5 to 400 kNTJ-125
Direct Compression Fixture
Flat, parallel platens. On a sandwich coupon the platens must stay parallel as load rises, or one facing takes the load before the other.
SpecificationsTesting standard
TAPPI T 811
Edgewise compressive strength of corrugated fiberboard (short column test)
Written and technically reviewed by Dak System Inc. engineeringLast reviewed
TAPPI T 811 determines the edgewise compressive strength of a short column of single-, double- or triple-wall corrugated fibreboard, loaded parallel to the flutes. It is the edge crush test that box compression is predicted from.
At a glance
- Test type
- Compression — the specimen is squeezed
- Published by
- TAPPI
- Edition
- ANSI/TAPPI T 811 om-23
- Material
- Paper, board & corrugated
- Runs on
- Series 7200 and Series 9000
What the test does
A short column of conditioned corrugated board is cut square, its loaded edges prepared as the method requires, and stood between flat parallel platens with the flutes running vertically. It is compressed at either a constant rate of strain or a constant rate of load — both are permitted — until it fails, and the maximum force is divided by the specimen width to give the edgewise compressive strength. Single-, double- and triple-wall constructions are all covered.
What it measures, and why it matters
How much load a wall of corrugated board carries on its edge, which is the property a stacked box is designed around. Corrugated board is a structure rather than a material: the flutes are slender members braced by the liners, and loading parallel to them tests exactly the mechanism that keeps a pallet standing. ECT is also the middle link in a chain — the component paper's own compressive strength governs the board's ECT, and the board's ECT governs the compression resistance of the finished box — so testing at the wrong link answers a different question.
Two procedures, one answer
The method allows constant strain rate or constant load rate, and states that either gives the same result within its precision.
- Board
- Single-, double- or triple-wall corrugated fibreboard
- Direction
- Parallel to the flutesThat is the direction the flutes act as columns, which is how a box wall carries a stack.
- Loading
- Constant strain rate or constant load rateBoth are permitted and studies show either yields the same result with the stated precision — an unusual and useful piece of latitude.
- Edge support
- Waxed edges, or the alternative the method providesUnsupported edges crush locally and the specimen fails at the platen instead of in its body.
- Specimen
- A short column, cut square
- Check the specimen stands square before loading
- DakA leaning column loads one edge first and fails early. It is the commonest avoidable ECT error.
ECT is the property box compression is predicted from. It is the middle link in the chain: the paper's own compressive strength governs ECT, and ECT governs how the finished box behaves under a stack.
Test speed
- Rate
- Constant strain or constant load, as chosen
- Reported
- Edgewise compressive strength per unit width
- Edges
- Prepared as the method specifies
- Record which loading procedure was used
- DakEven where the two agree, a reader cannot verify that unless the report says which was run.
Calculations
Edgewise compressive strengthECT
Maximum force divided by the specimen width
Force per unit width, commonly kN/m. Board thickness is not a usable area — the flutes are mostly air.
Where it sits in the chain—
Paper compressive strength → board ECT → box compression
Each link is measured by a different standard, and testing at the wrong one answers a different question.
How the test runs
- 01Condition the board in the standard atmosphere.
- 02Cut short-column specimens square, parallel to the flutes.
- 03Prepare the loaded edges as the method requires.
- 04Choose the loading procedure and record the choice.
- 05Check the platens are parallel.
- 06Stand the specimen between the platens and confirm it is square, not leaning.
- 07Load at the chosen constant rate to failure.
- 08Record the maximum force.
- 09Confirm the failure was in the body of the specimen, not at a platen edge.
- 10Divide by the specimen width to give ECT.
- 11Report the wall construction, the flute profile and the loading procedure with the value.
The fixture this method needs
What the report has to contain
- Reference to ANSI/TAPPI T 811 and the revision
- Board construction — single, double or triple wall — and flute profile
- Component papers where known
- Conditioning atmosphere
- Specimen dimensions and edge preparation
- Which loading procedure was used
- Maximum force and edgewise compressive strength per unit width
- Mean and variability
- Number of specimens rejected for edge failure or lean
What the machine must be capable of
Modest force, from a few hundred newtons to a few kilonewtons, through flat platens that stay parallel as load rises. What is unusual is the latitude on rate: the method permits either a constant rate of strain or a constant rate of load, on the evidence that any combination of its permitted procedures yields the same result within the stated precision. That is a genuine convenience, but the procedure used still belongs in the report so a reader can see which was relied on.
