Woven Fabric Weight Tolerances and Linear Metre Yield Calculations
Reconcile woven fabric purchases by calculating linear yield from conditioned mass and usable cuttable width under ISO 3801 and ISO 139 parameters.
Bow and Skew Measurement
Deformation Assessment
Weft distortion analysis calculates the physical displacement of filling yarns from a straight line perpendicular to the selvages of a woven fabric. Technicians conduct bow and skew measurement to verify that the fabric structure remains square and balanced after finishing. This method applies directly to woven materials subject to torque and skew during tentering and drying.
It ceases to apply to knit structures where wale and course distortion must be assessed by separate multidirectional dimensional tests.
Measurement Method
Inspectors draw a straight line perpendicular to the selvage using a standard rule. They measure the distance from this line to the furthest point of the curved or diagonal weft yarn. A metal ruler captures the maximum deviation in millimetres.
This value is then divided by the fabric width to determine the distortion percentage.
Finishing Control
Tentering machines must continuously adjust their skew rolls to keep the weft straight. If the bow or skew exceeds the tolerated limit, the fabric will twist when cut into garments. This distortion causes twisted side seams in finished shirts and trousers.
Proper alignment during drying is essential to avoid this.
Quality Standard
Buyers specify maximum allowable deformation limits, typically between two and three percent, to avoid assembly defects. Rolls exceeding these limits are flagged for reprocessing. Re-running the fabric through a straightener can correct the alignment.
This intervention ensures the fabric meets the specifications.