Calculating Wet Spinning Yarn Scrap Loss Allowance during Mass Balance Auditing
Mass balance auditing of wet spinning yarn requires separating chemical pectin bath leaching from physical scrap losses using dry-mass regain corrections.
Doffing Hard Scrap
Material Output
Yarn manufacturing logs define the tangled or severed linen yarn that accumulates on the spindle base during the mechanical ejection of completed bobbins. This material, categorized as doffing hard scrap, consists of fully twisted yarn that cannot be wound or knitted. Spinning mills track this output as a direct loss of processed fibre.
The weight of this waste is recorded at the end of each shift.
Waste Cause
Malfunctions in the automatic doffing mechanism or incorrect timing on the spinning frame release arm generate excess scrap during the transfer cycle. The twisted fibers in the doffing hard scrap are highly resistant to simple reprocessing due to the high turns per inch introduced during spinning. If the cutter fails to sever the yarn cleanly, the tail wraps around the spindle, creating dense knots.
Operators manually clean these spindles with specialized hook knives, which increases machine downtime and risk of spindle damage.
Mechanical Reclamation
Specialised pulling machines must shred this waste to recover short-staple fibres for blending. Because the fibers have been spun and twisted, this process requires high energy and yields a low-grade cottonized flax suitable only for coarse industrial yarn. Proper calibration of the doffing arms minimizes this material.