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The Dark Arts – Using Lasers To Illuminate Welding Processes.

Now we get into The Dark Arts ….. well actually we use light to see it…

Ever seen, with startling clarity, the process of a welding event? Need to see why some welds are weaker and fail?

Our friends at cavitar can illuminate us on this… while also illuminating the welding event! The info below is from our friends at Cavitar.

The imaging of welding is often challenging since the camera can easily be blinded by the large amount of light emitted by the welding process. Logically, too much light is sorted by filtering. With neutral density filters one can reduce the amount of process light but at the same time areas with less process light become darker and darker.  Such filtering thus merely makes it possible to “select” which features can be seen and which not.

In order to be able to see both the “hot” and the “cold” regions of the object at the same time, the following conditions have to be fulfilled:

  1. apply a filter which prevents the saturation of the image by reducing the amount of process light in the image
  2. apply illumination which can illuminate the object appropriately and fits with the applied filter transmission band

The video below gives an excellent example of this.

 

This video shows welding defect porosity as it is happening in a CMT (Cold Metal Transfer) process. You can see the tiny round formations shooting upwards from the melt pool leading to porosity in the weld.

TWI Global says that “Porosity is caused by the absorption of nitrogen, oxygen and hydrogen in the molten weld pool which is then released on solidification to become trapped in the weld metal”.

The footage was captured using a high-speed camera at 7.000 frames per second and our CAVILUX laser illumination as the light source.

To read more on this, please visit our friends at Cavitar, for a more detailed explanation on illumination