Testing standard
Textiles — Yarns from packages — Determination of single-end breaking force and elongation at break using constant rate of extension (CRE) tester
Written and technically reviewed by Dak System Inc. engineeringLast reviewed
ISO 2062 determines the single-end breaking force and elongation at break of yarn taken from a package, on a constant rate of extension tester. It runs at 100 % of the gauge length per minute — 500 mm/min at the usual 500 mm gauge — and offers four methods: A manual, B automatic, C from relaxed skeins, and D wet. Breaking tenacity in cN/tex is derived from a linear density determined to ISO 2060.
From the test method to your testing system
Explore the DAK machines already listed for ISO 2062, then review the grips, measurement and setup requirements below.
Universal Testing MachineSeries 7200Explore the machine →
Universal Testing MachineSeries 9000Explore the machine →01Understand the method
Clause 1 sets out four methods, not one: A, manual from conditioned packages; B, the same on an automatic tester; C, from relaxed test skeins; D, after wetting. Clause 1.2 makes C the referee route where elongation at break is disputed, its note explaining that A, B and C are expected to agree on strength while C might give somewhat truer, and higher, values of elongation. D is likely to differ from all three.
Clause 4 fixes a rate, not a time: a constant 100 % per minute of the gauge length — 500 mm/min at the usual 500 mm gauge, or 250 mm/min at 250 mm, which Clause 8.1.2 allows only where travel is insufficient or by agreement. Pretension at clamping is 0.5 cN/tex ± 0.1, or 0.25 ± 0.05 wet, defining the initial length rather than assuming it.
Clause 3 defines the quantities: breaking force, preferably in centinewtons; elongation at break, as a percentage of the initial length; and breaking tenacity, force divided by linear density, in cN/tex, that density determined to ISO 2060.
A relaxed-skein and a straight-from-package elongation are both valid ISO 2062 figures and will not match; a wet result differs again. Clause 8.1.1 requires every interested party to use the same gauge length, rate, clamp, temperature and pretension, so a certificate naming only ISO 2062 says too little.
02Prepare the specimen and test settings
ISO 2062 prescribes the sampling rather than leaving it to the laboratory, because the spread between packages is part of what the buyer is paying to learn.
The method letter belongs on the certificate. A relaxed-skein elongation and a straight-from-package elongation are both valid ISO 2062 results and they will not be the same number.
ISO 2062 states a rate, not a time to break. The 20 s convention existed to reconcile CRT and CRL machines with CRE, and the third edition dropped it once CRE was recognised as the better instrument.
03Build the test setup on a DAK machine
Clause 5.1 states its requirements as tolerances: a gauge length of 500 mm ± 2 mm or 250 mm ± 1 mm, preferably both; a moving clamp at 500 or 250 mm/min, to ± 10 or ± 5 mm/min and accurate to ± 2 %; and indicated force in error by no more than 2 % of true force.
The clamping requirement is the one most often misread. Flat-faced unlined jaws are the normal type; lined jaws, bollard clamps and other snubbing devices are permitted only where flat jaws cannot prevent slippage, and then by agreement — clamp type changes the elongation reading, so all parties must use one type. Automatic testers may run 2 000 or 5 000 mm/min where agreed, and 50 %/min or 20 %/min are also allowed.
Clause 5.1 makes flat-faced unlined jaws the normal type without specifying a face size; ours are 25 mm square. Foot-pedal closing matters here because Clause 6.4 asks for a minimum of 50 specimens on a single-spun yarn, and both hands stay free to align each one.
Specifications
Rubber-coated faces are the lined jaws ISO 2062 names first when flat unlined jaws cannot prevent slipping or cutting. Clause 5.1 permits them on agreement between the interested parties, and requires all of those parties to use the same type — because the clamp changes the elongation reading.
Specifications
The bollard clamp named in Clause 5.1 as an alternative where flat jaws cannot prevent breaks at the jaws. Wrapping spreads the grip stress around the arc; quick release keeps a 200-specimen run moving.
Specifications
A snubbing device of the kind Clause 5.1 permits by agreement, for strong industrial yarns that pull out of flat jaws. Constant closing pressure stops the progressive slip that Clause 8.1.11 caps at 2 mm.
