Synchrotron X-rays Show Causal Link Between Height Defects and Gas Entrapped Porosity.
Additive manufacturing (AM) is increasingly being used to manufacture critical end-use components. The technology can reduce part weight, part count, lead times, as well as create complex geometries in still relatively small-batch production sizes. To reach the touted benefits, AM has some pitfalls to overcome.
Phase3D’s goal is to detect and predict anomalies impacting 3D-printed parts to in the end reduce the cost per part of AM. Access to an incredibly advanced X-ray system validates how we will reach this goal.
In 2021, Phase3D was accepted into Argonne National Laboratory’s Chain Reaction Innovation fellowship program, granting the team access to the Advanced Photon Source (APS), a U.S. Department of Energy Office of Science User Facility. Here, Phase3D collected data showing the correlation between powder height defects and porosity formation.
To gather the data, APS uses a particle accelerator to emit synchrotron radiation in the form of ultrabright X-rays. With this technology, we can observe how a pore forms in metal powder bed fusion (PBF), where in most cases the laser or electron beam outputs a constant energy source. If an insufficient amount of powder is spread in certain locations of the build area, which is the case in the above video, the energy source creates a gas entrapped pore. How pores are formed in metal PBF is critical to understand since they strongly impact the fatigue performance and crack growth characteristics of parts.
Phase3D’s Project Finge inspection system measures the build area before and after melting. The APS system validates that subsurface pores are created when an inadequate amount of powder is spread across the build area in PBF. In this way, we are working on correlating the observed anomalies to predict when defects are created.
PBF Quality Assurance & Inspection
The precision and geometric complexity possible with PBF rely on an evenly distributed powder height in the 50–70 micron range across a build area. An uneven layer or less powder in one area due to a recoater problem can lead to part defects, potentially causing a build failure and/or scrapped parts.
Defects can lead to high scrap rates in industries mandating tight tolerances and no defects. Metal AM researchers have estimated that in aerospace, part scrap rates can be as high as 30%.
A high scrap rate is unacceptable and uneconomical. To date, the main inspection methods to detect defects are subjective visual analysis (i.e., identifying outliers) and CT scanning, a passive and expensive process.
There has long been a gap in understanding where a defect is forming and offering actionable data to negate that shortcoming without losing the entire build.
Project Fringe & Argonne APS
To address existing shortcomings in PBF quality assurance, Phase3D developed an optical in-situ monitoring system that detects several process anomalies that can lead to part defects. Identifying a part defect can decrease schedule delays and reduce the energy wasted in continuing to build a part that will be scrapped. Phase3D’s flagship technology, called Project Fringe, uses a stereo vision system to collect layer height data. This information can be used to correlate height defects to porosity formation.
Project Fringe goes beyond real-time monitoring and into real-time inspection, collecting quantitative data for every layer of a build. Project Fringe will continue to use Argonne’s APS to correlate final part defects to in-situ monitoring data, allowing the inspection system to save time and money and provide confidence that a part was built without defects.
Want to learn more? The Early Adopter Program opened in February 2023, bringing Project Fringe to its first commercial customers. Space is limited, yet at the time of this publication the program has room for more Early Adopters to sign up. Learn more at our website.