Stenter Chain Width, Overfeed & Target GSM Solver

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: Entry Fabric Weight, Entry Width, Chain Width Set, Overfeed, Finish Add-On, Target Exit Weight and Line 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 Exit Fabric Weight together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Overfeed the Target Needs, Current Overfeed Minus Required, Exit Weight Before the Add-On, Width Change, Length Lost to Overfeed, Production, Fabric Delivered and Fabric Fed In — 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

Most of the weight gain here is not finish. The width change alone lifts 165 to 182.4 g/m2, the overfeed adds another 10.9, and the 2.5% add-on contributes only 4.8. A GSM complaint on this cloth is a chain-width and overfeed conversation, not a recipe one.

How to use it

1. Work through the input groups in order — Entry & Chain and Finish & Target. 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 Exit Fabric Weight in the dark results panel — that is the headline figure, expressed in g/m2.
4. Check the supporting rows underneath (Overfeed the Target Needs, Current Overfeed Minus Required, Exit Weight Before the Add-On, Width Change, Length Lost to Overfeed, Production, Fabric Delivered and Fabric Fed In) 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 Exit Fabric Weight before a trial is booked, so machine time and material in Finishing, Coating, Lamination & Functional Performance are committed against a calculated figure rather than an estimate.
• Costing and quotation — Exit Fabric 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 Entry Fabric Weight) shows how much of the gap in Exit Fabric Weight each variable explains.
• Teaching and study — the accepted ranges bracket normal Finishing, Coating, Lamination & Functional Performance 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 balance assumes mass is conserved apart from the stated finish add-on, so it excludes any weight loss from the drying of residual moisture beyond the finish and any fibre loss from shearing or brushing on the same line. Add-on is dry solids on the weight of the entering fabric; if the recipe is stated as a bath concentration and a wet pickup, convert it first. Width change is treated as uniform across the frame, which ignores the bowing and edge effects a real stenter produces - the delivered width at the centre and at the selvedge differ, and a GSM cut from the centre is not representative. The frame is assumed to hold the set chain width, which a heavily overfed knit will resist.
• Every input is bounded to the range normal practice occupies (Entry Fabric Weight 20 to 1200 g/m2, Entry Width 30 to 500 cm and Chain Width Set 30 to 500 cm, 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 3801 / ASTM D3776 - mass per unit area of fabric, the quantity being controlled.
• ISO 22198 - Textiles, fabrics, determination of width and length.
• ISO 5077 - dimensional change in washing and drying, which the overfeed is set against.

Questions people ask