Sigma Labs Inc (SASI)

[3dtdman]

Thanks, T&L. If you're interested in knowing what that graph labeled "Melt Pool Thermal Cycle, aka, instantaneous thermal cycle" is all about, here's a copy of an Email I sent Chris Witty last month:

"Hi Chris,
Back in 2002 Mark Cola, Vivek Dave, and others authored a paper titled “NONDESTRUCTIVE, IN-PROCESS INSPECTION OF INERTIA FRICTION WELDING: AN INVESTIGATION INTO A NEW SENSING TECHINQUE”. And in 2003 another paper was published titled “Stategy for Small-Lot Manufacturing In-process monitoring and control “. And Sigma Labs has also used ultrasonic information for monitoring build quality during resistance spot welding:
http://3dprint.com/73525/metalfab1-quality-assurance/ and from the same link it appears that ultrasonics has also been used in the AM process.

But on the B6 website three types of sensors are mentioned—thermal, optical, and spectral (see attached .PDF). No mention is made of ultrasonics. The graph on the left (intensity vs. wavelength) is a spectrograph, the one on the right is, I think, brightness vs. time. As described in the paper I sent you yesterday (), a Fast Fourier Transform (FFT) can be used to map the time realm info to the frequency realm, enabling extraction of the fundamental weld pool oscillation frequency, which is one of the keys to controlling the weld pool volume in the Sigma Labs patent US 20100288734 A1. This seems to be what EOS is doing with their EOSTATE SW for their “melt pool monitoring”:

“For melt pool monitoring, EOS has taken a somewhat different approach. Rather than pursuing in-house development, the company has partnered with plasmo Industrietechnik GmbH (Vienna, Austria), whose fastprocessobserver system has been field-proven in laser welding environments. The system utilizes one or more off-axis photodiodes to collect broadband light emission from the laser-induced plasma. The signals are analyzed in the time and frequency domains, employing a number of proprietary signal-processing algorithms. Anomalies detected by the analysis can be correlated with different types of defects once the system is "trained" with reference known-defective and defect-free process conditions. Challenges for adoption in powder-bed AM environments include the much higher required sampling and signal-processing rates [8]. As of press time, plasmo's monitoring system has been integrated with EOS's machines and is undergoing evaluation at a major end user.”
http://www.industrial-lasers.com/articles/print/volume-29/issue-5/features/process-monitoring-in-laser-additive-manufacturing.html

I have two questions for you:
1) Are ultrasonic sensors used in the SENSORPAK™ bundle of sensors? Are they maybe used for SOME custom installations? Or are they not used at all?
2) Why is the EOS software NOT a violation of Sigma Labs patent previously mentioned? Is it because the Sigma Labs patent is US only? "
Chris answered both questions, stating "No UT sensors currently"--not sure what a "UT" sensor is, maybe it stands for "Ultrasonic Transducer" which would make the term "sensor" redundant. As for the possible patent infringement, he stated,
"EOState is not yet available as a commercial system and is not expected to be released until next year sometime as they are still in a pilot study phase. Our technology is complementary with EOS's and we continue to explore opportunities to collaborate."

Link to the referenced paper about the FFT melt pool frequency extraction is here:
http://www.aws.org/library/doclib/WJ-2015-05-s176.pdf
Please see pages 180-s and 181-s.