A plant that uses a standard 25 × 35 cm wipe on a 20 cm fixture cuts or folds it every time. The waste is visible, the labour is not, and someone eventually asks whether a converted size would be cheaper. Sometimes it is; often the arithmetic says no.
What a special size actually costs
There is a tooling cost for the cutting or sealing die, a setup cost for the converting line, and a minimum run length below which the setup dominates the piece price. There may also be a separate packaging setup, especially for a pre-wetted format where the fill weight has to be re-validated.
Then there is the qualification. A new size is a new reference: it needs a specification, a first-article inspection and, if it is used in a critical area, a re-qualification of the cleaning step. That cost is real and usually larger than the tooling.
The savings side
Three savings are measurable. Material: a sheet sized to the fixture uses less fibre per task. Labour: no folding or tearing, which is often the largest number. Waste: fewer part-sheets in the bin and less solvent lost to an oversized sheet.
Measure the labour before you assume it. A ten-second fold, twenty times a shift, is 200 seconds; across a year and a team it becomes a number worth converting for. A two-second adjustment is not.
A worked example
Assume a standard sheet costs $0.11 and the converted size costs $0.085 at a run of 50,000 sheets, with a $1,800 die and a $600 first-article qualification. The saving is $0.025 per sheet. The payback run is 2,400 / 0.025 = 96,000 sheets, or about two production runs.
That looks attractive until the annual volume is considered. At 8,000 sheets a month, 96,000 sheets is a year of production, and the tooling sits idle between runs. If the supplier will not hold the die and run smaller batches, the lead time becomes the constraint and the saving is financed by inventory.
| Line | Value | Comment |
|---|---|---|
| Standard price | $0.110 / sheet | From current PO |
| Converted price | $0.085 / sheet | At 50,000 run |
| Tooling + qualification | $2,400 | One-off |
| Break-even volume | 96,000 sheets | ~12 months at 8,000/month |
When it never pays
Low volume, a size that may change with the next product revision, or a format that already has a close standard equivalent. A converted size locked to a fixture that is due to be replaced is a cost with no payback.
The other case is a pre-wetted product. The fill weight, the pouch and the open life all have to be re-validated, and the saving per sheet rarely covers the validation for a small volume.
Before you approve the tooling
Ask whether the fixture is likely to change within the payback period, whether the supplier will hold the die, and whether a second source can run the same size. A converted size with one source and a fixture under revision is a lock-in, not a saving.
Ask also for the first-article report before the full run. A dimension that is 2 mm out at first article is a rework at full run, and the tooling cost has already been spent. If the supplier cannot produce a first article, the size is not ready to order at volume.
Who owns the die?
Agree this in writing. If the supplier owns it, moving the business means paying again. If you own it, you need a storage arrangement and a clause for retrieval.
Can a converted size use the same specification?
The performance parameters can carry over, but the dimensions, pack count and fold need their own specification. Do not issue a new size under an old part number.
How long does a first run take?
Typically four to eight weeks including tooling and first-article approval, longer if the product is sterile and needs re-validation.
