Batch Homogenization
Combining multiple drawn slivers of varying flax origins into a single unified output strand stabilizes linear density and mean fiber length across mill production runs. In long flax spinning, composite sliver blending combines inputs from disparate hackling lots at the initial draw frame to mitigate natural variation in bundle strength and fineness. Mills record this mechanical integration on draw frame production sheets to guarantee that subsequent roving operations encounter uniform mass distribution.
The operation applies strictly to mechanical doubling during yarn preparation before twisting begins, ending where roving frame draft zones take control of single strand attenuation.
Drafting Mechanism
Rollers set at specific speed differentials pull parallelized flax fibers past one another to reduce aggregate cross-sectional thickness. During composite sliver blending, six or eight individual slivers feed simultaneously into the draft zone where top rubber rollers press against fluted bottom steel rollers. This physical compression creates friction, preventing uncontrolled sliver slip while roller speed ratios dictate the final linear density.
Variations in roller gauge settings directly alter short fiber control, which changes the total mass variation along the output sliver.
Variance Boundary
Linear density variation limits defined by yarn specifications restrict the allowable difference in input sliver linear mass. If raw flax lots differ beyond two fineness grades, mechanical doubling fails to prevent yarn count irregularities in final winding.
