Blowroom & Carding
The hole in the middle of an open-coiled can is capacity you paid for.
— kg
Usable annulus volume at the stated fill factor
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.
Sliver Coil Geometry, Can Packing Density & Capacity — free, with the formula and a worked example, at Textile School.