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Weld Deposition Rate

Calculate theoretical welding deposition rates, filler metal volume, and required arc time based on joint dimensions and wire feed speed.

Consumable Params

Bead X-Sect Area

sq in

Cross-sectional fill

Total Length

Length of all passes

Wire Feed (WFS)

IPM

Inches per Min driving

Wire Diameter

Spool size (MIG/FCAW)

Theoretical Deposition Output

Target Yield

Cu Inches

Machine Deposit Rate

0.34

in³/Min

Arc Time (Minutes)	89.1
Arc Time (Hours)	1.48

Note: Assumes 100% transfer efficiency and unbroken continuous arc time. Actual project hours will be significantly higher depending on operator duty cycle.

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What is MIG/FCAW Deposition Physics: How Wire Becomes Weld?

Deposition rate defines how much weld metal a process physically lays down per minute or hour. In wire-fed processes (GMAW/FCAW), the machine drives wire at a set speed into the arc. Knowing the wire cross-section and feed speed gives you the exact volumetric deposition rate — the foundation for calculating arc time, consumable requirements, and labor cost.

Mathematical Foundation

Wire Cross-Sectional Area

A_{wire} = \pi \times (\frac{d}{2})^2

d

= Wire diameter (inches) — e.g., 0.035", 0.045", 1/16"

Deposition Rate (Volume per Minute)

\dot{V} = A_{wire} \times WFS

WFS

= Wire feed speed in inches per minute (IPM)

\dot{V}

= Volume of metal entering the puddle per minute (in³/min)

Total Arc Time

t_{arc} = \frac{V_{joint}}{\dot{V}}

V_{joint}

= Total joint volume = cross-section area × weld length (in³)

Laws & Principles

Linear Proportionality: Under constant voltage, deposition rate is directly proportional to WFS. Double the WFS = double the metal per minute entering the puddle.
The 100% Efficiency Fallacy: Theoretical math assumes every cubic inch of wire becomes a cubic inch of weld. Reality: solid MIG wire = ~95% efficiency. FCAW = ~85% (flux weight + slag). Stick = ~60%. This calculator gives raw theoretical output — apply your process yield factor.
Arc Time ≠ Clock Time: Arc time is pure trigger time. Human operators typically have 20-45% operating factor. A 1-hour arc time estimate means 2-5 hours of wall-clock time including setup, repositioning, grinding, and breaks.
Wire Size Matters Exponentially: Going from 0.035" to 0.045" wire increases cross-section area by 65% — at the same WFS, you deposit 65% more metal per minute. This is the primary lever for increasing productivity on fill passes.

Step-by-Step Example Walkthrough

" Filling a 10-foot V-groove joint (0.25 in² cross-section) with 0.035" solid MIG wire at 350 IPM. "

1. Joint volume: 0.25 in² × 120 in = 30.0 in³ required.
2. Wire cross-section: π × (0.0175)² = 0.000962 in².
3. Deposition rate: 0.000962 × 350 = 0.337 in³/min.
4. Arc time: 30.0 / 0.337 = 89.1 minutes.

Final Result: 89 minutes of pure trigger time (~1.5 hours). At 40% operating factor, this joint takes ~3.7 hours of clock time to complete.

Quick Answer: How Do You Calculate Weld Deposition Rate?

Multiply the wire cross-section area by the wire feed speed (IPM). For 0.035" wire at 350 IPM: area = 0.000962 in², rate = 0.337 in³/min. Convert to lbs/hr by multiplying by steel density (0.283 lb/in³) × 60 = 5.7 lbs/hr. This is the theoretical maximum — multiply by your process yield (95% for solid MIG) for actual deposited metal.

Deposition Rates by Wire Size & WFS (Steel, Solid Wire)

Wire Size	200 IPM	300 IPM	400 IPM	500 IPM
0.023"	1.4 lbs/hr	2.1 lbs/hr	2.8 lbs/hr	3.5 lbs/hr
0.030"	2.4 lbs/hr	3.6 lbs/hr	4.8 lbs/hr	6.0 lbs/hr
0.035"	3.3 lbs/hr	4.9 lbs/hr	6.5 lbs/hr	8.2 lbs/hr
0.045"	5.4 lbs/hr	8.1 lbs/hr	10.8 lbs/hr	13.5 lbs/hr
1/16"	8.3 lbs/hr	12.5 lbs/hr	16.6 lbs/hr	20.8 lbs/hr

Going from 0.035" to 0.045" wire at the same WFS increases deposition by 65%. For fill passes on heavy plate, upsizing wire is the fastest way to increase productivity without changing anything else.

