Fabric Hand & Performance Specification Matrix

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 15 inputs are read from the form on every keystroke: Bending Rigidity, Compression, Drape Coefficient, Stretch, Surface Friction, Target Bending Rigidity, Target Compression, Target Drape, Target Stretch, Target Friction, Bending Weight, Compression Weight, Drape Weight, Stretch Weight and Friction Weight.
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 Composite Hand Index together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Weighted Deviation, Bending Deviation, Compression Deviation, Drape Deviation, Stretch Deviation and Largest Single Deviation — 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 Composite Hand Index 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 — Measured Properties and Target Profile & Weights. 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 Composite Hand Index in the dark results panel — that is the headline figure, expressed in index.
4. Check the supporting rows underneath (Weighted Deviation, Bending Deviation, Compression Deviation, Drape Deviation, Stretch Deviation and Largest Single Deviation) 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 Composite Hand Index before a trial is booked, so machine time and material in Product Engineering, Specifications & Feasibility are committed against a calculated figure rather than an estimate.
• Costing and quotation — Composite Hand Index 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 Bending Rigidity) shows how much of the gap in Composite Hand Index each variable explains.
• Teaching and study — the accepted ranges bracket normal Product Engineering, Specifications & Feasibility practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Assumptions and limits

• The index is a management summary and the signed deviations are the engineering content — a fabric 25% too stiff and one 25% too limp score identically on the index and need opposite corrections, so never act on the composite alone. Weights should sum to 1 for the index to sit on a sensible scale, and they are category-specific: bending dominates hand for shirting and matters far less for fleece. Human perception is also not linear in any of these properties, so equal percentage deviations are not equally noticeable, and the mapping needs anchoring against a trained panel before it means anything to a customer.
• Every input is bounded to the range normal practice occupies (Bending Rigidity 0.5 to 200 µN·m, Compression 1 to 80 % and Drape Coefficient 10 to 95 %, 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