Five machines, twelve hours a day, every day: 4,380 wall-clock hours and 21,900 machine-hours. In PLA at $22 a kilogram, with an 8% scrap rate and a modest wear allowance, that year costs $31,535.
| Term | Annual | Share |
|---|---|---|
| Filament, about 1,003 kg | $22,059 | seventy percent |
| Machine wear at $1.50 an hour across five machines | $6,570 | twenty-one percent |
| Scrap allowance at 8% | $2,523 | eight percent |
| Electricity, 2,190 kWh | $383 | one percent |
Electricity is a rounding error and filament is the business
At five machines aggregated to 500 W, a full year of twelve-hour days is 2,190 kWh — $383. That is roughly what one week of filament costs.
Anyone optimising a farm for power consumption is optimising the smallest line on the page. Anyone negotiating filament pricing is working on seventy percent of it, and a ten percent supply discount here is worth $2,206 a year — nearly six times the entire electricity bill.
The number that is missing from this table
Labour. Five machines running twelve-hour days need plates cleared, prints inspected, spools changed, files sliced and failures diagnosed, and none of that is in the $31,535.
At any realistic wage, a person spending half their week on those machines costs more than the filament does. That is the real reason farms automate plate handling before they chase anything else.
Two structural risks the arithmetic hides
- Utilisation is an assumption, not a fact. The whole model rests on twelve hours a day. At six hours the fixed costs do not halve and the cost per part rises sharply.
- Scrap concentrates. An 8% rate averaged over a year is fine; 8% arriving as one bad week of a wet spool is a different problem, and it is the one that actually hurts.
- The wear allowance is a guess until it is not. A year of receipts for nozzles, plates, hotends and belts turns $1.50 an hour from an assumption into a measurement, and it is the only line here you can improve by record-keeping alone.
Scale the model to your own machine count, hours and material price in the print cost calculator. The electricity cost method explains why the power term stays small even at this scale.