Metal additive manufacturing

Also known as Metal 3D printing, Metal AM, Laser powder bed fusion, Powder bed fusion of metals

Metal additive manufacturing builds metal parts layer by layer, most often by using a laser to melt fine metal powder. It is already in production for some aerospace parts, but flaws inside printed metal, slow qualification and limited data for many alloys still stop it being used for every critical component.

CommercialDemonstratedReviewed 21 Oct 2026
AI illustration · Illustrative scene, not a photograph of the specific device or experiment.

In plain language

Metal additive manufacturing, often called metal 3D printing, builds a metal part one thin layer at a time. A layer of very fine metal powder is spread across a build platform, and a laser traces the shape of that layer so the powder melts and fuses into solid metal. The platform then lowers, another layer of powder is spread, and the process repeats until the part is complete. Shapes that are hard or impossible to make by cutting or casting can be built this way.

The appeal is that one printed piece can replace an assembly of many parts that would otherwise be welded or brazed together. Aerospace is the clearest example: GE Aviation reported in 2018 that its printed fuel nozzle tip replaced about 20 separate parts and was about 25 percent lighter. The method is harder to trust for critical parts, though. Tiny gas bubbles, or gaps where the metal did not fully melt, can weaken a part, and checking that every part is sound needs new tests and agreed standards.

Technical explanation

The most widely used metal process is laser powder bed fusion (LPBF). A recoater spreads a thin layer of metal powder, a focused laser scans the cross-section of the part and melts the powder into a continuous track, and the cycle repeats layer after layer. Because each new track and layer must fuse into the one below, process conditions such as laser power, scan speed and scan strategy control whether the material is fully dense. A DSIAC technical inquiry (2024) carries a photo caption describing a high-power laser spot scanning back and forth over a layer of cobalt-chrome powder on a NIST powder bed fusion machine.

Two defect types dominate the discussion. Gas porosity forms when gas is trapped in the powder or in the melt, and lack-of-fusion flaws form when the melt does not properly bond to the material beneath it. Snow, Nassar and Reutzel (2020) review how these flaws form and describe gas porosity and lack-of-fusion flaws as widely understood to reduce static and dynamic mechanical performance. Many alloys are harder to process than others: Wu and colleagues (2023) state that poor printability and unacceptable metallurgical defects are still the primary concerns limiting the use of most alloys in metal powder additive manufacturing.

Qualification is the other major hurdle. The DSIAC inquiry (2024) reports that, outside NASA standards, there is no DoD-approved qualification and certification process for additive manufacturing, so many organisations have written their own guidance. NIST work addresses this gap through in-process monitoring and non-destructive evaluation (NISTIR 8538, 2024) and through a laboratory testbed for studying laser-matter interaction in LPBF (NIST AMS 100-66, 2025).

What the evidence says

Each statement is typed by the strength of its evidence and linked to the source that supports it.

Demonstrated Shown in a published experiment, test or shipping product.

NIST has built a laboratory testbed for studying laser-matter interaction in laser powder bed fusion, and NISTIR 8538 (2024) reviews the state of the art in in-process monitoring and in-process non-destructive evaluation for metal additive manufacturing.

Sources: [4], [3] · Summary

Reported, unverified Stated by a company or team but not independently confirmed.

A DSIAC photo caption describes a high-power laser spot scanning back and forth over a layer of cobalt-chrome powder in NIST's laser powder bed fusion machine.

Sources: [5] · Photo caption · medium confidence

GE Aviation's Auburn, Alabama plant produced its 30,000th additively manufactured LEAP fuel nozzle tip in 2018, and GE reports the printed tip weighs about 25 percent less than the earlier welded and brazed version.

Sources: [6] · Article body · medium confidence

The printed nozzle tip replaced about 20 parts that had been welded and brazed together, according to GE's 2018 announcement.

Sources: [6] · Article body · medium confidence

Snow and colleagues state that gas porosity and lack-of-fusion flaws are widely understood to reduce static and dynamic mechanical performance of powder bed fusion parts.

Sources: [1] · Abstract · medium confidence

Wu and colleagues state that poor printability and unacceptable metallurgical defects are still the primary concerns limiting the use of most alloys in metal powder additive manufacturing.

Sources: [2] · Editorial text · medium confidence

DSIAC (2024) reports a lack of military or DoD-approved qualification and certification processes for additive manufacturing outside NASA standards, and says additive manufacturing is not as trusted across the Services and DoD as traditional manufacturing processes.