SpecificationsDak 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 | Very low — from under 1 N on fine spun yarn to a few hundred newtons on industrial filament | Load cells from 1 kg to 60 ton on the Series 7200, and 0.5 to 100 kN on the Series 9000 |
| Force accuracy | Indicated force in error by no more than 2 % of the true force (Clause 5.1) | ISO 7500-1 Class 0.5, verified to ASTM E4, DIN 51221 and BS 1610 |
| Gripping | Flat-faced unlined jaws are the normal type; lined jaws, bollard clamps or other snubbing devices only where flat jaws cannot prevent slipping, cutting or jaw breaks, and then by agreement | Our vice-action grips or split capstan grips, built to the specimen |
| Environment | ISO 139 standard atmosphere — 20.0 °C and 65.0 % relative humidity, to ± 2.0 °C and ± 4.0 %. Clause 3.2 permits two alternatives only by agreement between the parties, and the one used shall be reported: 23.0 °C / 50.0 % specific, or 27.0 °C / 65.0 % tropical. Precondition methods A to C for at least 4 h and condition tightly wound packages for 48 h; Clause 7.4 exempts Method D | 3009 series chambers, −150 °C to +400 °C — temperature only |
04Run the test
Repeated slipping is a clamp problem, not a retest problem. Clause 8.1.11 asks for the clamps or the jaw lining to be changed rather than for more attempts on the same setup.
05Calculate, report and interpret
The maximum force applied to the specimen, in cN
Clause 3.1. For yarns the standard prefers centinewtons.
ε = ΔL / L₀ × 100
Clause 3.2 and 3.8. The denominator is the initial length taken under pretension, not the nominal gauge setting.
Breaking tenacity = breaking force / linear density
Clause 3.3, in cN/tex. Clause 8.1.3 makes the ISO 2060 determination a condition of quoting tenacity at all.
Three things in the readable part of the source chain are stated as recorded or reported, and only those are listed as requirements. The test-report clause of ISO 2062 sits beyond the publisher preview and has not been read.
Clause 8.1.11 replaces judgement with two numbers. Slip of more than 2 mm voids the result, and repeated slipping calls for different clamps or a new jaw lining. A break 5 mm from a jaw or closer is discarded too — but the number discarded must be recorded, a high discard rate being evidence about the grip.
The second failure is a scope error. Clause 1.4 excludes glass, elastomeric, aramid, HMPE, UHMPE, ceramic and carbon yarns, and polyolefin tape; glass goes to ISO 3341. A frame can pull such a yarn; the result simply may not be reported against this document.
The third is importing a time to break. That convention existed to reconcile CRT and CRL machines with CRE; the third edition dropped it, so a twenty-second break is not conformance here.
06Compare methods and find answers
Both are single-end yarn tensile methods and a buyer may be asked for either, so the overlap is real. The setups are not interchangeable, and the differences below all move the number.
| ISO 2062:2009 | ASTM D2256/D2256M-21 | |
|---|---|---|
| Machine types | CRE in the body; CRT and CRL held in informative Annex A as deprecated | CRT, CRE and CRL all recognised, with the CRE type preferred |
| Rate principle | A rate: 100 % of the gauge length per minute | A time: average time-to-break of 20 ± 3 s |
| Gauge length | 500 mm usually, with 250 mm only for want of travel or by agreement (8.1.2) | Not fixed in the retrievable record; 250 mm is named once, as the gauge the alternate rate of 300 ± 10 mm/min is written for (5.9.2) |
| Clamping | Flat-faced unlined jaws are the normal type; lined jaws, bollards and other snubbing devices only where flat jaws slip, and then by agreement (5.1) | No clamp type named; 5.4 leaves the arrangement to the individual laboratory, provided a representative force-elongation curve is obtained |
| Conditioning | ISO 139 — 20.0 °C / 65.0 %, or by agreement 23.0 / 50.0 or the tropical 27.0 / 65.0, which must then be reported | Six test conditions are named in 1.2.2, from conditioned air to low temperature; the atmosphere itself is not printed in the retrievable record |
| Named variants | Four lettered methods, including relaxed skein and wet | Straight, knotted or looped specimens (1.2.1); conditioned air, wet, oven-dried, or at high or low temperature (1.2.2) |
| Calculated properties | Breaking tenacity in cN/tex, from a linear density determined to ISO 2060 (3.3, 8.1.3) | Breaking tenacity, initial modulus, chord modulus and breaking toughness (1.2) |
Name the document that was actually run. Quoting one against a specification written for the other invites a rejection that the numbers themselves do not justify.
