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3 PRIZE
rd

FINALLY UNITED: OCT-BASED PROCESS CONTROL AND
ON-THE-FLY REMOTE LASER WELDING IN ONE TOOL

> Thibault Bautze-Scherff, Sales Manager
Blackbird Robotersysteme GmbH
Garching b. München, Germany

The use of OCT (optical coherence tomography) as a sensor to enhance the process monitoring Five years after the first steps were taken, the collaborative development of Blackbird and Scanlab
capabilities in laser material processing applications was first shown to public around 2012. In the was able to prove its full extent. All of the traditional monitoring tasks for laser welding are
following years, the technology has shown its potential to dramatically improve the pre-, in- and united within one tool and combined with the flexibility of on-the-fly remote laser welding. The
post-process monitoring in laser welding applications. combination consisting of main and OCT scanner, the OCT device itself, on-the-fly functionality, all
Remote laser welding with galvanometer scanners is widely used in the automotive production, accessed through a common user interface, will allow for a continuous improvement of all remote
however always lacked the capability to perform seam tracking or online seam inspection, due to laser welding applications over the next decades.
the size of the scan field and the highly dynamical changes in direction. Blackbird was the first
company to introduce on-the-fly welding (2010) and a coaxial, camera-based seam tracking for The feedback from trial customers is overwhelming and confirms the need, usability and profitability
remote laser welding (2014). of such a universal, yet powerful welding tool. It is the kind of tool needed to face the future
flexibility in production lines, for example to weld different parts in one station, each having their
In 2015, Blackbird took the decision to implement OCT as a universal tool for pre-, in-, and post- own requirements for process monitoring. Quality management relies on gathering all information
processes tasks in remote laser welding applications with Scanlab’s galvanometer scanners. This available for a production step, which can be easily done with the Blackbird OCT solution.
endeavor comprised of challenges of unprecedented complexity.
The OCT beam requires its own, coaxially mounted 3D scanner. Scanlab was thrilled to develop These demands do not only exist in the automotive sector. Galvanometer scanners are used in
such a scanner, relying on their years of experience with scanning devices. The Blackbird software several industries. Some have high quality constraints and rely on additional sensors mounted onto
considers the six degrees of freedom of the manipulating robot, the three axes of a scanner and four the scanner. A prominent example is the powder bed based additive manufacturing. Production
axes of the OCT scanner. These movements have to be combined to accurately localize the position times up to several days demand for faultless parts. In case a defect occurs, the production should
of the measured OCT distance. Lastly, the generated OCT scan profile need to be evaluated, the immediately stop, or process parameters are adapted to a changed situation. By using the newly
workpiece’s edge identified and a control signal provided to the main scanner. developed Blackboard hardware platform that synchronizes the data streams from the processing
scanner and third-party sensors, the process monitoring can be dramatically improved. Over and
These requirements led to the development of a hardware interface internally named “Blackboard”, above, additional closed-loop control of the laser power is made available.
to which both scanners and the OCT sensor are connected. It deals with position data and measuring Integrators benefit from the flexibility of the hardware interface. Any sensor working with a signal
data with sample rates beyond 100 kHz. Its firmware has a scope that goes far beyond seam tracking: coded as voltage, amperage or transmitted via RS-422 can be integrated. As of writing, most
keyhole depth monitoring can be used to evaluate the penetration of the laser and control the laser Scanlab scanners can be used.
power. For seam inspection tasks, multiple scan lines are combined and processed at once. Process monitoring for scanner-based applications will never be the same again!

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