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
ASTM D1683/D1683M
Standard Test Method for Failure in Sewn Seams of Woven Fabrics
Written and technically reviewed by Dak System Inc. engineeringLast reviewed
ASTM D1683/D1683M pulls a sewn seam apart perpendicular to the stitch line and records the maximum force together with how it failed. The failure mode is the practical output: broken stitching can be re-sewn, while displaced or severed fabric yarns cannot, so the two outcomes have entirely different consequences.
At a glance
- Test type
- Tensile — the specimen is pulled apart
- Published by
- ASTM
- Edition
- D1683/D1683M-22
- Runs on
- Series 7200 and Series 9000
What the test does
A specimen containing a sewn seam, either cut from a finished article or made up as one of the standard seam assemblies the method defines, is conditioned and clamped in wide-faced grips so that the seam lies centrally between them and runs across the specimen. It is then pulled at the specified constant rate of extension until the seam gives way. Two things are recorded: the maximum force, and which of three things failed — the sewing thread, the fabric yarns at the stitch line, or the grip of the seam on the cloth as yarns slide out of the weave.
What it measures, and why it matters
Nominally the strength of a seam; practically, what to do about it. The failure mode carries the commercial consequence. A thread rupture with the fabric intact means the article can be re-sewn and returned to stock. Severed fabric yarns or slippage mean the cloth itself has been compromised, a new seam would go into damaged fabric, and the article is scrap. Two garments can post identical seam strengths and have opposite outcomes, which is why a force reported without a mode tells a manufacturer nothing about whether to change the thread, the needle, the stitch density or the fabric.
Seam and failure mode
Three things can give way — the thread, the fabric yarns, or the grip of the seam on the cloth — and only one of them is repairable.
- Sewing thread rupture
- The stitching breaks, fabric intactThe repairable outcome. The garment can be re-sewn and returned to service.
- Yarn severance
- Fabric yarns cut at the stitch lineNot repairable — the cloth itself is damaged and re-sewing puts the new seam into damaged fabric.
- Seam slippage
- Yarns pull away from the seam without breakingA hole opens beside the stitching. It looks like a construction fault and is usually a fabric one.
- Seam assembly
- One of the standard assemblies, or as taken from the articleA seam from a finished garment and a laboratory-sewn seam answer different questions.
- Orientation
- Force applied perpendicular to the seam
- Condition to the standard textile atmosphere before testing
- DakSewing thread and fabric both change strength with moisture, and a seam result combines the two.
Record the mode on every specimen. A seam strength quoted without it cannot tell a manufacturer whether to change the thread, the needle, the stitch density, or the cloth.
Test speed
- Rate
- The constant rate of extension the method specifies
- Reported
- Maximum force and failure mode
- Seam efficiency
- Seam strength as a proportion of fabric strengthRequires the unseamed fabric to be tested as well, in the same direction.
- Check needle damage under magnification
- On slippage and severance failuresDakA blunt or oversized needle cuts yarns during sewing, and the seam then fails at a load the cloth should have carried easily.
Calculations
Sewn seam strength—
The maximum force recorded before the seam fails
A force, not a stress. The seam has no meaningful cross-sectional area, so nothing is normalised.
Seam efficiencyE
E = (seam strength / fabric strength) × 100
- seam strength
- maximum force at the seam, N
- fabric strength
- breaking force of the unseamed fabric in the same direction, N
Only meaningful when both are measured on the same fabric in the same direction, so the fabric has to be tested too.
How the test runs
- 01Decide whether the seam comes from a finished article or a standard seam assembly.
- 02Where a standard assembly is used, select it from the method for the fabric's yarn count.
- 03Condition the specimens to the standard textile atmosphere.
- 04Cut specimens with the seam central and running across the specimen.
- 05Fit wide-faced pneumatic grips and set the clamping pressure to hold without cutting.
- 06Mount so the force will be applied perpendicular to the seam.
- 07Load at the specified constant rate of extension.
- 08Record the maximum force.
- 09Classify the failure as thread rupture, yarn severance or seam slippage.
- 10Inspect severance and slippage failures under magnification for needle damage.
- 11Where efficiency is required, test the unseamed fabric in the same direction and calculate it.
