# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DZVKGWzgdy9
- **Gondola URL:** https://gondola.cc/posts/66591656-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/a0fc7f26e0.jpg
- **Posted:** 2026-06-08T15:52:21.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

Calling it “metal SLS” is a small lie we all tell. True selective laser sintering fuses polymer powder below its melting point. When the powder is metal, the laser doesn’t sinter, it fully melts, and the process is more honestly called Selective Laser Melting or Direct Metal Laser Sintering, both branches of Laser Powder Bed Fusion (L-PBF).

The premise is deceptively simple. A recoater blade spreads a layer of gas-atomized metal powder, typically spherical particles 15 to 45 microns across, just 20 to 60 microns thick. A fiber laser, usually 200 to 500 watts, traces the cross section, creating a molten pool that fuses to the solidified layer beneath. The platform drops one layer. Repeat ten thousand times.

What makes it brutal is the physics inside that melt pool:

	•	Cooling rates reach 10^6 K per second, freezing in ultra-fine grain structures impossible to achieve by casting
	•	Marangoni convection driven by surface tension gradients stirs the pool, governing penetration depth
	•	Everything runs under argon or nitrogen, because molten titanium will happily ignite in air

Energy delivery is a balancing act captured by volumetric energy density, E = P / (v h t), where P is laser power, v scan speed, h hatch spacing, t layer thickness. Too little and you get unfused porosity. Too much and the melt pool collapses into keyhole voids.

The thermal violence leaves residual stress strong enough to peel parts off the build plate, which is why scan paths use island and stripe strategies, and why finished parts get stress-relieved and often hot isostatic pressed to crush internal porosity shut.

The result: Inconel turbine blades, titanium spinal implants, and conformal-cooled tooling that no mold or mill could ever make.

We stopped removing material. Now we grow it, one melt pool at a time.

#stemantics #metal3dprinting #additivemanufacturing #materialsscience #engineering

## Stats

- **Views:** 11,800
- **Likes:** 194
- **Shares:** 0
- **Comments:** 2

## Tags

engineering, materialsscience, additivemanufacturing, metal3dprinting, stemantics

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