Standard 25 mm
Pneumatic Vice Action Grip
Pneumatic vice action grips clamp the full specimen width at a constant, even pressure — which is what stops one side slipping or tearing before the other.
SpecificationsTesting standard
ISO 9073-3
Nonwovens — Test methods — Part 3: Determination of tensile strength and elongation at break using the strip method
Written and technically reviewed by Dak System Inc. engineeringLast reviewed
ISO 9073-3 determines the tensile strength and elongation at break of nonwovens by the strip method, in which the full specimen width is clamped. Two specimen widths are offered — 25 mm as Option A and 50 mm as Option B — and both conditioned and wet states are covered.
At a glance
- Test type
- Tensile — the specimen is pulled apart
- Published by
- ISO
- Edition
- ISO 9073-3:2023
- Runs on
- Series 7200 and Series 9000
What the test does
A strip of nonwoven is cut to one of two widths — 25 mm under Option A or 50 mm under Option B — conditioned in the standard atmosphere or prepared wet, and clamped across its full width in a constant rate of extension machine. It is then extended to break, and the maximum force and the elongation at break are recorded. Machine and cross-machine directions are tested and reported separately, and the option used is stated with every value, because results from the two widths are not comparable with one another.
What it measures, and why it matters
How much load a nonwoven web carries before it comes apart, and how far it stretches getting there. Both matter in use: a wipe or a medical drape has to survive handling, and a filter medium has to survive the pressure differential across it. The strip geometry is what makes the number interpretable — the full width is clamped, so every fibre in the section is loaded, and the result belongs to a defined width rather than to whatever portion of the material the grips happened to recruit. The figure is a force for that width, not a stress, because a lofty web's thickness depends mostly on how hard it is measured.
Two options
Option A is 25 mm wide, Option B is 50 mm. They are alternatives, not a progression, and the results are not comparable.
- Option A
- 25 mm specimen width
- Option B
- 50 mm specimen widthThe wider option suits light or open webs where a 25 mm strip has too few bonds in section to be representative.
- Machine type
- Constant rate of extension
- States
- Conditioned and wetHygiene and medical nonwovens are used wet, and many lose most of their strength when they are.
- Directions
- Machine and cross-machine, separatelyA nonwoven laid on a moving belt is strongly oriented by the process itself.
- Cut specimens with a sharp die or template
- Not with scissorsDakA ragged edge on a nonwoven is a starting notch, and there are no yarns to arrest a tear once it begins.
Nonwovens are not weaves. There is no yarn to redistribute load around a flaw, so edge quality and specimen width matter more here than they do on a woven fabric.
Test speed
- Rate
- A constant rate of specimen extension
- Reported
- Maximum force and elongation at break
- Option
- A or B, always statedA result without the option named cannot be compared with anything.
- Reject jaw breaks
- And record how manyDak
Calculations
Tensile strength—
The maximum force recorded before break, for the stated specimen width
A force for a defined strip width. Nonwoven thickness is highly compressible, so nothing is divided by an area.
Elongation at breakEb
Eb = (ΔL / L₀) × 100
- ΔL
- extension at break
- L₀
- initial gauge length
Normally from grip separation on these materials, which is acceptable because nonwoven elongations are large enough that grip take-up is a small share of them.
How the test runs
- 01Choose Option A or Option B, from the specification.
- 02Cut specimens to that width with a sharp die or template, in both directions.
- 03Condition them in the standard atmosphere, or prepare wet specimens as specified.
- 04Fit wide pneumatic grips with faces suited to a bonded web.
- 05Set the clamping pressure to hold without cutting.
- 06Mount the specimen square and free of pre-tension.
- 07Load at the specified constant rate of extension.
- 08Record the maximum force and the elongation at break.
- 09Reject any specimen that broke in or at the jaws.
- 10Repeat for the machine and cross-machine directions.
- 11Report the option used alongside every value.
