Formation Error
Irregularities occurring during the mechanical layering of carded webs result in uneven thickness across the width of the non-woven mat. A cross lap defect appears when the oscillating arm of the lapper fails to deposit the flax web with precise overlaps. This creates visible ridges or thin spots in the material before it enters the needle punching or bonding stage.
Mechanical Cause
Friction in the transport belts or incorrect speed synchronization between the card and the lapper usually triggers the problem. If a cross lap defect is left uncorrected, the resulting felt or padding will have inconsistent density and poor structural strength. Operators must calibrate the timing of the traverse motion to ensure that each layer seats perfectly against the previous one.
Constant monitoring of the web tension prevents the formation of folds at the edges of the mat.
Inspection Impact
Visual checks at the end of the line identify these faults as longitudinal bands or shadowed regions in the finished roll. Because a cross lap defect alters the weight per square meter, it causes the product to fail the uniformity tests required for industrial geotextiles or high-end upholstery linings. Correcting the tension in the apron belts is the standard remedy for this issue.
