The Xiris Blog

Peter Serles

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Using Weld Cameras to Minimize Excessive Spatter on GMAW

Posted by Peter Serles on Wednesday, June 28, 2017 @ 04:00 AM

Gas Metal Arc Welding (GMAW) is characterized by the creation of sparks and spatter ejecting from the workpiece as the weld wire/filament shorts and melts over 100 times per second. The creation of spatter is an inevitable part of the GMAW process but it presents a number of issues for the production process, including damaging functional surfaces, increased consumables, and poor finish aesthetics. It may not be possible to eliminate spatter altogether, but it can be greatly reduced with a better understanding of why spatter is created and how to tune your process parameters to control it.

Spatter is the discharge of high temperature material as a result of melt pool surface tension and the conversion of thermal energy to kinetic energy. This sprays small droplets of molten metal onto the surrounding area where they cool and solidify creating a non-uniform surface finish. It is well known that different GMAW processes produce varying levels of spatter but even spray GMAW, which is known for spatter control, can greatly benefit from spatter reduction.

See the full video: Spatter Ejected from GMAW Short Circuit Process on Stainless Steel

June 28 Image 1.jpg

 

As well as being a nuisance to clean, spatter can be a costly problem for GMAW welding. A case study performed by Welding Answers [1] looked at the benefits of parameter tuning and found that spatter reduction by as much as 85% was possible through better parameter settings, leading to operating cost reductions of 21%. This was achieved through reduced labour costs, less lost filler material and fewer consumables required to post-process the weld.

In order to reduce the total spatter, a strong understanding of welding parameters and their effect on the weld pool is required. According to the ASME, 77% of welding defects including high spatter content are caused by improper processing conditions or operator error [2]. Most commonly, adjusting the amperage, voltage, and distance of electrode to workpiece are the significant factors influencing spatter production. Other factors that influence spatter include wire-feed speed, electrode thickness, and surface contamination.

With the use of a Xiris High Dynamic Range welding camera, the weld arc, spatter ejection, and surrounding material can all be clearly observed and the amount of spatter created during the welding process can be monitored and evaluated. This allows better understanding of the effects of varying the welding parameters and their influence on spatter formation. With a clear view of the operating field, welding parameters for every material and thickness can be adjusted to reduce spatter content and inefficiencies as a result of spatter production and cleaning can be greatly reduced.

 

For more information on how Xiris Weld Cameras can reduce splatter and enhance your GMAW welding processes visit Xiris.com 

You can visit our

 WELD VIDEO LIBRARY

for dozens of examples of the camera in action. 

Don't miss any of our amazing videos! Sign up to receive the Weld Video of the Month 

 

References:

[1] http://weldinganswers.com/the-real-cost-of-welding-spatter/

[2] C. Matthews, ‘ASME Engineer’s Data Book’, ASME Press, January 2001

Topics: quality control, Xiris, High Dynamic Range, GMAW, weld monitoring, additive manufacturing

Get Better Quality from Your Laser Additive Manufacturing Process

Posted by Peter Serles on Wednesday, May 31, 2017 @ 01:26 PM

Additive manufacturing is an increasingly attractive technology that has in recent years graduated from a basic prototyping technology to one capable of producing large volumes of highly intricate part geometries in a wide range of materials. Of particular interest is the ability to produce complex geometries from industry grade metals for use in several fields including aerospace, biomechanics, and mold and die.

ASTM defines three subfamilies of additive manufacturing that are currently able to process metals: direct energy deposition, powder bed fusion, and sheet lamination. These families differ in their setup of feedstock material but all employ a directed energy source such as a laser or electron beam to process it. These laser additive manufacturing processes are characterized by rapid melting and solidification of subsequent layers in a tightly controlled environment.

Due to the repeated melting and solidification of layered material, parts undergo a complex thermal history and present a set of unique thermo-physical and metallurgical challenges. The most common defects seen in the laser additive process are a result of difficulties with maintaining a consistent melt pool caused by insufficient/excessive heat, oxidation, or contamination of the melt pool. The resulting micro-porosity in the build commonly propagates fatigue cracking in finished parts.

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SEM image of fatigue cracking in stainless steel created by selective laser melting [1]

Introducing a Xiris high dynamic range weld camera during the manufacturing process allows the operator to see exactly what is happening during the laser additive manufacturing process, namely how the laser keyhole and melt pool are interacting with the surrounding material and previous layers. With such a camera, the size, shape, and consistency of the melt pool can be directly observed making critical problems such as an uneven melt pool, unfocused or unsuitable laser power, misalignment of the powder supply, or material powder contamination easy to identify and correct.

