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Cone Build, Winding Tension and Knitting Breakage: The Yarn Package Spec Mills Should Specify
2026-09-10
The Lot That Tested Clean and Broke Anyway
A circular knitting mill in Gaziantep running 180 single-jersey machines at 26 gauge took in 14 tonnes of 32s/2 Polyester Yarn on 1.67 kg cones. The count certificate was right and the tensile results in band. Two shifts later the stop rate tripled to 13.6 per hundred revs. The yarn had not changed. The package had.
The mill had no claim, because nothing on the test report was out of tolerance. What moved was a 14 percent rise in package density, a traverse shortened by 6 mm, and a winding tension profile the previous supplier never ran. All three are package specification items, and all three are missing from most purchase contracts. When you buy a 32s/2 raw white polyester yarn for single-jersey knitting, the cone is part of the product.
Cone Geometry: Taper, Traverse and the Speed Ceiling
Taper decides whether yarn leaves the cone cleanly or fights itself. A 9 degree 15 minute cone is standard for over-end withdrawal on circular knitting; a 5 degree 57 minute cheese suits side withdrawal and package dyeing. Run the wrong one and you get slough-off at the shoulder, where several coils release together.
Traverse and diameter set the speed ceiling. A 150 mm traverse with a 250 mm maximum diameter is the safe pair for most knitting creels; pushing to 280 mm raises balloon tension. Above about 1,200 m/min over-end withdrawal the balloon is unstable whatever the taper.
Package Density and Hardness: The Window Is Narrow
Density is the number most mills never ask for. For polyester spun packages the workable band is 0.34 to 0.40 grams per cubic centimetre. Below it the cone deforms in transit; above roughly 0.44 it crushes the surface layer and the yarn unwinds at uneven tension.
Hardness is the shop-floor proxy. Take a durometer reading at three points on the barrel and require the spread within a cone to stay under 5 points, and across a lot under 8. A lot that averages correctly but swings 15 points cone to cone puts alternating packages on one creel. Where a mill runs a 21s/1 black polyester yarn for everyday knitwear, get the density band in writing before you discuss price.
Winding Tension, Hairiness and the Knots at the Needle
A tension spike of 25 percent above set point does damage no tensile test shows. It stretches outer filaments past yield while inner ones stay slack, so the bundle no longer loads evenly at the needle. That is why the laboratory report looks clean and the knitting floor does not.
Hairiness is the other half of the same failure. Loose fibre loops longer than 3 mm tangle with the neighbouring end and reach the needle as a knot. Hold Uster hairiness within 8 percent of lot average and require a documented set point with a stated tolerance in centinewtons.
Withdrawal Direction, Residual Torque and Intermingling
Over-end and side withdrawal are not interchangeable. Over-end withdrawal from a tapered cone is what knitting creels want; side withdrawal belongs on warping creels and needs no taper and an even build. Put the wrong package on a knitting creel and every revolution adds twist, which on singles yarn shows as snarling at the feed.
Torque is measurable, so it is specifiable. Suspend a 500 mm length under light tension and count the snarls that form; four or fewer is a workable limit for fine gauge. For filament running without twist, intermingling carries the load: 80 to 120 nips per metre. Below 60 the filaments separate; above 150 the yarn stiffens. On a high strength polyester yarn for technical knits, both figures belong on the sheet.
Finish Level, Storage and Cone Weight Tolerance
Finish is a two-sided tolerance. Below about 0.2 percent on weight, the needle runs dry; above roughly 1.2 percent, wax builds on hook and cam and you trade breakage for needle wear and oil-stained fabric. The band for knitting is 0.4 to 0.8 percent as a range. Storage is the part nobody audits: hold cones at 60 to 70 percent RH and 20 to 25 degrees Celsius. Below 45 percent RH, static pulls fly onto the package and the first twenty metres of every cone is waste. Past six months, filament packages gain set that raises snarling.
Cone weight is a costing item dressed up as a packing detail. A 1.67 kg cone delivered at 1.60 kg is 4 percent short: across a 3,000-cone container, 210 kg of paid-for yarn. Scatter of more than about 1.5 percent within a lot and creel change intervals stop being predictable. State nominal cone weight plus or minus 1 percent, a carton net weight on a calibrated scale, and an agreed short-weight credit rate. On a custom colour polyester yarn developed to a shade brief, cover the make-up lot too, since re-running small dyed quantities is rarely possible.
Package Spec Line Items for the Purchase Contract
Send this list with the enquiry. Anything the supplier will not answer in writing is a variable you have accepted.
- Cone taper and tube type: angle in degrees and minutes, tube material, over-end or side withdrawal.
- Traverse and maximum diameter: in millimetres, with the maximum safe unwinding speed.
- Density and hardness: gram per cubic centimetre band, durometer range, spread across the lot.
- Winding tension: set point in centinewtons, permitted deviation, and the logging interval.
- Hairiness, torque and weight: Uster value, snarl count limit, cone weight tolerance and short-weight credit.
The Bottom Line
Yarn quality and package quality are two purchases, and only one is on your contract today. These items cost nothing to specify and turn an argument about whose fault the breakage was into a measurement both sides signed. Put them in the enquiry, not in the complaint.