Laser Spot Welding ✨ - Video

???? Original footage on YT: @tochtech9249

What you're seeing: A worker sets a small polished disc onto a chuck, lines up a thin metal rod against the back of it, and steps away to watch a monitor. The joint is made without a torch, without a filler rod and without anything touching the parts. What holds the two pieces together afterwards is metal that was briefly liquid and is now solid again.

The mechanism: A laser beam is focused down to a spot smaller than a pinhead, which concentrates enough power density to vaporise metal instantly rather than merely melting it. That vapour blows open a narrow cavity, and the beam travels down inside it, so instead of heating the surface and waiting for conduction to carry heat inward, the energy is delivered along the full depth of the joint at once. Molten metal flows around the cavity and closes behind it, fusing both parts into one. Because the whole event lasts milliseconds, heat has almost no time to spread sideways, which is why the surrounding metal stays cool and the polished surface nearby is unaffected.

Why it exists: Ordinary welding heats a wide region, and hot metal expands then contracts as it cools, which pulls a part out of shape and leaves residual stress behind. On something small and precisely machined that is fatal. A laser sidesteps the problem by keeping the heated region narrow, so a finished, polished, dimensionally accurate component can be welded and still be within tolerance afterwards. That is why the technique took over in places where precision matters more than speed of deposition, from medical instruments and sensors to battery tabs and optical assemblies.

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