Why is STEP-AM not the complete solution?
RECODE.AM #13
For several months now, more and more voices have been calling for abandoning the outdated – and rather limited – STL format in favor of other, more advanced solutions. I described the problems with STL here:
In another article, I analyzed an alternative approach to the topic:
In addition, for several years, there has also been the increasingly popular 3MF format, which has even recently been granted its own ISO standard (ISO/IEC 25422:2025).
But regardless of all the above, we also still have at our disposal the equally important STEP format, which even has its own AM version!
Some claim that the STEP-AM standard (ISO 10303-242) is the solution to most of the problems faced by the 3D printing software sector. It is supposed to streamline information flow within the “digital thread” and replace the old STL file as a neutral common language for the entire additive manufacturing industry.
The vision is tempting: from CAD model to finished part – with no data loss.
The problem is, this is still just an illusion. Or rather – premature celebration.
STEP-AM is indeed a solid foundation on which a new quality of data exchange can be built, but treating it as the “end goal” rather than a “starting point” is a serious mistake. Believing that this one standard will solve all interoperability problems leads us directly into new set disappointments.
Before we go further, though – let’s briefly introduce the topic. What is STEP, when was it created, and what advantages does it have over STL?
STEP: a short background
STEP, or Standard for the Exchange of Product model data (ISO 10303), is one of the most important initiatives in the history of digital design and manufacturing. Its beginnings date back to the 1980s, when industry was starting to experience serious problems with data exchange between different CAD systems. Each software vendor created its own file formats, which led to enormous difficulties in international cooperation, particularly in the aerospace and automotive industries.
In 1984, the International Organization for Standardization (ISO) launched work on a new standard, and four years later, the first working groups were formed under ISO TC 184/SC 4, focused on industrial automation and product data exchange.
In 1994, the first official version of the STEP standard was published, which allowed not only geometry but also assembly structure and material data to be described. From that point, the format evolved through successive “Application Protocols” (AP), tailored to different industrial sectors.
AP203 focused on data exchange in mechanical design.
AP214 addressed the needs of the automotive industry.
AP209 integrated engineering analysis with product description.
A new stage came with AP242, known as “STEP for Managed Model-Based 3D Engineering.” First published in 2014, its goal was to merge previous versions and introduce support for PMI (Product Manufacturing Information), such as tolerances, geometric requirements, and material data.
AP242 became the foundation for the extension that gained special importance for 3D printing – STEP-AM.
STEP-AM: origins and purpose
Work on adapting the standard to additive manufacturing needs began around 2016–2018, when AM technologies started being widely adopted in aerospace and automotive. At that time, a joint ISO and ASTM group (JWG 21) was established to develop a unified data exchange language for 3D printing.
STEP-AM was meant to address the limitations of STL – a format that only stores geometry as a triangular mesh without any additional product information. With STEP-AM, it became possible to store richer data: not only shape but also production parameters, tolerances, and internal structures.
The idea was simple: to ensure digital continuity from CAD design, through engineering analysis, to print preparation and production.
Although STEP-AM represents a huge step forward, in 2025 it remains only a partial solution. The standard handles geometry and design information very well, but falls short in the rapidly evolving area of process data. As a result, instead of one universal product definition, users still rely on combinations of formats and tools.
Problems with STEP-AM
Metadata – disappearing information
The biggest advantage of STEP-AM is that, unlike STL, it can transfer not just geometry but also design intent and PMI. But this only applies during the design phase. Once you start preparing a part for printing, issues arise.
What happens to lattice parameters generated in specialized software? Or to print process settings, material strategies, or thermal management rules defined in the slicer?
They disappear.
STEP-AM was not designed as a container for the entire complex body of process knowledge. It’s like having a perfect box for transporting a machine, but without compartments for screws or electronics. Everything is tossed in loosely, and the recipient has to guess what fits where.
In practice, this means manually re-entering data – exactly what STEP-AM was supposed to save us from.
The innovation problem – a standard can’t predict the future
The 3D printing industry thrives on innovation and unique, proprietary processes from manufacturers. Technologies such as Velo3D’s Intelligent Fusion or Formlabs’ special resin settings are competitive advantages that cannot be captured in a universal standard.
Can anyone seriously believe that STEP-AM will natively support all current and future parameters? That’s impossible – the standard would become bloated and unusable.
This leaves manufacturers with two choices:
ignore the standard and continue operating in closed ecosystems,
or use STEP-AM as a foundation, but add their own configuration files or APIs to carry critical process data.
In practice, the second option only repeats the old problem: instead of “STL + config file” we get “STEP-AM + config file”. Is that real progress? Debatable.
Different interpretations – multiple versions of the “truth”
The most insidious problem is file interpretation. STL is simply a list of triangles, while STEP-AM is a complex semantic model. This brings risk: different software may interpret the same data differently.
A premium CAD system and a free slicer may read tolerances, surface specifications, or spline geometry in inconsistent ways. In traditional manufacturing, this might not matter. In AM – where microns determine success or failure – it’s disastrous.
Instead of “one source of truth,” we end up with multiple conflicting versions. The promise “design once, print anywhere” loses meaning when everyone sees the same file differently.
The way forward – from geometry to process
So does this mean STEP-AM is a dead end? Absolutely not. It’s an essential foundation. But it is not a complete solution.
To truly solve interoperability, the industry must move further – from a geometry standard to a process protocol. This means:
developing APIs and data exchange agreements – STEP-AM can be the skeleton, but lightweight APIs are needed to transfer process metadata without loss
certification of interpreters – just as a PDF looks the same in different viewers, a STEP-AM file should be interpreted identically by all software
realistic expectations – limitations must be acknowledged openly; presenting STEP-AM as a miracle cure will only slow its adoption when users become disillusioned.
STEP-AM is not the end of the fight for interoperability. It’s only the first stage – moving away from the archaic STL and beginning a much harder battle: to preserve full process data, support innovation, and ensure consistency of interpretation.
Rules, agreements, and certifications are needed to truly turn the vision of interoperability into reality.