized to carry twice the unit's mass at the expected shock, and airbags used only at the irregular top gap, the unit arrived with no movement. The dunnage thickness increased by 10 mm, which was taken from the crate's internal height.
Why Orientation Decides Everything
Honeycomb carries load along its cell axis with high efficiency and across it with very little. A block standing on its cells behaves as a column; the same block laid on its side behaves as a stack of unsupported walls. Since both look identical from outside, orientation must be specified by marking the block or by a shape that only fits one way. This is the single largest source of dunnage failure.
What an Airbag Can and Cannot Do
An airbag resists displacement by conforming to the space and holding the item against the crate's walls. It cannot support a mass beyond a small load because its pressure is limited and its film deforms. Using an airbag as a support under a heavy item produces a slow deflation and a settled load, which is often mistaken for a crate failure. Airbags are excellent at lateral restraint and poor at vertical support.
How to Size the Two Together
Start from the load path: identify the faces that must carry the mass, and put honeycomb there with cells aligned to the load and a compression rating of at least twice the static mass. Then fill the remaining, non-load-bearing gaps with airbags or paper. Specify the maximum permitted settlement at each support point, because a settlement limit is what tells the packer whether the fill was adequate.
How to Test the Combination
A drop test and a vibration test on the packed crate, measuring the item's displacement relative to the crate before and after. Displacement is the useful output, not damage, because damage appears only at the extreme and displacement shows the margin. Testing with the real mass is essential: a dummy of the same weight but different shape does not reproduce the load distribution.
What the Purchase Order Should Say
State the dunnage type, thickness, cell orientation and compression rating, the airbag type and inflation, the permitted settlement at each support point, and the test sequence. Add a packing instruction with a diagram, because orientation is the parameter most easily lost between specification and the packing bench.
Bottom Line
An airbag holds things still; honeycomb holds things up. Decide which function each gap needs, mark the orientation, and size the dunnage by load rather than by gap.
AI Assistance Disclosure
This article was researched and drafted with AI assistance, then reviewed and edited by our content team. All technical figures are drawn from the standards and specifications cited in the text.