Dyehouse Light-to-Dark Sequencing & Wash-down Saving

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 8 inputs are read from the form on every keystroke: Batches per Cycle, Shade Depth Steps, Cycles per Week, Base Wash-down per Batch, Extra Time per Shade Step Dropped, Average Drop, Unsequenced, Water Rate During Wash-down and Chemical Rate During Wash-down.
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 Machine Time Saved per Cycle together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Wash-down, Sequenced, Wash-down, Unsequenced, Water Saved per Cycle, Chemicals Saved per Cycle and Machine Hours Saved per Week — 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 Machine Time Saved per Cycle 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 — Cycle and Wash-down Cost. 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 Machine Time Saved per Cycle in the dark results panel — that is the headline figure, expressed in min.
4. Check the supporting rows underneath (Wash-down, Sequenced, Wash-down, Unsequenced, Water Saved per Cycle, Chemicals Saved per Cycle and Machine Hours Saved per Week) 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 Machine Time Saved per Cycle before a trial is booked, so machine time and material in Production Planning & Sequencing are committed against a calculated figure rather than an estimate.
• Costing and quotation — Machine Time Saved per Cycle 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 Batches per Cycle) shows how much of the gap in Machine Time Saved per Cycle each variable explains.
• Teaching and study — the accepted ranges bracket normal Production Planning & Sequencing practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Assumptions and limits

• Sequencing freely assumes the batches are actually available to reorder, and they usually are not — delivery dates, dye lot availability and machine-size fit constrain the sequence long before shade does, so the saving here is the theoretical ceiling rather than a plan. The wash-down penalty is also treated as proportional to shade steps, whereas in practice a few specific pigments and dye classes contaminate far worse than their depth suggests and force a full reset regardless of position. Whites and pastels after any deep shade are the usual exception and are best scheduled on dedicated machines rather than sequenced.
• Every input is bounded to the range normal practice occupies (Batches per Cycle 2 to 60 no., Shade Depth Steps 2 to 20 no. and Cycles per Week 1 to 40 no., 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