Deposition Rate Reality Checks

The Arc Time Surprise

A fabrication manager estimates a 500-foot pipe rack project at "2 weeks" based on gut feel. The estimator uses the deposition calculator: total joint volume requires 850 lbs of weld metal. At 6.5 lbs/hr theoretical with 0.035" wire and 40% operating factor, actual deposition = 2.6 lbs/hr. Clock time = 850 / 2.6 = 327 hours = 41 eight-hour shifts. With 4 welders, that's 10.2 working days minimum. The "2 week" estimate was correct — but only with 4 welders running full shifts. With the planned crew of 2 welders, it's a 4-week job.

The Wire Size Upgrade

A structural steel shop runs 0.035" wire on all MIG stations — root, fill and cap. An engineer uses the deposition calculator to show that switching fill passes to 0.045" wire at the same WFS increases deposition from 6.5 to 10.8 lbs/hr — a 66% increase. On a 200-foot beam splice requiring 12 fill/cap passes, the wire change alone saves 18 hours of arc time per splice. At $55/hr burdened, that's $990 per splice. With 40 splices on the project, total savings: $39,600 — from a wire diameter change that costs nothing extra.

Pro Tips for Deposition Estimating

Do This

✓Always apply the operating factor to convert arc time to clock time. An estimate of "4 hours of arc time" sounds manageable. At 35% operating factor, it's actually 11.4 hours of clock time. Labor planning must use clock time, not arc time.
✓Use the bigger wire on fill passes. Root passes need small wire for control (0.030"-0.035"). But fill and cap passes benefit from maximum deposition. Switch to 0.045" or 1/16" for fill — the D² law gives you 65-240% more metal per minute at the same WFS.

Avoid This

✗Don't confuse theoretical and actual deposition. The calculator gives raw output assuming 100% of wire becomes weld. Solid MIG wire is 95% efficient. FCAW dual-shield is ~85%. Stick is ~60%. Multiply the theoretical rate by your process yield to get pounds of actual deposited, usable weld metal.
✗Don't ignore the reinforcement/overweld factor. Weld procedures typically specify 1/16"-1/8" of cap reinforcement above the plate surface. This adds 10-20% to the calculated joint volume. Also factor in inter-pass grinding waste on critical welds — each grind pass removes deposited metal that must be re-deposited.

Frequently Asked Questions

How do I convert deposition rate from in³/min to lbs/hr?

Multiply in³/min × 60 (minutes/hour) × steel density (0.283 lb/in³) = lbs/hr. For example: 0.337 in³/min × 60 × 0.283 = 5.72 lbs/hr. For aluminum, use 0.098 lb/in³. For stainless, use 0.289 lb/in³. The density factor is critical — aluminum weighs 1/3 as much as steel per cubic inch, so the same volumetric rate produces far fewer pounds per hour.

What WFS should I use for estimating?

Use the WFS from your actual WPS (Welding Procedure Specification). If estimating for bidding, use conservative values: 0.035" short-circuit = 250-350 IPM. 0.035" spray transfer = 400-600 IPM. 0.045" spray = 300-450 IPM. These produce mid-range deposition rates that account for average operator skill. Using maximum machine settings produces deposition estimates only an expert operator could achieve.

Does this work for flux-cored wire?

The volumetric math works, but FCAW wire is tubular — the cross-section contains metal powder/flux inside a thin metal sheath. The effective metal area is smaller than the full wire diameter suggests. Additionally, ~15% of the wire weight is flux that becomes slag, not weld metal. For FCAW, multiply the theoretical deposition by 0.85 to get actual deposited metal. Some manufacturers publish specific deposition rate charts for their FCAW products that account for this automatically.

Why does wire diameter affect deposition so dramatically?

Because area scales with the square of the diameter (πr²). Going from 0.035" to 0.045" increases diameter by only 29%, but area increases by 65% (0.000962 vs 0.00159 in²). Going from 0.035" to 1/16" (0.0625") increases area by 219%. This is the D² law. At identical WFS, these wire size changes deliver proportionally more metal. It is the single most effective parameter for increasing deposition rate without changing any machine settings.