The market for spacer fabrics is a comparatively new and growing market. Accordingly, uniform testing of spacer fabrics did not exist until recently. Instead of special test equipment and test standards designed for spacer fabrics, spacer fabrics were tested using conventional test methods of 2-dimensional fabrics or with test methods for foams. These test devices are usually only of limited suitability for the analysis of spacer fabrics. Due to the 3-dimensionality of the fabrics, the actual properties of the spacer fabrics cannot be correctly recorded using these conventional methods. In addition, test methods for foams are usually destructive when applied to spacer fabrics. Therefore, by using the existing test methods, the results of the mechanical properties of spacer fabrics are misleading.
Since 2018, the ITA has been actively researching new test methods and devices for spacer fabrics together with project partners and members of the technical committee and the standards committee "Test devices and test methods for spacer fabrics". As a first step, a prioritization of possible tests was initiated. Sample preparation turned out to be the most important point. Even if this is not necessarily a test, a standardized and uniform sample preparation is indispensable for comparable test results.”
3 new standards already published, more are planned
In November 2020, the first DIN standard in the 60022 spacer fabric series was released with the name "DIN-60022-1, Spacer textiles – Terms and definitions, sample preparation". DIN-60022-1 is the first standard to define the technical terms used to describe a spacer fabric, such as the spacer or pile yarn. In addition, this standard defines the quality of samples. During the analysis and development of tests for spacer fabrics, it became apparent that different tests require different qualities of samples. In tests where the sample is clamped, such as the tensile test, a clean and perpendicular sample edge is very essential. In tests where the edges of the sample are not considered, such as thickness testing, the quality of the edge (Fig. 1) is of secondary importance in sample preparation.
In August and October 2021, the 2 standards "DIN 60022-2, Spacer textiles – Determination of air resistance" and "DIN 60022-3, Spacer textiles – Determination of thickness" were issued. Unlike "ISO 9237 – Textiles – Determination of permeability of fabrics to air", the DIN-60022-2 standard for determining the air resistance of spacer textiles distinguishes between horizontal and vertical air resistance (Fig. 3). This means that the direction of the air flow is considered and thus the special properties of spacer fabrics are taken into account. DIN 60022-3 for determining the thickness of spacer fabrics makes it possible, above all, to consider thicker spacer fabrics in accordance with the standard, which previously could only be tested to a limited extent with the standard "ISO 5084 – Textiles – Determination of thickness of textiles and textile products".
Further standards for spacer textiles are already being planned. In the DIN standards committee "Test equipment and test methods for spacer textiles", test methods for compression hardness, compression set, tilt stability, pressure point distribution, abrasion, and tensile strength are considered next.
Important step for the German textile industry
To ensure that the developed tests are not only applicable in university laboratories, great attention was paid to close cooperation with industry during the development of the test specifications. This is to ensure that the new testing standards can also be carried out in the laboratories of spacer fabric manufacturers and their customers.
For German textile manufacturers, the standard development will result in cost savings in the development process of their spacer fabrics. Uniform and reproducible testing of spacer fabrics can reduce the development cycles for new products. The development of new test methods and testing equipment also ensures comprehensive quality assurance of the fabrics and reproducibility of the structures.
The described testing and standardization development has been carried out within the framework of the project "NormATex – Standardization for Spacer Fabrics". The authors thank the German Federal Ministry for Economic Affairs and Climate Action (BMWi) and Projektträger Jülich (PtJ), which funded the above-mentioned standardization developments as part of the Wipano program – "Knowledge and Technology Transfer via Patents and Standards".
This article was published in melliand international 4/2022.