Woven Fabric Warp Breakage on a New Loom Set
A weaving shed has installed 24 new rapier looms running a 100% cotton poplin, 40s x 40s, 110 gsm, at 450 picks per minute. Within the first two weeks, warp breakage rate is 4.8 breaks per 100,000 picks against a target of 1.5. The warp is sized with a size pick-up of 9% and the sizing machine recorded a size add-on of 7.5%. Shed humidity is 58% RH at 30 degrees C, while the recommended range for this yarn is 65-70% RH. Weavers report breaks concentrated at the selvedge and at the back rest, and the warp sheet shows visible hairiness and some sticking between ends. Ends per cm is 52 and the warp beam is 1,000 mm wide with 5,200 ends.
1. Identify the likely causes of the elevated warp breakage and rank them by probable contribution.
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Three factors stand out. First, humidity: 58% RH is well below the 65-70% recommended for cotton. Low humidity makes cotton brittle and increases static and hairiness, directly raising breakage. This is likely the largest single contributor because it affects the whole warp sheet uniformly.
Second, sizing: a 9% size pick-up with only 7.5% measured add-on suggests inconsistency between the recipe and actual application, possibly uneven sizing or size that is not penetrating. Visible sticking between ends and hairiness indicate insufficient or poorly applied size film, so abrasion resistance at the shedding zone is inadequate.
Third, break concentration at the selvedge and back rest points to mechanical issues: selvedge ends suffer the highest abrasion and need tighter quality control, and the back rest height or tension may be causing excessive rubbing. Rank order: humidity (highest), sizing consistency, then back-rest and selvedge mechanics.
2. Propose immediate and medium-term corrective actions with measurable acceptance criteria.
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Immediate: raise shed humidity to 65-70% RH using the humidification plant and monitor with calibrated hygrometers at loom level, not just at the plant return. Re-check back-rest height and warp tension per the loom manufacturer's setting for this fabric. Inspect and replace worn droppers and healds at the selvedge. Acceptance: breakage should fall measurably within 48 hours; track breaks per 100,000 picks daily.
Medium-term: audit the sizing process - verify size recipe concentration, squeeze pressure, and drying temperature; confirm size add-on by a proper test rather than the machine readout. Target add-on consistent with 9% pick-up and uniform film. Re-test warp abrasion resistance and hairiness. Acceptance: breakage at or below 1.5 per 100,000 picks sustained for one week, with fabric appearance (no warp streaks) meeting the customer's first-quality standard.