ASTM D2256 - Standard Test Method for Tensile Properties of Yarns by the Single-Strand Method

Due to its high data capture rate, we recommend our high tier 6800 Series test frame as the optimal solution for ASTM D2256 testing, although our more affordable 3400 Series is also appropriate. A single column frame is adequate for most single-strand yarn specimens as the loads rarely exceed 5 kN. In cases where yarn specimens require greater force, a dual column system may be needed.

The most common gripping solution for ASTM D2256 are pneumatic cord and yarn grips with smooth clamping blocks, which are well suited for testing nearly all types of yarn specimens while maintaining high throughput. A specially designed horn with a smooth finish and a contoured surface with a graduated cam allows for easy loading and a stress reduced clamping area on the specimen. By incorporating a design that evenly distributes gripping force over the surface of a curved half capstan, the chances of specimen failures are reduced. 

Instron’s 2 kN capacity cord and yarn grips can also be paired with jaw faces with several other finishes to provide adequate clamping and avoid damage to the specimens during testing. The pneumatic grips allow users to fine-tune the gripping pressure in order to avoid jaw breaks or slippage. In some cases with strong or slippery yarn specimens, use of extra padding material within the clamping blocks, such as paper or emery cloth, can also be helpful.