Weld Metal Deposition Rate Calculator — GMAW, FCAW, SMAW, and SAW
Weld metal deposition rate — the mass of filler metal deposited per unit time, expressed in kg/h — is the primary productivity metric in arc welding operations. Knowing the deposition rate for your process, wire diameter, and operating parameters allows accurate calculation of weld completion time, filler metal consumption per joint, consumable purchasing requirements, and cost per metre of weld. This calculator covers all major continuous-wire and electrode processes: GMAW (MIG/MAG) solid and metal-cored wire, FCAW-G (gas-shielded flux-cored), FCAW-S (self-shielded flux-cored), SMAW (manual metal arc), and SAW (submerged arc), with full deposition efficiency factors and integrated weld cost estimation.
Key Takeaways
- Deposition rate (kg/h) = (π/4) × d² × WFS × ρ × 60 × ηdep, where d is wire diameter (cm), WFS is wire feed speed (cm/min), ρ is density (g/cm³), and ηdep is deposition efficiency.
- SAW achieves the highest deposition rate (5–25 kg/h single wire) due to high current operation with near-zero spatter losses; SMAW has the lowest (0.5–3 kg/h) due to stub losses and low duty cycle.
- Deposition efficiency differs from deposition rate: efficiency measures material utilisation (% of filler deposited vs consumed); rate measures productivity (kg/h of arc-on time).
- Actual deposition rate = theoretical rate × duty cycle; duty cycle is the fraction of working time the arc is burning — 25–40% for manual SMAW, 40–70% for manual GMAW, 70–90% for robotic GMAW.
- Wire consumption rate (kg/h) = deposition rate / deposition efficiency — this is the number used for purchasing consumables.
- Switching from SMAW to GMAW or FCAW typically delivers 3–8× higher actual deposition rate, the single greatest productivity improvement available in manual welding.
- For weld cost estimation: total filler cost per joint = (weld volume × density) / deposition efficiency × wire unit cost.
Weld Metal Deposition Rate Calculator
GMAW • FCAW • SMAW • SAW — deposition rate, wire consumption, and weld cost estimation
Optional — Weld Cost Estimation
The Deposition Rate Formula Explained
For all continuous-wire processes (GMAW, FCAW, SAW), the theoretical deposition rate is derived directly from the wire geometry and feed speed:
Theoretical deposition rate (100% arc-on, 100% efficiency):
DR_theo (g/min) = A_wire × WFS × ρ
where:
A_wire = π/4 × d² [wire cross-sectional area, cm²]
d = wire diameter (cm = mm/10)
WFS = wire feed speed (cm/min = m/min × 100)
ρ = wire density (g/cm³)
Converting to kg/h:
DR_theo (kg/h) = DR_theo (g/min) × 60 / 1000
= (π/4) × d² × WFS × ρ × 60 / 1000
Applying deposition efficiency and duty cycle:
DR_actual (kg/h) = DR_theo × (η_dep / 100) × (duty_cycle / 100)
Wire consumption rate (purchasing quantity):
Wire_consumed (kg/h) = DR_theo × (duty_cycle / 100)
[Note: efficiency loss is wasted; you buy all the wire consumed,
not just what is deposited]
Example — GMAW 1.2 mm solid wire at 8 m/min, carbon steel, 95% efficiency, 50% duty:
d = 0.12 cm; WFS = 800 cm/min; ρ = 7.87 g/cm³
A = π/4 × 0.12² = 0.01131 cm²
DR_theo = 0.01131 × 800 × 7.87 × 60/1000 = 4.27 kg/h
DR_actual = 4.27 × 0.95 × 0.50 = 2.03 kg/h
Wire consumed = 4.27 × 0.50 = 2.14 kg/h
Deposition Efficiency by Process
Deposition efficiency (ηdep) is the fraction of filler metal consumed that actually ends up in the weld joint. Losses occur through several mechanisms that vary by process:
| Process | Deposition Efficiency | Primary Loss Mechanism | Notes |
|---|---|---|---|
| SAW (submerged arc) | 97–99% | Minimal — flux recovered, no spatter, no UV exposure loss | Highest efficiency of all processes; granular flux slag is separated and discarded (or recycled) |
