Mechanical Extension
Dual roller systems operating at different surface speeds stretch the incoming flax sliver to reduce its linear density before twist is inserted. The process of high-draft attenuation enables mills to produce fine linen yarns from coarser output strands by applying draft ratios above twenty. This mechanical action requires precise spacing between the nip points of the rollers to match the average length of the flax fibers.
Tension forces must be maintained carefully to prevent premature strand parting.
Fiber Control
Short fibers present in the blend tend to move in an uncontrolled manner when the gap between the drafting rollers is too wide. During high-draft attenuation, these uncontrolled elements accelerate ahead of schedule, producing erratic shifts in yarn thickness. Spinning frames employ rubber aprons and pressure bars to hold these floating fibers in check as they pass through the draft zone.
The resulting yarn structure depends heavily on this friction-driven stabilization.
Spinning Limits
High speed draft settings are constrained by the tensile strength of the roving being fed. Applying excessive high-draft attenuation causes drafting breaks that force operators to stop the frame. Mills record these incidents in the daily spinning log to adjust the machine settings for each specific flax batch.
