Loom Stop Cause Pareto, Lost Metres & Annual Cost

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 11 inputs are read from the form on every keystroke: Warp Breaks, Weft Breaks, Mechanical & Other Stops, Mean Time to Mend a Warp Break, Mean Time to Clear a Weft Stop, Mean Time for a Mechanical Stop, Loom Speed, Pick Density, Looms in the Shed, Scheduled Running Hours and Contribution per Metre.
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 Loom Efficiency from Stops Alone together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Largest Cause Share of Downtime, Warp Breaks Share, Weft Stops Share, Mechanical Share, Downtime per Loom Hour, Stops per Loom Hour, Lost Production, Lost Production Across the Shed and Contribution Lost — 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

Count the stops and weft looks like a third of the problem; count the minutes and it is an eighth. The ranking that matters is warp first, mechanical second - and mechanical is the one a stop-count report will always bury, because 0.396 stops an hour looks like nothing until it is multiplied by eight minutes.

How to use it

1. Work through the input groups in order — Stop Rates and Machine & Value. 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 Loom Efficiency from Stops Alone in the dark results panel — that is the headline figure, expressed in %.
4. Check the supporting rows underneath (Largest Cause Share of Downtime, Warp Breaks Share, Weft Stops Share, Mechanical Share, Downtime per Loom Hour, Stops per Loom Hour, Lost Production, Lost Production Across the Shed and Contribution Lost) 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 Loom Efficiency from Stops Alone before a trial is booked, so machine time and material in Warping, Sizing, Weaving & Fabric Formation Control are committed against a calculated figure rather than an estimate.
• Costing and quotation — Loom Efficiency from Stops Alone 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 Warp Breaks) shows how much of the gap in Loom Efficiency from Stops Alone each variable explains.
• Teaching and study — the accepted ranges bracket normal Warping, Sizing, Weaving & Fabric Formation Control 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

• Efficiency here is the stop-driven figure only: scheduled changeovers, beam gaiting, style changes, waiting for a weaver and planned maintenance are excluded, so it will always read higher than posted machine efficiency. Mean repair times are treated as constants per cause, which is right for totalling minutes and wrong for predicting any individual stop - the distributions are strongly right-skewed and the tail often carries a third of the time. The three causes here are the standard first cut; a monitoring system that separates weft break from weft feeder, or warp break from drop-wire fault, will produce a sharper Pareto and should be used where available. Lost metres assume the loom would otherwise have run at full speed on the same construction, which overstates the recoverable portion slightly because some stops occur during periods the loom would have been stopped anyway. Contribution per metre, not selling price, is the correct value to apply: the variable cost of yarn not woven is not incurred.
• Every input is bounded to the range normal practice occupies (Warp Breaks 0 to 100 /100k picks, Weft Breaks 0 to 100 /100k picks and Mechanical & Other Stops 0 to 100 /100k picks, 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 8498 - woven fabrics, description of defects, vocabulary.
• ASTM D3990 - terminology relating to fabric defects.
• ASTM D5430 - visually inspecting and grading fabrics, for the defect consequences of stops.
• ISO 13053-2 - quantitative methods in process improvement, Six Sigma, tools and techniques.

Questions people ask