PST offers oxygen and moisture measurement solutions for safety and quality in AM
July 4, 2024
Process Sensing Technologies (PST), based in Ely, Cambridgeshire, UK, offers a range of oxygen and moisture measurement analysers developed to ensure the highest safety and quality in metal Additive Manufacturing processes. The systems are said to provide a means of achieving precision and maintaining build consistency, which is critical to successful production
Oxygen measurement for quality
Oxygen levels in the build chamber can significantly impact quality, explains PST. Excess oxygen can lead to oxidation, compromising the integrity and strength. To prevent oxidation, the oxygen concentration should typically be below 500 ppm for metal Additive Manufacturing processes such as Laser Beam Powder Bed Fusion (PBF-LB).
PST’s oxygen analysers have been specifically designed to be integrated into the Additive Manufacturing machine manufacturer’s control and safety systems. These analysers provide real-time monitoring and control, maintaining optimal oxygen levels during the build process, and can trigger inert gas purges (like argon or nitrogen) to maintain low oxygen levels. When measuring oxygen, PST has sensors capable of detecting oxygen from as little as 1 ppm. Operating ranges from 0-10 ppm to 0-25% with a response time T90<15 seconds.
For ease of use and compact design, PST offers the Microx Oxygen Analyzer, an integrated solution featuring three configurable alarm contacts, an LCD screen displaying O2 concentration, a remote sensor and three analyser mounting options for flexibility. Its zirconia sensor performance is proven in the harsh environment of an Additive Manufacturing build chamber.
Measuring oxygen for safety
PST’s zirconia and solid-state technologies have been specially developed for harsh process applications. They can be supplied with SIL2-capable oxygen analysers or transmitters designed to comply with the requirements of IEC 61508 (SIL Capable) for fail-safe oxygen measurement in inert gas blanketing applications.
For example, the SIL-O2 Process Oxygen Analyzer is engineered for highly reliable oxygen measurement in safety-critical applications, including the Additive Manufacturing machine, depowdering system, and sieve station. It includes a DIN rail-mounted control unit with galvanic barrier and a remote electrochemical (solid state) sensor with interconnecting cable (up to 30 m), providing a flexible, easily integrated package.
The inert gas (argon or nitrogen) used to create an oxygen-free environment should have a purity level of 99.99% or higher. Gas purity analysers, such as PST’s Oxydew, can ensure the supplied gas meets the required purity standards, preventing contamination during the building process.
Controlling moisture for enhanced performance
Moisture is another critical factor in metal Additive Manufacturing, adds PST. High moisture levels can cause defects in the manufactured parts, such as porosity and reduced mechanical properties. The SF82 Dew-Point Transmitter from PST provides accurate moisture measurement in critical phases of the AM process, such as the Additive Manufacturing machine, de-powdering system, and sieve station.
Inside the Additive Manufacturing machine build chamber, the SF82 Transmitter continuously monitors and controls humidity levels. This helps improve the structural integrity and performance of the final product. This level of control is also essential within the post-processing process to help ensure the integrity of the powder material. Moisture in powder materials can cause particles to clump together, leading to inconsistent powder flow and poor layer deposition during Additive Manufacturing. This can result in defects in the manufactured part.
Integrated solutions for complete process control
What PST notes as setting it apart, is the ability to provide a complete solution for measuring oxygen and moisture in different applications within the whole AM process – from gas feed to powder recovery. By integrating these advanced analysers into Additive Manufacturing systems, PST enables manufacturers to achieve comprehensive control over critical environmental parameters.
This integration ensures that oxygen and moisture levels are precisely monitored and maintained within optimal ranges, preventing potential issues such as oxidation, material degradation, and build defects. As a result, manufacturers can consistently produce high-quality parts with superior mechanical properties and surface finishes. Additionally, PST’s solutions enhance process efficiency and reliability by reducing the risk of equipment malfunctions and minimising downtime.