Laser Welder Not Melting Wire? Three Things to Check First
A laser welder not melting wire the way it used to — or not melting it at all — is almost never a dead machine. Filler wire feeding is a chain of small alignments, and the laser only sees the last link. When the wire will not melt, or melts unevenly, the cause is nearly always one of three things: the spot is not where it used to be, the energy is not what it used to be, or the wire is not where the spot is.
Laser welder not melting wire: match the symptom first
- Wire passes through, no melt at all — spot and wire are missing each other, or energy has collapsed
- Wire melts but the bead sits on the surface — energy or focus is wrong for the wire diameter
- Melted last week, weak this week — optics contamination or a drifting setting, not wiring
- Melts only sometimes — feed slipping or wire wandering off the spot
Each symptom has a different first check. Doing them in the wrong order wastes an hour.
Check 1: where the spot actually is
The focus lens position drifts whenever anything moves: a swapped nozzle, a bumped workholder, a cleaned-and-reseated lens a fraction of a millimeter out. Fire a test pulse on scrap at your working height.
- The burn mark should be a small, sharp-edged circle
- A large fuzzy mark means the focus is off — adjust focus height in small steps, test firing between each
- An off-center mark means the spot and the wire path are no longer coaxial — recheck the nozzle and wire guide
A spot that is even slightly out of focus can lose most of its power density; the same joules spread over twice the area melts far less wire — a classic not-melting-wire symptom that looks like a power fault.
Check 2: how much energy is left
If the spot is sharp but the wire is still not melting, look at energy.
- Confirm pulse voltage and width have not been changed — compare against your settings notebook
- Pull the protective lens and inspect it against light. A hazed lens silently eats 20–30% of output; cleaning it brings the weld back the same afternoon
- A tired xenon lamp arcs weakly and delivers less peak energy — a dull violet flicker in the observation window is the tell. See YAG Laser Xenon Lamp Replacement
Remember that wire is a heat sink: the same settings that melt a seam on bare metal may barely wet a thick filler wire. Going up a wire diameter means going up in energy — that is expected behavior, not a fault.
Check 3: where the wire meets the spot
Not melting wire is often a geometry miss: the laser does not chase the wire; the wire has to arrive at the spot.
- Feed angle matters. Most bench work feeds wire at a shallow angle into the leading edge of the pool. Straight-on into the plume splashes and spatters; too shallow and the wire skates over the surface.
- Feed consistency beats feed speed. A slipping drive roller gives pulses of wire — so you get intermittent melting even with perfect laser settings. Check roller tension and clean wire shavings out of the guide.
- Wire condition. Oily or oxidized wire wets badly. Wipe it; store it sealed.
- Wire diameter. Thick wire needs a bigger melt pool to wet at all. If you recently upsized the wire, retune before blaming the machine.
Put it together
The order that works: spot first, energy second, wire path third. The first two take ten minutes and are the causes most of the time. If all three check out and the wire is still not melting, the fault is upstream — control board or lamp drive — and that is engineer territory. Our complete troubleshooting checklist picks up from there.
Send us a video of the feed and we’ll tell you which link is broken
A laser welder not melting wire usually comes down to one link in one chain — and a 20-second phone video of a test fire with the wire visible tells us more than a page of description. Send it with your wire diameter and material — an engineer replies with what we would adjust first, and whether the fix is a setting or a part.
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