Understanding the Safety Challenge in Powder Bed Fusion Metal Additive Manufacturing

For all the benefits of PBF Metal Additive Manufacturing (AM), there are real safety challenges that must be addressed to protect people, equipment, and productivity.

The fire and explosion risk

We know that powder bed fusion (PBF) often combines lasers or electron beams with fine powders such as aluminium or titanium, and this mix of intense heat and highly reactive fuel is an ignition risk in the presence of oxygen with the potential for an explosion. The risk increases because metal powders are supplied with an oxide layer that can be stripped away during handling and printing, leaving exposed surfaces that react violently when oxygen is present.

Safeguarding with inert atmospheres

To address these risks, most PBF machines operate with an inert gas atmosphere, using argon or nitrogen to keep oxygen concentration low. This removes one side of the fire triangle, preventing flammable or explosive conditions from developing. This safety approach hinges on knowing and controlling the amount of oxygen in the inert atmosphere. If oxygen creeps above a critical threshold, the environment inside the 3D printer/build chamber can quickly shift from “safe” to “explosive”; with ignition sources such as lasers always present, robust oxygen monitoring becomes central to both safety and compliance.

The regulatory picture

Europe’s ATEX directives classify how workplaces should manage explosive atmospheres. Zones (20, 21, 22) define how often such atmospheres are expected to occur, and they set the level of control required. For AM, the challenge lies in deciding whether an inert environment such as a PBF build chamber should be considered a hazardous zone and if so, at what level. That depends entirely on the reliability of the inerting and monitoring systems in place.

Different perspectives, same problem

If the challenge here is clear, the path to managing it is more complex. A web of international standards guides how machine suppliers and operators should approach safety, and these are not always perfectly aligned.

This means a safety system designed to meet a supplier’s requirements may not be enough for an operator’s broader responsibilities.

Why SIL matters

Safety Integrity Level (SIL) is the global measure of how reliable a safety system is. In AM, SIL applies to systems that keep oxygen levels low enough to prevent explosive conditions. For suppliers, this often means designing in “high demand” mode, assuming failures happen at least once a year. Operators, however, may want to take credit for less frequent failures (“low demand” mode) and use proof testing and diagnostics to justify a higher SIL.

Regulations make this point clear: the safety system must be separate from the process control system. In practice, this means AM machines need two layers of control:

This dual approach ensures compliance with directives like ATEX 2014/34/EU, which explicitly require safety devices to function independently. Maintaining that independence also means ensuring sensors perform reliably over time. As part of ongoing research with Ireland’s leading independent research and technology organization Irish Manufacturing Research (IMR), Ntron Gas Measurement is studying how the off gas (condensates) in PBF machines can affect oxygen sensor performance and developing mitigation methods. At IMR’s advanced additive manufacturing facility, our analyzers are installed on production-scale machines to be tested under real-world operating conditions, reflecting the demands of OEMs and end-users. This work is key to ensuring independent safety systems remain dependable in theory and practice.

Our SILO2 oxygen analyzer is purpose-built for that dual approach, made for environments where both quality and safety depend on ultra-low oxygen levels, the SILO2 provides:

By delivering reliable, standards-compliant oxygen measurement, the SILO2 analyzer enables suppliers to design safer systems, and gives operators the assurance they need to classify their processes as “safe” rather than hazardous.

Metal AM’s potential is enormous, but the risks are real. Aligning machine design, operator responsibilities, and safety standards require robust, independent oxygen monitoring. With the SILO2 analyzer, suppliers can deliver systems that meet demanding safety requirements while operators gain peace of mind that their processes are protected.

By David Beirne, Senior Product Manager Dewpoint & Oxygen