The Xiris Blog

Triggering Weld Cameras from a MIG Process

Posted by Cameron Serles on Thursday, February 07, 2019 @ 11:00 AM

MIG processes, particularly short circuit MIG, will generate a huge range in brightness during their metal transfer cycle:  when the arc is extinguished as the wire makes contact with the parent material prior to expulsion, the image can be quite dark. However, after an explusion occurs and the arc is re-established, the image may be very bright as the arc intensifies to its maximum.

Using a camera to acquire images of a MIG weld process in free running mode can be problematic when the amount of light present in the image varies considerably. The variation in light is based on when during the metal transfer process the image exposure takes place: when the arc is extinguished, the image will be dark; when there is a full arc, there will be a bright image. However, if the camera acquisition is triggered by an electrical pulse generated by the camera power supply, the result will be a consistent image of the weld process that is repeatable because it is at the same point of the weld cycle.

Image4

(courtesy ESAB Group, Inc.)

A few words about how Short Circuit MIG and certain other kinds of MIG welding function:

  • Wire is fed continuously and makes contact with the workpiece to complete the electrical circuit.
  • At the point of contact, a short circuit occurs, resulting in a huge spike of current moving through the wire between the torch and the workpiece.
  • At point of wire contacting the workpiece, arc gets extinguished.
  • Segment of wire rapidly vaporizes under high current and an arc gets re-established.
  • Current falls as there is no short circuit.
  • Process repeats.

In a constant voltage welding power supply, the current being fed to the torch can rise and fall based on the metal transfer process. When there is a gap between the wire and the workpiece, the conducting current is low, and increases as the wire begins to touch the workpiece and create a short circuit. Then, once the wire tip explodes, the current falls as there is no conducting circuit. The plot of the current levels look something like this:

 Image3

(courtesy ESAB Group, Inc.)

While capturing the welding process to see certain features, it is sometimes interesting to only take images at a certain point in the metal transfer cycle. Rather than using a weld camera in free running mode where image acquisition is based on the clock cycles inside the camera, an efficient alternative is to use an external trigger that is based on the current levels present in the welding power supply.  If a circuit can be designed to generate a trigger signal based on the rising edge of the current level, then the trigger could be used to initiate image acquisition, resulting in video with an increased consistentency in brightness and quality because each frame will be acquired at precisely the same point in the metal transfer process. 

Further enhancement to the performance of the imaging process is possible by tweaking exactly when the images are acquired through adding a delay.  A delay can be added after the trigger signal is generated so that the exact imaging characteristic can be seen.

For example, imagine wanting to see only images of the metal transfer process after the weld arc is extinguished.  To do this, a trigger signal should be generated based on the current pulses coming from the weld power supply.  It may not be possible to receive the trigger at the ideal point in the metal transfer process, so a programmable delay can be added to make sure that the image acquisition occurs at exactly the right point.

With Triggering:

Image2Image1

Successive Snapshots of a MIG Welding Process Triggered from the Rising Edge of Welding Power Supply’s Current Pulse

The above two successive images show a MiG process at roughly the same point of the metal transfer process over different cycles of the metal transfer.  In this case, the imaging was tuned to see exactly what the viewer wanted to see: the melt pool fully visible with the welding arc present.

In Summary

Imaging a MIG welding process can be fairly difficult if using a weld camera in free running mode.  However, if a circuit can be designed to clamp on the rising edge of the current pulse, it can provide an excellent trigger to use to acquire consistent images at similar points in the metal transfer cycle.  The result is much more uniform images with similar brightness levels, allowing for better analysis and increased efficiency of the welding process. 

Better Images. Better Decisions. Better Process Control.

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Topics: quality control, image processing, HDR, mig welding, reduced costs, weld camera system, consistent, MIG process

Customer Testimonial: Xiris Tube & Pipe Inspection Systems Transform Quality Control

Posted by Emily Blackborow on Thursday, January 24, 2019 @ 11:02 AM

Who doesn’t love an inspiring transformation story? Weld inspection systems truly are capable of transforming your quality assurance processes and one of our Spanish customers has quite the story to prove it.

Tubos de Legutiano Automoción (TLA) is a manufacturer of high-quality tubular products for the automotive market. By producing thin-walled exhaust pipes, TLA helps their customers reduce the weight of their parts, while maintaining high quality standards that are able to withstand the strict demands of the automotive industry.

TLA

TLA recently said that their most important customer, a large automotive parts supplier based in France, was both surprised and delighted to notice a sudden, significant improvement in TLA’s quality, so much so that they wanted to pay them a visit.

Once visiting TLA, the French automotive parts supplier realized that the improvement in quality was due to the introduction and implementation of the Xiris WI2000 Weld Inspection system used on their two tube lines.  By detecting defects that were previously not detectable using any other NDT test process, TLA was able to address the imperfections that were plaguing their production for years.

The management of TLA commended Xiris’ systems saying:

“Without precision tools that allow us to move forward and work under this precept, it would be difficult to be able to develop products according to the new demands. That is why the Xiris WI2000 has been the key for increasing the quality of our company, reducing set-up times, monitoring the quality of the product in real time and allowing to interact with accurate information in the production process.”

The result was that, once implemented, the WI2000 systems were able to catch defects and help perform better process monitoring to keep their tube product in control.  Consequently, fewer defects made their way to the end of the production line and shipped to their customer in France.

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Topics: quality control, tube, defects, WI-2000p, reduced costs, automotive, tubedefects, tube mill

Using Weld Cameras to Enable a Continuous Coil Joining Process

Posted by Cameron Serles on Thursday, January 10, 2019 @ 01:00 PM

Xiris’ High Dynamic Range (HDR) welding cameras can be used in a multitude of ways, some of which our customers have discovered on their own.

For example, a manufacturer of thick-walled steel pipe recently figured out how to use our cameras in a way that has greatly improved the efficiency of their coil joining process.

Operators only have about 10 minutes to end-sheer, mate, and weld coils during the semi-automatic front-end part of the process. The cost of coil joint failure is high, so the manufacturer would stop the tube mill to check on the integrity of the coil joint before continuing.

Even though the stoppage prevented more-costly failures, it had its own cost. What our customer needed was a way to adequately monitor the end joining in the infeed buffer of the pipe mill without having to stop the process to assure correct coil matching.

They knew the capabilities of our cameras to enable real-time remote monitoring of weld processes with greater visibility than ever before possible. So they developed a plan to use Xiris XVC-110e50 cameras to monitor the coil joining during the front end of the process. This monitoring eliminates the need for routine stoppages.

This solution also keeps operators safer. Coil joining is performed using a MIG welding torch mounted onto a linear track with dual-axis torch position. Previously, operators had to be close enough to the torch to see what was happening with the weld. With the Xiris HDR cameras, they have a clear view of the coil joining process from a safe remote location.

With their creative use of our HDR camera technology, this manufacturer was able to significantly reduce the time and cost of coil joining, while increasing consistency.

For a video of the coil joining process taken by the XVC-1100e50 camera, please view the video below

Coil Joining Video 

Better Images. Better Decisions. Better Process Control.

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Topics: quality control, tube, reduced costs, weld camera system, coil joining, tube mill

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