The fixture this method needs
What the report has to contain
- Reference to ISO 9073-3 and the edition
- Whether Option A or Option B was used
- Material identification and mass per unit area
- Direction tested
- Conditioning, or the wet preparation applied
- Gauge length and rate of extension
- Maximum force for each specimen
- Elongation at break, and how it was measured
- Mean and variability for each direction
- Number of specimens rejected for jaw breaks
What the machine must be capable of
Small forces, measured properly. Most nonwovens break between a few newtons and a few hundred, so the load cell is chosen for that range rather than for the frame. Grips must hold the full strip width at a pressure that does not cut a bonded web, since anything the jaw damages is simply lost from the section. A constant rate of extension is specified. Elongation is normally taken from grip separation, which is acceptable on these materials because nonwoven elongations are large enough that take-up is a small proportion of them.
What goes wrong in practice
Reporting a strength without naming the option, which makes it uncomparable. Averaging the machine and cross-machine directions, when a web laid on a moving belt is oriented by the process and the two commonly differ several-fold. Scissor-cut specimens. And testing only conditioned material for a product used wet — wipes, hygiene articles, medical drapes and filters all work saturated, and webs relying on hydrogen bonding lose most of their strength when they are.
ISO 9073-3 or ISO 9073-18
| ISO 9073-3 | ISO 9073-18 | |
|---|---|---|
| Method | Strip — full width clamped | Grab — part of the width clamped |
| Gives | Strength and elongation | Strength and elongation |
| Specimen | 25 mm or 50 mm wide | Grab geometry |
| Comparable | No | No |
Two parts of the same series covering the same property by different clamping. Neither converts into the other, and a specification names one.
Questions we are asked about this test
What is ISO 9073-3?
It is Part 3 of the ISO 9073 series of nonwoven test methods, covering tensile strength and elongation at break by the strip method — the full specimen width is clamped, so every fibre in the section carries load. The current edition is ISO 9073-3:2023, the second, published in June 2023 and replacing the 1989 first edition.
Should I use Option A or Option B?
Whichever the specification names, and it must be stated in the report because the two are not comparable. Option A uses a 25 mm specimen and Option B a 50 mm one. The wider option tends to suit light or open webs, where a 25 mm strip contains too few bonds across its section to represent the material — the result then swings with where the strip happened to be cut.
Why does specimen edge quality matter so much on a nonwoven?
Because there are no yarns. In a woven fabric a damaged edge yarn sheds its load into its neighbours through the weave, so a slightly ragged cut is partly forgiven. A nonwoven is a bonded web, and a torn or crushed edge is simply a notch with nothing to arrest a tear once it starts. Cutting with a sharp die or template rather than scissors removes an entire class of low results.
Why does the standard cover wet testing?
Because a large share of nonwovens are used wet — wipes, hygiene products, medical drapes and filters — and many lose most of their strength when saturated, particularly those relying on hydrogen bonding rather than thermal or chemical bonds. Reporting only the conditioned value would describe a property the product does not have at the moment it matters.
Why are machine and cross-machine directions so different?
Because a nonwoven web is laid down on a moving belt, and the process orients the fibres along the direction of travel to a degree that depends on how it was formed. The machine direction is commonly several times stronger than the cross direction. Averaging them would produce a figure describing neither, and would let a product pass a specification while being weak across the web.
Is elongation taken from the crosshead?
Normally yes on these materials, and the method accommodates it. Nonwoven elongations at break are often large — tens of per cent — so grip take-up and machine compliance are a small share of the total and the error they introduce is proportionally minor. That reasoning does not carry over to stiff, low-elongation materials, where an extensometer is required.
Why is the result a force rather than a stress?
Because nonwoven thickness is not a usable area. A lofty web compresses substantially under the pressure needed to measure it, so a stress computed from that thickness would depend mostly on how hard the gauge pressed. Reporting the breaking force for a stated strip width keeps the measurement honest, which is also why the option used has to accompany every value.
Running ISO 9073-3 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 — most nonwovens break between a few newtons and a few hundred newtons | 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 at the working load, which for a light nonwoven is small | ISO 7500-1 Class 0.5 — a class tighter than the method asks |
| Gripping | Wide flat grips holding the full strip width, with faces that do not cut a bonded web | Wedge, vice-action, pneumatic and hydraulic grips, 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.