CSP shortfall in a 30s cotton warp lot
A co-operative spinning mill in Tiruppur supplies 1,200 kg of 30s cotton yarn to a handloom society for warp. The contract specifies CSP 2,150 minimum. The society reports 18 warp breaks per loom per shift against its usual 6, and several beams show cracked end bands. The mill's own test on the disputed lot gives count 30.8 Ne, CSP 1,850, Uster CV 17.5%, neps +200% 240 per km, trash 1.8%, and moisture 6.8%. The mill used 25% comber noil in the mixing to reduce cost, reduced spinning-room humidity to 48% RH during the afternoon, and ran a twist multiplier of 3.9 against the standard 4.2. The mill manager argues that the yarn was tested after two weeks in the society's godown and that moisture regain explains the CSP result. The society wants to reject the full lot; the mill offers a 5% price cut. Both need a decision before the next warp beam is sized.
1. Using the test data, separate the results that justify rejection from those that could be explained by storage or testing. What is your judgement on the lot?
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Judgement: reject the lot for warp use. The decisive results are intrinsic: CSP 1,850 against a 2,150 minimum is a 14% shortfall; Uster CV 17.5% and 240 neps/km mean many weak places; twist multiplier 3.9 instead of 4.2 lowers strength; and 25% comber noil raises short-fibre content. Moisture 6.8% is within a normal cotton range and cannot explain a 300-point CSP gap. Two weeks in a godown might change regain by one or two percentage points, not count strength by 14%. The 5% price cut does not remove the break problem: at 18 breaks per loom per shift, the society will lose more in stoppage time and repair than it gains on price. The lot is technically unsuitable for warp. It could be considered for weft or coarse-count use only after re-testing, with a clear written end-use agreement and a price that reflects the lower value.
2. What immediate technical and commercial action should the mill take before sizing the next beam?
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Quarantine the remaining 1,200 kg and stop it from entering the warp line. Replace it with a lot that has a release test of CSP at least 2,150, CV below the agreed limit and neps within contract; bear the freight for replacement. Technically, stop using 25% noil, restore twist multiplier to 4.2, and bring spinning-room RH back to 55-60%. Re-test the corrected lot before dispatch. Commercially, offer a replacement or full credit rather than forcing a 5% discount, because a discount leaves the society with the break problem. If the society can use the yarn as weft, negotiate a separate weft price and record the end use. The root cause is the mixing and twist change, not the society's storage.
3. Which single control would you prioritise to prevent recurrence, and why?
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Prioritise the mixing plan and cap comber noil at a level that still meets CSP. Noil is the largest intrinsic change here: it directly raises short fibres, neps and CV, and no amount of humidity control will restore the lost strength. Twist multiplier and RH are also controls, but they are easier to restore and monitor. Add a dispatch release test so no warp beam leaves without CSP, CV and neps results against the contract. This is stronger than a price discount because it prevents the defective lot from reaching the loom. A monthly audit of mixing cost versus claim cost would show management that cheap noil is expensive when warp breaks and replacement freight are counted.