The fixture this method needs
What the report has to contain
- Reference to ASTM D1683/D1683M and the edition
- Fabric identification, construction and direction tested
- Whether the seam was from an article or a standard assembly, and which assembly
- Sewing thread type and size, needle size, stitch type and stitches per unit length
- Conditioning atmosphere
- Rate of extension
- Maximum force for each specimen
- Failure mode for each specimen
- Seam efficiency where calculated, with the fabric strength used
- Any evidence of needle damage
What the machine must be capable of
Modest force — sewn seam strengths in woven fabrics run from tens to a few hundred newtons — with grips wide enough to hold the full specimen width at an even pressure. Even clamping is the requirement that matters: if one side of the specimen is held more firmly than the other, that end of the seam takes load first and the failure runs from there rather than from the weakest stitch, which changes both the force and the mode. Pneumatic vice action grips deliver a constant pressure across the face, which mechanical screw grips do not.
What goes wrong in practice
Reporting a force without a failure mode, which discards the half of the result that determines the response. Mixing seams cut from articles with laboratory-sewn assemblies within one data set, so that production variation and fabric differences are confounded. Uneven grip pressure, which biases where the failure starts. And missing needle damage: a blunt or oversized needle severs yarns during sewing, and under magnification those severed yarns line up with the needle holes rather than with the point of maximum load — the difference between changing needles and changing supplier.
ASTM D1683 or ISO 13935
| ASTM D1683/D1683M | ISO 13935 | |
|---|---|---|
| Family | ASTM | ISO |
| Scope | Sewn seams in woven fabrics | Seam tensile properties, strip and grab methods |
| Failure mode | Classified and reported | Recorded |
| Efficiency | Calculated against fabric strength | Comparable approach |
Both pull a seam perpendicular to the stitch line and both treat the failure mode as part of the result. Specify which was used, because the specimen widths and clamping arrangements differ enough to shift the force.
Questions we are asked about this test
What is ASTM D1683?
It is the ASTM test method for failure in sewn seams of woven fabrics. A specimen containing a seam is pulled perpendicular to the stitch line until the seam fails, and both the maximum force and the way it failed are recorded. Earlier editions were titled for apparel fabrics; the current designation covers woven fabrics generally.
Why does the failure mode matter more than the force?
Because it decides what happens to the product. If the sewing thread ruptured and the fabric is intact, the article can be re-sewn and sold. If fabric yarns were severed or pulled out of the weave, the cloth itself is damaged, re-sewing puts a new seam into damaged fabric, and the article is scrap. Two garments can record the same seam strength and have entirely different commercial outcomes.
What is seam slippage?
Yarns sliding out of the weave beside the stitching rather than breaking, so a hole opens next to an intact seam. It reads as a sewing fault and is usually a fabric one — a low yarn count, a slippery filament yarn or an open construction lets the yarns move under load. Increasing stitch density does not fix it, and that is precisely why the mode is reported.
What is seam efficiency?
The seam strength expressed as a proportion of the strength of the same fabric without a seam, tested in the same direction. It answers how much of the cloth's own capability the seam preserves, which is more useful for comparing constructions than an absolute force. It requires the unseamed fabric to be tested as well, so it is not available from the seam specimens alone.
Should the seam come from a garment or be sewn for the test?
It depends on the question. A seam cut from a finished article measures what was actually produced, including whatever the production line did on the day. A standard seam assembly sewn to the method holds thread, needle and stitch density constant so that fabrics can be compared with each other. Using one where the other was intended is a common source of arguments about results.
Why inspect the needle damage?
Because a blunt or oversized needle cuts fabric yarns as it sews, and the seam then fails at a load the cloth should have carried comfortably. Under magnification the severed yarns line up with the needle holes rather than with the point of maximum load, which distinguishes a sewing-room problem from a fabric one. It is the difference between changing needles and changing supplier.
Is the result a stress?
No, it is a force. A seam has no meaningful cross-sectional area to divide by — its strength depends on stitch type, stitch density, thread and fabric all at once — so nothing is normalised. That is why seam efficiency exists as a second figure: it gives a dimensionless way to compare seams across fabrics of different weights.
Running ASTM D1683/D1683M 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 — sewn seam strengths in woven fabrics are typically tens to 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 | ASTM D76 requirements for textile testing machines | ISO 7500-1 Class 0.5, verified to ASTM E4, DIN 51221 and BS 1610 |
| Gripping | Wide-faced grips clamping the fabric each side of the seam, with the seam central and perpendicular to the pull | 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.