Troubleshooting guide › Weld defects › Overlap (cold lap)
Overlap, also called cold lap or rollover, is weld metal that has flowed over the plate surface at the toe without melting into it. It looks like a generous weld but the edge is a sharp unfused notch. It is the mirror image of undercut: too much metal, too little heat where the bead meets the plate.
Reviewed by the Cruxweld technical team, October 2026. Settings are starting points to confirm on a test piece; acceptance is decided by the code or drawing the job is built to. Checks marked “call” are for our technical team.
The bead has a rounded edge that curls over the plate like a wave; you can often slide a feeler gauge or a fingernail under it. Common on the bottom plate of a horizontal fillet and on vertical-down welds. In cross-section the bead toe forms an acute angle with the plate.
Illustration, not a photo. Orange marks the defect.
More wire is melting than the arc can fuse into the plate; the excess piles up and rolls over the toe.
The pool grows too big, runs ahead of the arc, and freezes on cold plate.
Metal piles on the lower plate and overlaps it while the vertical plate is starved.
A large electrode at low current deposits metal faster than the arc can fuse it.
Long stick-out preheats the wire and lowers the current for the same wire speed, so the deposit is cold.
Mill scale and oil stop the pool from wetting the plate at the toe.
At the edges of a wide weave the arc is away from the pool and the metal freezes cold at the toe.
| Process | Typical reason | What to do |
|---|---|---|
| MIG / MAG | Wire speed high, voltage low; torch aimed at the bottom plate | Voltage up a step; aim at the corner; stick-out 10-15 mm |
| ARC / MMA | Large electrode at low current; vertical-down on thick plate | Smaller electrode at full current; vertical-up for plate over 5 mm |
| Submerged arc | Stick-out too long; voltage too low; groove too small | Shorten stick-out; raise voltage; open the groove |
| Welding carriage | Torch set too low on the slide; speed too slow for the leg size | Reset torch height and angle; use the speed table for the leg size |
MIG / MAG horizontal fillet, 1.2 mm wire, 6 mm leg on 6 mm plate. A starting point only.
| Current / voltage | 220-250 A / 25-27 V |
| Travel | 35-45 cm/min |
| Torch angle | 40-45 degrees between the plates, 10-15 degrees drag |
| Aim | Wire at the corner, slightly favouring the vertical plate |
| Stick-out | 12-15 mm |
| Gas | CO2 or Ar-CO2, 15-20 L/min |
If the bead still rolls over, raise voltage before touching anything else.
Repair: grind the overlapped edge back to fused metal and blend the toe. On a fatigue-loaded joint the toe angle matters as much as the size.
The extra metal is not attached to the plate. A fillet is only as strong as its throat, and overlap adds nothing to the throat while creating a sharp notch where cracks start.
Less, but it still wastes wire and time. Overlap means you are putting down 20-30 % more metal than the joint needs, which the cost calculator will show as rupees per metre.
Overlap is a settings problem. On MIG it almost always means wire speed is too high for the voltage. A machine with a clear voltage and wire-speed display, or synergic control that keeps them matched, makes it easy to avoid. Cheap machines with only a single “power” knob hide this relationship from the operator.
Send a photo of the weld or cut, your machine model, consumable and plate thickness. Our technical team replies on WhatsApp with the likely causes and the next checks to make.
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