Warp Guidance
The vertical position of the loom’s primary guide roller determines the yarn path from the warp beam to the heddles. Optimizing the back rest height is essential for balancing the tension between the upper and lower sheds on a shuttleless loom. Adjusting this height changes the angle of the warp line relative to the horizontal plane of the breast beam.
This mechanical setting directly influences the dynamic tension during the pick insertion. Quality managers record this parameter on the weaving beam card before the production of flax fabrics begins.
Yarn Protection
Lowering this roller below the normal alignment increases the tension in the bottom warp sheet when the shed opens. If a mill maintains a high back rest height, the yarn layers experience equalized strain, which increases the likelihood of abrasive wear among the raw flax fibers. Maintaining the correct elevation prevents warp yarn breakages by distributing the load during peak shedding cycles.
Technicians adjust this setting on the loom side frame according to the yarn count and the pick density of the specification, executing manual measurements before running a trial of fifty meters to prove the stability of the yarn under load.
Surface Texture
Weaving with a raised back rest leads to a smoother fabric surface by ensuring that both yarn layers receive identical tension at the moment of beat-up. This balanced alignment suppresses the formation of reedy lines and promotes an even surface structure in high-density linen weaves. Finished fabric inspects often rely on these adjustments to meet buyer criteria for uniformity.
The setting is documented in the final mill inspection report.
