Linear Density of Fibers and Yarns
Linear density is the thickness of fibers and yarns
It can be directly expressed by the cross-sectional diameter, cross-sectional perimeter or cross-sectional area of fibers and yarns. When the cross-sectional shape is close to a circle, the diameter is used to express the thickness, and its unit of measurement is microns or millimeters. However, the cross-section of fibers and yarns is generally irregular and thin. The measurement of the diameter or the measurement of the cross-sectional area must be measured one by one with the eyepiece micrometer and the objective micrometer under the microscope, or on the microscope projector. Testing is time-consuming and labor-intensive, and the fibers and yarns have uneven thickness. Using the average diameter of the cross-section as the linear density index may affect the evaluation results. Because the length and weight test are more convenient, the relationship between length and weight is often used in production to indirectly indicate its thickness. That is, an indirect index is used to represent the linear density of fibers and yarns. The indirect indicators of linear density are divided into fixed length and fixed weight.