Can you laser weld aluminum?

Yes, you can laser weld aluminum with any of our laser welders. However laser welding aluminum requires high power density, and some competing brands or models lack the intensity to weld it well.

laser welded aluminium 1mm internal fillet with shiny metallic finish
laser welded aluminium 1mm internal fillet for sign construction

Why is aluminum difficult to laser weld?

Aluminum is difficult to laser weld because all commercially available handheld laser welders currently use near infrared, but aluminium is very reflective to infrared. This is why heat shields and reflective insulation usually use aluminum. 

5000 series aluminum such as 5052 or marine grade aluminum are easy to laser weld, with no hot cracking issues.  6000 series is generally known for hot cracking problems with TIG and MIG, but laser welding has the benefit of a much narrower heat path, so thermal shrinkage (the root cause of most cracking) is much less.

What is the secret to laser welding aluminum?

Despite its high relectivity when solid, fortunately aluminum absorbs infrared when molten.  Hence the secret to initiating laser welding is to initiate a small weld pool.  Our laser welders have high power and a high energy density, which allows them to get a small spot molten quite quickly. This then absorbs the laser light, creating a wide molten band that gives a good weld and allows us to travel quickly. You may have seen videos of a big brand of laser welder where they take time to start the weld, or move the welding head (gun) back and forth. This is because their welder lacks the power density, or power, and it takes longer to form a small molten area.  Wobble frequency and width are also key factors, which our user manual explains in full.

Aluminum tube 3mm laser welded to eighth inch sheet
Aluminum tube 3mm laser welded to eighth inch sheet
Touch Screen Display Panel

Correct focusing is a key parameter for obtaining maximum power density. Our user manual that comes with every laser welder explains how to focus the laser.

Other parameters such as wobble distance, pattern and frequency are important for alumimum welding, and these are optimised in the pre-sets in our class-leading touchscreen display. The optimal parameters vary with thickness, so each thickness has different pre-set values for weaving width, pattern and frequency.  Note that our Gen5 laser welding machines have a double wobble head (two axes) whereas IPG and others have a single wobble head (one axis).  Our two axis weaving weld modes offer significant benefits in many situations.

What is the maximum thickness you can laser weld?

Our 2kW laser welders can weld up to 4 gauge (6mm) aluminum with full penetration in one pass. This requires good fit up and slower welding speed.  Processing this way is similar to laser cutting, in that we use the focused laser beam to penetrate deeply, but our wobble system manipulates the beam pattern to melt the two pieces together.  In comparison MIG or TIG would require grinding a large V recess and then filling it in.  We can do the same weld much faster overall, with minimal preparation, much less heat input and no spatter.  With less heat input, laser welding has far less effect on the parent metal properties, meaning a stronger weld.  In comparison TIG and MIG cause annealing of the base metal with consequent loss of strength.

For the ultimate performance, our new 3kW (3000 Watt) laser welder can easily and quickly weld 1/4″ thick aluminum at high speed, or even thicker by slowing down.

Quarter inch aluminum laser fillet welds comparing pulsed effects
Quarter inch aluminum laser fillet welds comparing pulsed effects
Laser welding aluminum internal fillet

How to laser weld anodized aluminum

Laser welded clear anodized aluminum
Neat laser weld on anodized aluminum

Laser welders with high power density have no problem welding anodized aluminum.  We have welded many types, such as the typical aluminum window or door extrusion shown here.  This was fused (autogenous welding) by drag welding the head at constant speed, at our regular half inch per second travel speed.  Note the beautiful consistent finish.  

The only slightly negative aspect is the anodizing leaves a grainy finish on the surface of the weld.  However such welds on our equipment have beautifully consistent penetration.  All of this was done with zero preparation.  In fact, it’s much better to have a square edge which can be butted up with zero clearance.  Then our control system assists the keyhole welding.  Wobble or weaving pattern is key factor, and this weld was done with our triangle pattern, which gives an amazing result on aluminum.

What new developments are planned for welding aluminum?

If you look at a chart of absorption against wavelength, known as the absorption spectrum, aluminum absorbs much more blue light than infrared. For this reason blue lasers are being developed. At present they are very expensive but in future blue light lasers could provide another solution for laser welding aluminum and also copper.

Close up comparison of pulse frequency on 3mm aluminum
Close up comparison of pulse frequency on 3mm aluminum