What goes wrong in practice
Specimens that are not standing square, which is the commonest avoidable error and leaves no trace. Unsupported edges, which move the failure to the platen. Dividing by the board caliper to produce a stress, when corrugated board is mostly air and the thickness is not a usable area. Reporting ECT without the wall construction and flute profile, which makes it uncomparable. And using an ECT figure where a box compression result was wanted, or the reverse: they are adjacent links in a chain, not the same measurement, and a formula exists to get from one to the other precisely because they are not interchangeable.
TAPPI T 811 or ISO 3037
| TAPPI T 811 | ISO 3037 | |
|---|---|---|
| Family | TAPPI / ANSI | ISO |
| Test | Edgewise crush, short column | Edgewise crush |
| Loading | Constant strain or constant load | As the standard specifies |
| Cite | Where the specification names it | Where the specification names it |
The same property in two families, and packaging specifications name one. Keep a data set to a single method: specimen preparation and edge support differ enough to move the number.
Questions we are asked about this test
What is TAPPI T 811?
It is the edge crush test — the North American method for the edgewise compressive strength of corrugated fibreboard, measured on a short column loaded parallel to the flutes. It covers single-, double- and triple-wall board. The current revision is ANSI/TAPPI T 811 om-23.
Why load parallel to the flutes?
Because that is the direction in which the flutes act as columns, and it is how a box wall carries a stack. Corrugated board is a structure rather than a material: the flutes are slender members braced by the liners, and their resistance to buckling in that direction is what keeps a stacked pallet standing. Loading across the flutes measures something else entirely.
Why are two loading procedures allowed?
Because studies referenced by the method showed that any combination of the specimen and loading procedures it permits yields the same result within the stated precision. That is unusual latitude for a test standard and it is evidence-based rather than a shrug — but the report should still say which procedure was used, since a reader cannot otherwise confirm the equivalence was relied on legitimately.
Why do the loaded edges need support?
Because an unsupported cut edge of corrugated board crushes locally before the specimen's body reaches its capacity. The liners buckle outward at the platen, the flutes have nothing holding them, and the failure happens where the knife cut rather than where the material is representative. Waxing the edges, or the alternative the method provides, stiffens that zone so the column fails in its middle.
How does ECT relate to box compression?
It is the middle link in a three-part chain. The component paper's own compressive strength — measured by ring crush or short-span — governs the board's ECT, and the board's ECT governs the compression resistance of the finished box. Each link has its own standard, and testing at the wrong one answers a different question from the one asked.
Why is the result reported per unit width?
Because the board's thickness is not a usable area. Corrugated board is mostly air: the flutes occupy the space between the liners without filling it, so dividing by the caliper would produce a stress that means nothing physically. Force per unit width, commonly kilonewtons per metre, is the quantity box compression formulae actually consume.
What is the commonest avoidable error?
A specimen that is not standing square. A short column that leans even slightly puts one edge into contact first, so that edge takes the load alone and the specimen fails early. It costs nothing to check and it is invisible afterwards — a leaning specimen and a weak board produce the same low number and the same unremarkable-looking failure.
Running TAPPI T 811 on the Series 7200 and Series 9000
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 | Low to moderate — corrugated ECT values commonly run from a few hundred newtons to a few kilonewtons | Load cells from 1 kg to 60 ton on the Series 7200, and 0.5 to 100 kN on the Series 9000 |
| Force accuracy | ASTM E4 over the working range | Verified to ASTM E4, and to ISO 7500-1 Class 0.5 |
| Gripping | Flat parallel platens, with the specimen edges waxed or otherwise supported as the method requires | Our compression anvils, built to the specimen |
| Environment | 23 ± 2 °C standard laboratory atmosphere | 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.