It is the ISO method for the single-end breaking force and elongation at break of yarn taken from a package, tested on a constant rate of extension machine. The third edition, ISO 2062:2009, is dated 2009-12-01 and cancels and replaces ISO 2062:1993, which it technically revised. It reports breaking force, elongation at break and breaking tenacity in cN/tex.
A constant rate of extension of 100 % of the gauge length per minute. In practice that is 500 mm/min with a tolerance of ± 10 mm/min at the usual 500 mm gauge length, or 250 mm/min ± 5 mm/min at a 250 mm gauge length, with the rate itself held to ± 2 %. Automatic testers may run 2 000 mm/min or 5 000 mm/min by agreement, and lower rates such as 50 %/min or 20 %/min are also allowed by agreement.
Method A is the manual default, taking specimens straight from conditioned packages, and Method B is the same test on an automatic tester. Method C works from relaxed test skeins and is the one to specify where elongation at break is in dispute: the standard's note to Clause 1.2 says Methods A, B and C are expected to agree on strength, but that C might give somewhat truer, and higher, values of elongation. Method D tests wet, and is likely to differ from all three on both properties.
No — and this is the most common misreading of the standard. Clause 5.1 makes flat-faced unlined jaws the normal type. Lined jaws, bollard clamps and other snubbing devices are permitted only where flat jaws cannot prevent slippage, and then only by agreement between the interested parties. Because the clamp type changes the elongation reading, Clause 5.1 requires everyone comparing results to use the same one — which is why we put the clamp used on the certificate, though no clause inside the publisher preview requires that.
Clause 6.4 sets a minimum of 50 specimens for single-spun yarns and 20 for all other yarns, distributed as evenly as possible over 10 packages. If you want the coefficient of variation as well as the mean, Clause 6.6 raises that to 20 packages and at least 200 specimens for single-spun yarns, or 100 for other types. Where the variability of similar material is already known and only a mean is needed, Clause 6.5 allows a calculated count of 0.17 CV².
Two categories, both with a number attached. Discard any test in which the specimen slipped between the jaws by more than 2 mm, and if that keeps happening, change the clamps or the jaw lining rather than simply testing again. Discard any break that occurs 5 mm from a jaw or closer. In both cases the number of discarded results must be recorded, because a high discard rate says something about the grip that the surviving results do not.
Clause 1.4 excludes glass, elastomeric, aramid, high molecular polyethylene, ultra high molecular polyethylene, ceramic and carbon yarns, and polyolefin tape. Glass yarn is covered by ISO 3341 instead. This is a reporting limit rather than a capability one: a frame will pull an aramid or UHMPE yarn without difficulty, but the result cannot be issued against ISO 2062. Tell us the fibre and we will confirm which document fits before anything is quoted.
They answer the same commercial question and they are not set up the same way. ISO 2062 works from a rate — 100 % of the gauge length per minute at a usual 500 mm gauge — while ASTM D2256/D2256M-21 works from an average time-to-break of 20 ± 3 s, its alternate speed of 300 ± 10 mm/min being written for a 250 mm gauge length. ISO 2062 covers CRE testers in the body of the standard and treats CRT and CRL as deprecated; D2256/D2256M recognises all three and prefers CRE. The clamping runs opposite ways: ISO 2062 Clause 5.1 names flat-faced unlined jaws as the normal type, while D2256's 5.4 names no clamp at all and leaves the arrangement to the individual laboratory. Run the one the specification names.
The one defined in ISO 139, whose Clause 3 was replaced in full by Amendment 1:2011. The standard atmosphere is 20.0 °C and 65.0 % relative humidity. Two alternatives exist and are not equivalent to it: the specific atmosphere at 23.0 °C and 50.0 %, and the tropical atmosphere at 27.0 °C and 65.0 %. Clause 3.2 allows either only if the parties involved agree on its use, and requires the alternative atmosphere used to be reported. The tolerance on any of them is ± 2.0 °C and ± 4.0 %. Preconditioning under ISO 2062 Clause 7.2 runs for a minimum of 4 h for methods A to C, after which skeins usually reach equilibrium overnight while tightly wound packages need at least 48 h. Clause 7.4 exempts wet tests under Method D from both steps.
Discuss your specimen, test requirements and reporting needs with DAK engineering.
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.