| GMAW solid wire — spray transfer | 95–98% | Fine spatter droplets; edge losses during out-of-position welding | Spray transfer (above transition current) has near-zero spatter; short-circuit and globular modes have higher spatter |
| GMAW solid wire — short-circuit/globular | 90–95% | Higher spatter from irregular droplet transfer | More common for thin plate and root passes; higher spatter vs spray |
| GMAW metal-cored wire | 90–96% | Low spatter; small slag islands on bead surface | Higher deposition rate than solid wire at same current; better penetration profile |
| FCAW-G (gas-shielded flux-cored) | 82–90% | Flux core slag (non-recoverable), spatter, fume | All-position capability; slag forms protective cover for out-of-position welding |
| FCAW-S (self-shielded) | 78–87% | Higher spatter, larger slag volume, flux fume | No external gas required; suitable for outdoor/windy conditions; lower efficiency vs FCAW-G |
| SMAW (covered electrode) | 60–85% | Stub loss (50–75 mm unusable end), slag, spatter, fume | E7018 basic: ~85%; E6010 cellulosic: ~60–65%; rutile E6013: ~75–80% |
| GTAW (TIG, non-consumable) | N/A | Non-consumable electrode — filler added separately | Filler wire consumption rate calculated separately from filler addition rate if manual |
Duty Cycle: The Most Overlooked Productivity Factor
Theoretical deposition rate assumes the arc is burning continuously. In practice, welding operations include substantial non-arc time for electrode changes (SMAW), inter-pass cleaning, repositioning, visual inspection, joint fit-up, and welder fatigue breaks. The actual deposition rate over a shift is the theoretical arc-on rate multiplied by the duty cycle.
| Process / Application | Typical Duty Cycle | Primary Non-Arc Time Causes | Improvement Strategies |
|---|---|---|---|
| Manual SMAW | 20–35% | Electrode change every 3–4 min; slag chip; re-strike; stub disposal | Pre-staged electrode holders; twin-torch setup; operator training |
| Manual GMAW (MIG) | 40–60% | Repositioning; wire spool change (every 12–20 kg); inter-pass cleaning; inspection | Drum spools (250 kg); fixturing for fewer repositions; automated travel |
| Manual FCAW | 35–55% | Slag removal mandatory between passes; repositioning; flux-core drum change | Power wire brushing; pneumatic chipping; optimised joint geometry |
| Semi-auto SAW | 60–75% | Flux refill; electrode reel change; flux recovery; seam tracking setup | Automated flux recovery; large electrode reels (500 kg); seam tracking |
| Fully automated SAW | 75–90% | Weld start/stop; seam end repositioning; flux maintenance | Continuous seam tracking; robotic gantry; inline flux recovery |
| Robotic GMAW | 70–90% | Part loading/unloading; tooling changes; wire breaks; arc faults | Twin-station rotary table; automatic wire break detection and restart |
Using Deposition Rate for Weld Cost Estimation
Deposition rate is the starting point for accurate weld cost analysis. A complete weld cost model involves four components: filler material cost, labour cost (including non-arc time), shielding gas and flux cost, and power cost. The filler material calculation from deposition rate is the most precise part:
Step 1 — Weld metal volume per joint:
V_weld (cm³) = A_cross_section × L_weld
For equal-leg fillet weld (leg size w mm):
A = 0.5 × (w/10)² cm²
e.g. 8 mm fillet: A = 0.5 × 0.64 = 0.32 cm²
For V-groove butt weld (60° included angle, root face 2 mm, plate 20 mm):
A ≈ (t − root_face) × tan(30°) × (t − root_face) / 2 + root_face × root_gap
(use joint cross-section diagram for accurate value)
Step 2 — Weld metal mass:
M_weld (kg) = V_weld × ρ / 1000
Step 3 — Wire consumed (accounting for deposition efficiency losses):
M_wire (kg) = M_weld / (η_dep / 100)
Step 4 — Arc time:
t_arc (h) = M_weld / DR_theo [theoretical deposition rate, 100% eff.]
