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Laser Welding explained simple

What is laser light?

What is laser radiation?

Light: It travels at 299.792.458 meters per sec. Its visible spectrum ranges from 400 to 700 nanometers. Its smallest unit is a packet of energy, a photon.  In most of its natural and artificial forms, light has little power.

However, a groundbreaking invention in the latter half of the 1950s increased its power and concentrated it in a small area.  Thus was born a modern and revolutionary concept: LASER - Light Amplification by Stimulated Emission of Radiation

LASER: It is concentrated light of one single frequency or one single colour.

Light We See

Mixture of different frequencies of light and colour

laser Light

Single frequency - single colour light beam

Laser Welding

INfrared Fiber laser welding, like other laser-machining methods, is a non-contact technology that has a limited, heat-affected zone (HAZ), which is why the technology is a preferred method for welding delicate and high tensile products at high speeds. Laser welding is also a more repeatable and consistent process than other welding methods, and is capable of producing high-strength bonds without the need for filler material, flux, prepping, or secondary cleaning and finishing processes. Laser Welding enables many applications to be manufactured at much lower costs, with greater consistency, at greater speeds, and with much less waste and quality-control issues. Moreover, a laser welding manufacturing process is much more reliable than other welding technologies, as the latest laser-welding machines require little to no maintenance, and virtually have no downtime.

The laser as a heating source to weld metal

Laser welding requires that the laser raise the temperature of the material to be welded. The laser light must be absorbed by the material to induce a temperature rise. In effect, the laser light beam is focused onto the material similar to the way the sun can be focused by a magnifying glass. The difference is that the laser’s power density is many orders of magnitude higher. 

Laser light photons (packets of light energy), impinge onto the material and are partly or wholly absorbed. The energy of the photon is absorbed in the metal material and causes a heat waves within the metal. Repeated absorption of photons eventually leads to metal melting.

Even for metals that absorb well, such as steel, the laser is initially mostly reflected. A smaller percentage of the laser beam is absorbed, heating the metal surface. The increased metal temperature increases the absorption of the laser light photons. This creates a snowball effect, in which the material is rapidly heated by the laser, leading to melting and formation of the weld.

Fiber Laser Welding

Unlimited possibilities

Laser Welding is a welding technology used to join several metal components. A laser produces a beam of high-intensity that is concentrated into one spot. This concentrated heat source enables fine, deep welding and high welding speeds.  
Traditional but old laser welding technologies, such as
  • continuous-wave CO2 welding lasers are limited in terms of accuracy and undesired, high heat input into the weld and
  • the traditional pulsed Nd:YAG welding lasers are limited by the maximum welding speed, the minimal spot size that can be achieved and the electrical to optical energy conversion efficiency that is very bad. 
With the latest fiber laser welding, the output power and the oscillation form of the laser beam is possible to change.  Fiber Laser Welding is also very suitable for welding materials with a high melting point or with high thermal conductivity due to a very low thermal effect during welding.  The energy conversion rate is very high and all this makes fiber laser highly adaptable to various applications for use in various welding assembly processes. 
The fiber laser beam used for welding can be adapted as follows and characterized by different laser oscillation modes :

 

 Pulsed laser beam welding (PWM- Pulse Wide Modulation)) 

and 

Continuous laser beam welding (CW - Continuous Wave)

 
Even more applications are demanding a higher precision control, lower heat input and lower electrical energy consumption.

Fiber Laser Welding is a technology that offers optimal solution for both: spot welding AND Seam Welding.

Laser welding does not operate on the same principles as other types of welding like TIG, MIG, MAG,..

Laser welding uses a beam of light, instead of electricity, to join two pieces of metal together through a superfast 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 Stir Welding - Laser Wobble Welding

Laser stir welding or Wobble Welding is a process in which a continuous beam laser is oscillated or wobbled at a relatively high frequency, which causes a stirring action within the molten weld pool – hence the term “stir welding or Wobble Welding.” The result is a manipulation of the weld pool/vapor cavity, which changes some key characteristics of the weld.

Benefits:

  • Laser Stir Welding results in largely defect free joints, with no hot cracking, porosity or solidification cracks.
  • More precise control of the weld pool for increased keyhole stability.
  • Improved control of the profile and geometry of the weld – as an example, joints can be designed with more width at the root of the weld, which can be very useful for Lap/Thru-/Blind welds.
  • Weld profiles can be manipulated into asymmetry, such as increasing the penetration on one side of the weld joint.
  • Patterns can be programmed to compensate for large gaps in weld joints and other potentially problematic weld geometry problems.
  • Higher feed rates can be achieved than with pulsed laser techniques.
  • No filler materials is required.

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 higher-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 photonweld 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.

Industrial Laser Welding Systems

Industrial laser welding has had a dramatic impact in the Machine Tool Industry over the years and has become the answer to many problems brought about by traditional welding methods. Many metalworking companies have turned to laser spot and laser seam welding due to these advantages. Automation, high welding speeds and contact-free processing help laser welding users achieve economic advantages very quickly. 

Since laser welding produces pure, concentrated energy, it creates deeper welds while leaving high production output. This is one of the many reasons laser spot and seam welding systems are used in manufacturing in this industry. Items we use every day in our gadgets, electronics and parts have gone through laser welding technology in the course of their production.

Laser Spot Welding & Laser Seam Welding

Laser spot welding, laser seam welding, and direct welding are highly useful and slightly differing applications of laser welding technology. Laser spot and seam welding refer to welding functions applied to a single point or along a line. By setting a laser welding system to a high speed and extremely narrow weld geometry, the laser welder can produce extremely fine spot welding. Also, you can adjust the system to weld on continuous wave mode, welding with several kilowatts of power. The ideal laser speed for laser spot or seam welding projects varies according to the particular laser model, the laser power setting, and the material being laser welded.