IS 1670 : 2025 Textiles - Yarn - Determination of Single-End Breaking Force and Elongation at Break
1 SCOPE
1.1 This standard prescribes method for determination of breaking load and elongation at break of yarn using a constant rate of elongation (CRE) testing system. For the purpose of comparing yarns with different linear densities, this standard also specifies the method for converting the observed breaking load into breaking tenacity, expressed in centinewtons or millinewtons per tex.
1.2 The method prescribed in this standard is applicable to monofilaments and multi-filaments (other than tyre cords and industrial yarns), and spun yarns (single, plied or cabled) and textured yarns made from all kinds of textile fibres or their blends with the exception of yarns that stretch more than 5.0 percent when tension is increased from 0.5 g to 1.0 g (5 mN to 10 mN) per unit linear density of the yarn in tex. The method prescribed in this standard is not applicable to fancy yarns.
1.3 This standard is designed primarily for yarn in package form but can be used for single strands removed/extracted from a woven/knitted fabric.
1.4 This test method provides two options concerning the moisture content of specimens at the time of testing:
1.4.1 Option 1 - Conditioning to moisture equilibrium in the standard atmosphere for testing textiles (see IS 6359).
1.4.2 Option 2 - Testing in wet condition. Tests on wet specimens are usually made only on yarns which show a reduced strength when wet or when exposed to high humidity, for example, yarns made from animal fibres or regenerated and modified cellulosebased man-made fibres. Wet tests are also employed on flax yarns to detect adulteration by failure to gain strength.
1.5 This method also offers three options for the physical configuration of the test specimen:
1.5.1 Option A - Straight (see Note 4).
1.5.2 Option B - Knotted (see Note 1, Note 2 and Note 3).
1.5.3 Option C - Looped (see Note 1 and Note 3).
NOTES
1 The reduction in strength due to the presence of a knot or loop is considered a measure of brittleness of yarn. If a textile yarn is looped or knotted, its tensile strength may reduce. This can arise when a yarn is bent to a small radius of curvature (as in sewing or knitting) or knotted (as in the manufacture of nets). In order to assess the importance of these effects, loop strength and knot strength are described.
2 The knot strength test as described in this standard is not intended to assess the efficiency of any given type of knot for joining together two separate lengths of yarn.
3 Elongation in knot or loop test is not known to have any significance and is not usually recorded.
4 Unless otherwise indicated, ‘single-end breaking strength’ is assumed to refer to a straight, conditioned specimen (Option 1A).
2 REFERENCES
The standards listed in Annex A contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent edition of these standards.
| IS No. | Title |
| IS 196 : 2024 | Atmospheric conditions for testing (first revision) |
| IS 570 : 2024 | Textiles - Methods for determination of universal count of jute yarn (second revision) |
| IS 681 : 2015 | Textiles - Methods for determination of universal count of woollen and worsted yarn (first revision) |
| IS 1070 : 2023 | Reagent grade water - Specification (fourth revision) |
| IS 1315 : 2025 | Textiles - Linear density of yarns spun on cotton system - Method of test (second revision) |
| IS 3920 : 1985 | Methods for sampling of cotton yarn for determination of physical characteristics (first revision) |
| IS 6359 : 2023 | Method for conditioning of textiles (first revision) |