Sources: [5] · Article body · medium confidence

Limitations and open problems

  • Gas porosity and lack-of-fusion flaws are widely understood to reduce static and dynamic mechanical performance, which limits use in critical parts (Snow and colleagues, 2020).
  • Poor printability and metallurgical defects are still the primary concerns limiting most alloys (Wu and colleagues, 2023).
  • There is no DoD-approved qualification and certification route for additive manufacturing outside NASA standards, so organisations rely on their own guidance (DSIAC, 2024).
  • In-process monitoring and non-destructive evaluation are still an active research area (NISTIR 8538, 2024).
  • The sources reviewed here do not give verified cost or speed comparisons with conventional manufacturing, so the economics of a given part cannot be judged from them.

Possible future uses

Speculative

Ideas, not predictions. None of these has been demonstrated.

  • Heat exchangers with internal cooling channels that are too complex to cast or machine.
  • On-site printing of spare metal parts for remote bases, ships or spacecraft.
  • Lightweight lattice structures for road vehicles, if qualification costs fall.

Timeline

  1. 4 Oct 2018GE Aviation's Auburn, Alabama plant produces its 30,000th additively manufactured LEAP fuel nozzle tip, a company-reported milestone. Sources: [6]
  2. Dec 2020Snow, Nassar and Reutzel publish a review of how flaws form in powder bed fusion and how they affect performance in Additive Manufacturing. Sources: [1]
  3. 26 May 2023Wu and colleagues publish an editorial in Materials highlighting poor printability and metallurgical defects as primary concerns for metal powder additive manufacturing. Sources: [2]
  4. 17 Sept 2024NIST publishes NISTIR 8538, a review of in-process monitoring and in-process non-destructive evaluation for metal additive manufacturing. Sources: [3]
  5. 21 Feb 2025NIST publishes AMS 100-66, describing a laboratory testbed for studying laser-matter interaction in laser powder bed fusion. Sources: [4]

Futures this could help bring about

AI illustration
How far away?

Metal 3D printing as a mass-production method

Scaling up · 3 of 7 steps done

Related breakthroughs

Glossary

Powder bed fusion
A family of additive manufacturing processes in which a thin layer of powder is selectively melted or fused by a laser or electron beam, then the next layer is added.
Gas porosity
Small bubbles or voids in a printed part, formed when gas is trapped in the powder or the melt.
Lack-of-fusion flaw
A gap or void left where the melted metal did not fully bond to the layer or track beneath it.
Qualification and certification
The process of showing that a part, process or machine is reliable enough for a particular use, often required before critical parts can be approved.
Non-destructive evaluation
Inspection methods that check a part for flaws without damaging it.

Sources

  1. peer reviewed paper
    Invited Review Article: Review of the formation and impact of flaws in powder bed fusion additive manufacturing
    Zackary Snow, Abdalla R. Nassar, Edward W. Reutzel. Additive Manufacturing, Dec 2020. DOI: 10.1016/j.addma.2020.101457. Accessed 21 Oct 2026.
  2. other
    Recent Advances in Metal Powder-Based Additive Manufacturing
    Hong Wu, Yaojia Ren, Yingtao Tian et al.. Materials (MDPI), 26 May 2023. DOI: 10.3390/ma16113975. Accessed 21 Oct 2026.
  3. government report
    In-process monitoring and non-destructive evaluation for metal additive manufacturing processes (NISTIR 8538)
    Alkan Donmez, Jason Fox, Felix Kim et al.. National Institute of Standards and Technology, 17 Sept 2024. Accessed 21 Oct 2026.
  4. government report
    Design and Calibration of the Fundamentals of Laser-Matter Interaction (FLaMI) Powder Bed Fusion Testbed at the National Institute of Standards and Technology (NIST AMS 100-66)
    David Deisenroth, Sergey Mekhontsev, Steven Grantham. National Institute of Standards and Technology, 21 Feb 2025. Accessed 21 Oct 2026.
  5. government report
    Qualification and Certification of Powder Bed Fusion Additively Manufactured Components
    Travis J. Kneen. Defense Systems Information Analysis Center (DSIAC), 6 Mar 2024. Accessed 21 Oct 2026.
  6. company announcement
    Manufacturing milestone: 30,000 additive fuel nozzles
    GE Aerospace, 4 Oct 2018. Accessed 21 Oct 2026.

Revision history

3 changes since this profile was created.

Changes on 21 Oct 2026
Published on owner instruction via content loop; AI-researched, QA-checked and link-checkeddb92240
Sources and claims re-checked against originalsfbb434c
Initial profile drafted from primary sources7e66249