Step 5 — Total weld time (including non-arc time):
t_total (h) = t_arc / (duty_cycle / 100)
Step 6 — Costs:
Filler cost = M_wire × price_per_kg
Labour cost = t_total × labour_rate_per_hour
Gas cost = t_arc × gas_flow_rate (L/min) × 60 / 1000 × gas_price (per m³)
Example:
8 mm fillet weld, 500 mm long, GMAW 1.2mm, WFS=8 m/min, carbon steel:
A = 0.32 cm²; L = 50 cm; V = 16 cm³
M_weld = 16 × 7.87 / 1000 = 0.126 kg
DR_theo = 4.27 kg/h (from formula); η_dep = 95%; duty = 50%
M_wire = 0.126 / 0.95 = 0.133 kg
t_arc = 0.126 / 4.27 = 0.030 h = 1.78 min
t_total = 0.030 / 0.50 = 0.059 h = 3.56 min
Filler cost @ ₹180/kg = 0.133 × 180 = ₹23.9
Deposition Rate Reference Table — Typical Values by Process
| Process | Wire/Electrode Dia. | Typical Current (A) | Dep. Rate (kg/h) | Dep. Efficiency | Typical Duty Cycle |
|---|---|---|---|---|---|
| GMAW solid (spray) | 0.9–1.2 mm | 150–280 | 2–5 kg/h | 95–98% | 40–60% |
| GMAW solid (spray) | 1.6 mm | 250–380 | 4–8 kg/h | 95–98% | 40–60% |
| GMAW metal-cored | 1.2–1.6 mm | 180–350 | 3–8 kg/h | 90–96% | 45–65% |
| FCAW-G (gas-shielded) | 1.2 mm | 180–280 | 3–6 kg/h | 82–90% | 40–55% |
| FCAW-G (gas-shielded) | 1.6–2.0 mm | 250–400 | 5–10 kg/h | 82–90% | 40–55% |
| FCAW-S (self-shielded) | 1.6–3.2 mm | 200–500 | 3–9 kg/h | 78–87% | 35–50% |
| SMAW E7018 basic | 2.5 mm | 80–120 | 0.5–1.2 kg/h | 80–85% | 20–35% |
| SMAW E7018 basic | 3.2 mm | 120–170 | 1.0–2.0 kg/h | 80–85% | 20–35% |
| SMAW E7018 basic | 4.0 mm | 160–210 | 1.5–3.0 kg/h | 80–85% | 20–35% |
| SMAW E6010 cellulosic | 3.2–4.0 mm | 100–175 | 0.8–2.2 kg/h | 60–68% | 20–35% |
| SAW single wire | 2.4 mm | 300–600 | 5–10 kg/h | 97–99% | 65–80% |
| SAW single wire | 4.0 mm | 600–900 | 10–20 kg/h | 97–99% | 65–80% |
| SAW tandem 2-wire | 2×3.2–4.0 mm | 500–1500 total | 15–40 kg/h | 97–99% | 70–90% |
Improving Deposition Rate in Production
The following strategies are ranked by their typical return on investment for structural fabrication operations:
Process Upgrade: SMAW to GMAW or FCAW
The single largest deposition rate improvement available is replacing SMAW with GMAW or FCAW. For a typical structural steel application, this delivers a 4–8× increase in actual shift output — not just theoretical arc-on rate, but real kg/h deposited over a full shift, because GMAW/FCAW also raises duty cycle from 20–35% to 40–65%. The investment in constant-voltage power sources, wire feeders, and operator retraining typically pays back within 3–6 months in medium-volume fabrication shops.
Larger Wire Diameter at Higher Current
For SAW and FCAW, moving from smaller to larger diameter wire at correspondingly higher current substantially increases deposition rate. A SAW upgrade from 3.2 mm wire at 500 A to 4.0 mm wire at 800 A roughly doubles the deposition rate from approximately 9 kg/h to 18 kg/h. The joint must be accessible for the larger arc and the increased penetration depth must be accounted for in the joint design.
