Mislabelled Warp Count on a 30 Ne Sheeting Order
A weaving mill in Kanpur has to weave a 63-inch sheeting order of 30 Ne warp × 20 Ne weft, 68 ends/inch × 60 picks/inch (4,284 ends). The store holds two 30 Ne cotton warp lots from one supplier, both invoiced at Rs 285/kg. Quality control tests 120-yard skeins on a quadrant balance after conditioning: Lot A averages 2.02 g per skein and Lot B averages 2.18 g. Lea CSP is 2,180 for Lot A and 2,050 for Lot B. Both supplier tickets state 30 Ne, and the mill has already sized 40 beams from Lot A for this order before the count test was finished. The buyer's construction tolerance is 30 Ne ± 2.5%, fabric mass must stay within ±4% of 130 g/m², and the mill earns Rs 12/m contribution on first-quality cloth. A rejected roll costs about Rs 4,500 in freight, handling and re-inspection, and the buyer tests yarn count from the fabric.
1. Calculate the actual English count and tex of both lots from the skein weights, and state whether either lot meets the 30 Ne ± 2.5% specification.
Read the worked answer
Count from skein weight
A 120-yard skein is 120/840 = 0.142857 hank, so:
- Ne = 0.142857 ÷ weight in lb
- Lot A: 2.02 g = 2.02/453.6 = 0.004454 lb → Ne = 0.142857/0.004454 = 32.1 Ne
- Lot B: 2.18 g = 0.004806 lb → Ne = 29.7 Ne
- tex = 590.5/Ne: Lot A = 18.4 tex, Lot B = 19.9 tex
Against the specification
The tolerance band is 29.25–30.75 Ne. Lot B at 29.7 Ne is inside (−1.0%). Lot A at 32.1 Ne is +7.0% finer and fails.
Cross-check the result before acting
A 120-yard skein is only 1/7 hank, so a 1% weighing error becomes a 1% count error. The test should be repeated on at least five skeins per lot, conditioned at 65% RH ± 2% and 20 °C ± 2 °C, with the balance checked against a standard weight. The difference between the lots (2.4 Ne, about 8%) is far larger than normal test error, so the conclusion is robust; the single-skein values above should still be replaced by lot averages before a supplier claim is raised.
2. What should be done with the 40 beams already sized from Lot A, and with the balance of the two lots? Support the decision with fabric mass and cover reasoning rather than only the count result.
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Quantify what Lot A does to the cloth
Warp mass at 68 ends/inch (2,677 ends/m):
- 30 Ne (19.68 tex): 2,677 × 19.68/1000 = 52.7 g/m²
- 32.1 Ne (18.4 tex): 2,677 × 18.4/1000 = 49.3 g/m²
Weft at 60 picks/inch (2,362 picks/m, 1.6 m pick length, 29.5 tex) = 69.7 g/m². Nominal total = 122.4 g/m² before crimp, about 130 g/m² with crimp; Lot A gives about 126.5 g/m², a fall of roughly 2.7%. That is inside the buyer's ±4% mass tolerance, so mass alone will not expose the fault. The construction declaration will: 32.1 Ne is outside 30 Ne ± 2.5%, the buyer tests count from the fabric, and the warp cover factor also falls by about 3%, which changes opacity and handle.
Decision
- Do not issue Lot B for any other order; it is the only compliant lot and should be reserved for this quality.
- For the 40 sized beams, the cheapest compliant route is a written variance request to the buyer quoting the measured mass and count. If refused, re-sley the beams from 68 to about 72.7 ends/inch to restore mass and cover, but this changes the construction to 72 × 60 and also needs buyer approval. Weaving and selling as a 32 × 20 quality at second-quality price is the fallback.
- Do not simply run the beams and hope. At Rs 12/m contribution, a downgrade of even Rs 5/m on the order outweighs any yarn saving, and a rejection adds Rs 4,500 per roll plus the loss of the account.
- Raise a supplier debit note for Lot A and quarantine the remaining Lot A stock pending settlement.
3. Compare the warp yarn cost per metre of cloth for the two lots and explain why the apparent saving from Lot A is misleading.
Read the worked answer
Yarn mass per metre of cloth (1.6 m wide, 4,284 ends)
- Lot A: 4,284 × 18.4/1000 = 78.8 g/m → at Rs 285/kg = Rs 22.47/m
- Lot B: 4,284 × 19.68/1000 = 84.3 g/m → at Rs 285/kg = Rs 24.03/m
Apparent saving with Lot A = Rs 1.56/m of cloth, or about Rs 1,560 per 1,000 m.
Why it is misleading
The saving exists only because less yarn mass is being bought per metre, not because the yarn is cheaper. At identical sett the lighter warp reduces fabric mass by about 2.7% and shifts the count outside the declared tolerance. The buyer is paying for a declared construction, so the mill is selling a lighter cloth at a first-quality price while carrying the risk of a count claim and rejection. One rejected roll of, say, 200 m costs Rs 4,500 in handling plus the lost contribution of roughly Rs 2,400, which is more than the annual-looking saving on a few thousand metres.
Also compare on a like-for-like basis: if Lot A is genuinely 32.1 Ne, its fair price per kg should be higher than 30 Ne because it yields about 7% more length per kg. Settling at the 30 Ne rate is therefore not automatically a gain to the mill; the correct action is a count-based price or a return, not silent substitution.