How is metal powder manufactured and what types exist?

Metal powder for additive manufacturing is produced by atomizing liquid metal: the alloy is melted and the jet is broken into droplets that solidify in the air before touching anything. Depending on what breaks the jet, the process is called gas atomization, plasma atomization, or water atomization, and each produces a powder with a different shape. For powder bed laser melting, only the first two are suitable, and for a very specific reason: the particle shape.

The three methods

Method	How the jet breaks	Particle shape	Typical use in LPBF
Inert gas atomization	High-pressure argon or nitrogen jets	Very spherical, with some satellite particles	The industry standard
Plasma atomization	A wire or powder is remelted in plasma torches	Extremely spherical and very clean	Titanium and demanding alloys; expensive
Water atomization	High-pressure water jets	Irregular, angular	Not suitable for LPBF; used in conventional powder metallurgy

The water cools so much and so quickly that the droplet doesn't have time to round due to surface tension: it solidifies in the irregular shape it had when it broke. This is much cheaper and perfectly suitable for pressing and sintering, but an angular powder doesn't flow.

Why sphericity decides everything

In an LPBF machine, the recoater has to spread a layer of twenty to one hundred microns, flat and uniform, in less than a second, and repeat it thousands of times without failing once.

A spherical powder rolls: it settles on its own and leaves a dense, even layer. An angular powder clumps together, forms bridges, and leaves gaps. And each gap in the layer is a pore in the part. That's why sphericity isn't an aesthetic preference: it's the property that determines whether the part turns out dense or porous.

The same applies to satellites, those small particles attached to larger ones that appear in gas atomization when two droplets collide before solidifying. The fewer of them, the better the powder flows.

Particle size: neither too fine nor too coarse

The size distribution usually ranges between 15 and 45 microns for LPBF, and it is a balance between things that pull in opposite directions.

Too fine. The powder clumps together, becomes difficult to handle, and increases the exposed surface area, multiplying the risk of oxidation and, in titanium or aluminium, the risk of explosion.
Too coarse. Thin layers cannot be worked with, detail is lost, and more energy is needed to melt each particle.

That's why a powder is always specified with a range, not a number. And that's why sieving is a routine operation, not a whim.

Where does the price come from?

kilo of powder for additives costs considerably more than a kilo of the same metal in bar form, and it's not an excessive margin: it's the process.

The starting alloy is already expensive in many cases: titanium, nickel, cobalt.
Atomization consumes a lot of inert gas, which is not fully recovered.
Only a fraction of the batch falls within the usable range. The rest must be reprocessed or sold for other uses. This fraction is what truly determines the price.
Quality control is expensive: chemistry, particle size distribution, bulk density, flowability, and residual oxygen, batch by batch.

Don't throw away leftover powder

In a typical build, the part occupies a small part of the vat's volume. All the rest is unmelted powder, which is recovered.

The cycle is as follows: vacuum up the excess powder, sieve it to remove splashes and agglomerates, mix it with virgin powder in a controlled ratio, and reuse it. What needs to be monitored is drift: each pass through the machine exposes the powder to heat and traces of oxygen, and with each cycle, the chemical composition changes. In sensitive alloys, oxygen levels are systematically monitored, and the number of acceptable cycles is defined.

With titanium and aluminium, this operation also has a serious safety component: in fine powder form, they are reactive and can create explosive atmospheres. Therefore, screening is carried out in equipment designed for ATEX environments, with an inertable interior and no ignition sources. The GARBI sieve combines vibration and ultrasound precisely to avoid having to strike the screen.

What to ask before buying powder

The particle size range, not just the nominal “15–45”: how it is distributed within that range.
Residual oxygen, especially in titanium.
The atomization method, because it affects sphericity.
Batch traceability, if your end customer will require proof.
Whether the machine requires you to purchase it from the manufacturer. This is the least asked question and the most costly in the long run: a captive consumable leaves you with no room to maneuver the day a better or cheaper material appears.

Where is it going?

The most interesting approach right now isn't to produce better powder, but to produce it cheaper and with a smaller footprint. Within the CDTI's MISIONES program, we're working on obtaining powder suitable for additive manufacturing from ceramic and metal waste. If the starting material is waste with management costs instead of virgin raw material, two numbers change simultaneously.

It's not easy: a residue starts without sphericity, without controlled particle size, and without stable chemistry, which are precisely the three things the process requires. That's where the work lies.

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If you want to see which alloys we use today and what each one is used for, they're listed in the materials catalog. If you're interested in how that powder becomes a finished part, we explain it in what is a metal 3D printer. And what safety requirements apply when handling titanium or aluminium, in what does ATEX mean in a metal 3D printing facility.