If you've ever tried to figure out why a 3D-printed bracket can fly on one aircraft program but needs a mountain of paperwork on another, ASTM International thinks it has a fix. The organization's Additive Manufacturing Center of Excellence (AM CoE), working with the UK Ministry of Defence's Project TAMPA accelerator, has published a free guide meant to give defense primes and their suppliers a common vocabulary for qualifying additively manufactured parts — instead of each program office inventing its own rulebook.
The document, titled "Strategic Guide to Certification of Additively Manufactured Parts in Defence Applications," was written by ASTM's AM CoE and funded by the UK MOD through Project TAMPA. It's available as a free download from the AM CoE's website, and notably, it isn't a new standard. ASTM is explicit that this is a signposting resource — a map of the qualification landscape, not a rulebook that supersedes existing test methods or specifications.
A Shared Language for Criticality
The core of the guide is a four-tier classification system, Class A through Class D, that ties the amount of certification evidence a part needs to the severity of what happens if it fails. Neither ASTM's summary nor the trade coverage of it spells out exactly where each tier's line gets drawn, but the logic of a scheme like this runs the way it typically does in aerospace: a Class A part — the kind of high-consequence, load-bearing component whose failure could be catastrophic — would demand the most rigorous qualification trail, while a Class D part — something cosmetic or non-critical — needs far less. That's not a novel concept in aerospace engineering generally, but applying it consistently across additive manufacturing programs, where every branch of service and every contractor has historically drawn its own lines, is the point.
Layered on top of the classification system are two certification pathways. The first is process qualification: prove that your printer, your material, your parameters, and your quality system are locked down and repeatable, and the parts that come off that qualified process inherit trust from the process itself. The second is testing-based certification: qualify the individual part (or part family) through direct testing regardless of how tightly the underlying process is controlled. Programs can choose whichever pathway fits a given part's risk profile and their own supply chain maturity, rather than being forced into one model by default.
Crucially, the guide isn't limited to one branch of the military or one flavor of printing. According to VoxelMatters' reporting, the document spans air, land, and maritime domains, and it applies across AM processes and material families rather than being tied to any one printing technology. It's also nation-agnostic by design — ASTM wrote it specifically to be nation- and technology-agnostic — meaning allied supply chains outside the UK can reference the same framework rather than needing a bespoke version for every partner nation.
Why This Problem Needed Solving
Additive manufacturing has been creeping into defense procurement for years, from spare parts printed at the point of need to flight-critical brackets qualified for specific aircraft. But qualification and certification requirements for those parts have grown up piecemeal — one program's process-qualification framework doesn't necessarily translate to another's, even within the same service branch, let alone across the air-land-maritime split or between allied nations. That's expensive. Every time a supplier has to re-derive qualification evidence from scratch for a program with slightly different documentation expectations, it slows down the adoption of AM for exactly the use case — rapid, flexible part production — that makes it attractive to defense logistics in the first place.
Mohsen Seifi, ASTM's vice president of global advanced manufacturing, framed the effort in blunt terms. In a single statement carried by both VoxelMatters and TCT Magazine, Seifi said: "Additive manufacturing earns a place in defense only when a part can be trusted in service, and that trust depends on qualification and certification that hold up consistently across organizations, domains, and borders. This guide gives manufacturers and authorities across the global defence community a shared, criticality-based reference point."
That "shared reference point" framing is the whole thesis. ASTM isn't claiming this guide will make qualification faster or cheaper on its own — sorting parts into four buckets doesn't eliminate the underlying test burden for a Class A structural part. What it's aiming to do is stop different programs, services, and allied nations from talking past each other when they discuss what "qualified" even means for a given AM part, so evidence generated under one program has a better chance of being recognized elsewhere instead of being thrown out and redone.
What It Means for Makers
For hobbyists running a Bambu Lab or Prusa in the garage, this guide has zero direct application — nobody is testing your PLA vase mode prints against Class A defense criticality tiers. But for the growing slice of the maker and small-shop community doing contract or prototype work that touches defense supply chains — metal AM shops, polymer specialists chasing DoD or MOD subcontracts, or engineers moving from hobbyist printing into professional qualification work — this is worth reading closely. It's a preview of the vocabulary that primes and program offices are going to expect suppliers to speak. If you're a small AM shop hoping to eventually bid on defense work, understanding whether a part you'd be asked to produce falls under a process-qualification model versus a testing-based model tells you a lot about what kind of documentation, process control, and inspection infrastructure you'd need to invest in before you're even competitive for that contract. And because the framework is explicitly technology- and nation-agnostic, it's a reasonable bet that similar tiered-criticality thinking will show up in civil aerospace and other regulated AM sectors before long, even though this specific document is defense-focused.
The practical takeaway: this isn't a new certification you need to chase, and it doesn't replace any existing standard you're already working against. It's a map that should, in theory, make the qualification maze a little less arbitrary — assuming defense programs across services and allied nations actually adopt the shared classification rather than layering it on top of their existing bespoke requirements.
