Dynamic Tension Control and Dobby Shedding Parameters for Flax Warps
Active tension control and asymmetrical dobby dwell minimize stress spikes on low-stretch flax warps to prevent end breaks and starting marks.
Starting Mark Prevention
Loom Operation
Loom stoppages during the weaving process can cause localized density variations in the fabric when the machine restarts. The execution of starting mark prevention involves automated adjustments that align the cloth fell to the correct position before the first new pick is inserted. This function is managed by the electronic loom controller and is logged as active on the loom setting program.
Successful execution ensures that the fabric maintains a continuous, uniform appearance without thick or thin bands at stop points.
Mechanical Compensation
Creep and relaxation of both the warp yarns and the take-up mechanism occur while the loom sits idle during a stop. To implement starting mark prevention, the loom drive reverses the fabric position by a fraction of a millimeter or adjusts warp tension before restarting. This fine mechanical compensation counters yarn relaxation, ensuring the first pick receives the exact same beat-up force as the preceding ones.
Technicians fine-tune these movement offsets depending on the fabric density and yarn count of the linen style being produced. Proper calibration prevents the formation of double-picks or light-picks that mar the fabric surface.
Quality Standards
Visible density defects decrease the fabric grade from first-quality to second-quality. Premium buyers refuse rolls when starting mark prevention fails to maintain uniform density along the length of the fabric. Automatic tension adjustments are therefore standard practice in modern high-speed weaving mills.