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Laser Welding in Sheet Metal Fabrication

Many sheet metal fabrication shops still hesitate to invest in laser welding.
They are missing out on the numerous competitive advantages and opportunities that it offers over conventional welding processes.
As one of the most substantial advancements in modern welding technology, the laser welding process allows industry professionals to achieve much higher precision and speed in welding operations.
Additionally, products manufactured using the process perform at least as well as those produced using MIG or TIG—if not better—with lower overall production costs and shorter lead-times.
Here are some insights that you need to know:

HAZ (Heat affected Zone) is reduced to almost non exisiting compared to Arc Welding

Due to the small spot size of the laser, the heat input is typically 200 times lower than with arc welding processes like MIG, MAG or TIG welding.

Laser welding has been widely accepted by the automotive industry for decades, but in sheet metal fabrication many shops are still hesitant to take the leap. The latest advancements have made laser welding a more viable solution, reducing the cost of entry and providing sheet metal fabricators greater access to the numerous advantages laser welding offers compared to conventional welding processes.

In heat conduction welding, cosmetic weld seams with smooth surfaces result and often eliminate or dramatically reduce secondary processes like grinding or straightening. Typical applications include covers and boxes, or fixtures such as countertops and sinks for the medical or food service industries.

With deep penetration welding, weld speeds of 1000 mm/min to 5000 mm/min, in combination with high weld strength, can be realized. This welding technique is used when full penetration, high part stiffness or sealed and tight weld seams are required. Applications include pressure tanks, brackets or flanges.

Both techniques offer consistent weld seam quality, decreased heat input and negligible distortion of welded components.

Due to the small spot size of the laser, the heat input is typically 200 times lower than with arc welding processes like MIG, MAG or TIG welding.

To fully reap the benefits of laser welding, a fabricator must commit with a normal laser welding machine to high-quality sheet metal processing prior to welding.

As a rule of thumb: material gaps in the weld zone should be limited to approximately maximum 0.10~0.12mm, although this can limit can be extended to gaps of 0.50~0.80mm and more with our new wobble3+ laser welding torch with adjustable welding width.

Luckily, these tolerances are easily met by modern 2D laser cutting machines and press brakes. Although parts can typically be converted from arc welding to laser welding with just minor adjustments to the design, laser welding does provide design engineers with new opportunities, such as overlap welds, corner welds and flange welds. Even complex joint geometries like curved shapes or materials with different sheet thicknesses can be laser welded easily.

Laser welding does not operate on the same principles other types of welding in that laser welding uses a beam of light, instead of electricity, to join two pieces of metal together through a melting and cooling process.  

Another key difference with laser welding is the intensity and ability to focus the heat source: the laser. The much higher, focused heat than, say, the electricity of a MIG welder or TIG welder, means that the weld occurs much more quickly. What’s more, the ability to narrowly pinpoint the weld area leads to much greater precision and more accurate and attractive weld joints.

What does this mean for you?

  • Higher speeds: till 10x faster than MIG welding, and till 40x faster than TIG welding.
  • Minimal/no finishing: The accuracy of the laser welding process means that little to no grinding or finishing is needed.
  • Visually superior: Laser welding is ideal for straight line joints in furniture and other consumer products, since there is a much smaller heat-affected zone and a much tighter weld.
  • Greater strength: A smaller heat-affected zone also means less weakening of the material.

So when wouldn’t you want to use laser welding? Thicker materials and parts where the weld joint construction does not allow the fit-up to be consistently maintained generally are not good candidates for laser welding.

Laser welding of sheet metal is very cost-effective

Many customers are misled into thinking that laser welding is out of their price range. However, despite its superior results and use of advanced technology, laser welding is actually highly affordable, with producttion prices much lower than conventional ARC welding when compared to the total process cost.

Laser welding minimizes drastically the need for grinding or finishing in post-welding.

During both MIG and TIG welding operations, residual spatter can—and often does—occur on the workpiece. In addition, both of these processes usually add filler metal to the weld joint. This excess material must be removed, generally through grinding or similar fnishing processes, before the part goes on to further processing operations or into use. By contrast, laser welding employs such a focused, brief application of heat that there is virtually no spatter or material buildup. This quality 
streamlines the manufacturing process for laser welded parts as the pieces do not need to undergo post-welding grinding or other fnishing operations and can proceed directly to painting and/or assembly

Laser welding is very fast and highly efficient.

Faster processing speeds are important to both reducing project lead-times and decreasing overall production costs. Laser welding is far quicker than alternative welding methods.

For example:  Laser welding has proven to be…

Up to 40 times faster than TIG welding
• Up to 10 times faster than MIG welding

By choosing to use the laser welding process for your welding projects, you as industry professionals can drastically cut lead-times and labor costs.  The increase in processing speeds when using laser welding techniques is aided by the employment of eventual advanced robotic technology. The robotic components support even more faster welding speeds (ranging from 1250 to 2500 mm per minute) as well as more precise and accurate weld locations. These qualities translate to quick and consistent results with an extremely low error rate.

Laser welding uses highly focused, high-intensity heat transfer application with very small heat-affected zone

The use of a highly focused, high-intensity laser beam during laser welding operations provides a much higher weld speed and minimizes the size of the workpiece’s heat-affected zone (HAZ). This smaller HAZ translates to better functional and aesthetic characteristics—in particular, the main benefit is the mitigation or elimination of thermal warping.
When heat is applied to a large area or for an extended period of time, the metal workpiece often experiences warping, which can weaken the structural integrity and aesthetic quality of the fnished piece. The laser welding process addresses both of these concerns as it creates a strong and aesthetically appealing weld.

Preventing warping is especially crucial for parts where the joint may be visible or subjected to heavy loads.

Laser welding creates strong joints comparable to those produced by conventional welding.

During laser welding operations, welders can create two different types of welds: keyhole and cosmetic (or conduction) welds. Keyhole welds are generally deeper than they are wide and are generally not cosmetic in appearance. In contrast, conduction or cosmetic welds are wider than they are deep and are more likely to be produced with longer applications of continuous waves. Both methods yield extremely strong welds with a high depth-to-width ratio comparable to those produced during conventional welding operations.