Fabrisonic, in collaboration with EWI and Luna Innovations, designed and built an instrumented PBF build plate called the SmartPlate. The SmartPlate has embedded sensors and extracts data for real-time or post-processing analysis.
The idea for this new platform started with a simple question: How can we measure the loads going through the build plate during an AM process?
Customers encountering distortion of parts due to residual stress buildup, delaminated parts during printing, and bolts detaching from build plates needed a way to measure real-time stress during AM builds. They also needed to identify the track (stress layer) that led to distorted or unusable parts.
To solve these problems, the SmartPlate has optical strain gauges and thermal sensors built into the metal. The printed geometry on top was created using Powder Bed Fusion (PBF) while simultaneously recording strain/time and temperature/time data.
To create a SmartPlate, Fabrisonic starts with a billet build plate and mills channels in locations where sensors are to be embedded. Sensors are placed in the milled cavities, and ultrasonic additive manufacturing is used to print solid metal over the sensor. The low-temperature process does not harm the sensors; thus, the metal has continuous, contiguous, and direct contact with the sensors. When the product is completed, the customer has a fully consolidated metal plate with integral sensors buried within it.
To test the concept, the team put the SmartPlate in EWI’s PBF machine and began a PBF build that included “highly problematic features.” The team found that the device picked up significantly more information from this initial build than the bulk stress state. Among some of the additional data that was uncovered were:
- The resolution and scan rate was high enough to discern the scan strategy of each layer.
- Defects appeared as large compressive strains that formed early in the build at localized points.
- Slow delamination of a specific feature was seen in the data even though the recoater blade never hit the build.
The following video shows actual strain-time plots resolved in the X-Y plane (left) and the raw data along the length of the fiber (right).
These colorful strain-time histories easily communicate what is happening in the build. Further data analysis can provide a deep understanding of the quality of the build by:
- Analyzing individual “pixels” for sudden vector changes and tell-tale signs of many build issues.
- Comparing time histories of adjacent pixels to highlight problems in the build.
Fabrisonic continues to evolve the concept of the SmartPlate by adding various sensors, including thermocouples and vibration sensors. The team recently upgraded an EOS M290 for further investigations for quality monitoring.
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