Bast Fiber Defect Quantification in Mechanical Scutching Operations
Mechanical scutching defect quantification relies on precise gravimetric or optical mass-balance analysis to measure residual shive and control long fiber yield.
Yarn Drafting Defects
Quality Failure
Irregularities in the linear density of the yarn produced by the uneven drawing out of the fibre strand during the spinning process represent the main source of mechanical defects in linen yarn. These yarn drafting defects appear as thick and thin places that reduce both the aesthetic appeal and the mechanical strength of the finished fabric. They are identified using automated optical sensors mounted directly on the spinning frame or winding machine.
Defect Origin
During drafting, the fibre strand is passed between rollers running at different speeds to reduce its thickness. If the moisture level of the roving is incorrect, or if the drafting rollers are worn, the fibres do not slide smoothly past one another. This uneven movement creates periodic thick spots followed by thin sections that are highly susceptible to breakage under the tension of the weaving loom.
Spinning mills prevent yarn drafting defects by maintaining strict control over the water temperature in the spinning troughs and the pressure of the drafting rollers.
Industrial Correction
When the sensors detect a defect that exceeds the preset quality limits, the winding machine automatically cuts the yarn and splices the ends with a pneumatic knotter. This action prevents the defective yarn from reaching the warp beams or weaving looms.