Joules vs Watts: What Really Matters in a Laser Welder

Ask ten salesmen “how many watts is it” and they’ll all answer proudly. Then ask them “how many joules per pulse” and watch the room go quiet. Most buyers compare laser welders by wattage — which is a bit like comparing cars by the size of the fuel tank. Here’s what each number actually does, and the one question that tells you more than the whole brochure.

What each number actually does

• Joules (J) — single pulse energy. How hard one pulse hits, and therefore how deep it bites. This is the number that matters for casting repair and platinum.
• Peak power (kW) — how fast the pulse hits. Matters for reflective metals like silver and platinum that bounce light back until they melt.
• Average power (W) — the “200W” on the box. How long the machine can keep working. Useful, but the least interesting number.
• Frequency (Hz) — pulses per second. Chain work and batch jobs go faster with more.
• Pulse width (ms) — how long each pulse lasts. Short for thin material, longer for heavy sections.
• Spot size (mm) — how small the weld point is. Fine prongs need small; filling pores needs big.

Same three letters every time — “200W” — can hide completely different machines underneath.

Why two “200W” machines are not the same machine

On paper, most 200W-class pulse welders look identical. In practice, the pulse energy on this class of machine ranges from about 60 to 130 joules depending on the power supply design. That’s more than a 2× difference in what one pulse can do.

What does that mean on the bench? On a platinum prong or a casting sprue, a 60-joule machine needs more passes, runs hotter, and leaves a weaker joint. A 130-joule machine melts the metal in one clean hit. Same wattage, different machine — and the difference shows up exactly where you can’t afford it: the jobs you get paid for.

The honest part of the spec sheet

We put the numbers we can defend on ours — and leave off the ones we can’t. A few we’re happy to print: 130 joules per pulse, pulse width 0.1–20 ms, frequency 1–20 Hz, spot 0.1–3 mm at F=110 mm. If we haven’t measured a number, we don’t print it — ask us and we’ll tell you straight.

Here’s the thing: every number on this page is bench-verifiable. Set 60 joules, you get 60 joules — shot after shot, all afternoon. That repeatability is what your parameters actually depend on, and it comes from the power supply, not the sticker.

The one question to ask any supplier

Whatever machine you’re comparing — ours or anyone else’s — ask: “What is the single pulse energy, and can I see it weld silver on video?” The first question separates the people who know their machine from the people who read the brochure. The second shows you the weld before you spend a cent.