Detection Trigger
Automated sensing equipment identifies horizontal yarn breakage or depletion during the loom operation phase to initiate an immediate mechanical halt. A weft stop finder monitors the tension and presence of the pick across the entire breadth of the warp. When a missing strand occurs, the device detects the absence of the typical resistance against the contact pin.
This interruption triggers a magnetic switch that cuts power to the drive motor. Prevention of defects depends on the timing of this engagement, as any lag allows the reed to carry a partial pick into the cloth fell. Quality control protocols in linen manufacturing mandate the inspection of these triggers prior to every production run.
Consistent response prevents the loom from firing empty picks that result in a missing bar. The mechanism relies on a piezoelectric sensor or a mechanical feeler that completes a circuit only when the tension remains constant within narrow factory specifications.
Operation Logic
Electrical signals from the sensing head travel to the main loom control board to register an error state. Each sensing cycle corresponds to the insertion velocity of the shuttle or rapier. If the signal fails to arrive within the millisecond window allotted for the pick, the processor identifies a fault.
Operators define these windows based on the specific count of the linen yarn, where heavier flax fibres require greater travel time. Tension variation between different flax crops sometimes forces a manual recalibration of the sensitivity threshold. Proper maintenance of the contact surface reduces false positives caused by lint accumulation or static discharge.
Adjusting the proximity of the sensor ensures that even fine threads are identified before the beat up occurs.
Process Constraint
Failure to verify the operational state of these units leads to fabric rejection during the final grading at the export warehouse. Mill standards usually demand a zero tolerance policy for missing picks in top grade linen cloth. Buyer contracts specify these acceptance criteria as part of the technical annex for woven goods.
Independent inspectors verify the integrity of these signals during pre-shipment audits. Accurate sensing reduces waste and material loss.
