GB/T 2543.1-2015 Textiles — Determination of twist in yarns — Part 1: Direct counting method
1 Scope
1.1 This part of GB/T 2543 specifies a method for the determination of the direction of twist in yarns, the amount of twist, in terms of turns per unit length, and the change in length on untwisting, by the direct counting method.
1.2 This part is applicable to:
a) single yarns (spun and filament);
b) plied yarn;
c) cabled yarns.
Separate procedures are given for each type of yarn. The method is designed primarily for yarns in packages, but, with special precautions, the procedures can be used for yarns taken from fabrics.
Note: For yarns removed from textiles, see GB/T 29256.4.
1.3 This part covers the determination of twist in plied and cabled yarns as follows:
a) in plied yarns: the final twist of the plied yarns and the original twist of the single yarn before plying;
b) in cabled yarns:
— the final cabling twist of the yarn;
— the original twist of the plied yarn after plying, but prior to the last stage of processing;
— the twist of the single yarn before plying.
1.4 If desired, the twist of single and plied yarn components as they lie in the final structure can be determined by the special procedrue given in 10.5.7.
1.5 This part is not applicable, except by agreement, to yarns which stretch more than 0.5% when the tension increases from 0.5 cN to 1.0 cN per unit linear density of the yarn expressed in tex. Such yarns can be tested under special conditions of tension which are accepted by all parties interested in the test results.
1.6 This part is not suitable for products of open-end spinning and intermingled (interlaced) multifilament yarns.
1.7 This part is not applicable to yarns which are too large to permit their being placed in the clamps of the testing apparatus without crushing or distortion severe enough to affect the test results.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6529 Textiles - Standard atmospheres for conditioning and testing (GB/T 6529-2008, ISO 139:2005, MOD)
GB/T 8693 Textiles - Designation of yarns (GB/T 8693-2008, ISO 1139:1973, MOD)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
twist
number of turns about the axis of a yarn based on its nominal gauge length before untwisting
Note: Twist should preferably be expressed as turns per metre (turns/m), but it may be expressed as turns per centimetre (turns/cm).
3.2
gauge length
distance between two effective clamping points of the test specimen mounted in the testing equipment
3.3
initial length
length of a test specimen under a specified pretension at the beginning of a test
3.4
change in length on untwisting
increase or decrease in initial length observed when the specimen is untwisted, expressed as the percentage extension, or contraction, based on the specimen initial length
不适用于自由端纺纱产品和交缠复丝捻度的测定。 1.7 本部分不适用于太粗的纱线。这类纱线在试验仪的夹钳中会严重轧伤变形,影响试验结果。
Contents
Foreword II
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus
6 Standard atmosphere
7 Sampling
8 Test specimens
9 Determination of the direction of twist
10 Determination of the amount of twist
11 Calculation of results
12 Expression of results
13 Test report
Annex A (Informative) Suggested procedure for sampling
Bibliography
GB/T 2543.1-2015 Textiles — Determination of twist in yarns — Part 1: Direct counting method
1 Scope
1.1 This part of GB/T 2543 specifies a method for the determination of the direction of twist in yarns, the amount of twist, in terms of turns per unit length, and the change in length on untwisting, by the direct counting method.
1.2 This part is applicable to:
a) single yarns (spun and filament);
b) plied yarn;
c) cabled yarns.
Separate procedures are given for each type of yarn. The method is designed primarily for yarns in packages, but, with special precautions, the procedures can be used for yarns taken from fabrics.
Note: For yarns removed from textiles, see GB/T 29256.4.
1.3 This part covers the determination of twist in plied and cabled yarns as follows:
a) in plied yarns: the final twist of the plied yarns and the original twist of the single yarn before plying;
b) in cabled yarns:
— the final cabling twist of the yarn;
— the original twist of the plied yarn after plying, but prior to the last stage of processing;
— the twist of the single yarn before plying.
1.4 If desired, the twist of single and plied yarn components as they lie in the final structure can be determined by the special procedrue given in 10.5.7.
1.5 This part is not applicable, except by agreement, to yarns which stretch more than 0.5% when the tension increases from 0.5 cN to 1.0 cN per unit linear density of the yarn expressed in tex. Such yarns can be tested under special conditions of tension which are accepted by all parties interested in the test results.
1.6 This part is not suitable for products of open-end spinning and intermingled (interlaced) multifilament yarns.
1.7 This part is not applicable to yarns which are too large to permit their being placed in the clamps of the testing apparatus without crushing or distortion severe enough to affect the test results.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6529 Textiles - Standard atmospheres for conditioning and testing (GB/T 6529-2008, ISO 139:2005, MOD)
GB/T 8693 Textiles - Designation of yarns (GB/T 8693-2008, ISO 1139:1973, MOD)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
twist
number of turns about the axis of a yarn based on its nominal gauge length before untwisting
Note: Twist should preferably be expressed as turns per metre (turns/m), but it may be expressed as turns per centimetre (turns/cm).
3.2
gauge length
distance between two effective clamping points of the test specimen mounted in the testing equipment
3.3
initial length
length of a test specimen under a specified pretension at the beginning of a test
3.4
change in length on untwisting
increase or decrease in initial length observed when the specimen is untwisted, expressed as the percentage extension, or contraction, based on the specimen initial length
不适用于自由端纺纱产品和交缠复丝捻度的测定。 1.7 本部分不适用于太粗的纱线。这类纱线在试验仪的夹钳中会严重轧伤变形,影响试验结果。
Contents of GB/T 2543.1-2015
Contents
Foreword II
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus
6 Standard atmosphere
7 Sampling
8 Test specimens
9 Determination of the direction of twist
10 Determination of the amount of twist
11 Calculation of results
12 Expression of results
13 Test report
Annex A (Informative) Suggested procedure for sampling
Bibliography
