Comber Feed, Noil Extraction & Short-Fibre Balance

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 9 inputs are read from the form on every keystroke: Lap Linear Density, Feed per Nip, Nip Rate, Combing Heads, Machine Efficiency, Delivered Sliver, Noil Extraction, Short Fibre in the Lap and Short Fibre in the Noil.
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Combed Production together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Short-Fibre Removal Efficiency, Short Fibre Left in the Sliver, Noil Selectivity, Noil Extracted, Lap Consumed, Short Fibre Removed, Total Draft and Lap Feed Rate — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

Substituting

Removing 16% of the lap cut short fibre content from 18% to 9.6% - a halving. Of the 9.50 kg/h extracted, 5.89 kg was short fibre doing its job and 3.61 kg was good long fibre going out with it. That 3.61 kg is what combing costs per hour, and no setting removes it entirely.

How to use it

1. Work through the input groups in order — Feed & Machine and Noil & Short Fibre. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Combed Production in the dark results panel — that is the headline figure, expressed in kg/h.
4. Check the supporting rows underneath (Short-Fibre Removal Efficiency, Short Fibre Left in the Sliver, Noil Selectivity, Noil Extracted, Lap Consumed, Short Fibre Removed, Total Draft and Lap Feed Rate) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Combed Production before a trial is booked, so machine time and material in Blowroom, Carding, Drawing & Roving Control are committed against a calculated figure rather than an estimate.
• Costing and quotation — Combed Production is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Lap Linear Density) shows how much of the gap in Combed Production each variable explains.
• Teaching and study — the accepted ranges bracket normal Blowroom, Carding, Drawing & Roving Control practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Reading the result

Typical bands and what each one is telling you.

Assumptions and limits

• Noil is quoted on the lap fed, which is the industry convention; quoting it on the sliver delivered gives a larger number for the same machine and the two are frequently confused between mills. Production assumes all heads run and are fed equally - a head with a broken lap reduces output and shifts the effective noil, since the noil percentage is measured on what actually passed. The short-fibre balance needs all three percentages measured to the same length threshold and on the same instrument; short fibre content below 12.7 mm and below half an inch are different quantities, and mixing an HVI-derived feed figure with an AFIS-derived noil figure will not close. Total draft is from the combined lap mass to the delivered sliver and includes the draft in the draw box after combing.
• Every input is bounded to the range normal practice occupies (Lap Linear Density 20 to 200 ktex, Feed per Nip 3 to 8 mm and Nip Rate 100 to 700 nips/min, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Standards and further reading

• ASTM D1440 - Length and Length Distribution of Cotton Fibers, the basis of the short-fibre percentages.
• ASTM D5867 - Measurement of Physical Properties of Cotton Fibers by HVI.
• ISO 4913 - Textile machinery and accessories, Combing machinery terminology.

Questions people ask