Increasing Duty Cycle Through Fixturing and Workflow
Improving duty cycle from 35% to 60% (a common achievable target in manual GMAW shops) increases actual deposition 71% with no change to the process or wire speed. Strategies include: dedicated positioners that keep the joint in the 1G/1F flat position (eliminating positional welding slowdowns), drum wire spools (250 kg) replacing small 15 kg reels (eliminating frequent spool changes), pre-set inter-pass temperature gauges eliminating manual temperature checks, and organised workstations eliminating material handling time.
Metal-Cored Wire Over Solid Wire
Metal-cored GMAW wire (AWS A5.18 EC70S-X class) achieves 10–20% higher deposition rates than solid wire at the same current because the hollow core allows higher current density in the outer metal sheath, increasing the melt-off rate. It also produces lower spatter than solid wire in globular transfer, wider bead profiles, and better penetration into joint corners — all beneficial for structural fillet welds on heavy plate.
Weld Metal Volume and Joint Cross-Section Reference
| Joint Type | Leg / Throat (mm) | Approx. Cross-Section (mm²) | Wire per metre, carbon steel (kg/m) | Comment |
|---|---|---|---|---|
| Equal-leg fillet | 4 mm | 8 | 0.065 | Throat = 2.83 mm |
| Equal-leg fillet | 6 mm | 18 | 0.146 | Throat = 4.24 mm |
| Equal-leg fillet | 8 mm | 32 | 0.259 | Throat = 5.66 mm |
| Equal-leg fillet | 10 mm | 50 | 0.404 | Throat = 7.07 mm |
| Equal-leg fillet | 12 mm | 72 | 0.582 | Throat = 8.49 mm |
| Butt weld V-groove (60°, 20mm plate) | — | ≈ 160 | 1.293 | Includes root bead; single-sided |
| Butt weld V-groove (60°, 30mm plate) | — | ≈ 350 | 2.829 | Includes root bead; single-sided |
| Butt weld DV-groove (60°, 30mm plate) | — | ≈ 200 | 1.617 | Double-V; 37% less weld metal vs single V |
The wire per metre figures above use a deposition efficiency of 95% (GMAW) and carbon steel density of 7.87 g/cm³. For other processes, multiply by (95 / ηdep) to adjust for your process efficiency.
Frequently Asked Questions
What is weld metal deposition rate and how is it calculated?
Weld metal deposition rate is the mass of filler metal deposited per unit time (kg/h). For continuous wire processes: DR (kg/h) = (π/4) × d² × WFS × ρ × 60 × ηdep / 1000, where d is wire diameter in cm, WFS is wire feed speed in cm/min, ρ is density in g/cm³, and ηdep is deposition efficiency (0–1). For SMAW, deposition rate is estimated from electrode burn-off rate charts provided by electrode manufacturers, or from weld test measurements.
What is deposition efficiency in welding?
Deposition efficiency is the ratio of weld metal deposited to filler metal consumed, expressed as a percentage. Losses occur through spatter, slag, fume, and stub losses. Typical values: SAW 97–99% (no spatter), GMAW solid spray 95–98%, FCAW-G 82–90% (flux slag losses), FCAW-S 78–87%, SMAW 60–85% (stub + slag + spatter). Higher deposition efficiency means less filler metal wasted and lower material cost per kg of deposited weld metal.
What is the difference between deposition rate and deposition efficiency?
Deposition rate (kg/h) measures productivity — how fast weld metal is deposited during arc-on time. Deposition efficiency (%) measures material utilisation — what fraction of consumed filler actually reaches the joint. A process can have high deposition rate but low efficiency (wasting filler) or moderate rate with very high efficiency (SAW). Wire consumption rate = Deposition rate / Deposition efficiency — this is the figure used for ordering consumables.
How does duty cycle affect the actual deposition rate?
