Determining Recovered Yarn Linear Density from Woven Fabrics
Determining recovered yarn linear density involves unraveling measured lengths, removing crimp under standardized tension, and correcting dry mass for size.
Decrimping Force
Tensile Measurement
The tension required to remove the structural waves or crimps from a textured yarn is a critical baseline value in yarn testing. To measure decrimping force, a low-load tensile test extends the yarn until the physical crimp is completely pulled out. This threshold must be reached before the actual elastomeric or fiber drafting starts.
Determining this value prevents errors during subsequent strength and elongation tests.
Fiber Behavior
Textured filament yarns possess an artificial wave that provides bulk and elasticity. The decrimping force indicates the stability of this textured structure during processing. High values suggest a tightly locked textured geometry, while low values indicate a loose crimp that might easily pull out under typical weaving or knitting tensions.
Test Execution
Automated tensile testers record the load-elongation curve as the specimen is stretched. The decrimping force is identified at the inflection point where the initial low-tension crimp-removal phase transitions to the high-tension fiber-extension phase. This is done by applying a specific pretension defined by international standards.
Production Feedback
Yarn processing mills use this parameter to adjust tension settings on knitting machines or warping creels to avoid premature de-texturing. When the decrimping force is known, machines can run at high speeds without the risk of over-stretching the yarn. This ensures that the finished knitted or woven fabric maintains its intended hand and thermal insulation.
Conversely, ignoring this threshold leads to uneven dyeing and loss of fabric elasticity.