How CleanWeld™ Improves Your Fiber Laser Weld Quality and Yield
While fiber lasers have been used in welding for over a decade, efforts still continue to improve their utility and extend the results they deliver in terms of part quality, production throughput and process costs.
The CleanWeld initiative from Coherent is an integrated approach to fiber laser welding that addresses these issues and delivers up to 80% spatter reduction, as well as minimal cracking and porosity. And − in addition to improved process consistency − it allows some welding processes to be performed with 40% less laser power.
Understanding Key Laser Welding Parameters
To understand how our CleanWeld technology accomplishes these goals, it’s useful to review some basics of “keyhole” or deep penetration welding processes.
Schematic of laser keyhole welding
As shown in this figure, a focused laser melts material, creating a “keyhole” of vaporized metal surrounded by molten material, which is held back by vapor pressure. This is a highly dynamic process, which can become chaotic, especially when multiple materials with different boiling points are present in the alloys. For example, lower melting point materials can produce bubbles in the melt pool which introduces spatter or reduces the porosity of the final weld seam. The quality of a weld is determined by the stability of the keyhole during the welding process. The goal is to achieve a stable energy balance through the entire depth of the keyhole to ensure uniform absorption and non-perturbed molten flow around the keyhole. This in turn provides consistent weld depth and, more importantly, minimized spatter and porosity in your welding process.
How to Optimize Keyhole Welding
In fact, there are several tools which can be employed to control the various process parameters, and therefore optimize a specific welding process, and this is the essence of our CleanWeld approach. Probably the most obvious of these are laser power and the focused laser spot size, as well as the spot’s spatial intensity distribution. In fact, it’s really only useful to consider these three factors together, since it is really the power density at the workpiece, rather than the overall power, which affects welding results. For example, even the highest power laser won’t weld at all if the focused spot size is too large. Focus position is also critical – the depth of smallest laser focus relative to the top material surface.
What Else Can Matter?
In addition to focusing optics, laser welding process heads may also incorporate nozzles for delivering process gases, and for removing the expanding laser vapor. In particular, certain assist gases can be used to stabilize the heating of specific materials and calm melt pool dynamics. Gas flow can also be used to clear the plume and protect optics from debris.
Improved Welding Results
Typical applications that can benefit dramatically from CleanWeld range from the welding of powertrain components, zinc-coated steel, motor stator "hairpins", electric car battery lids, to the welding of aluminum hang-on parts.
By optimizing all relevant factors, we are able to supply you with a complete, cost-effective CleanWeld solution that delivers a specific weld quality and throughput speed, rather than just a laser with a given output power – since spatter matters.
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Risk factors: Except for the historical information contained here, many of the matters discussed in this Web site are forward-looking statements, based on expectations at the time they were made, that involve risks and uncertainties that could cause our results to differ materially from those expressed or implied by such statements. These risks are detailed in the “Factors That May Affect Future Results” section of our latest 10-K or 10-Q filing. Coherent assumes no obligation to update these forward-looking statements.