Nonwoven Line Product Mix & Contribution per Line Hour

How to read this sheet

Contribution per line hour is the right unit only while the line is the constraint. A line short of orders should be ranked on margin per square metre like anything else, because the hour is then free and the question is which order to accept rather than which to run; the two rankings coincide when nothing is scarce and diverge exactly as the line fills. The achievable mass rate is the lesser of what the extruders can deliver and what the line speed allows at that basis weight, which is why a light fabric can fall short of a throughput rating that is perfectly real at a heavier one - the limit switches from mass to speed as the fabric gets lighter and nothing announces the switch. Efficiency is applied to the achievable rate rather than to the rating, so a speed-limited product is derated once and not twice. Conversion cost is charged per line hour and is the same whatever runs, which is what makes the hour the unit worth maximising; it excludes polymer, which is in the material column and varies by product. Margin is reported per thousand square metres rather than per square metre: on a lightweight nonwoven the per-square-metre figure is a few thousandths of a currency unit and would be published at a precision too coarse to reconcile against the contribution beside it. Edge trim is assumed already removed from the web width, so enter the saleable width rather than the die width, and a product needing a narrower width than the line makes will carry trim this tool does not model. Changeover between products is not modelled at all: a plan that alternates products every hour will not achieve these figures, and the free changeover calculators on this site price that separately.