Crosslapper Mass Balance, Layer Count & Lay Angle

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 6 inputs are read from the form on every keystroke: Card Web Weight, Card Web Width, Web Infeed Speed, Batt Width, Output Conveyor Speed and Drafter Draft.
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 Batt Basis Weight together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Layers in the Batt, Carriage Speed, Time for One Traverse, Traverses per Minute, Advance per Traverse, Lay Angle from Cross-Direction, Web Throughput, Batt Throughput, Weight After Drafting and Batt Area Produced — 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

The tool loads with this case already solved — the Batt Basis Weight shown above is its answer. Change one value and the difference from this baseline is the sensitivity of the result to that variable.

How to use it

1. Work through the input groups in order — Card Web In and Batt Out. 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 Batt Basis Weight in the dark results panel — that is the headline figure, expressed in g/m2.
4. Check the supporting rows underneath (Layers in the Batt, Carriage Speed, Time for One Traverse, Traverses per Minute, Advance per Traverse, Lay Angle from Cross-Direction, Web Throughput, Batt Throughput, Weight After Drafting and Batt Area Produced) 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 Batt Basis Weight before a trial is booked, so machine time and material in Nonwovens, Filtration, Hygiene & Technical Webs are committed against a calculated figure rather than an estimate.
• Costing and quotation — Batt Basis Weight 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 Card Web Weight) shows how much of the gap in Batt Basis Weight each variable explains.
• Teaching and study — the accepted ranges bracket normal Nonwovens, Filtration, Hygiene & Technical Webs practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Assumptions and limits

• The mass balance is exact and the two throughput figures are printed side by side precisely so that it can be seen to close; if they differ, an input is wrong rather than the machine. Carriage speed is taken as equal to the web infeed speed, which is what a well-set lapper does - the carriage has to consume the web at the speed it arrives or the web is either stretched or heaped at the apron. Real machines vary carriage speed through the stroke and decelerate at the reversal, which is what produces the heavier selvedges every crosslapped batt has, and profiling systems exist specifically to compensate for it; none of that is modelled here, so the batt weight computed is a mean across the width rather than a profile. Lay angle is reported from the cross-direction, so a small number means fibre laid nearly across the machine and a strongly cross-oriented batt. Drafting after the lapper reduces weight and rotates fibre toward the machine direction, trading the cross-direction strength the lapper just built for machine-direction strength; the weight after drafting is given but the reorientation is not, and a heavily drafted batt is a different fabric rather than a lighter one.
• Every input is bounded to the range normal practice occupies (Card Web Weight 3 to 200 g/m2, Card Web Width 0.3 to 6 m and Web Infeed Speed 2 to 300 m/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.

Questions people ask