Duty cycle is the fraction of total working time the arc is burning. Actual deposition rate = theoretical rate × (duty cycle / 100). Manual GMAW typically achieves 40–60% duty; manual SMAW only 20–35% due to electrode changes and slag removal. Robotic GMAW achieves 70–90%. Improving duty cycle from 35% to 60% increases actual shift output by 71% with no process or consumable change — it is often the highest-ROI productivity improvement in manual welding operations.
Which welding process has the highest deposition rate?
Submerged arc welding (SAW) has the highest deposition rate: 5–25 kg/h single wire, 15–40+ kg/h for tandem wire. SAW achieves these rates because the arc operates under granular flux, allowing very high currents (300–1500 A) without UV exposure or spatter issues. FCAW comes second at 3–10 kg/h, followed by GMAW at 2–8 kg/h, and SMAW at 0.5–3 kg/h. SAW is restricted to flat and horizontal positions due to the fluid flux pool requirement.
How do I calculate filler metal cost per metre of weld?
Filler cost per metre = (Weld cross-section area × length × density / deposition efficiency) × price per kg. For a 6 mm equal-leg fillet: cross-section = 18 mm² = 0.18 cm². Per metre: 0.18 × 100 = 18 cm³. Mass = 18 × 7.87 / 1000 = 0.142 kg weld metal. Wire needed = 0.142 / 0.95 = 0.149 kg. At €2/kg wire: cost = €0.30 per metre of fillet weld. Labour and shielding gas must be added separately for total weld cost.
What is the wire burn-off rate and how does it differ from deposition rate?
Wire burn-off rate is the total rate at which wire is consumed (deposited + lost). Burn-off rate = Deposition rate / Deposition efficiency. For GMAW at 5 kg/h deposition with 95% efficiency: burn-off = 5 / 0.95 = 5.26 kg/h. The 0.26 kg/h difference is spatter and fume. Wire feed speed and burn-off rate are directly linked by wire cross-section and density — this is the basis of the deposition rate formula.
How does wire diameter affect deposition rate at the same current?
At the same welding current, smaller diameter wire has higher current density (A/mm²), which produces higher melt-off rate and higher deposition rate. At 200 A with GMAW: 0.9 mm wire deposits ~3 kg/h; 1.2 mm wire deposits ~2.2 kg/h. Conversely, larger diameter wires require higher currents to match the same deposition rate, but deliver better penetration and bridge larger root gaps. SAW uses large wires (3–5 mm) at very high currents to maximise deposition while maintaining arc stability and penetration.
What factors limit SMAW deposition rate compared to GMAW?
SMAW is limited by: (1) fixed electrode length (350–450 mm) requiring frequent stops to change electrodes, dropping duty cycle to 20–35%; (2) mandatory slag removal between passes; (3) maximum current limited by flux coating degradation; (4) stub loss — the last 50–75 mm of each electrode is unusable (10–20% material waste). GMAW eliminates electrode changes (continuous wire spool) and stub losses, and requires minimal inter-pass cleaning, raising duty cycles to 40–70% and actual shift output 3–8× higher than SMAW.
Recommended Reference Books
The Procedure Handbook of Arc Welding — Lincoln Electric (14th Ed.)
The definitive practical reference for arc welding process parameters, deposition rate tables, duty cycle data, and weld cost calculation methodology. Every welding engineering library should include this.
View on AmazonAWS A5.18/A5.18M — Carbon Steel Electrodes for GMAW
The AWS specification governing solid and metal-cored GMAW wire classifications, chemical composition, and mechanical properties — the standard referenced in WPS qualification for GMAW.
View on AmazonAWS Welding Handbook Vol. 2 — Welding Processes, Part 1
Comprehensive coverage of SMAW, SAW, GMAW, and FCAW process physics, equipment, consumables, and productivity data including deposition rate and duty cycle benchmarks.
View on AmazonWelding Cost Engineering — Blodgett (Lincoln Electric)
Step-by-step methodology for calculating weld metal volume, filler consumption, arc time, and total weld cost across all major processes — the standard approach used in this calculator.
View on AmazonDisclosure: MetallurgyZone participates in the Amazon Associates programme. If you purchase through these links, we may earn a small commission at no extra cost to you. This helps support free technical content on this site.
Further Reading