By determining the root source of these problems, a better understanding of build failure can be obtained and potential issues can be identified before they continue through the entire production process. This is especially useful for products that contain internal cavities or other features that are difficult to inspect post-build. On average, one quarter of the total time required to complete a laser additive manufacturing build is spent on the post-build inspection. The Xiris weld camera provides increased confidence in the quality of your components and can reduce the need for post-build inspection or destructive testing.

Laser  Additive Manufacturing – Steel – Process Monitoring

For more information on how Xiris Weld Cameras can enhance your laser additive manufacturing processes visit Xiris.com 

You can visit our

 WELD VIDEO LIBRARY

for dozens of examples of the camera in action. 

Don't miss any of our amazing videos! Sign up to receive the Weld Video of the Month 

References: [1] Li. R. et al. Densification behavior of gas and water atomized 316L stainless steel powder during selective laser melting. Applied Surface science. 2010. 256(13) pp. 4350-4356. 

Topics: quality control, Xiris, High Dynamic Range, laser additive manufacturing, additive manufacturing, productivity tools

The Best Way to Cool a Weld Camera—Air or Liquid?

Posted by Peter Serles on Wednesday, May 08, 2013 @ 08:33 PM

A Weld Camera, like most electronics, needs to be kept from getting too hot (typically not greater than 50 ºC within the camera electronics or greater than 40 ºC in the internal camera frame) to minimize the electrical noise of the video signal and extend the lifetime of sensitive electronics such as the LED light sources.

Therefore, Weld Cameras need to be equipped with a form of cooling that allows for the camera to run indefinitely even in high-temperature environments. This is done using either air (with either passive or active cooling) or liquid cooling.

Usually the cooling medium flows through a channel that is isolated from the optical and electronic components of the camera, keeping everything cool via convection, while keeping the optical and electronic components free of contamination.

Passive Air Cooling

Passive Air Cooling refers to the use of compressed air fed directly into the camera to provide a flow of air through the Weld Camera. If compressed shop air is used, the ambient air temperature should be less than 25 ºC because the compressed air temperature is close to the ambient temperature of the welding environment and needs to be under 25 ºC to be an effective cooling medium.

Passive Cooling for XVC-O Weld CameraThe compressed air should be filtered to prevent build-up of a film of dirt on the internal cooling passages of the camera body, as this will reduce the cooling efficiency. If there is a separate cooling chamber in the camera, the air does not need to be dry to be used.  However, because of the typical small temperature differential between the incoming cooling air and the camera frame, a large air flow is required to maintain a cool camera, representing a significant operational cost.

Active Air Cooling

A better solution to cool a Weld Camera is to use Active Air Cooling.  If the ambient temperature in the vicinity of the camera is above 25º C, Active Air Cooling is the only air cooling option. The most common way to provide Active Air Cooling is to use a device called a vortex cooler—a mechanical component with no moving parts but which takes in compressed air and divides it into two low-pressure air flows – hot and cold.

Within the vortex tube, the air flow is converted into a very-high-speed swirl (vortex) and the air in the vortex separates into a high-temperature zone at the outside and a low-temperature zone at the center. The unit can be adjusted to provide very cold air that can then be fed into the Weld Camera for cooling. 

Cooling with a vortex cooler is extremely inefficient, using a high volume of compressed air that can mean high operating costs in the long run. However, it does provide a very cool air source to cool the Weld Camera in even very-high-temperature ambient environments.


Active Cooling Setup for XVC-O Weld Camera with Vortex Cooling

Active Cooling for XVC-O with Vortex Cooler

Water Cooling

Water cooling is the most efficient way to cool a camera. Because of the very efficient thermal transfer between the camera cooling channel and the water, and the high heat capacity of water versus air, water at 32 ºC can be used to maintain the camera frame at 40 ºC or less.

If a cooling water supply is already being used to cool some welding system components, the additional cooling load from the camera will be insignificant. If a main water supply at 32 ºC or less is available, 2-3 litres/minute is sufficient to cool the camera and the water can be recirculated through a water chiller—a standard component that is readily available and reasonably priced. The cooling system cost can then be reduced to some very simple plumbing and simple equipment.

Conclusion

The XVC-O Weld Camera from Xiris uses a sealed chamber to provide cooling to the camera, thereby eliminating the potential to contaminate the optics and electronics from the cooling medium. Both Air (Passive or Active) and Liquid cooling options are readily available, providing the best solution to fit each fabricator’s needs. 

Topics: camera selection, weld camera, weld environment