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[Fred Begum]

Hello, I would like to produce a stainless steel 316L bracket, 3 mm thick, cut by fiber laser. I need to include several small holes for drainage and fastening, and I’ve heard there might be a rule that the minimum hole diameter shouldn’t be smaller than the material thickness. Is this a strict limitation in practice for 316L, or are there process adjustments (e.g. slower cutting, gas type) that allow smaller holes without compromising quality?

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[Andreas]

You’re spot on. The laser cutting hole diameter should not be smaller than the material thickness. Therefore, use a minimum of 3 mm holes in a 3 mm plate. But it’s more of a guide than a hard limit. With 316L and a fiber laser, you can usually go a bit smaller, maybe 2mm on a well-calibrated machine with a skilled operator. I would avoid 1.5 mm though. It’s doable, but you will need a slow traverse speed and Nitrogen as your assist gas to avoid oxidation because of the speed. Piercing gets trickier at that size, as heat buildup can cause taper and/or slag. You’ll likely encounter burrs, requiring high-effort post-processing.

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[Fred Begum]

Are there specific tricks you’ve used to maintain quality with holes that small?

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[Andreas]

Definitely use high-pressure Nitrogen. And for small holes, drive the laser in pulse mode to reduce heat input. Some shops pre-drill with a punch and then finish with the laser for tighter tolerances. Also, check with your fabricator, ask them to use fine-cut nozzles specifically for micro features.

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