Machine Vision Control of Laser Coating Removal Process
Robotics & Automation Engineering

image of Cameras and lighting are used to image the laser for real-time control of the surface ablation process.

Cameras and lighting are used to image the laser for real-time control of the surface ablation process.

image of video for Manufacturing Technologies Department Capabilities

Laser Depaint Demonstration Video

Southwest Research Institute (SwRI) seeks to advance technology for the benefit of society and potential clients through robust internal research and development programs. Under one of these programs, Southwest Research Institute, EWI, and Wayne Trail Technologies collaborated to demonstrate a high-speed laser coating removal technology. The system incorporated a high-speed vision-based approach that provided closed-loop operation for coating removal. This technology was demonstrated to remove 10-mils of top coat at rates of over 5 ft2/minute from painted surfaces.

Coating Removal Process

SwRI has been developing robotic coating removal cells since 1987. Typical coating removal processes involve either blasting a surface with plastic media or utilizing chemicals for stripping. Laser coating removal is desired to reduce the waste stream created by the current processes, as well as to allow for selective coating removal.

Machine Vision as a Solution

SwRI developed a machine-vision solution to provide real-time monitoring and control of the laser based on the perceived spectral characteristics of the surface. This allowed for selective removal of the coatings, such as leaving the primer intact or complete removal of the coating to the substrate. The cameras, lighting, and optics were all integrated to provide the ability to capture the laser ablation process. The system used the machine-vision results to provide feedback control of the laser power.

This problem was a particularly challenging machine-vision application due to the high rate of required image acquisition (600hz) and the optical complexity of the laser ablation process such as smoke, flare-ups, and other process-related anomalies. Process applications can often be solved by generic off-the-shelf vision solutions, but unique challenges of this problem proved a good match for SwRI's real-world machine vision expertise.

Related Terminology

machine vision  •  real-time monitoring  •  vision-based laser control  •  product development  •  prototype  •  laser processing  •  coating removal  •  depaint

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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 10 technical divisions.