A New Way To Look At Welding: High Dynamic Range (HDR) Imaging 

Quality managers, automation specialists, and weld technologists, this is for you…

Have you ever wanted to see what’s really going on in the weld arc? As anyone who has struck an arc knows, the contrast between the brightness of the arc and the (relatively) dim surroundings during welding make viewing the complete weld process extremely difficult. High Dynamic Range (HDR) imaging, now being incorporated into many welding cameras, drastically improves the visibility of the weld process. Combine HDR with high speed photography, and you can see some truly impressive images of a weld in-progress.

MaJIC recently hosted Ontario-based company Enceladus Imaging in our labs to record and render images of a number of different weld processes using high-speed HDR and their own proprietary image processing technology.  For our part, this is the sharpest imaging capability we’ve seen to-date. We have shared some of the resulting video - and a few observations - below.

This first video is of a manual GTAW process on carbon steel. The intent of sharing this video is really just to introduce the capability of the system. Note the detail in the full colour image. You can clearly see the filler metal melt into the pool as it enters the arc. Replay it a few times, and you’ll see that you can make out all kinds of details that get lost in a typical image.

Note:  For best viewing, expand the video to full size in your monitor.  During posting a bit of the sharpness has been lost compared to what we see in the lab, but you can still make out the most important details here.

The next two are great examples of the utility of this type of system.

The first video is mechanized GMAW (shielding gas 95% Ar, 5% O2) travelling at 20in/min on a well-cleaned aluminum fillet joint. As with above, note the detail in the transfer of metal across the arc, the ripples in the weld pool, and other details right down to the notching of the wire due to the rollers in the gun.
 


More importantly from an industrial standpoint, we can use this type of imaging to learn more about the welds we are performing. For example: Note the shiny, consistent appearance of the weld pool in this video as compared to the one below. The below video was shot using the exact same process and variables, but on un-prepped aluminum. Those who read the previous newsletter on welding Aluminum may remember the emphasis we put on cleaning the joint thoroughly. This video shows a great example of why:


 

Note that by about the 5 second point in the video, you can see a buildup of dark particles at the front of the weld pool. This continues and the particles remain (and flow around the arc to the back of the pool) for the duration of the weld. These impurities, coming from oxides and contaminants on the Al surface, mix into the weld and can ruin its integrity. As we’ve mentioned before, by cleaning the surface properly prior to welding, you can avoid contamination and ensure a clean weld. These visuals really help to emphasize the point.

As you can see, for both research and quality control purposes, there is great potential for HDR imaging. Stay tuned to future newsletters for additional videos.

We would like to know about your welding imaging challenges. If you see a potential use for this technology, please contact us and let us know what you would like to see. If you are interested in a demonstration of the Enceladus system, please contact their team at contact@enceladusimaging.com.