Covers yarn and value lost on downgraded fabric. Excludes downstream costs — customer claims, reprocessing, lost orders and reputational damage — which are typically larger again.
The second line is the one worth staring at. It is not a rate — it is a duration. Detection time is the only variable in the whole calculation that inspection technology actually changes, and it changes it by orders of magnitude: from tens of minutes to milliseconds.
Each of these is real and none is included, which means the figure above should be read as a floor, not an estimate of total cost.
Four things: the yarn already consumed, the machine hours already spent, the value lost when the roll is downgraded to seconds, and the downstream cost if the defect escapes to the customer. This calculator covers the first three — the fourth is usually far larger and much harder to quantify.
It varies enormously with yarn quality, machine condition and maintenance discipline. Many mills run a downgrade rate somewhere between 2% and 8% of production. If you do not measure it, the honest answer is that you do not know — and unmeasured rates are usually higher than assumed.
A needle break at the start of a shift can produce hours of faulted fabric before anyone notices, because the fault is on the inside of the roll. The machine reports full efficiency the whole time. The cost is not the defect — it is the duration.
Inspection at the table finds defects after the yarn and the machine time are already spent. Inspection at the machine stops production at the moment of the fault, so the loss is bounded by detection speed rather than by how long until someone happens to look.
You cannot make yarn perfect or needles immortal. You can change how long a machine runs before anyone notices. Knit-I detects defects as the loop forms and halts the machine in 20 milliseconds — turning the “fabric per fault” figure above into centimetres.
See Knit-I on your machines →