Applicable Systems
Dornier Weaving Machine
Symptoms
The weft insertion rate is inconsistent. The fabric shows weft bars (density variation) and occasional weft breakage stops the loom.
Possible Causes
- Weft feeder tension spring worn, causing inconsistent weft tension
- Weft insertion (rapier, projectile, or air-jet) mechanism out of adjustment
- Weft detector sensor dirty or misaligned
- Weft yarn quality inconsistent (yarn count or twist variation)
Troubleshooting Steps
- Step 1: Check the weft feeder tension setting and the condition of the tension spring
Replace the spring if it shows fatigue or set - Step 2: Inspect the weft insertion mechanism per the loom type
For air-jet: check the main and relay nozzle pressures and timing - Step 3: Clean the weft detector sensor with compressed air and verify alignment
The sensor should detect the weft arrival at the correct angle - Step 4: Check the weft yarn lot and verify count and twist against specification
Change to a new lot if quality issues are suspected
How to Reset
Reset: After correction, run the loom and verify weft density is consistent and no weft stops occur for 100 picks.
Common Replacement Parts
- Weft feeder spring: Tension spring, match to feeder model (Replace if fatigued)
- Weft detector sensor: Optical or piezo, match to loom model (Clean and align per manual)
- Air nozzle: For air-jet looms, match to loom model (Check bore and alignment)
Frequently Asked Questions
- Q: What is weft insertion?
The process of inserting the crosswise yarn (weft) between the warp threads. Methods: rapier, projectile, air-jet, and water-jet. Each has specific maintenance needs.
- Q: How do I adjust air-jet nozzles?
Follow the timing chart in the manual. Main nozzle pressure and relay nozzle timing must be synchronized with the reed beat-up position. Use a stroboscope for adjustment.
- Q: What causes weft breakage?
High tension, worn feeder components, damaged yarn guides, and poor yarn quality. Inspect the entire weft path for damage.
Source: OEM Operation Manual
Category: Textile