Testing standard
Packaging — Complete, filled transport packages — Compression and stacking tests using a compression tester
Written and technically reviewed by Dak System Inc. engineeringLast reviewed
ISO 12048 tests complete, filled transport packages in compression. It offers two methods: a constant-speed test that squashes the package to failure and reports peak force, and a constant-load test that applies a defined load and checks whether the package survives it for a defined time. The second is much closer to what a warehouse actually does.
A complete transport package, filled and closed as it ships, is conditioned to a defined atmosphere and stood between two large flat platens. The standard then offers two routes. In the constant-speed method the platens close at 10 ± 3 mm/min and the package is compressed until it fails, with the peak force and the deflection at peak recorded. In the constant-load method a load calculated from the intended stack is applied and held for a defined period — hours or days — and the package is judged on whether it survives, with deflection tracked throughout. Whether the upper platen is fixed or free to pivot is selected and recorded in both cases.
Between them the two methods answer two different questions: how strong the package is now, and whether it will still be standing after the storage period the supply chain imposes. The distinction matters because fibreboard creeps. A package with an ample margin on peak compression can collapse under a sustained load well below that peak, and every warehouse failure of an apparently well-qualified package traces back to this. The constant-speed method is the practical tool for development and quality control; the constant-load method is what qualifies a package against real storage, and it is the closer analogue of what actually happens to goods in a stack.
The choice between the two methods is the most consequential decision in this standard, and it should follow the question being asked rather than laboratory convenience.
A package that passes the constant-speed test at a comfortable margin can still fail the constant-load test, because fibreboard creeps. Peak strength and sustained-load survival are different properties and one does not imply the other.
Maximum force sustained in the constant-speed test, in N
Reported directly, with no area normalisation.
F = m × g × n × k
The safety factor is where the difference between a laboratory minute and a warehouse month is accounted for. It is not a formality.
Direct compression platens sized above the package footprint. For the constant-load method the requirement is different from a normal compression test — the frame must hold a steady load for hours or days rather than ramp to a peak.
SpecificationsLarge platens, enough daylight for the package height, and force measurement to ISO 7500-1 Class 1 across a range from under a kilonewton to tens of kilonewtons. For the constant-speed method the crosshead must hold 10 ± 3 mm/min. The constant-load method places a quite different demand on the frame: it must hold a steady load for hours or days without drift, which is a control problem rather than a ramping one, and it occupies the machine for the whole period. The platen arrangement must be genuinely fixed or genuinely pivoting as selected, and the laboratory needs proper humidity control throughout.
The most consequential error is using the constant-speed result to qualify a package for storage, which ignores creep entirely and is the standard route to a stack that collapses after three weeks. Optimistic safety factors in the stacking load calculation do the same thing more subtly. In the laboratory, inadequate humidity control dominates the scatter, and long constant-load tests run in an uncontrolled room drift away from their conditioning as they go. Recording only pass or fail on a constant-load test throws away the deflection curve, which is the only evidence distinguishing a package with real margin from one that barely survived.
| Constant speed | Constant load | |
|---|---|---|
| Question answered | How strong is it now | Will it survive the stack |
| Duration | Minutes | Hours to days |
| Output | Peak force | Pass or fail, plus a creep curve |
| Accounts for creep | No | Yes |
These are not two ways of getting the same number. Fibreboard creeps, so a package with an ample peak strength can still collapse under a sustained load well below it. Development work uses the constant-speed test; qualification for real storage should use the constant-load test.
It is the ISO standard for compression and stacking tests on complete, filled transport packages. It offers two methods: a constant-speed compression to failure that reports peak force, and a constant-load test in which a defined load is applied and held for a defined time to see whether the package survives.
It depends on the question. For development and quality control — comparing board grades, verifying a design change, checking a production batch — the constant-speed test is quick and discriminating. For qualifying a package against real storage, the constant-load test is the right one, because it is the only one that accounts for creep. Many programmes use the first routinely and the second for type approval.
Because fibreboard creeps under sustained load. The constant-speed test squashes the package over a few minutes, during which creep has no time to act. In a warehouse the load sits there for weeks, and the board slowly deforms until the structure loses stability. A package with a comfortable margin on peak strength can still collapse under a steady load well below that peak.
From the mass of one package, the number of packages that will sit above the one at the bottom of the stack, gravity, and a safety factor. The safety factor is doing the important work: it covers the difference between a laboratory test and months of storage, humidity variation, uneven stacking and handling damage. Choosing it too optimistically is the usual reason a package that passed qualification fails in the field.
Because a package is rarely perfectly square. A pivoting upper platen follows the package and spreads the load across all its walls; a fixed platen does not, so a high corner takes the load first and the package fails earlier. Both arrangements are defined and both are used, but they can give substantially different results, so the arrangement is recorded and results from different arrangements are not compared.
Yes, and for fibreboard it is not a refinement. Compressive strength falls sharply as the board takes up moisture, so an uncontrolled laboratory produces results that vary with the weather. For long constant-load tests it is worth going further and holding the package in the conditioned atmosphere throughout the hold, since a package conditioned and then held in an ordinary room drifts away from its conditioning during the test.
The deflection through the hold, always. A package that survives but deflects steadily and continuously is close to its limit and will not survive a longer storage period, a warmer warehouse or a slightly heavier stack. A package that deflects a little at first and then stops has genuine margin. Those two outcomes are both recorded as a pass, and only the deflection curve distinguishes them.
Dak verifies against whichever standard the method names, and where a class applies our frames sit a class tighter than it asks.
| The method asks for | Dak supplies | |
|---|---|---|
| Capacity | Wide — from under 1 kN for a light carton to tens of kilonewtons for a heavy filled package | Load cells from 1 kg to 60 ton on the Series 7200, and 0.5 to 100 kN on the Series 9000 |
| Force accuracy | ISO 7500-1 Class 1 over the working range | ISO 7500-1 Class 0.5 — a class tighter than the method asks |
| Gripping | Two large flat platens, with the upper platen fixed or free to pivot as the selected method requires | Our compression anvils, built to the specimen |
| Environment | Conditioned to a defined atmosphere before test, commonly 23 °C and 50 % RH; other atmospheres are used for tropical or cold-chain qualification | 3009 series chambers, −150 °C to +400 °C — temperature only |
This page describes the method as practised. The governing text is the current edition from the issuing body. Tell us what you are testing and we will answer with the machine, the fixture and a quotation.
