Standard Test Method for Failure in Sewn Seams of Woven Fabrics
5.1 The manufacturing of textile products uses seam engineering to determine the best combination of sewing thread, stitch type, seam type, and stitch density to construct the end use structure. These four seam engineering variables contribute to a textile product being able to achieve the maximum sewn seam strength performance and structural integrity when cut pieces of fabric are joined together.
5.1.1 It is known that for some textile structures the seam engineering variables are selected to meet a “one time performance requirement.” This means that following the “single incident” during which the maximum performance potential or capability of the textile structure has been met, it is expected to be discarded and replaced with another “new” unit. For example: an inflatable restraint in an automobile. Once deployed, it must be replaced; it cannot be re-used. Likewise, there are other textile structures, intended to be used multiple times, while also being subjected to various care and maintenance regimens.
5.1.2 This test method enables the fabric producer of woven fabrics, the textile producer, and other users of the test method to determine which seam engineering choices can be made relative to: sewing thread tex size; seam type; stitch type; and stitch density to determine the potential outcomes that can occur when a particular woven fabric is used:
(a) What is the maximum force at which sewn seam strength failure will enable products made with this fabric to be repaired?
(b) What is the highest seam efficiency percentage attained?
(c) What is the maximum force at which the sewn seam strength results in seam slippage that can cause yarn slippage, yarn displacement and fabric failure?
220.127.116.11 The maximum force at which sewn seam strength or the highest seam efficiency retained demonstrate failure of the stitching without causing the displacement of one or more fabric yarns from their original position mean that the product can be repaired. When the failure results in displacement of yarns, the textile product will need to be replaced.
5.1.3 The procedures used in this test method represent two primary seam engineering techniques identified in Practice D6193 and used to manufacture products made of woven textile fabrics.
5.1.4 In case of dispute arising from differences in reported test results when using this test method for acceptance testing of commercial shipments, the purchaser and the supplier should perform comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens from the same lot of fabric to be evaluated, which utilize a like seam assembly (or standard seam assembly). The test specimens should then be randomly assigned in equal numbers to each laboratory for testing. If a bias is found, either its cause must be determined and corrected, or the purchaser and supplier must agree to interpret future test results in light of the known bias.
5.2 This test method can be used to determine the sewn seam strength and sewn seam efficiency of a specified seam assembly with each fabric. Because sewn seam strength and sewn seam efficiency varies with each fabric, both of the standard seam assemblies, noted in Table 1, should be used when comparing the seam strength of different fabrics. Table 1 lists the default seam assembly specifications to be used for fabrics made with fine, medium and heavy count yarns. If a determination cannot be made as to which seam is the best suited for a particular fabric, all should be evaluated.
5.3 Seams prepared for this test method should be made by competent factory sewing operators familiar with the potential for damage to the integrity of the sewn seam when stitching is improperly done.
5.3.1 If competent factory sewing operators are not accessible, a laboratory technician familiar with the potential for damage of an improperly sewn seam may prepare the seamed test specimens. It is imperative for purchaser/supplier to understand the impact an improperly sewn seam will have on test results.
5.4 This test method is applicable whenever a determination of sewn seam strength is required. The breaking force of the seam and fabric will permit estimation of seam efficiency. This test method can be used as an aid for estimating seam strength for any given fabric.
5.5 Seam engineering techniques for specific fabric types can also be determined by utilizing this test method.
5.6 This test method can be used to determine when the sewn seam is affected by seam slippage. While the ultimate consequence of this phenomenon is rupture, seam slippage greater than either the values stated in customer specifications, or as agreed upon by purchaser/supplier may severely reduce the integrity such that the product cannot be used for its intended purpose.
1.1 This test method measures the sewn seam strength in woven fabrics by applying a force perpendicular to the sewn seams.
1.1.1 The axis perpendicular to the sewn seam can represent either the warp yarn axis or filling yarn axis, the same axis tested when using grab Test Method D5034.
18.104.22.168 This test method is applicable to sewn seams obtained from a previously sewn article or seams sewn with fabric samples using one of two specific seam assemblies as shown in Table 1.
Note 1: When the performance of a woven textile structure requires data to indicate the maximum seam strength that will result in the failure of fabric on either side of seam, the standard seam can be changed to use the Lapped seam type construction with two or more rows of stitching: Lsc-2; Lsc-3; Lsc-4; and the maximum number of stitches per inch that can be used. (See Practice D6193.)
1.2 This test method is used when the maximum breaking force measurement to rupture of a woven fabric sewn seam is required.
1.2.1 This test method is used when the seam efficiency measurement of a woven fabric sewn seam is required.
1.2.2 This test method is used to identify the sewn seam strength threshold at which the failure of the stitching occurs, without damage to the fabric, so that the textile product can be repaired.
1.2.3 This test method is used to identify the force at which seam strength results in slippage and displacement of warp yarns, filling yarns, or any combination of these yarns.
1.3 This test method does not predict actual wear performance of a seam.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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