Sliver Coil Geometry, Can Packing Density & Capacity

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 7 inputs are read from the form on every keystroke: Can Diameter, Coil Diameter, Usable Can Height, Fill Factor, Sliver Linear Density, Sliver Bulk Density and Delivery Speed.
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 Can Capacity together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Sliver Diameter, Centre Hole Left, Can Cross-Section Used, Packed Density in the Can, Sliver Length per Can, Can Run Time, Coiler Speed Required, Sliver per Coil and Can Gross Volume — 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

At 480 mm coil in a 1000 mm can the hole is only 40 mm and 99.8% of the cross-section is working. Drop the coil to 400 mm and the hole opens to 200 mm - 4% of the can becomes air, and the same can holds nearly five kilograms less.

How to use it

1. Work through the input groups in order — Can & Coil and Sliver. 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 Can Capacity in the dark results panel — that is the headline figure, expressed in kg.
4. Check the supporting rows underneath (Sliver Diameter, Centre Hole Left, Can Cross-Section Used, Packed Density in the Can, Sliver Length per Can, Can Run Time, Coiler Speed Required, Sliver per Coil and Can Gross Volume) 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 Can Capacity 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 — Can Capacity 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 Can Diameter) shows how much of the gap in Can Capacity 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

• The geometry assumes the coil circle is laid tangent to the can wall, which is the normal arrangement; a coiler set to leave clearance at the wall reduces the annulus at both ends and this will read high. The fill factor is a lumped empirical term covering coil overlap, layer nesting and any compression under the weight of the column above, and it should be measured on a full can rather than taken from the default. Capacity is geometric and takes no account of the spring base or fixed bottom plate that real cans carry, nor of the fact that the top of a can is normally left short of the rim so it can be moved. Sliver bulk density varies with fibre, linear density and the tension at the trumpet - it is not a constant of the material.
• Every input is bounded to the range normal practice occupies (Can Diameter 200 to 1500 mm, Coil Diameter 50 to 900 mm and Usable Can Height 300 to 1600 mm, 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

• ISO 2060 / ASTM D1907 - linear density of the sliver.
• ASTM D1425 - sliver unevenness, which coiling disturbance shows up in.
• ISO 4912 - carding and drawing machinery terminology.

Questions people ask