Consumables, time and cost
Arc-on time and welder time from deposition rate
- where
- arc-on time (h)
- weld metal to deposit (kg)
- deposition rate (kg/h)
- welder time (h)
- operating factor (%)
Explain this equation
Estimates the arc-on time and total welder time for a job from the weld metal needed. Use it for pricing labour.
The deposition rate is how many kilograms an hour the process lays while the arc is struck. Weld metal divided by that gives the arc-on hours. Welders spend much of their time setting up, cleaning, changing position and grinding, so the arc is only on for a fraction of paid time, the operating factor. Dividing arc time by that fraction gives the paid hours.
Time equals quantity divided by rate, then scaled up for non-welding time.
Sense check: 2.5 kg at 3 kg/h is about 50 minutes of arc time; at a 40% operating factor that is about 2.1 hours of welder time.
Watch out: operating factors vary hugely, from around 10 to 20% for site MMA to over 50% for mechanised work. Use a figure from your own jobs if you can.
Estimates how long the welding takes: arc-on time from the deposition rate, and total welder time once fit-up, cleaning, changing rods and moving are allowed for.
Enter your values to see the result.
Good to know
Deposition rate rises with current and wire size; take it from the wire maker’s data at your settings (for example ESAB gives 1.3–8.0 kg/h for 1.2 mm solid wire over 120–380 A). The operating factor is arc-on time as a share of paid time; measure it on your own jobs. The Lincoln cost example assumes 40 % for mechanised work; manual stick work is usually lower.
Common mistake
Pricing on arc time alone. The arc is struck for well under half the shift on most fabrication work.
Limits
Average figures. Out-of-position welding needs lower currents and so lower deposition rates.
Sources
- ESAB OK Autrod 12.51 data sheet (1.0 mm: 80–300 A, 1.0–5.6 kg/h; 1.2 mm: 120–380 A, 1.3–8.0 kg/h deposition rate)
- Lincoln Electric (Decker), Determining the cost of welding, AWS Welding Journal, January 2024 (cost per length and per weight of weld metal; operating factor = arc-on time ÷ paid time)
- Determining the cost of welding (reprint): L&O per kg = rate ÷ (deposition rate × operating factor); filler per kg = price ÷ electrode efficiency; gas = flow × price ÷ deposition rate
Results are calculations from the published methods and figures shown, and depend on the data you enter. Follow the welding procedure specification (WPS), BS EN ISO 15614/9606, BS EN 1090, BS EN 1993 and manufacturers’ data. Structural welds need qualified welders and engineered designs.