You are here

Fiber Laser Welding

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 laser welding technologies, such as continuous-wave CO2 welding lasers are limited in terms of accuracy and undesired, high heat input into the weld. On the other hand, the limitations of traditional pulsed Nd:YAG are the maximum welding speed, the minimal spot size that can be achieved and the electrical to optical energy conversion efficiency that can be obtained. Ever more applications are demanding a higher precision control, lower heat input and lower electrical energy consumption. Continuous Wave Fiber Laser Welding is a technology that offers those features.

In a fiber laser, the laser light is generated in an active fiber and guided to the work piece by means of a flexible delivery fiber, which acts as a “light guide”. The flexibility of the delivery of this laser beam is an important feature for many forms of material processing such as laser cutting, laser welding, laser marking and laser engraving.

geen resultaat

fiber-laser-welding-02_0.jpg

Continuous Wave versus Pulsed Wave for metal welding

Fiber lasers are available with both type of energy delivery: Continuous and Pulsed. As the name states, the Continuous Wave (CW) lasers deliver a continuous, uninterrupted output. This output can have an upslope (soft-start) when switched on, an energy modulation while active, and a downslope when switched off (crater filler). Of course, this type of laser can also be switched on and off to create pulses. However, the maximum power level can never exceed the average power.

In contrast, the Pulsed Fiber lasers deliver a pulse of energy which is typically ten to twenty times higher than their average power. For example, a laser can have 300 W average power and 6000 W peak power. These lasers are often referred to as Quasi Continuous Wave (QCW) Fiber Lasers.

Laser welding of very small parts and fine structures

It is possible to weld even the smallest parts with low power Fiber lasers, typically in the 100 W to 200 W average power range. These lasers are well suited for this type of welding because of their features: [Fiber Laser Welding penetration depth]

  • Very small fiber core diameters. The low power level and high beam quality allow power of up to 500 W to be fired into 10 or 20 micron cores. This results in very small weld spot sizes. 
  • Excellent power stability. A fiber laser will be stable down to about 10% of its power level. For example, a 200 W laser will be stable to 20 W power. When combined with a 1 ms pulse length, it is possible to achieve weld pulse energies of 20 mJ. This is sufficient for the finest welds that can be found in precision metal welding.

 

Typical applications are stents, small medical meshes and thin membranes for pressure sensors. Typical materials are 50 micron Nitinol wires, 10 to 50 micron platinum coil wires, 10 micron stainless steel foils, etc.

 

 

fiber-laser-welding-close-up.jpg

fiber-laser-welding-copper-b.jpg

0.012" copper to 0.015" steel 

fiber-laser-welding-copper-a.jpg

0.012" Ni-clad copper to 0.015" steel 

Medium-power fine metal welding at high speed

Fiber lasers with 500 W to 1200 W and a fiber core diameter of between 100 and 300 microns, typically replace Pulsed YAG and disk lasers for precision metal welding. In this range, the fiber laser will provide greater welding speed for the same investment level. The welding speed may be up to ten times higher. As an indication, a 500 W fiber laser will give a weld of 1 mm deep and 1 mm wide at about 1 cm/second in mild steel. This laser is difficult to beat in terms of value for money if the application is suited to this type of welding.

Medium-power fine metal welding with single mode lasers

A special type of welding is achieved with lasers in the power range of up to 500 W that have a very small diameter fiber of 20 microns or below. Due to this small diameter, a very high energy concentration will be obtained. This produces keyhole welding.

This type of welding is normally coupled with a scanner head which allows the laser beam to progress at very high speeds. The laser beam can be moved in a linear manner or in a circular or wobble pattern to achieve a wider weld beam.

High Power Laser Welding of Metals

Fiber lasers in the power range of 1000 W to 5000 W can weld heavier metals connections at high speeds. Applications can be as diverse as stainless steel sheets for kitchen tops, galvanized steel backplates for flat screen LCD TV’s, sheet steel for stators in electric motors, structural parts such as turbocharger waste gates, stainless steel bellows, copper wires, tabs for batteries, etc. Thicknesses of up to 5 mm can be welded and speeds of up to 50 cm/second can be achieved. Fiber lasers in this power range are increasingly replacing other welding processes such as Resistance Welding (spot welding), TIG welding, MIG welding, Electron beam welding, etc. With lasers at these power levels, the weld speed is typically only limited to the speed of moving the system or the parts and feeding the parts to and from the system. In the coming years, the power of these lasers is expected to increase by 20% - 30% year on year and even more traditional welding processes will be replaced by laser welding.

Download our presentation “Laser Source Selection for Micro-welding Processes”

Presentation