Weld Deposition Rate Troubleshooting

Deposition Rate Failures Quick Answer

Most “calculator said 9 lbs/hr but we only put down 4” surprises come from confusing melt-off with deposition, entering the wrong wire diameter or WFS units, ignoring efficiency (especially Stick), measuring during feed problems, or treating shift output as if arc-on time were 100%.

1. Melt-Off Confused With Deposition

What it looks like: Spool weigh-back shows 10 lbs/hr used. The calculator (or a brochure) said ~9.5 lbs/hr deposition and you call it a match — then inspection finds less weld metal than expected, or cost models underbuy wire.

Likely causes: Melt-off is wire leaving the spool. Deposition is metal that becomes weld. Spatter, stub loss, and slag are the gap. MIG efficiency is high (~92–98%); Stick is not (~65–75%).

Fixes: Enter the correct process efficiency in the calculator. For audits: deposition ≈ melt-off × efficiency. Guide depth: actual vs theoretical.

2. Wrong Diameter, Density, or WFS Units

What it looks like: Math is clean; weigh-back is ~40–60% off. Or aluminum jobs look impossibly light/heavy.

Likely causes: Diameter enters as area (πr²) — 0.035 vs 0.045 is a huge swing. Machine displays sometimes in metric. Aluminum density (~0.098) vs steel (~0.283) must match the wire, not the base metal story you tell yourself.

Fixes: Mic the wire. Confirm IPM with a timed mark on the wire if the display is suspect. Pick the right density in the calculator. Then re-weigh a 5-minute arc coupon.

3. Feed Path Lies — Tips, Liners, Drive Rolls

What it looks like: Panel WFS is “correct,” arc sounds rough, burnback or bird-nesting, and weigh-back undershoots the formula.

Likely causes: Slippage and restriction mean less wire actually melts than the setpoint implies. Contact tip wear and wrong liner size are classic.

Fixes: Replace tip/liner sized to the wire; set drive-roll tension for the wire type (knurled for flux-core). Re-time a weigh test only after feed is stable. Consumable overrun patterns: Wire Consumption Troubleshooting.

4. Hourly Rate Treated Like Shift Output

What it looks like: “We should deposit 80 lbs per shift” from an 10 lbs/hr rate × 8 hours. Actuals are ~20 lbs.

Likely causes: Deposition rate is an arc-on rate. Manual shops often run 20–35% arc-on. The calculator page and guide both stress this — missed in job planning anyway.

Fixes: Shift deposit ≈ lbs/hr × hours × arc-on fraction. For bidding, push the honest OF into the Weld Cost Calculator (see also Cost Troubleshooting).

5. Stick — Stub Loss and Efficiency Ignored

What it looks like: Rods per joint estimate looks fine; stub buckets fill up and purchased lbs runaway.

Likely causes: SMAW deposition must include stub discard and coating/slag loss. Treating rod weight as deposited metal overstates productivity.

Fixes: Weigh stubs for a timed window; use 65–75% efficiency unless your procedure proves better. Estimating-method choice (weight vs length vs volume): Which Estimating Method.

6. Transfer Mode / Process Mismatch

What it looks like: Chart “spray transfer” rates entered while the job is short-circuit on thin sheet — or solid-wire efficiency used on FCAW.

Likely causes: Deposition capability changes with transfer mode and cored vs solid wire. Wrong process defaults in the calculator poison both productivity and cost.

Fixes: Match process and typical efficiency. For productivity levers (diameter, WFS, process choice), use the guide’s 5 ways to increase deposition — don’t invent a parallel technique page.

Frequently Asked Questions